Download pdf - NaOH Hand Book

OxyChemCaustic SodaHandbook 1 of 52

Page

•• Introduction & Principal Uses . . . . . . . . . . . . . . . .2

•• Forms of Caustic Soda . . . . . . . . . . . . . . . . . . . . .3

•• Manufacturing . . . . . . . . . . . . . . . . . . . . . . . . . . .4

•• Methods of Shipping Caustic Soda . . . . . . . . . . . .5

•• Safety in Handling Caustic Soda . . . . . . . . . . . . . .6

•• Unloading and Handling Liquid Caustic Soda . . . .8

•• Anhydrous Caustic Soda . . . . . . . . . . . . . . . . . .15

•• Shipments, Handling and Storage of . . . . . . . . .16Caustic Soda Beads

•• Dissolving Anhydrous Caustic Soda . . . . . . . . . .19

•• Equipment for Handling Caustic Soda . . . . . . . .20

•• Technical Data . . . . . . . . . . . . . . . . . . . . . . . . . .23

•• Dilution Calculations . . . . . . . . . . . . . . . . . . . . . .38

•• Methods of Analysis . . . . . . . . . . . . . . . . . . . . . .40

THE INFORMATION PRESENTED HEREIN WAS PREPARED BY TECHNICAL PERSONNEL AND IS TRUE AND ACCURATE TO THE BEST OF OURKNOWLEDGE. OXYCHEM DOES NOT MAKE ANY WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, EXPRESS ORIMPLIED, REGARDING PERFORMANCE, STABILITY OR ANY OTHER CHARACTERISTIC. THE INFORMATION CONTAINED HEREIN IS NOT TO BECONSTRUED AS AN EXPRESS WARRANTY CONCERNING THE PERFORMANCE, STABILITY OR ANY OTHER CHARACTERISTIC OF ANY OXYCHEMPRODUCT. THIS INFORMATION IS NOT INTENDED TO BE ALL-INCLUSIVE AS TO MANNER OR CONDITIONS OF USE. HANDLING, STORAGE, DIS-POSAL AND OTHER ACTIVITIES MAY INVOLVE OTHER OR ADDITIONAL LEGAL, SAFETY OR PERFORMANCE CONSIDERATIONS. WHILE OURTECHNICAL PERSONNEL WILL RESPOND TO ANY QUESTIONS REGARDING SAFE HANDLING AND USE PROCEDURES, SAFE HANDLING AND USEREMAINS THE RESPONSIBILITY OF THE CUSTOMER. NO SUGGESTIONS FOR USE ARE INTENDED AS, AND NOTHING HEREIN SHALL BE CON-STRUED AS A RECOMMENDATION TO INFRINGE ANY EXISTING PATENT OR TO VIOLATE ANY FEDERAL, STATE OR LOCAL LAW.

Occidental Chemical Corporation 2000

��

��

��

��

��

�

��

��

��

NaOHNaOH

Caustic SodaHandbook

OxyChemfifiOxyChem is a registered trademark of Occidental Chemical Corporation.

ForewordThis handbook outlines the methods for handling,

storing, preparing and using caustic soda. Itincludes information on the manufacture, physicalproperties and analytical methods for testing caus-tic soda.

Additional information and contacts can be foundat www.oxychem.com

Occidental Chemical CorporationBasic Chemicals GroupOccidental Tower5005 LBJ FreewayDallas, TX 75244

Principal Uses andConsumption ofCaustic Soda

Introduction2 of 52

Caustic soda is most commonlymanufactured by the electrolysis ofsodium chloride brine in either amercury amalgam, membrane ordiaphragm electrolytic cell. The co-products are chlorine and hydro-gen.

The largest users of caustic sodaare the pulp and paper, detergentand chemical industries. Causticsoda is also used in the alumina,oil and gas and textile industries,mostly for its alkalinity value.

OxyChem has played a leadingrole in providing caustic soda tomeet the increasing demands ofindustry. OxyChem plants arestrategically located to convenientlyand economically serve industry.Warehouse stocks of our caustic

soda and other products are main-tained in many principal cities.Distributor stocks are also availablein these and many other cities andform a network of supply for theend user’s convenience.

Caustic soda is one of the veryfew chemicals finding a very broadrange of applications. Some princi-pal products or processes in whichcaustic soda is used are:

• Acid Neutralization• Agricultural Chemicals• Aluminum Industry• Boiler Compounds• Cellulose Film• Chemicals:

AmmoniaAmyl AminesCresolEthylene AminesFormic AcidGlycerine

Maleic AnhydridePentaerythritolPhenolPropylene OxidePolycarbonatesSalicylic AcidSodium AluminateSodium HydrosulfideSodium HypochloriteSodium PhosphatesStyreneVinyl Chloride Monomer

• Detergents• Drain Cleaners• Drilling Muds• Dyestuffs• Food Processing• Fruit & Vegetable Peeling

• Glass-Batch Wetting• Ion-Exchange Resin

Regeneration• Ore Flotation and Processing• Paint Removers• Petroleum Refining• pH Adjustment• Pharmaceuticals• Pigments• Pulp & Paper• Rayon• Soap• Surfactants• Textile Bleaching, Dyeing, and

Mercerizing• Vegetable Oil Processing• Water Treatment

Forms ofCaustic Soda 3 of 52

Liquid caustic soda is availableas a 50% solution in four grades;diaphragm, rayon, membrane andpurified diaphragm. To be techni-cally correct, only molten causticsoda should be called liquid, butsince the term liquid caustic sodahas historically been used todescribe solutions of caustic soda,it is used in this document inter-changeably with the term solution.

Anhydrous caustic soda is mar-keted in four forms; beads, flakes,compounders and solid castings.These forms have the same chemi-cal composition and differ only inparticle size and shape.

OxyChem packages the anhy-drous forms of caustic soda in:

Solid: 735-lb. drums

Flake: 500-lb. drums100-lb. drums50-lb. bags 1,600-lb. mini bulk bags

Compounders:450-lb. drums

Beads: 500-lb. drums50-lb. bags 2,000-lb. mini bulk bagsBulk trucks and rail cars

Caustic Soda Beads Caustic Soda Compounders

Caustic Soda #4 Flake Caustic Soda #2 Flake

4 of 52

NaCl + H2O = Brine

Brine Treatment

Diaphragm Cell Membrane CellMercury Cell

Decomposers Cell Liquor 12% Caustic Soda

30% Liquid Caustic Soda

Filters

Evaporators Evaporators

Filters

50% LiquidCaustic Soda



ConcentratorConcentrator

DowthermDehydrator

DowthermDehydrator

Flaker Flaker Prilling Tower

Electricity

Chlorine

Water

Hydrogen

Electricity

Hydrogen

Chlorine

Rayon Flake Diaphragm Flakeand Compounders

Diaphragm Beads

RayonCaustic

Soda

Purification PurifiiedCaustic

Soda

MembraneCaustic

Soda

DiaphragmCaustic

Soda

Caustic soda is produced com-mercially by an electrolytic processas shown in the flow diagrambelow. Brine, prepared from sodi-um chloride, is electrolyzed ineither a mercury cell, diaphragmcell or membrane cell. The co-products are chlorine and hydro-gen.

In the mercury cell process, asodium-mercury amalgam isformed in the cell. The amalgam issent to a decomposer where it isreacted with water to form liquidNaOH, hydrogen and free mercury. The free mercury is returned to theelectrolytic cell. The resulting caus-tic soda solution is then inventoriedin storage tanks at a 50% solution.The solution is shipped in tanktrucks, tank cars or barges.

In the membrane process, asolution of approximately 30% instrength is formed. The solution isthen sent to evaporators, whichconcentrate it to a strength of 50%by removing the appropriateamount of water. The resultingcaustic soda solution is inventoriedin storage tanks prior to shipment.

The diaphragm process is verysimilar to the membrane processexcept that a solution of only 10-12% is formed in the cell.Therefore, additional evaporation isrequired to reach the saleable con-centration of 50%.

The anhydrous forms of causticsoda are obtained through furtherconcentration of 50% caustic soda.Solid caustic soda results whenmolten caustic soda, from which allthe water has been evaporated, isallowed to cool and solidify. Flakecaustic soda is made by passingmolten caustic soda over cooledflaking rolls to form flakes of uni-form thickness. The flakes can bemilled and screened into severalcrystalline products with controlledparticle size. The manufacture ofcaustic soda beads involves feed-ing molten liquor into a prillingtower under carefully controlledoperating conditions, producing aspherical bead.

ManufacturingProcess

Diagram 1: Production Flowchart

5 of 52Methods of ShippingLiquid Caustic Soda

Liquid caustic soda is availablefrom OxyChem’s many plants andterminals in tank truck, tank car,barge and ship quantities. Eachform of transportation has its ownadvantages. The type of serviceselected will depend upon suchfactors as size and location ofstorage, rate of consumption,plant location, freight rates, etc.OxyChem’s Technical Service Staffis well qualified to survey anyfacility and recommend the mosteconomical form of transportationwhich is best suited for a particularrequirement.Caustic soda, liquid and dry, is reg-ulated by the U.S. Department ofTransportation (DOT) and is classi-fied as a corrosive material.

The DOT identification number is UN I824 for liquid, andUN I823 for anhydrous product.

6 of 52

Safety in HandlingCaustic Soda

Caustic soda in any form mustbe respected by everyone whohandles and uses it. Beforestarting to work with it, the usershould be aware of its proper-ties, know what safety precau-tions to follow, and know how toreact in case of contact.Accidental exposure to causticsoda may occur under severalconditions. Potentially haz-ardous situations include han-dling and packaging operations,equipment cleaning and repair,decontamination following spillsand equipment failures.Employees who may be subjectto such exposure must be pro-vided with proper personal pro-tective equipment and trained inits use. Some general guidelinesfollow.• Read and understand the latest

Material Safety Data Sheet.• Provide eyewash fountains and

safety showers in all areas wherecaustic soda is used or handled.Any caustic soda burn may beserious. DO NOT use any kind ofneutralizing solution, particularlyin the eyes, without direction by aphysician.

• Move the patient to a hospitalemergency room immediatelyafter first aid measures areapplied.

FIRST AID MEASURESFor Eyes: If for any reason

caustic soda contacts the eyes,flood the eyes immediately withplenty of clean water. Continueflushing for at least 15 minutes.While flushing, forcibly hold theeyelids apart to ensure rinsing ofthe entire eye surface. Do not useany kind of neutralizing solutionin the eyes.GET MEDICAL ATTENTIONIMMEDIATELY.

For skin: If caustic soda comesin contact with skin or clothing,flush with plenty of clean water forat least 15 minutes. Remove conta-minated clothing and footwear.Thoroughly wash affected clothingand rubber/vinyl footwear. Discardcontaminated leather footwear.GET MEDICAL ATTENTIONIMMEDIATELY.

For inhalation: If a worker isovercome due to the inhalation ofcaustic soda dust, mist or spray,remove them from the contaminat-ed area to fresh air. If breathing isdifficult, have a trained personadminister oxygen. If breathing hasstopped, have a trained personadminister artificial respiration. GET MEDICAL ATTENTIONIMMEDIATELY.

For ingestion: Although it is unlikely in an industrial situation that caustic soda wouldbe ingested, it could be swallowedaccidentally. If that occurs, DONOT induce vomiting. Give largequantities of water. If available,give several glasses of milk. Ifvomiting occurs spontaneously,position individual’s head to keepairway clear. NEVER give anythingby mouth to an unconscious person. GET MEDICAL ATTEN-TION IMMEDIATELY.

PROTECTIVE EQUIPMENTOSHA requires employers to

supply suitable protective equip-ment for employees. When han-dling caustic soda, the followingprotective equipment is recom-mended:• Wear suitable chemical splash

goggles for eye protection dur-ing the handling of causticsoda in any form. The gogglesshould be close-fitting and pro-vide adequate ventilation to pre-vent fogging, without allowingentry of liquids.

• The use of a face shield may beappropriate when splashing canoccur, including loading andunloading operations.

• Wear rubber gloves or glovescoated with rubber, syntheticelastomers, PVC, or other plas-tics to protect the hands whilehandling caustic soda. Glovesshould be long enough to comewell above the wrist. Sleevesshould be positioned over theglove wrists.

• Caustic soda causes leather todisintegrate quite rapidly. For thisreason, wear rubber boots. Wearthe bottoms of trouser legs out-side the boots. DO NOT tuck in.

• Wear chemical resistant clothingfor protection of the body.Impregnated vinyl or rubber suitsare recommended.

• Wear hard hats for some protec-tion of the head, face and neck.

• If exposures are expected toexceed accepted regulatory limitsor if respiratory discomfort isexperienced use a NIOSHapproved air purifying respiratorwith high efficiency dust and mistfilters.

FACESHIELD

CHEMICALSUIT

RUBBERBOOTS

CHEMICALSPLASH

GOGGLES

RUBBERGLOVES

7 of 52

Safety in HandlingCaustic Soda

PROTECTIVE PRACTICES

• Avoid breathing dust, mist orspray of caustic soda.

• Wear proper protective equip-ment. If warranted, wearapproved respiratory protection.

• Keep equipment clean by wash-ing off any accumulation of caus-tic soda.

• Weld pipelines where practical.Use flanged joints with gasketsmade of caustic soda resistantmaterial such as rubber, PTFE,or EPDM rubber. If a screwed fit-ting is used, apply Teflon® tape tothe threads.

• When disconnecting equipmentfor repairs, first verify that thereis no internal pressure on theequipment and that the equip-ment has been drained andwashed.

• Provide storage tanks with suit-able overflow pipes. Overflowpipes should be directed near thebottom of the diked area.

• Shield the packing glands ofpumps to prevent spraying ofcaustic solutions in the event of aleak.

• When releasing air pressure froma pressurized system, take everyprecaution to avoid spurts orsprays of caustic solution.

• When making solutions, alwaysadd the caustic soda slowly tothe surface of the water with con-stant agitation. Never add thewater to the caustic soda.Always start with lukewarm water(80 -100°F). Never start with hotor cold water. Dangerous boilingor splattering can occur if causticsoda is added too rapidly,allowed to concentrate in onearea or added to hot or cold liq-uids. Care must be taken toavoid these situations.

• Exercise extreme care whenbreaking solid caustic soda intosmaller pieces.

• In case of a spill or leak, stop theleak as soon as possible. Aftercontainment, collect the spilledmaterial and transfer to a chemi-cal waste area. Remove large liq-uid spills by vacuum truck.Neutralize residue with diluteacid. Flush spill area with waterand follow with a liberal coveringof sodium bicarbonate or otheracceptable drying agent.

HANDLING ANHYDROUSCAUSTIC SODA

Extreme care must be takenwhen adding anhydrous causticsoda to water or any solution. Itshigh heat of solution generateslarge amounts of heat which cancause local boiling or spurting.

When making solutions withanhydrous caustic soda, alwaysadd the caustic soda slowly to thewater surface with constant stirring.Never add the water to the caus-tic soda. Always start with luke-warm water (80 -100°F). Neverstart with hot or cold water.Dangerous boiling and/or splatter-ing can occur if caustic soda isadded too rapidly, is not sufficientlyagitated or added to hot or cold liq-uids. Care must be taken to avoidthese situations.

Anhydrous caustic soda will dis-solve freely in a well agitated solu-tion under proper conditions.Without agitation, the anhydrouscaustic soda will fall to the bottomand form a layer of hydrate whichdissolves quite slowly and can lead

to localized boiling and splattering.To operate safely, slowly add the

anhydrous caustic soda to the sur-face of a well-agitated solution. Thepreferred equipment utilizes a pro-peller-type agitator or a circulatingpump with sufficient mixing capaci-ty. Avoid agitation with air, becauseair will cause excessive formationof sodium carbonate.

HANDLING LIQUIDCAUSTIC SODA

In handling caustic soda solu-tions, care must be taken to avoidsolidification which will plugpipelines and equipment. Graph 1(pg. 29) shows the freezing pointsfor solutions of caustic soda at vari-ous concentrations.

Should a caustic soda solutionbecome frozen in process equip-ment or piping, care must be takenwhen thawing the material. Useonly low pressure (10 PSIG orless) steam. Accelerated corrosioncan occur in areas where equip-ment is subjected to extremely hightemperatures.

Unloading and Handling LiquidCaustic Soda in Tank Cars8 of 52

GENERAL INFORMATION

Caustic soda in liquid formhas a markedly corrosive actionon all body tissue. Even dilutesolutions may have a destructiveeffect on tissue after prolongedcontact. Inhalation of concentrat-ed mists can cause damage tothe upper respiratory tract, whileingestion of liquid caustic sodacan cause severe damage to themucous membranes or other tis-sues where contact is made. Inaddition, considerable heat isgenerated when liquid causticsoda is mixed with water whichcan result in boiling or splatter-ing. When diluting, always addcaustic soda to water; never addwater to caustic soda.

It is important that those whohandle caustic soda are aware ofits highly reactive and corrosiveproperties and know what pre-cautions to take. In case of acci-dental exposure, immediatelyflush exposed area with largeamounts of water and seek med-ical attention. For more specificinformation refer to the Safety inHandling Caustic Soda sectionof this handbook and to theMSDS.

PLACEMENT OF THE CAR FORUNLOADING

1. After the car is properly spot-ted, DOT regulations requirethat the hand brake be set andthe wheels blocked before anyconnections are made.

2. Caution signs must be placedat both ends of the car beingunloaded to warn people andswitching crews approachingthe car. DOT regulations statethat caution signs must beplaced on the track or car togive warning to personsapproaching the car from theopen end or ends of siding.Caution signs must be left upuntil the car is unloaded anddisconnected from the dis-charge connections. Signsmust be made of metal or othersuitable material, at least 12x15inches in size, and bear thewords, “STOP-TANK CARCONNECTED”, or “STOP-MENAT WORK.”

3. It is recommended that derailattachments be placed at theopen end or ends of siding,approximately one car lengthaway.

4. Before hooking up a car, theresponsible individual shouldfirst locate and test the nearesteyewash and safety shower.Purge water through each toremove rust that may haveaccumulated.

UNLOADING PRECAUTIONS

1. Only responsible and wellsupervised employees shouldbe entrusted with the unloadingof liquid caustic soda.Unloading operations must bemonitored while the car is con-nected.

2. Since serious burns can resultfrom contact of caustic sodawith the skin and eyes, workersshould be well protected andcautioned to exercise care.Persons hooking up a carshould wear the following per-sonal protective equipment:• Hard hat• Chemical splash goggles• Face shield• Rubber, steel-toed boots• Rubber gloves or

equivalent• Vinyl or rubber jacket and

pants• If warranted, wear approvedrespiratory protection

3. A car of caustic soda should beunloaded only when adequatelighting is available throughoutthe entire unloading process.

4. Before starting to unload, makecertain that the tank car is vent-ed and that the storage tank isvented and has sufficientcapacity.

5. No one should enter the carunder any circumstances.

6. If a tank car needs to be movedwhen partially unloaded, DOTregulations require that allunloading lines must be discon-nected and car closures mustbe replaced.

7. A suggested method for sam-pling is to draw intermittentsamples from a 1/2” sampleline, connected to a verticalsection of the unloading line.

Unloading and Handling LiquidCaustic Soda in Tank Cars 9 of 52

The sample line should be fit-ted with a valve and a 1/4” nip-ple.

8. OxyChem’s liquid caustic sodais shipped in well insulated andspecially lined tank cars.Linings in these tank cars willwithstand temperatures up to225°F. To prevent damage tothe linings, neither water norsteam should be added directlyinto the tank cars if the car con-tains a level of caustic.

9. Unloading lines should be cov-ered with suitable insulationand heated just prior to transferof liquid caustic soda to stor-age. The preferred method ofheating is to provide electric orsteam heat tracing around theunloading line, under the insu-lation. An alternate method isto provide tees in the unloadingline so that steam (or hotwater) can be run through theunloading line just prior to itsuse. These precautions willprevent the solidification of liq-uid caustic soda in cold unload-ing lines. Running steamthrough unloading lines willincrease corrosion in unlinedsteel piping systems and ironpickup in the product.

10. If compressed air is used inunloading operations, it isimportant that all fittings beinspected for leaks or otherdefects before unloading.Dome fittings in particularshould be inspected. If leaksare found, unloading operationsshould be suspended until theyare corrected.

HANDLING IN COLD WEATHER

Since OxyChem tank cars are well insulated and liquid causticsoda is loaded hot, it usuallyarrives at its destination in a liquidcondition. However, since 50% liq-uid caustic soda begins to crystal-lize at 54°F, in cases of unusualdelays in transit, freezing may takeplace in cold weather. If freezinghas occurred, the following proce-dure should be used.1. Carefully open tank car dome

cover.2. If a layer of caustic soda has

formed over the contents of thecar, this crust should be brokenbefore admitting steam to thejacket around the bottom dis-charge valve. The puncturing ofthe crust permits expansion ofthe liquid as it increases in tem-perature.

3. If no crust is present, determineif crystals have formed on thebottom of the car by probing thebottom with a rubber-cappedrod introduced through thedome opening.

4. If freezing has occurred, con-nect a steam line (10 PSIG orless) to the jacket around thebottom discharge valve.Connect a condensate returnline at the valve jacket steamoutlet. If a condensate returnline is not used, it is advisableto connect a valve at the steamoutlet, which should be openedsufficiently to relieve conden-sate and direct it toward theground or into a sewer. As con-

tents liquefy, the valve may beclosed further to conservesteam.

5. If necessary, steam can be con-nected to the rail car steamcoils. A condensate return line,pressure reducing valve, and/orsteam trap should be used. Donot exceed a steam pressure of10 PSIG.

6. When examination indicatesthat the contents have liquefiedand operation of the valve rodshows that the bottom dis-charge valve is free, the causticsoda is ready for unloading.The unloading temperature of50% caustic soda should beless than 120oF to minimizecorrosion of unlined steelpiping systems and equip-ment.

7. If the above measures do notliquefy the contents on the car,contact your OxyChem repre-sentative.

��

��

��

��Placard

Handbrake

��

�

Electrical Ground

��

��

Warning Signs

��

��

��

�

2. Manway

� �

��

��

��

��

19. 4" Insulation

20. 1/8" Steel Shell

��

7/16" Steel Tank

��

��

��

�

��

��

3. Safety Vent

��

Bottom Unloading Assembly

10. Steam Coil Inlet & Outlet

18. Outlet Valve Operating Rod

7. 1" Air Connection Valve

5. 2" Unloading Connection

11. Bottom Outlet Valve

12. Steam Chamber

13. Steam Inlet16. Steam Outlet

21. Plug Cock

14. Supplementary Valve

15. Plug in Bottom Outlet

Top Unloading Assembly

6. Protective Housing Cover

8. 2" Eduction Pipe

��

��

��

��

��

��

��

��

8. 2" Induction Pipe17. Heating Coils

9. Pipe Guide

19. 4" Insulation 20. 1/8" Steel Shell

7/16" Steel Tank

��

18. Outlet Valve Operating Rod

Eduction Pipe Assembly

Stuffing Box

1. Stuffing Box Cover

Safety Chain & Toggle

4. Manway Cover Safety Guard

Rail Car DrawingDetails of Caustic Soda Car(DOT 111A100W1)10 of 52

Figure 1

Unloading Liquid Caustic Soda in Tank Cars 11 of 52

Rail cars can be either bottomunloaded (gravity, pump or pressure)or top unloaded (with air pressure).Refer to appropriate unloading proce-dure based on the method to beemployed.

UNLOADING THROUGHBOTTOM DISCHARGE VALVE

1. Open the dome cover and deter-mine if the contents of the carare liquid. If not, see “Handlingin Cold Weather.” Keep thedome cover at least partiallyopen during the entire unloadingoperation to vent the tank car.

2. Refer to Figure 1. Insure that thebottom outlet valve is closedtightly. The valve rod which oper-ates the bottom discharge valvehas a handle on it which is locat-ed outside the dome of the car.The handle can be reversed andserves as a cap in transit.

3. Remove the pipe plug, then care-fully open the supplementaryvalve to drain any liquid that mayhave seeped past the bottomoutlet valve during transit. If thesupplementary valve cannot beopened, the application of steamfrom a steam lance, directed on

the valve, should free it for open-ing.

4. Attach the unloading line to thebottom of the supplementaryvalve.

5. Check the unloading line to seethat all valves are in the properposition for unloading.

6. Open the bottom outlet valve byturning the valve rod to allowcontents to flow by gravity topump or tank. If the bottom outletvalve does not open upon appli-cation of light pressure, frozencaustic soda is probably presentin the bottom of the car.Application of steam to the heatcoils may be necessary. See“Handling in Cold Weather.”

7. Compressed air can be used toincrease the flow rate of causticsoda to storage or to transfer liq-uid without the use of a pump. Ifcompressed air is to be used,check the rupture disk in thedome to be sure it is intact.Close the dome cover securely.Remove the one-inch air inletplug and connect a flexible airline at this point. The air lineshould have a release valve, oiltrap, pressure relief valve set at

20 PSIG, pressure reducingvalve set at 18 PSIG and a shut-off valve. Apply air pressure tothe car slowly. Note that thepressure relief device (rupturedisk and/or pressure relief valve)in the dome will relieve at a pres-sure between 75 PSIG and 165PSIG, depending on the type ofcar. Refer to the stenciling on theside of the railcar.

8. When the car and unloading lineare empty, shut off air supply andopen the release valve.

9. When the tank car is empty andthe discharge pipe has complete-ly drained, disconnect the airline, if used, close the bottomoutlet valve and supplementaryvalve, and detach the unloadingline at the car.

10. Prepare the car for return.

Steam jacket

UnionPump

2” Steel pipe

Pump inlet valve

Low line drain valveRail carunloading valve

Vent

Tank inlet valve

To process

Drain

TANK CAR

STORAGE TANK

Steam coils

Figure 2: Bottom Unloading

Unloading Liquid Caustic Soda in Tank Cars12 of 52

UNLOADING THROUGHDOME WITH AIR PRESSURE

1. Open the dome cover to deter-mine if the contents of the carare liquid. If not, see “Handling inCold Weather.”

2. Close the dome cover and fastensecurely, making certain that it isair tight. Check that the rupturedisk in the dome is intact.

3. Check that the product storagetank is vented and has sufficientcapacity.

4. After opening the protectivehousing cover, connect theunloading line to the two-inch topunloading valve. After removingthe protective housing cover, aflexible steel hose connection forthe unloading line is recommend-ed since a car may rise as muchas 2” during unloading.

5. Connect the flexible air supplyline to the one-inch air inletvalve. This line should have arelease valve, oil trap, pressurerelief valve set at 20 PSIG, pres-sure reducing valve set at 18PSIG and a shut-off valve. Notethat the relief device (rupture disk

or pressure relief valve) in thedome will relieve at a pressurebetween 75 and 165 PSIG,depending on the type of car.Refer to the stenciling on theside of the railcar.

6. Apply air pressure slowly untilthere is a normal flow of liquid tothe storage tank. The pressureshould be adjusted and main-tained until the tank car is com-pletely empty. A drop in air pres-sure or the sound of air rushingthrough the unloading line indi-cates that the tank car is empty.

7. Shut off the air supply, open therelease valve, and allow theeduction pipe to drain.

8. When the eduction pipe hasdrained and the tank car is atatmospheric pressure, discon-nect the air supply line at the car.

9. Do not enter the car to make aninspection.

10. Open the dome cover and deter-mine if the car is empty. If empty,disconnect the unloading line atthe car, replace pipe plugs andtightly replace the dome coverand the protective housing cover.

11. Care should be taken not to spill

caustic soda on the car, since itwill cause damage to the car andmay endanger workers handlingthe empty car on its return.

12. Prepare the car for return.

PREPARING EMPTY TANKCARS FOR RETURN

1. Make sure the bottom outletvalve and supplementary valveare closed.

2. Disconnect the unloading lineand replace the bottom outletplug. Do not replace closures onsteam openings.

3. Close dome cover and fastensecurely.

4. Return the empty tank carpromptly in accordance with theshipper’s instructions. The ship-per’s routing directions must befollowed in all instances.

��

��

��

��

��

��

��

��

��!��"��"�

��"��"�

��#��#�

��#��"��"��$%� ��#

��&��'�((��"��"�

��) ��

��)��

$��

��(�"��"��*� ��#

Figure 3: Top Unloading

Unloading Liquid Caustic Soda in Tank Trucks 13 of 52

CARRIER RESPONSIBILITIES

OxyChem tank truck drivers havereceived instructions regardingequipment and delivery proce-dures. If an OxyChem arrangedcarrier, delivering caustic soda toyour plant, fails to adhere to the fol-lowing guidelines, please contactOxyChem so that corrective actioncan be taken.

Equipment

Equipment must meetDepartment of Transportation regu-lations, Code of FederalRegulations (CFR), Title 49.

Tank Truck Specification

Tank trucks should meet theestablished DOT requirements forhauling liquid caustic soda.

Four DOT “CORROSIVE” plac-ards must be permanently affixedto the cargo tank.

Unloading Equipment

If unloading is by gravity to stor-age or customer’s unloading pump,no special equipment is needed.

If unloading is by truck-mountedpump, use only an all iron or nickelunit. The pump can be driven by atractor powered take-off or an aux-iliary gasoline engine. Use at leasta 2-inch pump line.

If unloading is by compressedair, the tank vessel must meet theDOT requirements of the CFR, Title49. The line used to supply air tothe tank truck is required to beequipped with: pressure reducingvalve, pressure release valve,pressure gauge, pressure reducingvalve and pressure relief valve.The relief valve should be set at amaximum pressure of 20 PSIG andthe pressure reducing valve shouldbe set at 2 to 3 pounds lower.Whether this equipment is attached permanently to the tank or carriedas an assembled unit to beattached at each unloading, itshould be properly maintained andperiodically tested.

A 40 foot length of air hose isrequired if the customer’s air sup-ply is used. When compressed airis not available from the customer’splant, trucks equipped with pumpsor air compressors can be providedat the customer’s request.

Unloading Lines

Unloading hoses must be con-structed of material resistant tocaustic soda. Hoses should be atleast 2 inches in diameter and 15to 30 feet in length.

Whether the unloading hose isfitted with a union, pipe flange, or aquick type coupler, the truck drivershould have available matching fit-tings and tools to facilitate a con-nection to a 2-inch or 3-inchthreaded pipe.

TRUCK DRIVER RESPONSIBILITIES

Truck drivers must obtain permis-sion to unload from the properauthorities and observe any specialinstructions from the customer.

Truck drivers must wear the pro-tective equipment required byOxyChem as listed underProtective Equipment, (pg. 6) or bycustomer, whichever is more inclu-sive, and at all times follow safehandling practices. Customersmust not allow truck drivers who donot meet these requirements tounload.

The following unloadingprocedures are recommended:• Check the operation of the safety

shower and eyewash fountain.Purge water through each toremove rust that may have accu-mulated.

• If a shower and eyewash are notavailable, a water hose connect-ed to a source of water isrequired. If the valve on the lineis not conveniently located nearthe unloading area, leave astream of water flowing duringunloading.

• Connect one end of the unload-ing hose to the customer’s stor-age tank fill line.

• During cold weather and if facili-ties are provided, preheat withsteam the fill line, the unloadinghose, and, if needed, the truckoutlet.

• Check the unloading line to besure that it is open.

• Connect the unloading hose tothe discharge outlet on the tanktruck.

• Start the pump or start pressuriz-ing the tank, depending on thetype of equipment used.

• Open the valves on the truckdischarge line.

• Stand by until the truck cargo iscompletely unloaded.

• If compressed air is used,allowthe air to flush out the lines to thestorage tank and then cut off theair supply.

• When a pump is used, flush outthe unloading line before discon-necting the hose. If water isavailable, a small quantity canbe added into the truck while thepump is running to flush out theline. Air or water can be used toflush the caustic soda in the lineinto the storage tank or back tothe truck. If no water is availablefor flushing out lines, exercisegreat caution when lines are dis-connected.

Unloading Liquid Caustic Soda in Tank Trucks14 of 52

• Close the valve on the storagefill line.

• Close all valves on the tanktruck.

• In some installations the cus-tomer’s fill line is fitted with adrain to be used instead of flush-ing the line before the hose isdisconnected.

• Disconnect the hose with cautionand discharge any caustic sodaremaining in the hose to a suit-able container.

• Unload caustic soda in an areawith adequate safeguards forspill control. No caustic sodashould be spilled, but in theevent a small amount is spilled,hose down the area with water.Clean up all spills and dispose inaccordance with federal, stateand local regulations.

FACILITY EQUIPMENT

Typical installations of storagevessels for receipt of truck ship-ments are similar to those shown inFigures 2 and 3 for rail car deliver-ies.

A storage tank with a minimumcapacity of 1.5 tank cars is recom-mended.

A fill line to the top of the storageis strongly recommended. If a bot-tom fill line is used, the truck drivermust be informed.

A permanent fill line in closeproximity to the tank truck unload-ing area is required.

A 2-inch or larger fill line is rec-ommended.

A 3/4-inch valve connection isrecommended on the fill line foruse in flushing out the line with air,water, or steam. It can be used asa drain.

Cap or close the end of the fillline when not in use.

A source of running water for useduring unloading operations isrequired. A safety shower and eye-wash fountain are recommended.

15 of 52Anhydrous Caustic Soda Dry Bulk Systems

Caustic soda beads have anangle of repose of 30 degrees ascompared to 40 degrees for crys-talline grades of caustic soda. Thismeasure of flowability means fasterunloading times for bulk handlingand easier transfer from storage toprocessing or mixing. In addition,beads dissolve faster than othergrades due to increased surfacearea.

OxyChem has long recognizedthe need for a system to conveyand store large quantities of bulkanhydrous caustic soda. Havingpioneered this concept in 1966 withthe introduction of the “source-to-silo” system, OxyChem has contin-ually strived to improve bulk han-dling of anhydrous caustic soda.OxyChem utilizes pressure differ-ential self-unloading trucks with aself-contained desiccating system.These trucks eliminate the need forthe customer to install dry aircapacity as is needed for unloadingcars. It also assures that the cus-tomer receives dry, free flowingcaustic soda.

To further satisfy the needs ofour customers, OxyChem manufac-tures caustic soda beads. The par-ticle size of caustic beads matchthose of most granular grades ofsoda ash, silicates and phos-phates. This leads to a more uni-form compound mixture with lesssegregation of the components.Typically, over 80% of the particlesare concentrated between the U.S.No. 20 and U.S. No. 40 screens.The uniform spherical nature of thebead also insures consistent andsuperior flow ability in handling,and storage of the final product.

16 of 52

Shipments, Handling and Storage ofCaustic Soda Beads

Caustic soda beads are manufactured at the OxyChemPlant near Houston, Texas. The fin-ished product is stored in desiccat-ed storage bins from which bothrail cars and trucks are loaded forshipment. Caustic soda beads areshipped to customers or terminalsin 100-ton, 15 PSIG, pressure-dif-ferential (P-D), center-flow cars; or20-ton, P-D, self-desiccating trucks.

When a bulk shipment arrives ata customer plant by either car ortruck, the beads are transferredwith dry air by either a blower or aircompressor (depending on the sys-tem installed) through a flexiblehose and a dry receiving line into apre-dried storage bin. The storagebin and receiving lines must bemoisture free and well sealed toprevent agglomeration and stickingof the beads. Dry air (-40°F DewPoint) must be used during theentire unloading process. Dewpoints should be checked hourlyduring railcar unloading.

TRUCKS

To receive bulk truck shipmentsof caustic soda beads, only a verysimple unloading system isrequired (See Figure 4). Since thetruck is equipped with its own blow-er and desiccator, these need notbe supplied by the customer. Also,since truck unloadings use anopen-loop system (air is exhaustedthrough the filter, not returned tothe compressor), an elaborate dustfilter and return system are notneeded. Basically, all that isrequired is a 4-inch unloading pipe,a storage bin, a simple dust filterand a vent air dryer.

Upon arrival of the truck, thetruck driver makes all the neces-sary hose connections. After this isdone, the air system of the truck isturned on and all of the piping, thestorage bin and the dust filter arepurged with dry air for 3-5 minutes.

Once the system is completelypurged, the unloading is started. Abulk truck unloading takes about 90to 120 minutes. Once completed,the lines are again purged with dryair to make sure no caustic soda isremaining.

RAIL CARS

The differences between unload-ing from a rail car versus unloadingfrom a truck are: (1) the rail carsare not equipped with a blower,hoses or an air dryer; these mustbe supplied by the customer aspart of their storage system, and(2) because the blower, hoses andair dryer are supplied by the cus-tomer, either a closed-loop oropen-loop system may be used.

Open Loop

The open-loop system used tounload rail cars is almost identicalin design to the system used tounload bulk trucks (See Fig. 4).After connecting the car to theunloading system, the lines are firstpurged for 3-5 minutes to removeany trace amounts of moisture.After purging the lines, the air isdiverted to the car and the hopperis pressurized. Once the car ispressurized, the unloading can pro-ceed. The unloading time for a railcar varies depending on the type ofcar and the configuration of thereceiving system, but generallyspeaking, 4-8 hours is an averagerange.

Closed-Loop System

As the name implies, a closed-loop system is based on the recircu-lation of dry air. After passingthrough the dust filter, the air isreturned to the compressor. Themajor advantage of a closed-loopversus an open-loop is that once theair has been dried (and assuming noloss due to leaks) the systemrequires very little additional air dry-ing capacity. Otherwise, the proce-dure for unloading a rail car is thesame as an open-loop system.

EQUIPMENT

A bulk handling system for causticsoda beads can be adapted to thesimplest or most sophisticated sys-tem. The OxyChem TechnicalService Department is available tosurvey your complete plant site andto assist you in choosing the bestsystem to fit your individual needs.They will consult and plan with youand even check the installation.

Although the design of individualhandling systems may vary greatly,the following is a general guidelinefor choosing storage and handlingequipment.

17 of 52Shipments, Handling and Storage ofCaustic Soda Beads

1. Storage CapacityThe storage bin or silo capacityshould be a minimum of 1.5 timesthe volume of the bulk vehicle.For truck shipments, the minimumbin size is 1,000 cubic feet. Forrail cars, a minimum of 4,500cubic feet is required. The binshould be fabricated from carbonsteel and should be of weldedconstruction to minimize potentialair leaks. It should have a conebottom with a slope of 55-60degrees. The type of valvearrangement on the bottomdepends on the in-plant transfersystem. In general, a quick-seal-ing valve, such as a knife-gate, orbutterfly, should be used so thatthe bin can be sealed off from therest of the system.

2. Air BlowersFor unloading rail cars, the blowershould be able to develop 10-12PSIG while drawing 600-700 cfmat the inlet. Positive displacementblowers are preferred.

3. Air DryerAir dryers can be fairly simple indesign (a tank containing desic-cant) or very sophisticated (twin-tower automatic system). Thebasic requirements, however, donot change. The dryer must becapable of producing dry air at a-40°F dew point temperature at680 cfm and 10 PSIG. It shouldbe able to operate effectively overa wide range of inlet tempera-tures, and should have a mini-mum operating time of 10 hours.

4. Vent DryerA vent dryer is required on allstorage bins. The purpose of thevent dryer is to maintain dry airabove the product while the con-tents of the bin are being dis-charged to the process. In thecase of a closed-looped system,the unloading air dryers can beused as vent dryers. For an open-loop system, a small air dryer isneeded. The type of dryer canvary, but it should be capable ofproducing -40°F dewpoint air.

Desiccant Bed

Slip-StreamAir

Butterfly Valves

Loading LineOutletVent to

Bag House

Air Filter

Air Blower

Air Cooler

Air Drier

Quick-ConnectCouplings

Vent Drier

DustCollector

UnloadingLIne

Support Beams

PressureRelief Vent

Air Recycle Line

Hopper(Optional)

HopperScale

(Optional)

To Process To Process

DiverterValves

Flexible BeadUnloading Hose

Fan/BeadDisperser

NaOH Bead Silo

RotaryValve

KnifeGate

Low-LevelIndicator

RotaryValve

KnifeGate

Figure 4: Typical Truck Unloading System for Caustic Soda Beads

Shipments, Handling and Storage ofCaustic Soda Beads18 of 52

5. Dust FilterWhile Caustic soda beads aredustless, some dust will be creat-ed during transport and unloadingdue to abrasion of the particlesagainst the pipe. Whether thesystem is open or closed loop, adust filter is required. It should becapable of removing virtually all ofthe dust from the air stream, but itshould only provide a nominalresistance to flow. If the pressuredrop across the dust filter is toogreat, the back-pressure createdwill slow or potentially stop theunloading. Call OxyChem’sTechnical Service for assistancein choosing the right kind of filter.

6. PipingThe transfer piping should be 4-inch steel pipe. The number ofbends should be as few as possi-ble. When necessary, they shouldbe minimum 4-foot radius bendsthat will not restrict the flow ofproduct. In addition, long horizon-tal runs should be avoided, asproduct will tend to drop out of theair stream and lay on the bottomon the pipe. This causes addition-al back pressure.

HANDLING CAUSTIC SODA

The final customer seldom usescaustic soda in the anhydrous form.For utilization in most processes, asolution must be prepared by dis-solving anhydrous caustic in water.For that reason, some knowledge ofthe properties and characteristics ofcaustic soda solutions is essential.The customer usually requires a def-inite weight of caustic soda in agiven solution. To assist in meetingsuch situations, the charts andtables contained in this handbook listpounds of actual caustic soda pergallon of solution. For easy refer-ence, the concentrations of causticsolutions are expressed in several ofthe most common ways in Tables 1and 2. (pgs. 23, 24)

Placard

Hatch Covers

Caustic SodaBeads

Air Filter

Air Blower

Air Cooler

Air Drier

Quick-ConnectCouplings

Flexible Air Inlet Hose

Vent Drier

DustCollector

UnloadingLIne

Support Beams

PressureRelief Vent

Air Recycle Line

Hopper(Optional)

HopperScale

(Optional)

To Process To Process

DiverterValves

Flexible BeadUnloading Hose

Fan/BeadDisperser

NaOH Bead Silo

RotaryValve

KnifeGate

Low-LevelIndicator

RotaryValve

KnifeGate

Slip Stream Air Inlet

Figure 5: Typical Rail Car Unloading System for Caustic Soda Beads

Dissolving AnhydrousCaustic Soda 19 of 52

Considerable heat is generatedwhen solid caustic soda is dis-solved in water. Graph 6 shows thetemperature that results when theindicated solutions are preparedwithout benefit of cooling. In manycases it is necessary to cool solu-tions during the dissolving processin order to avoid excessive temper-atures that can exceed material ofconstruction limitations.

In handling caustic solutions,care must be exercised to avoidsolidification which will plugpipelines and equipment. For thatreason, it is desirable to know atwhat temperature a solution ofknown concentration will freeze.Graph 1 shows that caustic sodasolutions exhibit peculiar freezingcharacteristics, as indicated by thepeaks and valleys of the freezingpoint curve. In addition to this infor-mation, Graph 1 also shows theboiling points for solutions of differ-ent concentrations.

There are several methods formeasuring the concentration of acaustic soda solution, but the onlyreally accurate method is chemicalanalysis. Since this is ratherlengthy and complicated, thestrength of a solution for processuse is usually determined as afunction of the density which isfound by use of a hydrometer.There are three scales for express-ing density of a caustic solution,namely specific gravity, degreesBaumé and degrees Twaddell. Nomatter which scale is used, thedensity of the solution will vary witha change in temperature.

DISSOLVING BEADS, FLAKEAND COMPOUNDERS

These three forms of causticsoda will dissolve freely in well agi-tated solutions under the properconditions. It is important toremember that while dry causticsoda dissolves freely, it is a haz-ardous material and should betreated with the utmost care andsafety. Protective equipment, asdescribed in this handbook, shouldbe worn at all times.

For best results, the beads, flakeor compounders should be addedslowly to the surface of a well-agi-tated solution of water. When largequantities of flake caustic soda areplaced in stagnant solutions, theflake material falls to the bottomand forms a layer of hydrate whichdissolves quite slowly. This condi-tion may lead to local overheatingand spurting of the solution. Becertain that most of the causticsoda has dissolved before addingmore. Agitation of the solution by apropeller-type agitator is preferred.A circulating pump may be usedinstead, providing it recirculates thesolution at a high enough capacity.An air lance is not recommendedsince it can cause excessive car-bonate formation. The followingtable lists relative rates of dissolu-tion for each grade.

DISSOLVING RATES OFVARIOUS GRADES OFANHYDROUS CAUSTIC SODA*

No. 2 Flake 44 SecondsNo. 4 Flake 41 SecondsCompounders 20 SecondsBeads 15 Seconds

*At 5% concentration, 50°F, and con-stant speed agitation with a magneticstirrer.

DANGER!Caustic soda, liquid and anhy-drous, has a very high heat ofsolution. If caustic soda is addedto a solution too rapidly, or if thesolution is not sufficiently agitat-ed, or if added to hot or cold liq-uid, a rapid temperature increasecan result in dangerous boilingand/or spattering which maycause an immediate violenteruption.

20 of 52

Equipment For HandlingCaustic Soda

GENERAL CONSIDERATIONS

Caustic soda is a corrosivechemical which is normally handledin either steel, nickel, nickel alloysor certain types of plastic equip-ment. The specific material willdepend on the conditions underwhich the material is being used.Temperature, solution concentra-tion, location and safety considera-tions are all important factors inequipment selection.

MATERIALS OF CONSTRUCTION

The most common constructionmaterials for handling and storingcaustic soda solutions are blackiron and mild steel; however, liquidcaustic soda will attack these met-als at elevated temperatures. Theideal storage temperature for caus-tic soda solutions is 80 to 100°F. Insteel systems, temperatures above120°F will cause accelerated corro-sion and iron contamination of thecaustic (above 120°F, cracking canoccur if concentrated caustic isprocessed in steel equipment thathas not been stress relieved.)Where iron contamination or corro-sion is unacceptable, epoxy linedsteel, 316L and 304L stainlesssteels are recommended. 316Land 304L stainless is acceptable to200°F. At temperatures above200°F, nickel is typically used butMonel®, Inconel®, or Hastelloy®can also be used. Consult with theepoxy supplier about the workingtemperature range of a particularepoxy lining.

Plastics, such as polyethylene,polypropylene, PVC, and CPVC,are chemically suitable with causticsoda. They can be used to preventiron contamination if maximumtemperatures for each material arenot exceeded. The manufacturer ofthe tank, drum, piping or equipmentin question should be contacted to

determine the exact limitations ofthe specific plastic. Aluminum, cop-per, zinc, lead and their alloys(e.g., brass and bronze) are NOTsuitable. Caustic soda readilyattacks these materials.STORAGE TANKS

Tanks can be either vertical orhorizontal. They are usually fabri-cated from at least 1/4-inch steelplate. A 1/8-inch corrosionallowance should be included inthe design. If iron contamination isa problem, tanks can be fabricatedfrom 304L or 316L stainless steel.If the tanks are large, it’s usuallymore economical to fabricate asteel tank and line it with an epoxycoating. Plastic tanks are usuallyfabricated from polypropylene orFRP (Since caustic can attackglass reinforcement fibers ofimproperly constructed FRP tanks,care must be taken to ensure thatthe FRP tanks are built with theproper reinforcing materials, resins,catalysts, curing procedures andcorrosion barriers).

The product draw-off line shouldbe at least 4 inches above the bot-tom of the tank and the drain con-nection should be at the lowestpoint in the tank. This will facilitatedrainage during periodic cleaningof the tank. Most tanks have a leveltransmitter for measuring liquidlevel.

Where heating is required, anexternal heat exchanger with a cir-culating pump or internal steamheating coils are most commonlyemployed. The preferred materialsfor the coils are nickel, Monel®, orInconel®. Despite this, stainlesssteel is most commonly usedbecause of cost considerations.(Athigh temperatures, stainless steel

may crack). If it is necessary toinsulate the storage tank, a two-inch layer of polyurethane foam orcellular glass should be adequate.

Proper design of a storage sys-tem will include adequate contain-ment in case of tank failure. Stateand local regulatory authoritiesshould always be consulted duringthe design phase of construction.

TANK CLEANING ANDPASSIVATION

Tank cleaning is dependent onthe product stored in it previously.A tank that previously containedcaustic soda requires scaleremoval, wall thickness testing,rinsing, passivation, floor cleaning,and immediate filling. A tank previ-ously containing another productrequires cleaning with an appropri-ate solvent or soap, as well as theother steps mentioned above.

Scale removal is accomplishedby blasting the walls with an abra-sive such as sand or pecan shells.Abrasives containing high percent-ages of metals are not recom-mended.

The wall thickness of the tankshould be measured to ensure thatthe tank has structural integrity forthe density of the product and theheight of product in the tank.

Passivation requires permeationof the steel tank walls with causticsoda. This is usually accomplishedby spraying the cleaned walls witha hot solution of caustic soda.Temperatures of 100 - 140°F andsolutions of 5 - 20% are recom-mended. While this is more of anart than a science, a standard rec-ommendation would be spraying

21of 52

Equipment For HandlingCaustic Soda

the walls for 2-4 hours with 10%solution at 140°F. The larger thetank the longer it should besprayed to complete the passiva-tion. Utilizing a hotter and strongersolutions will require less time forpassivation. One way to achievethe solution heat necessary is todilute 50% caustic soda to 20%.The heat of dilution will cause thecaustic soda temperature to rise.Additional heat may be necessaryto achieve optimal solution temper-atures. The coating of the tankwalls is best accomplished with anelliptical sprayer. If this type ofsprayer is not available, the spray-ing may be done manually withextreme caution taken to protectthe operator.

After passivation, the tank bottommust be cleaned out as well aspossible. The quality of the initialproduct stored in the tank willdepend greatly upon the extent towhich the tank bottom is cleaned ofscale abrasive compound. If anelliptical sprayer is used for thecleaning, a squeegee will need tobe used to clean the tank bottom. Ifmanual spraying is used for clean-ing, the sprayer can be used topush the scale and abrasive towardthe sump followed up by use of asqueegee.

After cleaning, the tank shouldbe filled with caustic soda as soonas possible. This will prevent thetank walls from losing their passi-vation. If the tank cleaning is notcompletely successful, it may benecessary to filter the initial productfrom the tank to keep it free fromparticulate matter. This wouldrequire a 5-10 micron filter mediahoused in a unit that would beacceptable with the temperature,pressure, and chemical.

PIPING AND VALVES

Pipelines are usually at least twoinches in diameter and constructedof Schedule 40 black iron or mildsteel with welded or flanged joints.Where disconnects are necessary,flanged joints are preferred to facili-tate maintenance. A safety shieldof wrap-around polypropylene isrecommended for all flanged joints.This will protect against spraying incase a gasket leaks.

Proper pipeline design includesan adequate pitch to permit com-plete draining. Avoid any loops orpockets. Lines should also includewater or air connections for purgingafter use.

Where slight iron contaminationis unacceptable, CPVC, polypropy-lene, polypropylene-lined steel, andTeflon® lined steel pipe are suit-able materials. Pay special atten-tion to suitable operating tempera-tures and pressures with thesematerials.

Ductile iron, cast steel, stainlesssteel, Alloy 20, and Teflon®-linedquarter-turn plug or ball valves arerecommended for caustic soda ser-vice. Various other types of valvescan also be used; however, keep inmind that less elaborate fittingsprovide better reliability in this ser-vice.

PUMPS

Centrifugal pump of stainlesssteel or Alloy 20 construction, witheither double mechanical seals or adeep packing gland, is recom-mended. Packing material shouldbe Teflon® impregnated, causticresistant fibers, or equivalent. Toavoid seals altogether, magneticallycoupled pumps could be used.

Pump location should receivecareful consideration. For ease ofoperation, keep the suction lines asshort as possible. A recirculatingline will help prevent excess wearon the pump and, in many cases,can assist in controlling flow rates.

METERSCaustic soda solutions can be

metered through standard rotame-ters having non-glass tubes andnickel or stainless steel floats.Magnetic, coriolis or orifice-typemeters are preferred for strong, hotsolutions. They should be made ofcorrosion resistant materials suchas stainless steel, alloy 20, monelor nickel.

Installation of Tanks22 of 52

��) ��)��"�

��

��#�

+��

��

��)��

��!�,��#��

��"�

��-��) ��,�.*��

�&�� (��

��!��!��

��-��,�.*��

��.��/��0�1

�&��)�0��

��

��-��,�.*��

�&�� (��

��!��!��

��.��/��0�1

�&��)�0��

��

��) ��)��"�

+��

��

��)��

��"�

��(��

��#�

��!�,��#��

-�"��+��

,�#&�-�"��)

-�"��+��

,�#&�-�"��)

*NOTE: All tanks should be located within a diked area.

Figure 6: Typical Storage Tank Installation

TechnicalData 23 of 52

Table 1 Density and Caustic Soda Content of Rayon/Membrane GradeCaustic Soda Solutions at 60°F

DEGREES TOTAL WT TOTAL WTWT% % SPECIFIC BAUMÉ NaOH NaOH SOLUTION NaOH SOLUTIONNaOH Na2O GRAVITY [AM STD] G/L LB/GAL LB/GAL LB/CU FT LB/CU FT

1.0 0.775 1.0120 1.706 10.118 0.084 8.437 0.631 63.1132.0 1.550 1.0230 3.259 20.457 0.171 8.529 1.277 63.8043.0 2.325 1.0342 4.782 31.019 0.259 8.622 1.935 64.4974.0 3.100 1.0453 6.274 41.803 0.349 8.715 2.608 65.1915.0 3.874 1.0564 7.736 52.811 0.440 8.807 3.295 65.8856.0 4.649 1.0676 9.170 64.042 0.534 8.900 3.995 66.5817.0 5.424 1.0787 10.580 75.496 0.630 8.993 4.710 67.2778.0 6.199 1.0899 11.960 87.174 0.727 9.087 5.438 67.9739.0 6.974 1.1010 13.310 99.076 0.826 9.180 6.181 68.670

10.0 7.748 1.1122 14.630 111.210 0.927 9.273 6.937 69.36711.0 8.523 1.1234 15.930 123.550 1.031 9.366 7.707 70.06312.0 9.298 1.1345 17.200 136.130 1.136 9.459 8.492 70.75913.0 10.080 1.1457 18.440 148.920 1.242 9.552 9.290 71.45514.0 10.850 1.1569 19.660 161.930 1.351 9.645 10.110 72.15015.0 11.630 1.1680 20.850 175.170 1.461 9.738 10.930 72.84516.0 12.400 1.1791 22.030 188.630 1.573 9.830 11.770 73.53917.0 13.180 1.1902 23.170 202.300 1.687 9.923 12.620 74.23118.0 13.950 1.2013 24.300 216.200 1.803 10.020 13.490 74.92219.0 14.730 1.2124 25.400 230.310 1.921 10.110 14.370 75.61220.0 15.500 1.2234 26.480 244.640 2.040 10.200 15.260 76.30021.0 16.280 1.2344 27.530 259.180 2.162 10.300 16.170 76.98722.0 17.050 1.2454 28.570 273.940 2.285 10.390 17.090 77.67223.0 17.830 1.2563 29.590 288.910 2.409 10.480 18.030 78.35524.0 18.600 1.2672 30.580 304.090 2.536 10.570 18.970 79.03525.0 19.370 1.2781 31.550 319.470 2.664 10.660 19.930 79.71326.0 20.150 1.2889 32.510 335.070 2.794 10.750 20.910 80.38927.0 20.920 1.2997 33.440 350.870 2.926 10.840 21.890 81.06228.0 21.700 1.3105 34.350 366.870 3.060 10.930 22.890 81.73129.0 22.470 1.3212 35.250 383.070 3.195 11.020 23.900 82.39830.0 23.250 1.3317 36.120 399.450 3.331 11.110 24.920 83.05731.0 24.020 1.3424 36.980 416.070 3.470 11.200 25.960 83.72232.0 24.800 1.3529 37.830 432.860 3.610 11.280 27.010 84.37933.0 25.570 1.3634 38.650 449.850 3.751 11.370 28.070 85.03334.0 26.350 1.3738 39.450 467.010 3.895 11.460 29.140 85.68135.0 27.120 1.3842 40.240 484.370 4.039 11.540 30.220 86.32736.0 27.900 1.3944 41.020 501.910 4.186 11.630 31.310 86.96837.0 28.670 1.4046 41.770 519.630 4.333 11.720 32.420 87.60538.0 29.450 1.4148 42.510 537.520 4.482 11.800 33.530 88.23739.0 30.220 1.4248 43.230 555.590 4,633 11.880 34.660 88.86440.0 31.000 1.4348 43.940 573.830 4.785 11.970 35.800 89.48741.0 31.770 1.4447 44.640 592.240 4.939 12.050 36.950 90.10542.0 32.550 1.4545 45.310 610.810 5.094 12.130 38.110 90.71743.0 33.320 1.4643 45.980 629.530 5.250 12.210 39.270 91.32444.0 34.100 1.4739 46.630 648.420 5.407 12.290 40.450 91.92645.0 34.870 1.4835 47.260 667.450 5.566 12.370 41.640 92.52246.0 35.650 1.4930 47.880 686.640 5.726 12.450 42.840 93.11347.0 36.420 1.5023 48.480 705.970 5.887 12.530 44.040 93.69748.0 37.200 1.5116 49.080 725.440 6.049 12.610 45.260 94.27549.0 37.970 1.5208 49.650 745.040 6.213 12.680 46.480 94.84750.0 38.740 1.5298 50.220 764.780 6.377 12.760 47.710 95.41251.0 39.520 1.5388 50.770 784.640 6.543 12.830 48.950 95.97152.0 40.290 1.5476 51.310 804.630 6.710 12.910 50.200 96.523

24 of 52

TechnicalData

Table 2 Density and Caustic Soda Content of Diaphragm GradeCaustic Soda Solutions at 60°F

DEGREES TOTAL WT TOTAL WTWT% % % SPECIFIC BAUMÉ NaOH NaOH SOLUTION SOLUTIONNaOH Na2O NaCl GRAVITY [AM STD] G/L LB/GAL LB/GAL LB/CU FT LB/CU FT

1.0 0.775 0.020 1.0121 1.726 10.120 0.084 8.438 0.631 63.1222.0 1.550 0.040 1.0233 3.300 20.463 0.171 8.532 1.277 63.8233.0 2.325 0.060 1.0346 4.842 31.032 0.259 8.626 1.936 64.5254.0 3.100 0.080 1.0459 6.351 41.827 0.349 8.719 2.610 65.2275.0 3.874 0.100 1.0571 7.829 52.846 0.441 8.813 3.297 65.9306.0 4.649 0.120 1.0684 9.282 64.095 0.535 8.908 3.999 66.6367.0 5.424 0.140 1.0797 10.710 75.568 0.630 9.002 4.714 67.3418.0 6.199 0.160 1.0911 12.100 87.269 0.728 9.096 5.444 68.0479.0 6.974 0.180 1.1024 13.460 99.195 0.827 9.191 6.188 68.75210.0 7.748 0.200 1.1137 14.800 111.350 0.928 9.285 6.946 69.45811.0 8.523 0.220 1.1250 16.110 123.730 1.032 9.379 7.718 70.16412.0 9.298 0.240 1.1363 17.390 136.340 1.137 9.474 8.505 70.87013.0 10.080 0.260 1.1476 18.650 149.170 1.244 9.568 9.305 71.57514.0 10.850 0.280 1.1589 19.880 162.220 1.353 9.662 10.120 72.27915.0 11.630 0.300 1.1702 21.090 175.500 1.464 9.756 10.950 72.98316.0 12.400 0.320 1.1815 22.270 189.000 1.576 9.850 11.790 73.68517.0 13.180 0.340 1.1927 23.430 202.730 1.691 9.944 12.650 74.38718.0 13.950 0.360 1.2040 24.560 216.680 1.807 10.040 13.520 75.08819.0 14.730 0.380 1.2152 25.670 230.840 1.925 10.140 14.400 75.78720.0 15.500 0.400 1.2263 26.760 245.230 2.045 10.230 15.300 76.48521.0 16.280 0.420 1.2375 27.830 259.830 2.167 10.320 16.210 77.18022.0 17.050 0.440 1.2486 28.870 274.650 2.291 10.410 17.140 77.87423.0 17.830 0.460 1.2597 29.900 289.690 2.416 10.510 18.080 78.56624.0 18.600 0.480 1.2708 30.900 304.930 2.543 10.600 19.030 79.25525.0 19.370 0.500 1.2818 31.880 320.400 2.672 10.690 19.990 79.94326.0 20.150 0.520 1.2928 32.840 336.070 2.803 10.780 20.970 80.62827.0 20.920 0.540 1.3037 33.780 351.940 2.935 10.870 21.960 81.31028.0 21.700 0.560 1.3146 34.700 368.020 3.069 10.960 22.960 81.98829.0 22.470 0.580 1.3254 35.600 384.310 3.205 11.050 23.980 82.66530.0 23.250 0.600 1.3362 36.490 400.800 3.342 11.140 25.010 83.33831.0 24.020 0.620 1.3470 37.350 417.490 3.482 11.230 26.050 84.00732.0 24.800 0.640 1.3576 38.200 434.370 3.622 11.320 27.100 84.67333.0 25.570 0.660 1.3683 39.030 451.450 3.765 11.410 28.170 85.33534.0 26.350 0.680 1.3788 39.840 468.720 3.909 11.500 29.240 85.99435.0 27.120 0.700 1.3893 40.630 486.170 4.054 11.590 30.330 86.64836.0 27.900 0.720 1.3997 41.410 503.820 4.201 11.670 31.430 87.29937.0 28.670 0.740 1.4101 42.170 521.640 4.350 11.760 32.540 87.94438.0 29.450 0.760 1.4204 42.920 539.650 4.500 11.850 33.670 88.58639.0 30.220 0.780 1.4306 43.640 557.830 4.652 11.930 34.800 89.22340.0 31.000 0.800 1.4407 44.360 576.190 4.805 12.020 35.950 89.85441.0 31.770 0.820 1.4508 45.050 594.710 4.959 12.100 37.100 90.48142.0 32.550 0.840 1.4607 45.740 613.400 5.115 12.180 38.270 91.10343.0 33.320 0.860 1.4706 46.400 632.260 5.272 12.270 39.440 91.72044.0 34.100 0.880 1.4804 47.060 651.270 5.431 12.350 40.630 92.33045.0 34.870 0.900 1.4901 47.690 670.440 5.591 12.430 41.830 92.93546.0 35.650 0.920 1.4997 48.320 689.760 5.752 12.510 43.030 93.53547.0 36.420 0.940 1.5092 48.930 709.220 5.914 12.590 44.250 94.12948.0 37.200 0.960 1.5187 49.520 728.830 6.078 12.670 45.470 94.71649.0 37.970 0.980 1.5280 50.100 748.580 6.242 12.740 46.700 95.29750.0 38.740 1.000 1.5372 50.670 768.460 6.408 12.820 47.940 95.87251.0 39.520 1.000 1.5506 51.490 790.690 6.594 12.930 49.330 96.71152.0 40.290 1.000 1.5604 52.070 811.250 6.765 13.010 50.610 97.317

TechnicalData

Table 3 Specific Heats of Caustic Soda Solutions in BTU’s per PoundPERCENT TEMPERATURE °FCAUSTIC 32 40 50 60 80 100 120 140 160 180 200 220 240 260 280 300

0 1.004 1.003 1.001 0.999 0.998 0.997 0.998 0.999 1.000 1.002 1.004 - - - - -

2 0.965 0.967 0.968 0.969 0.972 0.974 0.977 0.978 0.980 0.983 0.986 - - - - -

4 0.936 0.940 0.943 0.946 0.951 0.954 0.957 0.960 0.962 0.965 0.966 - - - - -

6 0.914 0.920 0.924 0.928 0.933 0.938 0.941 0.944 0.946 0.948 0.950 - - - - -

8 0.897 0.902 0.907 0.911 0.918 0.923 0.927 0.930 0.932 0.934 0.936 - - - - -

10 0.882 0.888 0.893 0.897 0.905 0.911 0.916 0.918 0.920 0.922 0.923 - - - - -

12 0.870 0.877 0.883 0.887 0.894 0.901 0.906 0.909 0.911 0.912 0.913 - - - - -

14 0.861 0.868 0.874 0.879 0.886 0.892 0.897 0.901 0.903 0.903 0.904 - - - - -

16 0.853 0.860 0.866 0.871 0.880 0.886 0.891 0.894 0.896 0.897 0.897 - - - - -

18 0.847 0.854 0.860 0.865 0.873 0.880 0.885 0.888 0.890 0.891 0.891 - - - - -

20 0.842 0.848 0.854 0.859 0.868 0.875 0.880 0.884 0.886 0.886 0.887 - - - - -

22 0.837 0.844 0.849 0.854 0.863 0.870 0.876 0.880 0.882 0.882 0.883 - - - - -

24 - 0.839 0.844 0.849 0.858 0.866 0.873 0.877 0.879 0.879 0.880 - - - - -

26 - 0.835 0.840 0.845 0.854 0.863 0.869 0.874 0.875 0.876 0.876 - - - - -

28 - 0.830 0.836 0.841 0.850 0.859 0.866 0.870 0.872 0.872 0.873 - - - - -

30 - 0.826 0.832 0.837 0.846 0.855 0.862 0.866 0.868 0.869 0.869 - - - - -

32 - 0.822 0.828 0.833 0.842 0.850 0.857 0.862 0.863 0.864 0.864 - - - - -

34 - - 0.823 0.828 0.837 0.845 0.852 0.856 0.857 0.858 0.858 - - - - -

36 - - 0.819 0.824 0.832 0.840 0.845 0.849 0.850 0.851 0.851 - - - - -

38 - - 0.816 0.820 0.827 0.833 0.837 0.841 0.842 0.842 0.843 - - - - -

40 - - 0.812 0.815 0.821 0.826 0.829 0.831 0.832 0.832 0.832 - - - - -

42 - - 0.807 0.809 0.813 0.816 0.819 0.819 0.820 0.820 0.820 - - - - -

44 - - - 0.802 0.804 0.806 0.807 0.807 0.807 0.806 0.804 - - - - -

46 - - - 0.793 0.794 0.795 0.794 0.794 0.793 0.791 0.789 - - - - -

48 - - - - 0.783 0.782 0.781 0.780 0.779 0.777 0.776 - - - - -

50 - - - - 0.771 0.769 0.768 0.767 0.765 0.765 0.764 0.763 0.762 0.762 0.761 0.761

52 - - - - 0.759 0.757 0.756 0.754 0.753 0.752 0.751 0.749 0.748 0.747 0.746 0.745

54 - - - - 0.746 0.744 0.741 0.739 0.739 0.738 0.737 0.735 0.733 0.731 0.730 0.728

56 - - - - 0.733 0.730 0.728 0.726 0.724 0.723 0.722 0.721 0.719 0.717 0.715 0.713

58 - - - - - 0.719 0.717 0.715 0.713 0.711 0.709 0.707 0.705 0.703 0.702 0.700

60 - - - - - 0.706 0.705 0.703 0.701 0.699 0.697 0.696 0.693 0.691 0.690 0.688

62 - - - - - - 0.694 0.692 0.690 0.688 0.687 0.685 0.683 0.681 0.679 0.677

64 - - - - - - 0.684 0.682 0.681 0.679 0.677 0.675 0.673 0.671 0.670 0.668

66 - - - - - - 0.675 0.673 0.671 0.669 0.668 0.666 0.664 0.662 0.660 0.658

68 - - - - - - - 0.663 0.662 0.660 0.658 0.656 0.655 0.653 0.651 0.649

70 - - - - - - - 0.655 0.653 0.651 0.649 0.647 0.646 0.644 0.642 0.640

72 - - - - - - - - 0.645 0.643 0.641 0.639 0.637 0.635 0.634 0.632

73 - - - - - - - - - 0.639 0.637 0.635 0.633 0.631 0.630 0.628

74 - - - - - - - - - 0.635 0.633 0.631 0.629 0.628 0.626 0.624

74.5 - - - - - - - - - 0.633 0.631 0.629 0.627 0.626 0.624 0.622

76 - - - - - - - - - 0.628 0.627 0.625 0.623 0.621 0.619 0.617

78 - - - - - - - - - - 0.620 0.618 0.616 0.615 0.613 0.611

25 of 52

26 of 52TechnicalData

Properties of Anhydrous Caustic Soda

Table 4Miscellaneous Properties

Property ValueChemical Formula . . . . . . .NaOHMolecular Weight . . . . . . . .40.00Freezing or meltingpoint . . . . . . . . . . . . . . . . .318°C or 604°FBoiling point . . . . . . . . . . . .1388°C or 2530°F at

760 mm Hg pressureSpecific heat . . . . . . . . . . .0.353 cal/gm/°C at

20°C or 0.353BTU/Ib/°F at 68°F

Free energy offormation . . . . . . . . . . . . . .-90,762 cal/mol at

25°C, 760 mm Hg pressure

Refractive index forlight wavelength of5894 A . . . . . . . . . . . . . . . .N = 1.433 at 320°C

N = 1.421 at 420°C

Latent heat of fusion . . . . .40.0 cal/gm or 72.0 BTU/lb

Lattice energy . . . . . . . . . .176.2 kg-cal/molEntropy . . . . . . . . . . . . . . .12.43 kg-cal/mol/°K

at 25°C, 760 mm Hg pressure

Heat of formation . . . . . . . . 101.723 kcal/molNa+1/2O2+1/2H2 = NaOH

Table 5Specific Gravity of Solid Caustic Soda

Temp.°C 20 299.6 320 350 400 450

Specificgravity 2.130 2.08 1.786 1.771 1.746 1.722

Note:The average bulk density of flake Caustic Soda is about 60 pounds per cubic foot. This value varies with the packing conditions and flake characteristics.

Table 6Enthalpy of

Anhydrous Caustic Soda(Above 32°F base temperature)

Solid NaOH Molten NaOHTemp.°F BTU/lb Temp.°F BTU/lb

32 0.00 605.1 356.0650 5.57 650 381.47

100 21.71 700 408.94150 38.82 750 435.59200 56.91 800 461.28250 75.98 850 486.48300 96.01 900 510.70350 117.03 950 534.12400 139.02 1000 556.72450 161.98 1050 578.52500 185.92 1100 599.51550 210.83 1150 619.68600 281.27 1300 675.35

605.1 283.97 1350 692.29

Table 7Viscosity of

Molten Caustic Soda Temp. °C . . . . . . . . . . . 350 400 450 500 550Viscosity, centipoise . . . 4.0 2.8 2.2 1.8 1.5

Table 8Vapor Pressure of

Molten Caustic Soda

Temp.°C . . . . . . . .1000 1050 1100 1200 1300 1388

Vapor Pressurein mm Hg . . . . . . . . .41 66 103 225 447 760

TechnicalData 27 of 52

Properties of Caustic Soda Solutions

Table 9Coefficient of Expansion of

Caustic Soda Solutions

The coefficient of expansion is the volume changeper unit change in temperature. It may be derivedfrom data on the change of density with tempera-ture according to the following formula:

d = 1.0200 + 0.0105OX - (0.0005+0.0000049X)t

Note: “d” is the density in g/cc; “X” is the concen-tration in percent by weight of NaOH; and “t” is thetemperature in °C. The formula is limited to con-centrations from 10% to 70% NaOH and to tem-peratures from 15°C to 70°C.

Table 10Compressibility of


Moles H2O/Mole NaOH Density B x 10

6

25.01 1.08670 31.2350.09 1.04391 36.15

100.15 1.02114 39.12

Note: The compressibility coefficient B is expressed as compressibilityper cc per megabar at 25°C. Data is valid between 100-300 megabars.

Table 11Heat of Solution of Caustic Soda

Heat Liberated % Moles H2O/ BTU/lb. BTU/lb. cal/g

NaOH Mole NaOH NaOH Solution NaOH0.44 500 455.8 2.0 253.20.55 400 456.0 2.5 253.31.10 200 456.6 5.0 253.72.17 100 458.3 9.9 254.64.26 50 462.0 19.7 256.78.16 25 462.6 37.7 257.0

14.14 13.5 470.1 66.5 261.219.80 9 462.2 91.5 256.824.10 7 457.9 110.4 254.430.77 5 419.2 129.0 232.942.55 3 323.5 137.6 179.7

Table 12Heat of Dilution of


Wt.% BTU/lb BTU/lbNaOH NaOH Solution

0 0 02 + 1.18 + 0.02364 - 2.04 - 0.08086 - 4.78 - 0.2878 - 7.15 - 0.572

10 - 8.60 - 0.86012 - 9.13 - 1.0914 - 8.65 - 1.2116 - 7.34 - 1.1718 - 4.99 - 0.89720 - 1.50 - 0.30122 + 3.28 + 0.72124 9.47 2.2726 17.14 4.4628 26.43 7.4030 37.34 11.2032 49.97 15.9934 64.05 21.7636 79.63 28.6638 96.50 36.6740 114.2 45.6942 132.8 55.7844 151.7 66.7646 170.7 78.5248 189.7 91.04

Note: Enthalpy of solutions at 68°F relative to infinitely dilute solutions.

Table 13

Index of Refraction ofCaustic Soda Solutions

NaOHTemp.°C g/L Refractive Index

20°C 0 1.333027.88 1.33517

13.12 1.3366035.44 1.3423655.12 1.3471498.48 1.35685

131.52 1.36364

25°C 0 1.332517.88 1.33467

13.08 1.3360535.4 1.3417455.04 1.3464498.28 1.35603

131.2 1.36279

30°C 0 1.331967.88 1.33411

13.04 1.3355135.36 1.3410854.96 1.3457298.08 1.35530

130.92 1.36204

TechnicalData28 of 52

Table 14

Hydrogen Ion Concentrations ofCaustic Soda Solutions at 25°C

NaOH% NaOH Moles/L pH

7.40 2.0 14.03.83 1.0 13.81.96 0.5 13.60.39 0.1 12.90.20 0.05 12.60.04 0.01 12.0

Due to the difficulty of obtaining accurate pH read-ings at values above 12, pH is not a valid methodto determine concentration.


-40

-20

0

20

40

60

80

100

120

140

160

180

200

-40

-4

32

68

104

140

176

212

248

284

320

356

392

0 10 20 30 40 50 60 70 80 90

Percent NaOH by weight

Tem

pera

ture

°C

Tem

pera

ture

°F

Range of Liquid Caustic Soda

Solidifying Curve

Boiling Point Curve(Atmospheric Pressure)

Solid Caustic Soda

Graph 1Boiling and Solidifying Temperatures of Aqueous Caustic Soda Solutions

30 of 52

TechnicalData

1

1.05

1.1

1.15

1.2

1.25

1.3

1.35

1.4

1.45

1.5

1.55

1.6

1.65

1.7

1.75

1.8

0 10 20 30 40 50 60 70 80 90 100

32 50 68 86 104 122 140 158 176 194 212

Temperature °F

Spe

cific

Gra

vity

70% by weight NaOH

60%

55%

50%

45%

40%

35%

30%

25%

20%

15%

10%

5%

Temperature °C

Graph 2Specific Gravity of Aqueous Caustic Soda Solutions

31 of 52

TechnicalData

0.2

1

10

100

10 20 30 40 50 60 70

50 68 86 104 122 140 158

Temperature °F

Temperature °C

Vis

cosi

ty, C

entip

oise

s

60% by weight NaOH

50%

40%

30%

20%

10%

0%

Graph 3Viscosity of Aqueous Caustic Soda Solutions


10

100

1000

10000

0 50 100 150 200 250

32 122 212 302 392 482

Temperature °F

Temperature °C

Vap

or P

ress

ure,

mm

Hg

0% NaOH

10% NaOH

20% NaOH

30% NaOH

40% NaOH

50% NaOH

60% NaOH

Graph 4Vapor Pressures of Aqueous Caustic Soda Solutions

33 of 52

50

100

150

200

0 10 20 30 40 50

80°F

100°F

120°F

140°F


Res

ultin

g F

inal

Tem

pera

ture

(°F

)

TechnicalData

50

100

150

200

250

300

0 10 20 30 40 50 60 70


Res

ultin

g F

inal

Tem

pera

ture

(°F

)

60°F Dilution Water



Graph 5Approximate Resultant Temperature When Diluting Caustic Soda

Solution

Anhydrous

Note: Graph for use starting with 50% Caustic Soda Solution using 70°F water.

Note: Graph for use starting with Anhydrous Caustic Soda.


0

100

200

300

400

500

0 10 20 30 40 50 60 70 80


Rel

ativ

e E

ntha

lpy,

BT

U/lb

of S

olut

ion

400°F

380°F

360°F

340°F

320°F

300°F

280°F

260°F

240°F

220°F

200°F

180°F

160°F

140°F

120°F

100°F

80°F

Graph 6Relative Enthalpy of Aqueous Caustic Soda Solutions

To approximate the final temperature after diluting a NaOHsolution, start on the bottom axis at the percentage of the origi-nal solution. Proceed up until the temperature of the originalsolution is reached. From that point, draw a line that intersectson the y-axis at the temperature of the water used for dilution.Then find the final diluted percentage on the x-axis and draw avertical line that intersects the second line drawn. The intersec-tion point of those lines represents the resultant temperature.

Example: Diluting 50% NaOH at 120°F to 20% using 80°F water.

* Approximate resultant temperature 143° F

•

35 of 52

TechnicalData

Graph 7Solubility of Sodium Chloride in Aqueous Caustic Soda Solutions


0.32

0.33

0.34

0.35

0.36

0.37

0.38

0.39

0.4

0.41

0.42

0 10 20 30 40 50 60 70 80

30°F

50°F

70°F

90°F

100°F

130°F

170°F

190°F


The

rmal

Con

duct

ivity

- B

TU

/HR

x S

Q. F

t x°F

Graph 8Thermal Conductivity of Aqueous Caustic Soda Solutions

37 of 52

TechnicalData

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

1.1

1.2

1.3

1.4

1.5

0 5 10 15 20 25 30 35 40 45 50


Spe

cific

Con

duct

ance

, ohm

-1cm

-1

0°C

18°C

50°C

100°C

Graph 9Specific Conductance of Aqueous Caustic Soda Solutions

Dilution Calculations38 of 52

HOW TO DILUTE CAUSTIC SODA SOLUTIONS

Sometimes it is necessary to dilute caustic sodabefore it is used, or when the potential for freezingexists. A procedure for calculating the amount ofconcentrated caustic and water required is givenbelow.

DILUTING A SOLUTION

Problem: To dilute 3,000 gallons of 50% NaOH toa 20% solution. How much water is necessary toaccomplish this task?

Solution: The dilution can be simplified by usingthe following formula:D=V[A(B-C)/C]

Where:A=Specific gravity of strong solutionB=Concentration of strong solution (% NaOH)C=Concentration of desired solution(% NaOH)D=Volume of water to be addedV=Volume of strong solution(The specific gravity of 50% NaOH is 1.5372 takenfrom Table 2)

Therefore:D=3,000((1.5372)(50-20)/20)D=3,000(2.3058)=6,917 gallonsResult: It will take 6,917 gallons of water to dilute3,000 gallons of 50% NaOH to a 20% solution.

VOLUME OF FINAL SOLUTION

It should be noted that when diluting caustic soda,volumes are not additive. Therefore, in the previousexample, the final volume of the solution would notbe 6,917 gallons of water + 3,000 gallons of 50%NaOH = 9,917 total gallons. The actual volume willbe slightly less. To calculate the final volume, thewater and caustic soda must be converted to aweight basis, and then divided by the density of thedesired solution.

DILUTION GRAPH

Graph 10 can also be used to determine approxi-mate volumes of 50% NaOH and water necessary toachieve a particular dilution. For example, you wantto produce 3,000 gallons of a 25% NaOH solutionand want to know how much water and 50% NaOHare needed to accomplish this goal.

Using the chart, start on the bottom axis at the3,000 gallon line. Proceed upward until you intersectthe first 25% line on the bottom half of the graph.From the intersection point go to the right and leftaxes to determine the volume and weight of waterneeded. In this case the volume is read at 1,920 gal-lons and the weight at 16,000 pounds.

Then continue upward until you intersect the 25%line at the top of the graph. Again from the intersec-tion point go to the left and right axes to determinethe volume and weight of 50% NaOH needed. In thiscase the volume is read at 1,248 gallons and theweight at 16,000 pounds.

Therefore, it would take 1,248 gallons of 50%NaOH to be added to 1,920 gallons of water to pro-duce 3,000 gallons of a 25% solution.

39 of 52DilutionCalculations

40000

30000

20000

10000

0

4800

3600

2400

1200

0

0 1000 2000 3000 4000 5000

0

10000

20000

30000

40000

0

780

1560

2340

31200 1000 2000 3000 4000 5000

Vol

ume

of 5

0% N

aOH

Req

uire

d (g

allo

ns)

Vol

ume

of W

ater

Req

uire

d (g

allo

ns)

40%

35%

30%

25%

20%

15%

10%

40%

35%

30%

25%

15%

10%

20%

50% Caustic Soda (NaOH)

Water

Wei

ght o

f 50%

NaO

H R

equi

red

(lbs)

Wei

ght o

f Wat

er R

equi

red

(lbs)

Volume of Desired Solution (gallons)

Graph 10Approximate Dilution Chart For 50% Caustic Soda

Methodsof Analysis40 of 52

DETERMINATION OFTHE TOTAL ALKALINITY OF CAUSTIC SODA

PURPOSE AND THEORY

The accurate determination ofthe total alkalinity value for causticsoda is necessary for calculatingthe correct billing concentrations ofthis product.

Total alkalinity in caustic sodaproducts is determined by titrationof a sample with a standardizedsolution of 1N hydrochloric acid.Modified methyl orange indicator isused to determine the titration endpoint.

APPARATUS

100 ml Buret; Class AVolumetric, Fisher Scientific Cat #:03-775 or equivalent.

Analytical Balance; capable ofweighing to 0.001 grams.250 ml Erlenmeyer Flasks; widemouth, Fisher Cat#: 10-090B orequivalent.

Magnetic Stirrer; Fisher Cat#:14-493-120S or equivalent.

Magnetic stirring bars; 1 1/2” x5/16” dia. Fisher Cat#: 14-511-64or equivalent.

REAGENTS

1N Hydrochloric Acid;measure 83.0 ml of ACS Reagentgrade concentrated hydrochloricacid into a graduated cylinder andtransfer it to a one liter volumetricflask containing approximately 500ml of deionized water. Dilute to vol-ume with additional water, mix welland store in a tightly closed con-tainer. A prepared solution of 1NHCl can also be purchased (FisherScientific Cat# SA48-20 or equiva-lent). Hydrochloric Acid must bestandardized to ±0.0001N beforeuse.

Sodium Carbonate;anhydrous, volumetric grade (EMScience Cat#: 6394-2 or equiva-lent.) Dry at 250°C in a platinum orporcelain crucible for 4 hours.Store in a desiccator.

Modified methyl orangeindicator; dissolve 0.14 grams ofmethyl orange (Fisher Cat#: M216-25) and 0.12 grams of XyleneCyanole FF (Fisher Cat#: BP565-10) in deionized water and dilute to100 ml.

Water, Deionized & CarbonDioxide free; boil and cool thedeionized water or purge it withnitrogen for two hours.

SAFETY

Refer to the MSDS for the properhandling procedures for each of thechemicals listed in this procedure.

Caustic soda is a strong base.Hydrochloric acid is a strongacid. These chemicals are corro-sive to body tissue and cancause immediate and severeburns to eyes. Wear propergloves, proper eye protectionand other protective clothingwhen handling these chemicals.

A. STANDARDIZATION OF 1NHYDROCHLORIC ACID

1. Weigh 4.2 grams of sodiumcarbonate to the nearest0.0001 gram into a weighing dish. Carefully transfer toan Erlenmeyer flask. Add 75ml of deionized water and swirl to dissolve. Add threedrops of the modified methylorange indicator and titrate with the HCl solution to asteel gray color change.

2. The following formula is usedto calculate the normality ofthe HCl.Let:N = Normality of HClW = Weight (g) of Na2CO3

usedV = Volume (ml) of HClrequired to endpoint.Milliequivalent weight ofNa2CO3= 0.053N = W/V x 0.053

3. Determine the normality byaveraging the result of atleast three titrations.

B. ANALYSIS

1. To a clean, dry Erlenmeyerflask, accurately weigh to thenearest 0.001 grams an amountof sample as determined in thetable below. Weighing should beperformed as rapidly aspossible. The sample sizes are:50% NaOH..............6 - 7 gAnhydrous NaOH....3 - 4 g

2. Immediately add 50 ml of deion-ized water, making sure thesides of the beaker are washeddown.

3. Add 3 to 4 drops of modifiedmethyl orange indicator andcarefully add the magnetic stir-ring bar.

4. Titrate the sample to a steelgray color with 1N HCl. Samplesshould be titrated as soon aspossible to avoid pick up of car-bon dioxide from the air.

5. Record the volume of acidrequired to reach this color.Estimate the buret reading tothe nearest 0.02 ml.

Methodsof Analysis 41 of 52

C. CALCULATIONS

The following are formulas usedto calculate total alkalinity.Let:W = Weight (g) of sample titratedN = Normality of HClV = Volume (ml) of HCl requiredMilliequivalent wt. of Na2O =0.03099

% Na2O = (V) (N) (0.03099)(100)W

% NaOH = 1.2907 (%Na2O)

EXAMPLE6.530 grams of caustic soda

required the addition of 81.77 ml of1.0011N HCl to reach the modifiedmethyl orange endpoint.

% Na2O = (V) (N) (0.03099)(100)W

% Na2O = (81.77)(1.0011)(3.099)6.530

% Na2O = 38.85%% NaOH = (1.2907) (38.85)% NaOH = 50.14%

QUALITY ASSURANCE

With each batch of samplesbeing analyzed, at least one of thesamples should be analyzed induplicate. On a regular basis, sam-ples that have been previouslyanalyzed for total alkalinity shouldbe reanalyzed and the results com-pared.

Alkalinity values obtained foreach sample should be comparedwith OxyChem specifications forthat product. Hydrochloric acidshould be restandardized at least monthly.

DETERMINATION OFSODIUM HYDROXIDEIN CAUSTIC SODA

PURPOSE AND THEORY

The sodium hydroxide content ofcaustic soda is determined byadding barium chloride to a pre-pared sample and titrating with 1 NHCl to the phenolphthalein endpoint. The results are reported aspercent NaOH on a sample weightbasis.

APPARATUS

100 ml Buret; Class AVolumetric, Fisher Scientific Cat #:03-775 or equivalent.Analytical Balance; capable ofweighing to 0.001 grams.250 ml Erlenmeyer Flasks; widemouth, Fisher Cat#:10-090B orequivalent.Magnetic Stirrer; Fisher Cat#: 14-493-120S or equivalent.Magnetic stirring bars; 1-1/2” x5/16” dia. Fisher Cat#: 14-511-64or equivalent.

REAGENTS

1N Hydrochloric Acid; thepreparation of this reagent isdescribed in the method for:“Determination of Total Alkalinity”.

1% Phenolphthalein Indicator;dissolve one gram of phenolph-thalein (Aldrich Cat#: 10,594-5 orequivalent) in 100 ml of methanol.

10% Barium Chloride; Dissolve120 g of reagent grade BaCl2.2H2O(Fisher Cat#: B34-500) in 880 ml ofdeionized water.

Water, Deionized & CarbonDioxide free; boil and cool thedeionized water or purge it withnitrogen for two hours.

SAFETY

Refer to the MSDS for theproper handling procedures foreach of the chemicals listed inthis procedure. Caustic soda is astrong base. Hydrochloric acidis a strong acid. These chemi-cals are corrosive to body tissueand can cause immediate andsevere burns to eyes. Wearproper gloves, proper eye pro-tection and other protectiveclothing when handling thesechemicals. Barium chloride ishighly toxic. Avoid inhaling bari-um chloride dust.

A. STANDARDIZATION OF 1NHYDROCHLORIC ACID

Standardization procedure isdescribed in the method for:“Determination of Total Alkalinity”.

B. ANALYSIS

1. To a clean, dry Erlenmeyer flask, accurately weigh to thenearest 0.001 grams an amountof sample described in the tablebelow. Weighing should be per-formed as rapidly as possible.The sample sizes are:50% NaOH................ 6 - 7 gAnhydrous NaOH...... 3 - 4 g

2. Immediately add 100 ml of bari-um chloride solution, makingsure the sides of the beaker arewashed down.

3. Add 3 to 4 drops of phenolph-thalein indicator and carefullyadd the magnetic stirring bar.

4. Titrate the sample with 1N HCluntil the pink color changes towater white. The sample shouldbe titrated as soon as possibleto avoid pick up of carbon diox-ide from the air.


5. Record the volume of acidrequired to reach this color, esti-mating the buret reading to thenearest 0.02 ml.

CALCULATIONS

The following are formulas usedto calculate % NaOH.Let:W = Weight (g) of sample titratedN = Normality of HClV = Volume (ml) of HCl requiredMilliequivalent wt. of NaOH =0.04000

% NaOH = (V) (N) (0.04000) (100)W

EXAMPLE6.467 grams of caustic soda

required the addition of 80.85 ml of1.0020N HCl to reach the phe-nolphthalein endpoint.

% NaOH = (V) (N) (0.04000) (100)W

% NaOH = (80.85) (1.0020)(4.000)6.467

% NaOH = 50.11%

QUALITY ASSURANCE

For each batch of samples beinganalyzed, at least one of the sam-ples should be analyzed in dupli-cate. On a regular basis, samplesthat have been previously analyzedfor total alkalinity should be reana-lyzed and the results compared.Alkalinity values obtained for eachsample should be compared withOxyChem specifications.

Hydrochloric acid should berestandardized at least monthly.

DETERMINATION OFSODIUM CARBONATEIN CAUSTIC SODA(Gravimetric)

PURPOSE AND THEORY

The sodium carbonate content of a sample of caustic sodais determined by a direct gravimet-ric method. The method involvesacidification of the caustic sodasample with dilute sulfuric acid,boiling, and weighing the carbondioxide evolved. Accurate resultscan be obtained when the sodiumcarbonate content is 0.01% orgreater. This method should beused to analyze samples of liquidcaustic soda or anhydrous causticsoda containing 0.01% to 0.25%Na2CO3.

APPARATUS

See the CO2 train sketch below.Air for sweep is drawn in through“A.” This air must be scrubbed freeof CO2. The ground-glass jointedtube fitted into the top of “A” shouldbe packed with 8-20 mesh ascaritewith a layer of anhydrous granularcopper sulfate on top.

U-tube “D”Add a few glass beads and 5 to

10 ml of concentrated H2SO4. Theacid takes up the bulk of the mois-ture passing through condenser “C”and should be changed oftendepending on frequency of use.

U-tube “E”Pack with dehydrated copper sul-

fate pumice. This packing materialis prepared by soaking pulverizedpumice having the grain size ofwheat in saturated copper sulfatesolution drying at 150 -180oF. Theproduct must be kept in a wellstoppered bottle.


U-tube “F”Pack with anhydrous

magnesium perchlorate. Thisremoves all final traces ofmoisture carried through the sys-tem.

Ascarite - Absorbing Tower “G”Pack inside tube with 8-20 mesh

ascarite. Over the top layer addabout 0.25 inch of magnesium per-chlorate and cover with absorbentcotton. The cotton will prevent lossof weight due to carry-over of dustparticles. After tower is packed, itshould be hooked into the systemand swept with CO2-free air for aperiod of 15 to 20 minutes.

U-tube “H”Pack with 8-20 mesh ascarite.

REAGENTS

Sulfuric Acid; 12 N with 27.8 g.FeSO4.7H2O per liter.Sulfuric Acid, concentrated.Ascarite II; 8-20 mesh (sodiumhydroxide coated silica.)Magnesium Perchlorate, anhy-drous.

Copper (II) Sulfate, anhydrous.Water, Deionized & CarbonDioxide free; boil and cool thedeionized water or purge it with nitro-gen for two hours.

SAFETY

Caustic soda as dust or mist isintensely irritating to the respiratory system, skin, andeyes. Become familiar with thefirst aid measures recommendedin this Handbook.

When preparing 12 N sulfuricacid, the concentrated acid mustbe poured slowly into water withconstant stirring.

Wear safety glasses with sideshields when handling causticsoda samples or acid solutions.

PROCEDURE

1. Sample PreparationThe 50% liquid caustic soda will

solidify at 54oF. If the sample is solidified at the time of analysis, it may be thawed out byplacing the container in hot wateruntil no solids are present. The lip ofthe bottle may be wiped before thesample is poured into a weighingbottle.

No special preparation is requiredfor anhydrous samples. Carbonateand moisture pickup should beavoided by rapid sample handling.

In all cases, samples for carbonateanalysis should be the first takenfrom the sample bottle to minimizecarbon dioxide pickup from theatmosphere.

2. AnalysisThe train must be conditioned daily

before any samples are run. This isdone by making a regular determina-tion using a sample that contains car-bonate. Following this, a blankshould be run on the train to makesure that the train is leak free. This isdone by making a regular determina-tion but omitting the sample. If theascarite weighing tower gains morethan 0.2 mg in weight during theblank run, the train probably has aleak.

After the train has been condi-tioned and found to be leak free, thesamples are run as follows:

1. Two absorbing towers (G) must beconditioned and weighed prior toanalysis. These will be called G1and G2 in the procedure. The use oftwo towers will enable the analyst toconserve time when performingmore than one analysis.

2. Weigh a sample of at least 20g.(50% basis) or large enough tocontain 5 mg of CO2 into a flask“B” using an analytical balance.Add 4 or 5 glass beads and 80 mlof CO2-free deionized water andimmediately place the flask into itsproper position in the train.

3. Add 50 ml of 12 N sulfuric acid tofunnel “A.”

4. Place tared tower G1 between U-tubes “F” and “H.”

5. Open the system starting at U-tube “H” and working back to “D.”

6. Open cock on funnel “A” andallow acid to run into flask “B” andimmediately hook vacuum line totube “H.” Adjust the flow of air to 4bubbles per second through thetip of the stem of funnel“A.”

7. Apply heat to flask “B” and bringto a boil. Hold “B” contents to boil-ing point for 3 minutes andremove heat.

8. Sweep the system for 20 minutes.While this is being done, the nextsample can be weighed intoanother flask (B), and the beadsand distilled water added. Thisflask is then stoppered and setaside until needed.

9. At the end of 20 minutes, the vac-uum line is removed,tower G1 isshut off and removed and towerG2 placed into position. The cockon funnel “A” is closed and 50 mlof 12 N sulfuric acid is againadded to funnel “A.”

10.Flask “B” is removed, the stem offunnel “A” is washed down withdeionized water and the new sam-ple is placed into position.

11.Tower G2 is opened and the pro-cedure is repeated beginning atStep 6.


12.When G1 is removed from thetrain, a period of 20 minutes willcondition the sample for weighing.During this 20 minute sweep time,another sample is prepared andtower G1 is reweighed in order todetermine the weight of CO2 foundin the first sample. Tower G1 isthen ready for Run No. 3.

CALCULATIONS

Report results as percent Na2CO3

calculated to the nearest 0.01. Let:W(CO2) = Weight of CO2

evolvedW(S) = Weight of sample% Na2CO3 = (W(CO2)(2.409)(100)

W(S)EXAMPLE

If a 25 gram sample were usedand the weight of CO2 absorbed intower “G” = 0.0125 grams, then:% Na2CO3 = (0.0125)(2.409)(100)

25% Na2CO3 = 0.12%

DETERMINATION OFSODIUM CHLORIDE INCAUSTIC SODA

PURPOSE AND THEORY

Chloride is a contaminant in allgrades of caustic soda. Sodiumchloride is present at <100 ppm in50% membrane caustic soda andat approximately 1% in 50%diaphragm caustic soda. Higherconcentrations of this compoundcan have undesirable effects inmany applications of the product.Consequently, accurate determina-tion of this impurity is most impor-tant.

When acid solutions of silver ionand an alkali thiocyanate are mixedin the presence of a ferric salt, thethiocyanate has a selective actiontoward silver, resulting in the for-mation of silver thiocyanate. Anyexcess of thiocyanate not requiredby the silver reacts with ferric saltto form reddish-brown ferric thio-cyanate. This color indicates thecompletion of the reaction.

An excess of silver nitrate andthe ferric indicator is added to asample of caustic soda that hasbeen acidified with nitric acid. Anychloride that is contained in thesample will react with the silvernitrate to form a silver chloride pre-cipitate. The silver nitrate that isremaining in the sample solutionafter this reaction is titrated with astandardized solution of ammoniumthiocyanate. The equationsinvolved are:AgNO3 + NaCl ⇒ AgCl + NaNO3

Excess AgNO3 + NH4CNS ⇒AgCNS + NH4NO3

6 NH4CNS + Fe2(SO4)3 ⇒2Fe(CNS)3 + 3(NH4)2SO4

(reddish brown color)

APPARATUS

25ml Buret; Class A Volumetric,Fisher Scientific Cat#:03-724-10Aor equivalent.20ml Pipet; Class A Volumetric,Fisher Cat#: 13-650-2N500ml Erlenmeyer flasks; widemouth, Fisher Cat#: 10-090C orequivalent.Magnetic stirrer; Fisher Cat#:14-493-120S or equivalent.Magnetic stirring bars; 1 1/2” x5/16” dia, Fisher Cat#: 14-511-64or equivalent.Analytical Balance; capable ofweighing to 0.001 grams.

REAGENTS

Water, Deionized.0.1N Silver Nitrate; accuratelyweigh 16.99 grams of ACSReagent grade silver nitrate (driedat 110°C for 1 hr) and transfer to a1L volumetric flask. Dilute to vol-ume with deionized water, mix welland store in a tightly closed ambercontainer. Silver nitrate and itsaqueous solutions are photode-composed by light and should bestored in a dark place.0.1N Ammonium Thiocyanate;accurately weigh 7.612 grams ofACS Reagent grade ammoniumthiocyanate and transfer to a onevolumetric flask. Dilute to volumewith deionized water, mix well andstore in a tightly stoppered glassbottle. The thiocyanate solutionmust be standardized to within±0.0001N prior to use.Ferric Indicator; prepare a satu-rated aqueous solution of ferricammonium sulfate [FeNH4(SO4)2],Aldrich Cat# 22,126-0 or equiva-lent.


1% Phenolphthalein Indicator;dissolve one gram of phenolph-thalein (Aldrich Cat#: 10,594-5 orequivalent) in 100 ml of methanol.Nitric Acid, 1:1 (v/v); slowly pour500 ml of ACS Reagent gradenitric acid in 500 ml of deionizedwater as it is stirring. Allow thesolution to cool.

SAFETY

Refer to the MSDS for the proper handling procedures foreach of the chemicals listed inthis method.

Caustic soda is a strong baseand nitric acid is a strong acid.These chemicals are corrosiveto body tissue and can causeimmediate and severe burns toeyes. Wear proper gloves, prop-er eye protection and other pro-tective clothing when handlingthese chemicals.

Silver Nitrate is a strong oxidizing agent. Wear rubbergloves when handling. Contactwith skin causes a black discol-oration. Keep away from heat,sparks and open flames.

METHOD

A. STANDARDIZATION OF0.1N SILVER NITRATE

Since this procedure determinesthe chloride content of a sample bycomparing the amount of unreact-ed silver nitrate remaining in asample with the amount that isremaining in a reagent blank, theexact normality of the silver nitrateneed not be known. If a reagentblank is not used, silver nitratestandardization is essential. Amanual titration method isdescribed in “ASTM StandardPractice for Preparation,Standardization and Storage ofStandard Solutions for ChemicalAnalysis”, Vol 15.05; E200-91, 44-48.

B. STANDARDIZATION OF0.1N AMMONIUM THIOCYANATE1.Use a volumetric pipet to transfer

20.00 ml of freshly standardized0.1 N silver nitrate into a 250 mlErlenmeyer flask containing 50ml deionized water, 5 ml of 1:1nitric acid and 1 ml of ferric indi-cator. Titrate the AgNO3 with theNH4SCN solution until the firstpermanent reddish-brown colorappears and persists after vigor-ous shaking for 15 seconds.Record the volume of NH4SCNrequired. Repeat the above pro-cedure on at least three moresolutions of silver nitrate.

2.Use the following formula to cal-culate the normality of theammonium thiocyanate solution:N1 = (N2)(V2)/(V1)where:N1 = Normality of NH4SCNN2 = Normality of AgNO3

V1 = Volume of NH4SCNrequiredV2 = Volume of AgNO3 added

3.Determine the normality by aver-aging the results of at least threetitrations.

C. PROCEDURE1. To a clean dry Erlenmeyer flask,

accurately weigh, to the nearest0.001 g for smaller samples and0.01 g for larger samples, anamount of product as determinedin the following table. Weighingshould be performed as rapidlyas possible.

SAMPLE SIZE FOR CHLORIDEANALYSIS

Product Sample size

50% Diaphragmgrade caustic soda . . . . . . . . .6 gDiaphragm gradebeads and flake . . . . . . . . . . .<6 g

50% Membranegrade caustic soda . . . . . . . .80 g

50% Rayon gradecaustic soda . . . . . . . . . . . . .80 g

50% Purified gradecaustic soda . . . . . . . . . . .40-80 g

2. Immediately add 100 ml ofdeionized water, making sure thesides of the beaker are washeddown.

3. Add 2 drops of 1% phenolph-thalein indicator and carefullyneutralize the sample with 1:1nitric acid. Caution: The samplesolutions generate consider-able heat when being neutral-ized with acid. The flaskshould be continuously cooledin an ice bath while the acid isslowly added. After the phe-nolphthalein endpoint hasbeen reached (color changesfrom pink to colorless), add anadditional 5.0 ml of acid.

4. Allow the solution to cool to roomtemperature and add a stirringbar to the flask.

5. Using a volumetric pipet add20.00 ml of 0.1N silver nitrate,also add approximately 1 ml ofthe ferric indicator solution (seeNote 1).

6. Prepare a reagent blank byadding two drops of phenolph-thalein, 5ml nitric acid, 20.00 mlsilver nitrate solution and 1ml offerric indicator to a flask contain-ing 100 ml of deionized waterand a stirring bar.


7. Place the flask containing thereagent blank on a magnetic stir-rer and titrate the solution with0.1N ammonium thiocyanateuntil a reddish-brown color per-sists for at least 15 seconds (seeNote 2). Record the volume ofNH4SCN required to reach thecolor change.

8. Titrate the sample solution with0.1N ammonium thiocyanateuntil the same color change isreached and record the volumeof NH4SCN (see Notes 3 and 4).

D. CALCULATIONSThe following is the formula

used to calculate the percent chlo-ride in the sample.Let:W = Weight of sample titratedN = Normality of NH4SCNV1= Volume of NH4SCN

required to titrate blankV2= Volume of NH4SCN

required to titrate sampleMilliequivalent wt. of Cl =

0.03545% Cl = (V1-V2)(N)(0.03545)(100)

WCalculate the percentage of sodi-

um chloride as follows:%NaCl = (%Cl)(1.6485)

EXAMPLE79.28 grams of 50% Membrane

grade caustic soda required theaddition of 19.54 ml of 0.1005 NNH4SCN to reach the titration end-point while the reagent blankrequired 19.95 ml of NH4SCN toreach the same endpoint.% Cl = (V1-V2)(N)(0.03545)(100)

W= (19.95-19.54)(0.1005)(3.545)

79.28% Cl = 0.00180% NaCl = (% Cl)(1.6485)% NaCl = (0.00180)(1.6485)% NaCl = 0.0030% or 30 ppm

NOTES1. Sample solutions should be

titrated within several minutes ofadding the silver nitrate. The sil-ver chloride has a tendency todecompose with exposure tolight giving the solution a pur-plish color. This color can inter-fere with an accurate determina-tion of the endpoint colorchange.

2. From the outset of the back-titra-tion with ammonium thiocyanate,an appreciable quantity of silverions are absorbed on the sur-face of the precipitates. Becauseof this, there is a tendency for apremature appearance of theendpoint color. Vigorous stirringor shaking of the solution isessential to bring about desorp-tion of silver ions from the pre-cipitates so they can react withthe thiocyanate.

3. As the endpoint is approached,increasing amounts of silverthiocyanate precipitating out ofsolution will actually increase thesolubility of silver chloride. Silverchloride that has precipitated willredissolve, allowing additionalsilver ions to react with the thio-cyanate. This causes a fadingendpoint and results in low chlo-ride values. For samples con-taining concentrations of chlo-ride greater than 0.01%, it isadvisable to filter the samplesolution through semi-quantita-tive paper after the addition ofsilver nitrate but prior to titrationwith thiocyanate. Removingmost of this precipitate willgreatly decrease the amount ofsilver that can be redissolvedduring the titration.

4. The white precipitate of silverthiocyanate interferes withobservation of the color changeat the titration endpoint. It issometimes helpful to stop thestirring or shaking of the sampleand allow the precipitate to set-tle, in order to observe the colorof the sample solution. If it isdetermined during this observa-tion that the endpoint has not yetbeen reached, resume vigorousstirring before addition of moreNH4SCN.

QUALITY ASSURANCE

Because of difficulties in deter-mining the exact endpoint whenusing this method, only skilled lab-oratory personnel should attempt toperform these titrations.

On a regular basis, samples thathave been previously analyzed forchloride content should be reana-lyzed and the results compared.

Chloride values should bechecked against OxyChem specifi-cations.


DETERMINATION OFIRON IN CAUSTICSODA

PURPOSE AND THEORY

Iron can result from contamina-tion during storage or transport ofthe product. Since iron is oftendetrimental to the end use of theproduct, accurate quantitation ofthis element is essential.

Ferric ion in an acidic mediumreacts with thiocyanate ions to pro-duce a red color complex. Theintensity of the color is proportionalto the amount of iron present. Bymeasuring the color intensity with aspectrophotometer, the concentra-tion of iron in a sample of causticsoda can be determined.

APPARATUS

Visible Spectrophotometer;able to perform absorbance or %transmittance measurements at awavelength of 480 nanometers.

Analytical Balance; capable ofweighing to 0.01 grams.

100 ml Volumetric Flasks;Fisher Scientific Cat# 10-210-8C orequivalent.

Pipets, Class A Volumetric;0.50 ml, Fisher Cat#: 13-650-2A or equivalent.1.00 ml, Fisher Cat#: 13-650-2B or equivalent. 2.00 ml, Fisher Cat#: 13-650-2C or equivalent. 5.00 ml, Fisher Cat#: 13-650-2F or equivalent. 10.00 ml, Fisher Cat#: 13-650-2L or equivalent. 20.00 ml, Fisher Cat#: 13-50-2N or equivalent.

Spectrophotometer Cells, stan-dard silica windows, 1 cm path-length; Fisher Cat#: 14-385-910C or equivalent.

REAGENTS

Deionized Water.Hydrochloric Acid; ACS

Reagent grade concentrated acid,Fisher Cat# A144 or equivalent.

1.5N Potassium Thiocyan-ate; add 145.77 grams of ACSReagent grade KSCN (Fisher Cat#:P317-500 or equivalent) to a oneliter volumetric flask, dilute to vol-ume with deionized water and mixthoroughly.

Sodium Chloride, 240 g/L; add292 grams of ACS Reagent gradeNaCl (Fisher Cat# S271-500 orequivalent) to a one liter volumetricflask, dilute to volume with deion-ized water and mix thoroughly.

Hydrogen Peroxide, 30%;Fisher Cat#: H325-500 or equiva-lent.

Iron Reference StandardSolution, 1000 ppm; Fisher Cat#:SI124-500 or equivalent.

pH Test Ribbons; Fisher Cat#:A979 or equivalent.

SAFETY

Refer to the MSDS for theproper handling procedures foreach of the chemicals listed inthis procedure.

Caustic soda is a strong base.Hydrochloric acid is a strongacid. Hydrogen peroxide is astrong oxidizing agent. The IronReference Solution is acidifiedwith HCl. All of these chemicalsare corrosive to body tissue andcan cause immediate and severeburns to eyes. Wear propergloves, proper eye protectionand other protective clothingwhen handling these materials.

Refer to instrument manual forthe proper use of equipmentdescribed in this method.

METHOD

A. CALIBRATION OF THE SPECTROPHOTOMETER

1.Prepare a stock iron standard bydiluting 1.00 ml of the 1000 ppmiron reference solution to 100.0ml with deionized water. Thisstandard will have an iron con-centration of 10 µg/ml.

2.From the stock standard, transfer0.50, 1.00, 2.00, 5.00, 10.0 and20.0 ml aliquots to 100 ml volu-metrics containing 50 ml of 292g/L NaCl. To the volumetrics,add 2.5 ml of conc. HCl and onedrop of 30% hydrogen peroxideand allow to set for approximate-ly one minute. After the minute,add 10.0 ml of 1.5N KSCN, fillthe flasks to the 100 ml markwith deionized water and mixthoroughly. These calibrationstandards will contain 5.0, 10.0,20.0, 50.0, 100, and 200 µg/100ml of iron,respectively (seeNotes 1,2 and 3).

3.A reagent blank is prepared inthe same manner although noiron solution is added to theblank.

4.Refer to the instruction manualsupplied with the spectropho-tometer for specific instructionson the proper use of the instru-ment.

5.Set the wavelength on the spec-trophotometer to 480 nanome-ters

6.Fill two matched 1 cm spec-trophotometer cells with thereagent blank. Place one cell inthe reference compartment andone cell in the sample compart-ment if the instrument is a dou-ble beam type or place thereagent blank in just the samplecompartment if it is a singlebeam unit. Adjust theabsorbance reading obtained bythe spectrophotometer to zero.


7. Proceed by taking absorbancereadings for each of the calibra-tion solutions, leaving thereagent blank in the referencecell of the spectrophotometer(double beam instrument).Absorbance readings must betaken within 15 minutes ofadding the KSCN to the solu-tions since the color complexthat is formed has limited stabili-ty.

8. Insert the concentrations of theiron standards (µg/100 ml) andtheir absorbance readings into alinear regression formula (avail-able on many hand held calcula-tors). Determine the best fitstraight line for this data and thecorrelation coefficient (r2) for theline. The correlation coefficientindicates how well the data con-forms to the best fit line that hasbeen calculated. It should begreater than 0.99. As an alterna-tive to using a linear regressionformula, the concentrations andabsorbance readings of the cali-bration standards can be plottedon quadrilinear graph paper andthe best straight line drawnthrough the data points.

B. ANALYSIS OF SAMPLES

1. Weigh to the nearest 0.1 gram,10 grams of anhydrous or 20 grams of liquid caustic soda intoa 100 ml volumetric.

2. Add 20 ml of deionized water anda 0.25 inch piece of pH test rib-bon.

3. Slowly add concentrated HCl untilthe test ribbon turns red, thenadd an additional 2.5ml of acid.

4. Cool the solution in a water bathuntil it has reached room temper-ature.

5. Add one drop of 30% hydrogenperoxide and mix. The purpose ofthe peroxide is to oxidize any fer-rous ion that may be present in

the sample to its ferric state sincethe KSCN only reacts with ferricion.

6. Add 10 ml of 1.5N KSCN. Diluteto volume with deionized waterand mix thoroughly.

7. Carefully transfer a portion of thesample solution to a 1 cm celland measure the absorbance onthe spectrophotometer at a wave-length of 480 nm. Use thereagent blank in the referencecell of the spectrophotometer(double beam instrument only).Absorbance reading should betaken within 15 minutes after theKSCN has been added to thesample.

8. Insert the absorbance reading forthe sample into the linear regres-sion program established with thecalibration standards and obtainthe concentration of Fe in µg/100ml of the solution.

CALCULATIONS

Report results as ppm Fe, basedon the weight of the sample.Let:C = concentration of Fe in

µg/100 ml solutionW = weight of sample in grams

ppm Fe = C/W

NOTES1. If a 20 gram sample of liquid

product is used, the calibrationstandards will correspond toconcentrations of 0.25 - 20.0ppm of iron in the sample. Ifmore or less iron is expected tobe found in the products, theamount of iron in the standardsshould be adjusted accordingly.

2. If concentrations of less than0.25 ppm iron are expected, thesensitivity of this method can beincreased. The instrument canbe calibrated with more diluteiron standards while using spec-trophotometer cells with a 5 cm

rather than 1 cm pathlength.Increasing the pathlength willproportionally increase theabsorbance readings.

3. When caustic soda samples areneutralized with HCl, the result-ing solutions contain NaCl.Calibration standards andreagent blanks should thereforecontain this compound. Adding50 ml of 240 g/L NaCl to thestandards and blanks approxi-mates the amount of NaClformed in neutralized samples ifa 20 gram sample of liquid prod-uct is used. If a sample sizeother than 20 grams is used, theamount of NaCl added shouldbe adjusted accordingly.

QUALITY ASSURANCE

With each batch of samples,analyze at least one of the samplesin duplicate. On a regular basis,reanalyze samples that have beenpreviously tested and compareresults.

Concentrations of iron found inthe analyzed samples should becompared with OxyChem specifica-tions.

Perform duplicate and samplespike analyses on a minimum of10% of all samples analyzed.Duplicate analyses should bereproducible within 15%. Samplesshould be spiked with iron atapproximately 1 to 2 times the con-centration that is expected to be inthe sample.


DETERMINATION OFNICKEL IN CAUSTICSODA

PURPOSE AND THEORY

Nickel may be present at varyingconcentrations in caustic sodaproducts. Nickel can be detrimentalto the end use of the product.When it is present at concentra-tions of less than 1 ppm in liquidcaustic soda, the heptoximemethod can be used for accuratelydetermining levels of at least 0.1ppm. By reducing the sample size,higher concentrations of nickel canbe measured, making this methodapplicable for all grades of causticsoda products. This procedure hasbeen found to be faster than meth-ods which require the nickel to beextracted by an ion exchange resinor an organic solvent.

Nickel in caustic matrices can bequantified by using a visible spec-trometer (at 445 nm) to measurethe intensity of the orange colorformed by the addition of hep-toxime (cycloheptanedione-dioxime). Nickel/heptoxime com-plexes are similar to those formedwith dimethylglyoxime, however,the heptoxime complex is reportedto be more stable (Ref. 1). Divalentnickel forms a pink color complexwith heptoxime which is lessintense than the orange coloredcomplex at higher oxidation states.To insure nickel is oxidized to ahigher valence state, bromine isadded as an oxidizing agent priorto addition of the heptoxime. Citricacid is also added to the samplesolution to complex any iron whichwould interfere with the analysis.

APPARATUS

Visible Spectrophotometer;capable of measuring absorbanceor % transmittance at a wavelengthof 445 nanometers.

Spectrophotometer Cells; stan-dard silica windows, 5 cm path-length; Fisher Cat#: 14-385932E orequivalent.

Analytical Balance; capable ofweighing 100 +/- .01 grams.100 ml Volumetric Flasks; ClassA Volumetric, Fisher Scientific Cat#10-210-8C or equivalent.Pipets, Class A Volumetric;2.00 ml, Fisher Cat#: 13-650-2C orequivalent. 4.00 ml, Fisher Cat#: 13-650-2E orequivalent. 6.00 ml, Fisher Cat#: 13-650-2G orequivalent. 10.00 ml, Fisher Cat#: 13-650-2Lor equivalent. 20.00 ml, Fisher Cat#: 13-650-2Nor equivalent.

REAGENTS

Water, Deionized.Hydrochloric Acid,Concentrated; Trace metal grade,Fisher Cat#: A508.Citric Acid, 10%; dissolve 10 g cit-ric acid (Aldrich Cat#: 24,062-1 orequivalent) into water and dilute to100 ml.Heptoxime (1,2-Cycloheptanedionedioxime),0.1%: dissolve 0.1g of cyclohep-tanedionedioxime (CAS# 530-97-2)(Pfaltz & Bauer. Cat#: C29880 orICN Cat#: 204213) into 100 ml ofethanol.Ammonium Hydroxide,Concentrated; Trace metal grade,Fisher Cat#: A470-250.Nickel Reference StandardSolution, 1000 ppm; AtomicAbsorption standard, Fisher Cat#:SN70-100 or equivalent.Bromine water, saturated; addapproximately 4-5 ml. of ACSReagent Grade bromine. (AldrichCat#: 27,757-6) to 100 ml of deion-ized water and mix.

pH Test Paper; pH range 1-12,Fisher Cat#: 14-850-llB or equiva-lent.

SAFETY

Refer to the MSDS for theproper handling procedures foreach of the chemicals listed inthis procedure.

Caustic soda and ammoniumhydroxide are strong bases andhydrochloric acid is a strongacid. These chemicals are corro-sive to body tissue and cancause immediate and severeburns to eyes. Wear propergloves, proper eye protectionand other protective clothingwhen handling these materials.

Bromine is highly toxic, verycorrosive and a strong oxidizingagent. Use only in a well ventilat-ed fume hood. Wear propergloves, proper eye protectionand other protective clothingwhen handling this material.

Refer to the instrument manualfor the proper use of equipmentdescribed in this method.

CALIBRATION OF THESPECTROPHOTOMETER

1. Transfer 1.00 ml of the 1000ppm nickel reference standardsolution to a 1 L volumetric flaskand dilute to volume with deion-ized water. This stock standardwill have nickel concentration of1.00 µg/ml.

2. Transfer 2.00, 4.00, 6.00, 10.00,and 20.00 ml aliquots of the 1.00µg/l nickel stock standard to 100ml volumetrics containingapproximately 50 ml of deionizedwater.Add one drop ofhydrochloric acid and mix. Add 5ml of the citric acid solution andmix. Add 2 ml. of saturatedbromine water and mix. Add 3ml of concentrated ammoniumhydroxide and mix. Add 2 ml. ofheptoxime solution, mix anddilute the flask to volume.


Note: These standard concentra-tions will be equivalent to 0.1,0.2, 0.3, 0.5 and 1.0 ppm ofnickel if a 20 gram sample ofcaustic soda is used.

3. A reagent blank is prepared inthe same manner although nonickel solution is added to theblank.

4. The solutions should set for 20minutes from the time the hep-toxime is added to allow for fullcolor development.

5. Set the spectrophotometerwavelength to 445 nm. Refer tothe instruction manual suppliedwith the spectrophotometer forspecific instructions on the prop-er use of the instrument.

6. Transfer portions of the reagentblank solution to matched spec-trophotometer cells and placethem in both the reference andsample cell holders of the spec-trophotometer if it is a doublebeam instrument or just the sam-ple cell holder if it is a singlebeam instrument. Zero theabsorbance reading of theinstrument.

7. With the blank solution remain-ing in the reference compart-ment (double beam instrumentonly), record the absorbancereadings for each calibrationstandard. Plot absorbance vs.nickel amount (µg) using a linearregression program to generatea calibration curve.

ANALYSIS OF SAMPLES

1. Into a 100 ml volumetric flask,weigh to the nearest 0.01grams, the amount of causticsoda product needed to accu-rately determine its nickel con-centration. After addition of theproduct, add 20 ml of deionizedwater. Use the following tableas a guideline for the correctsample size.

Expected Ni Sample Concentration Size0.0-0.1 ppm................20 g0.1-0.2 ppm................10 g0.2-0.4 ppm................. 5 g0.4-0.8 ppm...............2.5 g

2. Place the flask in an ice bath tocool the contents. Slowly neu-tralize the sample with concen-trated hydrochloric acid. Checkthe pH of the solution with pHtest paper. The paper can betouched to the flasks stopperafter HCl addition and somemixing. Do not add a piece ofpH paper to the flask itself. Thepaper can dissolve and theresulting turbidity can affect thefinal colorimetric reading. Forevery gram of 50% causticsoda, 1.04 ml of concentratedHCl will be required. When theneutralization point is near, thesolution can be adjusted toneutral by the addition of moredilute HCl. After the sample ispH neutral, add one additionaldrop of concentratedhydrochloric acid.

CAUTION: Neutralization ofthese products with concen-trated acid will generate aconsiderable amount of heat.Add the acid in small incre-ments and cool in betweenadditions to prevent splash-ing and excessive heating.

3. After the solution has reachedroom temperature, add 5 ml ofthe citric acid solution and mixwell. The purpose of the citricacid is to complex any iron thatmight be present so that itdoes not compete with thenickel for consumption of thecomplexing reagent. If concen-tration of iron in these samplesis known to be low, it may notbe necessary to add thisreagent.

4. Add 2 ml of saturated brominewater and mix thoroughly.

5. Add 3 ml of concentratedNH40H and mix.

6. Add 2 ml of heptoxime solutionand mix.

7. Dilute the flask to volume withdeionized H2O and mix thor-oughly.

8. Allow the flasks to set for 20minutes from the time the hep-toxime was added for full colordevelopment.

9. Carefully transfer a portion ofthe sample solution to a 5 cmcell, stopper the cell and placein the sample compartment ofthe spectrophotometer. (Fordouble beam instruments, thereagent blank should be placedin the reference compartment.)Read the absorbance of thesample solution at a wave-length of 445 nm.

10. Use the absorbance reading toobtain the amount (µg) of nick-el in the sample solution fromthe calibration curve.

11. Calculate the concentration ofnickel in the original productand report as ppm.

CALCULATIONS

Let:C = concentration of Ni in

µg/100 ml of solutionW = weight of sample in gramsppm Ni = C/W

EXAMPLE20.11 g of caustic soda were

analyzed by the above procedure for nickel. Anabsorbance reading of 0.1000 wasobtained on the sample solution.Standards containing 2 µg to 20 µgNi were prepared and a calibrationcurve generated using ProcedureA.

51 of 52

Methodsof Analysis

Standard AbsorbanceConcentration Reading2.00 µg Ni . . . . . . . . . . . .0.02584.00 µg Ni . . . . . . . . . . . . .0.0510 6.00 µg Ni . . . . . . . . . . . . .0.077510.00 µg Ni . . . . . . . . . . . .0.1287 20.00 µg Ni . . . . . . . . . . . .0.2610

A calibration curve was generat-ed by performing a linear regres-sion analysis on these readings. Inthis example, the coefficient of cor-relation is 1.000. Coefficients ofcorrelation greater than 0.99 areacceptable.

From the linear regression equa-tion, the absorbance readingobtained for the sample is 0.1000which is equivalent to 7.72 µg Ni.ppm Ni = 7.72 µg Ni/20.11 g ppm Ni = 0.38

QUALITY ASSURANCE

Perform duplicate and samplespike analyses on a minimum of10% of all samples analyzed.Duplicate analyses should bereproducible within 15%. Spikesamples with nickel at approxi-mately 1 to 2 times the concentra-tion that is expected.

Compare concentrations of nickelfound in the analyzed samples toOxyChem specifications.

REFERENCES

1. APHA, AWWA, WPCF;Standard Methods for theExamination of Water andWastewater; 17th ed.

2. Vogel, Arthur I., A Text bookof Quantitative Inorganic Analysis, 3rd edition, 1961.

Kolthoff, Sandell, Meehan &Bruckenstein; QuantitativeChemical Analysis; 4th ed.; Macmillan Co.

DETERMINATION OF MERCURY IN CAUSTIC SODA

PURPOSE AND THEORY

Mercury is a toxic material andmust be monitored as a pollu-tant. It can cause adverse effectsif present in caustic soda usedin certain manufacturingprocesses.

Mercury is converted to mercuricion by oxidation with sodium per-manganate, then reduced to metal-lic mercury which is aerated fromthe solution and determined byflameless (cold vapor) atomicabsorption spectroscopy.

PROCEDURE

ASTM E 538: “Standard TestMethod for Mercury in CausticSoda (Sodium Hydroxide)” is theprocedure used for analyzing mer-cury in caustic soda products andis published in the Annual Book ofASTM Standards, Vol. 15.05. For acopy of this test procedure, con-tact: ASTM, 1916 Race St.,Philadelphia, PA 19103 orOxyChem’s Technical ServiceDept.

Notes52 of 52

® Viton is a registered trademark of DuPont de Nemours.

® Teflon is a registered trademark of DuPont de Nemours.

® Hastelloy is a registered trademark of Haynes International.

® Inconel is a registered trademark of Inco Limited.

® Monel is a registered trademark of Inco Limited.