RPP · 1 RPP Corporation is a world-class manu-facturer of custom fabric reinforced elas - tomeric diaphragm seals and other highly engineered molded rubber products. RPP specializes

RPPThe Specialists in Custom Diaphragm Seals

ii ii

ContentsAbout RPP .............................................................................1Markets Served ..................................................................2RPP Value .............................................................................3Capabilities .........................................................................4

Large Diaphragms ........................................................4

Diaphragms for the Nuclear Power Industry ......4

Reverse Engineering ...................................................5

Inventory Stocking Programs ...................................5

Introduction to Diaphragm Seals ..............................6Diaphragm Seal Selection ............................................8Design Considerations ...............................................10Diaphragm Materials ..................................................12Typical Diaphragm Specifications ........................14

RPP Corporation12 Ballard Way, Lawrence, MA 01843 USA+1-800-232-2239 | www.rppcorp.com

1

RPP Corporation is a world-class manu-facturer of custom fabric reinforced elas-tomeric diaphragm seals and other highlyengineered molded rubber products. RPPspecializes in hard to make products suchas rolling “Top Hat,” convoluted and dou-ble acting diaphragms. With compressionmolding presses capable of exerting over1000 tons of pressure, RPP produces itslargest diaphragms for the nuclear, oil andgas industries.

Always matching materials to customer requirements, RPP utilizes over 45 stan-dard and custom elastomers such as nitrile,silicone, EPDM, AFLAS,® Polyurethane,and Viton,® and more than 25 differentfabrics including Nylon, Polyester, Vectran® and Nomex®.

Supplying industrial users around theglobe since 1963, RPP is committed toproviding unique and cost effective solutions for all application requirements.With 45,000 square feet of space and morethan 100 employees, RPP has the capacity,equipment and talent to take your projectfrom engineering concept to productiondeliveries. RPP customers also benefit froma stable workforce as the average term ofemployment is over 7 years.

The RPP technical team and its 200 yearsof combined industry experience can offersolutions to your most challenging in-fielddemands. From design assistance, to tool-ing fabrication, materials development andinventory management, RPP is there tohelp you develop high performing robustproducts to tight tolerances and withinshort lead times.

Why settle for an off-the-shelf, catalog sealwhen a custom diaphragm seal from RPPcan give you a competitive advantage? Contact us today to learn how RPP canhelp solve your current technical problemsor to develop your next generation product.

About RPP

With customers in over 30countries on six differentcontinents, RPP has the ex-perience and know-how toprovide technical supportand quality products to allparts of the globe. China,Japan, Hungary, Brazil andthe United Arab Emirates area few examples of the farreaching places where RPPproducts can be found.

RPP Europe is RPP’s manu-facturing, distribution andtechnical support operationserving customers locatedin Europe and Africa.

2

Markets Served

Supplying industrial users since 1963RPP fabric reinforced diaphragm seals are used in a widerange of industrial and scientific equipment.

Our OEM customers provide products toany industry where the flow of liquids orgasses must be controlled with zero frictionand/or leakage. Our primary markets include Process Control, LP and NaturalGas Regulation, Water Management andMedical/Industrial Systems.

Process Control: Control valves areused in closed loop systems whereprocesses such as temperature, pressure orflow are being controlled. RPP diaphragmsprovide the required sensitivity to react tochanges in differential pressure and assureaccurate control of the process. These mayoccur in any industry but are mainly in thepower generation, chemical and oil and gasmarkets.

Agriculture & Water Manage-

ment: The water management market includes products for the regulation, distribution and filtration of municipaland irrigation water. The primary endusers are in agriculture and recreation

such as golf courses, municipal parks andplaying fields. RPP diaphragms allow watermanagement valves and regulators to function under a wide range of pressuresand in all types of weather conditions fromextreme heat to extreme cold. They can beactuated from remote control centers witha high degree of reliability.

LPG and Natural Gas Regulators:

Regulators in the LPG and natural gasmarket are used primarily in thedistribution network to reduce systempressures from wellhead to end user. Oneof the largest applications is the houseservice regulator that is used in front of thegas meter. Because gas is compressible itmust be maintained at a constant pressureso that the gas meter can be used tomeasure the volume. The diaphragm alsoserves as a safety device by limiting themaximum pressure that is allowed throughthe meter. RPP diaphragms are used to sealthe piston in a regulator force/balancesystem because of their sensitivity to slightchanges in system pressure.

Medical Devices/Industrial

Systems:Many medical applicationsrequire the accurate dispensing andmetering of fluids and gases. Diaphragmsprovide positive displacement, plus aclinically clean seal which does not trapbacteria, as would interference type seals.Typical applications include measurementdevices and ventilators. RPP diaphragmsare also used in a wide range of industrialapplications such as pumps, pneumaticactuators, tensioning devices, shock andvibration apparatus, metering devices,axial fan controls, environmental controls,and in many other systems where zeroleakage, no breakaway friction andsensitivity are required.

Customer Requirements

Inquiries are reviewed byRPP engineering to deter-mine each Customer’s spe-cific requirements.Diaphragm height, cylinder& piston diameters, effectivearea, hardware design, op-erating temperatures andmedia are some of the de-termining factors. With athorough understanding ofthe key operating parame-ters, RPP will recommendan appropriate elastomer /fabric combination alongwith diaphragm dimen-sional specifications.

Diaphragm Design

The design of a di-aphragm is criticalto its performanceand life cycle. Cus-tomers often rely onRPP’s assistance tocome up with highperformance, costeffective, diaphragmdesigns.

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RPP Value

RPP utilizes its broad rangeof molding presses to pro-duce diaphragms from lessthan 1 inch (12mm) up to 46inches (1168mm) in diame-ter. One hundred moldingpresses means RPP canhandle annual quantity re-quirements that run any-where from single digits tomillions of parts per year.

Over 200 years of combined industry experienceOur technical team can offer solutions to your most challengingin-field demands.

From design assistance, to tooling fabrica-tion, materials development and inventorymanagement, RPP is there to help you develop high performance robust productsto tight tolerances within short lead times.

Diaphragm & HardwareDesign Assistance

RPP’s technical team has decades of experi-ence assisting customers with custom product designs focused on performance,quality, manufacturability and cost. Fromcustomer requirements, to diaphragm design and design validation, RPP is thereto help customers develop the best prod-ucts while avoiding costly mistakes. RPPcontinually reviews mold design tech-niques and raw material availability to en-sure we take advantage of technologicaladvancements and new material capabili-ties. We look forward to helping compa-nies with their toughest problems andregularly “come to the rescue” of those whomay have originally chosen a different sealing solution.

Standard & CustomizedElastomers & Fabrics

RPP uses a wide variety of standard andproprietary elastomers and fabrics. Weregularly produce products utilizingchallenging compounds such as EPDM,Viton®, AFLAS®, FFKM, Saturated Nitrile(HNBR) and Silicone and fabrics likePolyester, Nylon and high temperature/high strength fabrics such as Nomex® andVectran®. Our materials group has on-going projects to improve compounds &fabrics and identify alternative sources forhigh quality, cost competitive raw mate-rials. If an existing elastomer or fabric isnot sufficient, we will work with you andour suppliers on developing a uniquesolution to meet your requirement.

Tool Design & Fabrication

RPP fabricates molds and tools up to 26inches/660mm in diameter in its fullyequipped machine shop. RPP utilizesnearby, outside shops to produce largermolds. This combination of internal andlocal resources enables RPP to provide short

lead times for your critical applications.Because we have control of the process fromdesign concept through mold fabrication,RPP can also keep mold pricing low. This isjust one of the valuable resources ourcreative technical team uses to providecustomer solutions quickly and in a costeffective manner.

Tooling Design

Compression moldsand trim dies can befabricated once thediaphragm design isfinalized. In addi-tion to the di-aphragm shape, theelastomer and fab-ric properties im-pact the molddesign. The fabrica-tion of single ormultiple cavitymolds is dependenton annual quantityrequirements.

Design Verification

Molds are checkedfor dimensional accu-racy using a simu-lated elastomeric coldrubber test. This en-sures the moldedpart can beproduced asspecified withan optimally designedmold.

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Capabilities

Large Diaphragms

RPP specializes in very large custom diaphragms. Utilizing some of the largestcompression molding presses available inthe industry, RPP can manufacture dia-phragms up to 46 inches/1.168 meters indiameter and up to 15 inches/381mm tall(assuming a 1:1 bore to height ratio). Ourraw material preparation equipment, largeformat compression molding presses andour knowledge of elastomers and fabricsgive RPP the ability to manufacture large,high quality, fabric reinforced, single ordouble coated, diaphragms that very fewcompanies have the capability to provide.

Additionally, our customers obtain a cus-tomized elastomer/fabric combination thatfits their targeted requirements. Our largestdiaphragms are typically used in controlvalves and pumps for the oil & gas, utilityand nuclear industries.

Diaphragms for the NuclearPower Industry

RPP is a premier supplier of diaphragm sealsfor control valves for the power generationindustry. RPP manufactures some of itslargest diaphragms for the nuclear power industry in accordance with 10CFR50 Appendix B regulations. RPP employees arespecially trained in the production, qualityand record keeping requirements for nu-

clear products. RPP’s 10 CFR 50 Appendix B Certified Material

Option is a comprehensive

program of testing and documentedprocesses related to the tested physical char-acteristics of commercial grade material usedin “safety related applications.” An accred-ited testing lab verifies that raw materialsmeet specific critical characteristics. Bychoosing our Certified Material Option,customers can avoid the time associatedwith conducting outside testing of “safetyrelated materials” and the cost of purchasingASTM D412 slabs. There may also be op-portunities to reduce finished product leadtimes and inventory levels.

Typical elastomers for nuclear applicationsinclude Nitrile, Saturated Nitrile (HNBR),EPDM and Silicone. RPP diaphragms utilize highly engineered industrial fabricssuch as high temperature polyamides, multifilament meta-aramids, and liquidcrystal polymer based fabrics.

RPP can manufac-ture diaphragms upto 46 inches/ 1.168meters in diameterand up to 15 inches/381mm tall.

Material Procurement

RPP procures itsraw materialsfrom a select num-ber of approvedsuppliers. Elastomersuppliers mix com-pounds to specificrecipes. Textile millsproduce fabrics with pre-determined weave, knit andfinishing characteristics.This stable procurementprocess results in a consis-tent raw material delivery toRPP and consistent endproduct performance to ourcustomers.

Process Development / Design Validation

Experienced techni-cians are assignedthe task of develop-ing a robust and repeatable manu-facturing processthat includes elastomervolumes, cure times, and press tonnage andtemperatures. The end result is a sample lot that thecustomer uses for mold andpart approval, as well as cycletesting.

5

Reverse Engineering

Having trouble finding a replacement di-aphragm for an obsolete actuator valve orpump? RPP can help. By reverse engineeringyour legacy diaphragm, RPP can provide anew diaphragm that in most cases will bebetter than the original at a fraction of thecost to replace an entire hardware assembly.Starting with the legacy diaphragm, operat-ing requirements, and in some cases, the actual hardware, RPP will develop materialspecifications, design the diaphragm and acompression mold. If needed, RPP can alsoreverse engineer the elastomer and develop a custom material that will closely match theoriginal. Part samples are provided for cus-tomer life cycle testing and part and moldapproval before RPP produces whateverquantity of parts the customer desires. In ad-dition to avoiding the cost of new hardware,customers also end up with a diaphragm design and mold they can use for future repairs.

Over the past several years, RPP has helpedutility companies and other end users getolder equipment back on-line and produc-ing revenue. What do you need help with?

Production Verification

At the start of each pro-duction run, a first articleverification is completedto ensure that the specificprocess will produce di-aphragms that meet cus-tomer specifications. Inprocess inspections areconducted to verify theprocess remains in con-trol. Final inspection isused as a last step to en-sure customers only re-ceive top qualityproducts.

Product Delivery

RPP is committed toshort lead times andon-time-delivery.Where annual quantityrequire ments merit it,RPP will produceproduct according tocustomer forecastsand establish inven-tory stocking pro-grams. This approachallows customers tomaintain lower inven-tory levels while beingable to respond tosales opportunities.

On Time Delivery %99%

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2009 2010 2011 2012

Inventory Stocking Programs

RPP supports customers who require regu-lar shipments of product with CustomizedStocking Programs. With KanBan or Super-market arrangements, RPP maintains specified levels of inventory and managesJust-In-Time order fulfillment. In exchange,Customers issue blanket purchase ordersand communicate forecasted requirementson a regular basis. Customers can reducetheir inventory while building a safety stockand virtually eliminate purchase order lead-times. These programs work best for highervolume products or lower volume productsthat have a consistent requirement.

Superior Quality & On Time Delivery

RPP is committed to exceeding customerexpectations for quality, delivery and tech-nical support. RPP builds quality into theproduct at every step by following Designfor Manufacturability concepts throughoutthe process. We have an active ContinuousImprovement program based on LeanManufacturing principles and a customer-centric vision. RPP Corporation has beenISO-certified since 1997. We were one ofthe first companies in the industry to embrace the ISO standard, and are cur-rently certified to ISO 9001.

6

Introduction to Diaphragm Seals

The energy conversion in such systems isusually accomplished by a cylinder—anenclosed, stationary barrel containing amoveable piston. Liquid or gas introducedunder pressure into the cylinder exertsforce on the piston head, creating motionthat can pull, push, position, open, close orregulate a mechanical device or assembly.

To keep the pressurized fluid from leakingpast the moving piston, a dynamic (motion-tolerant) seal of some kind is required. Sev-eral types of dynamic seals are commonlyused, with the selection depending on thespecific requirements of the application.

Fabric reinforced molded diaphragms areflexible, circular seals, molded under hightemperature and pressure, with concentric3D contours. The contours flex to permitaxial motion of the central area with re-spect to the outer circumference.

Reinforced diaphragms are producedfrom tough, flexible elastomer (whichserves as a fluid barrier), bonded to oneor both sides of a high-tensile-strength fabric that supplies the mechanical rein-forcement needed to withstand high pres-sures. They are widely used instead ofinterference seals and flat diaphragmswherever a relatively long piston stroke isneeded, and where dynamic and break-away friction would adversely affect thespeed, accuracy or repeatability of an operation, and/or where blow-by leakagecannot be tolerated.

Fabric reinforced molded diaphragms oftenprovide the best possible solution to a seal-ing problem—and frequently they are theonly solution. They are widely used wher-ever accurate, reliable response to hydraulicor pneumatic pressure changes is needed.

Converting fluid or gas pressure into force or motionHydraulic and pneumatic systems that do this invariably usesome form of dynamic seal.

Pumps

Diaphragms are usedin double-actingpumps to move slur-ries and other difficult ma-terials without abrasion orleakage. Diaphragms arecommonly used in bilge(marine) pumps and as amechanical seal for pumpcontrols.

Pressure Regulators

The diaphragm ispart of a force /balance system,and senses deviation from the desiredset point, which in turn allows pressureto build up or vent down until the setpoint is once again attained. RPP di-aphragms are used in air, water andpropane regulators, natural gas houseservice regulators, back-flow prevention,medical respirators and relays.

7

RPP diaphragms are routinely used in suchdiverse applications as process controlequipment, water management, gasregulation, precision medical equipmentand in industrial systems such aspumps, tensioning devices, vibrationapparatus and metering devices. Sincethey can be custom designed quickly and

inexpensively to meet a wide variety ofconditions and requirements, RPPdiaphragms frequently represent invaluablesolutions to equipment design problems.

Molded diaphragms are composed oftough, flexible, carefully engineeredlaminates. In general, the laminates aremade out of elastomer and fabric. Metal orplastic inserts are sometimes molded in toserve as a piston or rigid backing for a valveseat. A layer of PTFE may also be moldedon to improve resistance to harsh chemicalsand abrasives.

The elastomer is one or two pressure-tightlayers of tough elastomeric (syntheticrubber) material selected (or speciallycompounded) for long life under a specificset of operating conditions (fluid type,temperatures, etc.). Depending on theapplication, the elastomer is bonded to oneor both sides of a fabric base. The fabric isa high tensile strength base layer of highlyengineered woven fabric, designed towithstand the stresses induced by highpressures. Medium tensile strength basefabrics are also available that have beenspecially designed for ultimate sensitivityand low hysteresis.

Dispensing & Metering

The accurate re-peatable mechan-ical motion of adiaphragm is fre-quently used indispensing veryprecise volumesof various liquids.

Air Brakes

Diaphragms allow theuse of inexpensive hard-ware design, yet providehigh reliability in theprocess of converting airpressure to braking force.RPP manufactures dia-phragms for large vehicleand train braking systemsas well as force transducers.

8

Diaphragm Seal Selection

A surprising number of parameters andphysical considerations are involved, and asuccessful design often depends on a com-plex multi-variable optimization relying onthe experience and understanding of thedesigner rather than a straightforward stepby step engineering method. As a result, itis usually preferable, and more cost effec-tive, to custom-design the seal to fit the jobrather than to attempt to use a standard,off-the-shelf product. Nevertheless, certainguidelines can be used in selecting the gen-eral type, configuration and, in some cases,the materials best suited to a proposed diaphragm seal.

The typical molded diaphragm will fallinto one of four categories:

• Rolling “Top Hat;” • Convoluted; • Offset-Convoluted, and;• Double Acting.

Rolling diaphragms are used when a con-stant effective area is needed in an applica-tion with a high stroke/diameter ratio.Convoluted diaphragms offer maximumcycle life and are pre-molded into the in-stalled shape for ease of installation. AnOffset-convoluted diaphragm is the choicefor longer stroke lengths and ease of instal-lation. Actuating pressure can be appliedfrom both directions in Double acting diaphragms, which are usually double-coated to withstand harsh media.

Design Considerations

Selection of the overall form of thediaphragm is determined, generally, by theneed to conform to existing or plannedhardware and/or special considerationsimposed by the mechanical operation to beperformed. Such considerations include:

1. Power Stroke Direction–Uni-directional or bi-directional (i.e. is actuatingpressure applied from one side or alternatelyfrom both sides of the piston). Double-Coated, Double Acting diaphragms are usedin bi-directional applications.

2. Stroke Requirement–The diaphragmheight relates to the overall height and diam-eter of the piston and the convolution heightand width. The piston travel on each side ofthe clamping flange determines the height ofthe diaphragm. If the projected piston mo-tion is relatively long, a rolling diaphragm isgenerally required. For shorter stroke lengths,offset or planar types can be used.

Specifying the right molded diaphragm Selecting the diaphragm that will perform best in a particularapplication can be a complex task.

Pressure switches

The diaphragm isused to effect themechanical openingand closing of anelectrical contact inresponse to an inputpressure signal. Typ-ical applications in-clude strumentationand HVAC systems.

Flow Meters

Requiring very little energy tomove, and with aconstant displace-ment, diaphragmsare used to meas-ure gas flow interms of volume.

9

3. Flange Type–Beaded, for quick, easyinstallation or flat for higher pressure capa-bilities and for less expensive hardware.

4. Effective Area–The EffectiveArea/Diameter is the center line betweenthe cylinder bore and the piston diameter.It represents the pressurized area of the diaphragm. If an application requires aconstant actuating pressure across the total piston stroke, a rolling diaphragm isrequired since it is the only configurationproviding a constant effective areathroughout the stroke cycle.

5. Pressure Capability–It is the baselayer of fabric that enables the diaphragmto withstand the stresses imposed by theactuating pressure. The anticipated maxi-mum differential pressure, therefore, willdetermine the type and strength of the fabric to be used. In addition, if back pres-sure is developed at the bottom of the pis-ton stroke (i.e., if the cylinder is notvented), this will affect the type of coatingspecified.

6. Temperature Capability–The temperature extremes anticipated in an application play a major role in the selec-tion of both the elastomer and fabric.

7. Operating Media–The chemical &physical nature of the fluid (or fluids) andgases, which will be contacting the di-aphragm naturally, plays a key role in theanticipated service life of the diaphragm.Care in the selection of the elastomer isneeded to provide maximum resistance tocorrosive or harsh media.

Pneumatic Positioning

With their constanteffective area andquick, accurate response to slight pressurechanges, diaphragms are fre-quently used to position devicesprecisely in response to minutechanges in signal pressure. Atypical use for these types of diaphragms is in air cylinders.

Valves and Valve Actuators

As a valve seat, the diaphragmcontrols the flow of liquids inwater management, irrigation,blowout prevention and slurry systems. In an actuator appli-cation, the diaphragm reacts to small changes in system con-trol pressure to open or close a process control valve used formaintaining temperature or pressure. Valve actuators areused in a wide variety of applications (high pressure, naturalgas and liquid propane regulators, vibration dampening, webtensioning) and industries (chemical, petroleum, mining, nu-clear, paper, textiles, heating and air conditioning).

550°F 288°C

500° 260°

450° 232°

400° 204°

350° 177°

300° 149°

250° 121°

200° 93°

150° 65°

100° 38°

50° 10°

0°F -18°C

-50° -45°

-100° -73°

Silicone

Flurosilicone

EPDM

Fluorocarbon

Polyu

rethane

Nitrile

Neoprene

Epichlorohydrin

Polyamide (Nylo

n)

Polye

ster (D

acron)

High Temperature Polyamide (Nom

ex®)

10

Design Considerations

Elastomer/Fabric LaminateFactors to consider include pressure, media,cycle life & sensitivity

Single Coat Construction

For use in single-acting cylinders (pressureapplied in one direction). A single layer ofelastomer is bonded to one side of the basefabric. This construction is generallyemployed in long-stroke diaphragms.

Double-Coat Construction

Used for double-acting cylinders (pressureapplied alternately in each direction), orwhere extra durability is required forlonger life or abrasive media and thestroke/diameter ratio is not excessivelylarge. Elastomer is bonded to both sides of the base fabric.

In the axial direction,fabric provides high resistance to elongationand furnishes the tensilestrength that enables theseal to withstand highdifferential pressures.

In the radial directionfabric stretches to allowa diaphragm to roll witha constant effective area.

Operating pressurerequirements drivefabric choice. Si

licon

eFlu

rosilico

neEPDM

Fluorocarbo

nPo

lyurethan

eNitrile

Neop

rene

Epich

loroh

ydrin

Polya

mide (Nylo

n)Po

lyeste

r (Da

cron

)High Te

mpe

rature Poly

amide (Nom

ex®)

Elastomer/Fabric Operating Temperatures

11

Flange DesignFlange retention design is a function ofcost and application requirements.

Beaded Flange

The bead simplifies assembly of thediaphragm to the hardware. The seal isenhanced by the bead, which spreadsunder pressure in a properly sizedhardware groove.

Opposing Beaded Flange

With double-coated applications RPPcan produce diaphragms with opposingbeads and even offset-opposing beadswhere the top bead is not in alignmentwith the lower bead.

Flat Flange

Used for larger diaphragms and all highpressure applications. Flat flange allowsfor less expensive hardware.

Operating temperature isa primary factor in fabricand elastomer selection.

The elastomer andoperating media mustbe compatible

Fabric to elastomer adhesionis a key to long cycle life.

A number of standard elastomers are available, one of which usually meets theapplication requirements. RPP materialspecialists also work closely with our syn-thetic rubber compounders to develop custom materials to meet specific customerneeds. RPP’s proprietary EPDM elastomer

comes in three colors, white, purple andstandard black. Its high degree of inertnessand robust physical properties makes itideal for harsh water environments withhigh chloromine & chlorine levels. A newlow cost Type A FKM is a popular choicefor the toughest chemical applications.

12

Diaphragm Materials

Elastomer

The elastomer layer must be extremely thin (for maximum flexibility), very tough(to withstand repeated flexing over a longlifetime), able to handle anticipatedoperating temperatures, and resistant towhatever chemicals, fluids or gases it maybe contacting.

Typical Diaphragm Elastomers

Elastomer Temperature Air Generally Resistant Generally Range Permiability To: Attacked By:

Nitrile (NBR) -40F — 250F 0.80 Petroleum-Based Oils Esters and Chlorinated Solvents-40C — 121C

Neoprene (CR) -25F — 250F 1.40 Weather and Ozone Esters and Chlorinated Solvents-32C — 121C

Ethylene Propylene (EPDM) -40F — 250F 10.00 Weather and Ozone Aromatic Hydrocarbons-40C — 149C

Epichlorohydrin (CO/ECO) -20F — 300F 0.40 Petroleum-Based Oils Esters and Chlorinated Solvents-29C — 149C

Silicone (SI) -85F — 500F 175.00 Weather and Ozone Gasoline and Chlorinated Solvents-65C — 260C

Fluorosilicone (FSI) -85F — 450F 85.00 Petroleum-Based Oils and Ozone Ketones and some Hydralic Fluids-65C — 232C

Fluorocarbon (FKM) (Viton®) 10F — 550F 0.30 Gasoline and Chlorinated Solvents Ketones and some Esters-12C — 288C

Polyacrylate (ACM) -20F — 350F 1.50 Hot Oil, Ozone, Petroleum Solvents Water, Esters and -29C — 177C Aromatic Hydrocarbons

Polyurethane (PUR) -40F — 250F 0.40 Good Abrasion & Ozone Resistance Acids,Ketones, Esters, Chlorinated & -40C — 121C Nitro Hydrocarbons

Note: RPP Corporation also has several specialty compounds for applications requiring AFLAS, Saturated Nitrile, and Epichlorohydrin

13

Additionally, because RPP manufactures its own coated fabrics, diaphragms can beproduced with almost any combination of elastomers and fabrics. RPP can evenproduce coated fabrics with different elastomers on each side of the fabric.

The elastomers listed in the table on page12 are typical of those frequently used inmolded diaphragm construction. RPP utilizes over 45 standard and custom compounds based on these elastomers.

Typical Diaphragm Fabrics

Fabric Type Maximum Typical Temperature Usage

Polyester 325F / 163C Generally used for single-coated diaphragms Medium to high strength

Polyamide 275F / 135C Generally used for double-coated diaphragms High Strength & extremely high temperature

High-Temp 500F / 260C Used in high-temperature, single and double-Polyamide/Meta-Aramid coated applications. Medium to high strength

Liquid Crystal 500F / 260C High temperature, extremely high tensile Polymer based fabrics strength applications.

Fabric

The fabric used in molded diaphragms is a highly engineered industrial textile with a unique property. When formed in the diaphragm, it stretches easily in the radialdirection, allowing for flexing of the diaphragm convolution in the axial direc-tion, it provides high resistance to elonga-tion and furnishes the tensile strength thatenables the seal to withstand high differen-tial pressures and transmit force to the pis-ton head. A variety of diaphragm fabrics,woven specially for RPP, are available. RPPhas developed over 20 unique varieties offabric designed to meet specific operatingconditions. Special, low cost knit versionsare also available for high volume and lowhysteresis (for more sensitive applications).

RPP engineers havedeveloped less costlymaterial equivalents forhigh temperature/highstrength fabrics such asNomex® and Vectran®.

14

Typical Diaphragm Specifications

Rolling “Top Hat”• Maximum Stroke to approximately 1.8 x cylinderbore diameter

• Differential pressure capability up to 150 psi

• Pressure applied from one direction only

• Must be formed into convoluted shape

Offset Convoluted• Moderate stroke to approximately 0.5 x cylinder bore diameter

• Pre-molded shape for easy installation

• Double coating limits diaphragm height whileincreasing durability when in contact withrough surfaces

Bead Width

Cylinder Bore

Bead Height

Piston Radius

Head/FlangeThickness

Piston Diameter

HeightFlangeRadius

SidewallThickness

ConvolutionWidth

Fabric PatternVisible This

Side

Single & Double Coated; Beaded & Flat Flange

Cylinder Bore Range 0.25-0.99 1.00-2.50 2.51-4.00 4.01-8.00 over 8.00

Sidewall Thickness 0.013/0.017 0.014/0.020 0.020/0.028 0.030/0.040 0.038/0.052Double Coated Flat Flange Only: 0.035/0.055

Head/Flange Thickness 0.015/0.025 0.015/0.025 0.025/0.035 0.030/0.040 0.035/0.055

Piston Radius 0.094 0.125 0.156 0.250 0.250Double Coated Flat Flange Only: 0.310

Flange Radius 0.031 0.062 0.094 0.125 0.125Double Coated Flat Flange Only: 0.250

Convolution Width 0.085 0.094 0.156 0.250 0.250

Bead Width 0.090/0.096 0.122/0.128 0.184/0.190 0.247/0.253 0.247/0.253

Bead Height 0.091/0.097 0.131/0.139 0.195/0.205 0.263/0.277 0.263/0.277

Single Coated

Cylinder Bore Range 1.00-2.50 2.51-4.00 4.01-8.00 over 8.00

Sidewall Thickness 0.015/0.025 0.020/0.030 0.030/0.040 0.038/0.052

Head/Flange Thickness 0.015/0.025 0.020/0.030 0.030/0.040 0.035/0.055

Piston Radius 0.125 0.156 0.250 0.310

Flange Radius 0.062 0.094 0.125 0.188

Convolution Width 0.125 0.156 0.250 0.375

Cylinder Bore

OffsetPiston Radius

Head/Flange Thickness

Piston Diameter

Height

FlangeRadius

SidewallThickness

ConvolutionWidth

Double Coated




Piston Radius 0.125 0.156 0.250 0.370

Flange Radius 0.094 0.125 0.250 0.250


15

For more detailed specifications, including metric equivalents, visit our website, rppcorp.com

Single Coated; Beaded Flange

Cylinder Bore Range 1.00 - 2.50 2.51 - 4.00 4.01 - 8.00 over 8.00



Piston Radius 0.062 0.094 0.125 0.188

Flange Radius 0.062 0.094 0.125 0.125


Bead Width 0.122/0.128 0.184/0.190 0.247/0.253 0.247/0.253

Bead Height 0.131/0.139 0.195/0.205 0.263/0.277 0.263/0.277

Single & Double Coated; Flat Flange

Cylinder Bore Range 0.25 - 0.99 1.00 - 2.50 2.51 - 4.00 4.01 - 8.00 over 8.00

Sidewall Thickness 0.013/0.017 0.014/0.020 0.020/0.030 0.030/0.040 0.038/0.055


Piston Radius 0.031 0.062 0.094 0.125 0.125(Double Coated) 0.062 0.094 0.125 0.187 0.250

Flange Radius 0.031 0.062 0.094 0.125 0.125(Double Coated) 0.062 0.094 0.125 0.187 0.250

Width 0.085 0.094 0.250 0.250 0.250

Bead Width

Cylinder Bore

Bead Height

Piston Radius

Bead Width


Convolution Width

Sidewall Thickness

FlangeRadius

Convoluted• Limited stroke to approximately 0.25 x cylinder bore diameter

• Pre-molded shape for easy installation

• Differential pressure capability to 150 psi

• Pressure applied from one direction only

• Double coating increases durability when in con-tact with rough surfaces.

Cylinder Bore

Piston Radius


SidewallThickness

FlangeRadius Convolution

Width

Height

Cylinder Bore

Piston Radius

Head/Flange Thickness Sidewall ThicknessFlangeRadius

ConvolutionWidth

Height

Double Coated; Flat Flange




Piston Radius 0.094 0.125 0.188 0.250

Flange Radius 0.094 0.125 0.188 0.250


Double-ActingDished• Moderate stroke to approximately 0.5 x cylinder bore diameter

• Pressure can be applied from both directions

• Double coating increases durability when incontact with rough surfaces.

The RPP Difference

Selecting and specifying the diaphragm sealthat will provide maximum performance andthe longest possible service life calls for adegree of expertise gained only through yearsof experience in diaphragm seal design andapplication. RPP's technical team averages over25 years of experience in the art and science offabric reinforced diaphragm seals. Customersoften see them as an extension of their ownengineering staffs.

To have RPP be your resource for customdiaphragm seals or for more information,please vist our website at rppcorp.com or callus at +1-800-232-2239.

Nomex® and Viton® are a registered trademarks of E. I. du Pont de Nemours and Company

AFLAS® is a registered trademark of Asahi Glass Co. Ltd.

Vectran® is a registered trademark of Kuraray Co. Ltd.

16

Specifications

Cylinder Bore Range 0.25-0.99 1.00-2.50 2.51-4.00 4.01-8.00 over 8.00

Cylinder Bore Range 0.25-0.99 1.00-2.50 2.51-4.00 4.01-800 over 8.00

Sidewall Thickness 0.013/0.017 0.014/0.020 0.020/0.028 0.030/0.040 0.030/0.040


Piston Radius 0.094 0.125 0.156 0.25 0.25

Flange Radius 0.031 0.062 0.094 0.125 0.125

Convolution Width 0.085 0.094 0.156 0.25 0.25

Bead Width 0.090/0.097 0.122/0.128 0.184/0.190 0.247/0.253 0.247/0.253

Bead Height 0.091/0.097 0.131/0.139 0.195/0.205 0.263/0.277 0.263/0.277

RPPCorporation

Rolling Single-Coated BeadedFlange (SCRB)

RPP Corporation 12 Ballard Way, Lawrence, MA 01843 USA www.rppcorp.com+1-978-689-2800 phone +1-978-683-7356 fax

© 2012 RPP Corporation 20120309

• Maximum stroke/diameter ratio.

• Broad range of fabrics andelastomers.

• Differential pressure capability(limited by beaded flange) isnormally to 150 psi.

• Pressure applied from one direction only.

• Must be formed into convoluttedshape during assembly

• Beaded flange assists in assembly

• Seal enhanced by bead, whichspreads under pressure in a properlydimensioned hardware groove.

• Outside flange diameter is generallyless than that of a flat-flange design.

Cylinder Bore

Bead Height

Piston Radius

Piston Diameter

Bead Width

Head/FlangeThickness

ConvolutionWidth

SidewallThickness

FlangeRadius

Height

Fabric PatternVisible this side

17

RPP Corporation12 Ballard WayLawrence, MA 01843USA

Tel: +1-978-689-2800+1-800-232-2239

Fax: +1-978-683-7356

[email protected]

RPP Europe GmbHGottlieb-Fecht-Strasse 20D-77694 Kehl-KorkGERMANY

Tel: +49 7851 99 43 50

Fax: +49 7851 99 43 51

[email protected]

Documents

RPP · 1 RPP Corporation is a world-class manu-facturer of custom fabric reinforced elas - tomeric diaphragm seals and other highly engineered molded rubber products. RPP specializes