100 Hp Sihi Pumps

8/10/2019 100 Hp Sihi Pumps

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SIHI Pumps Asiawww.sihipumpsasia.com

LPG Applications Pumps & Plants


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In accordance with Technische Regeln fr Flssiggas TRF 1996-2.1 (Technical regulations for LPG), propane,butane and their mixtures are regarded as liquid gases in this brochure. Other liquefied gases such as ammonia,propylene, methylene etc. can also be handled by Sterling SIHI pumps and the following information should also beconsidered.

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CEH liquid gas pumps at the PTT depot, Bangkok


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At filling stations this overpressure at the vapourpressure is in most cases produced by the differencein static head between feed tank and pump.

Arrangements such as these create additionalinstallation costs. The required suction head of thepump therefore is a quality factor which is of specialsignificance for pumps handling LPG. With SterlingSIHI LPG pumps, low suction heads are achieved.

It is absolutely essential that the requiredfeeding head (NPSHR) of the pump is available atthe suction nozzle.

When pumping close to vapour pressure, partialvaporization in the feed pipe, suction pipe, or in the

first pump stage occurs frequently so the pump has to handle a liquid / vapour mixture. This is only possible how-ever ifthe pump has been designed hydraulically for this application.

The design and pumping principles of Sterling SIHI LPG pumps in the CEH range meet these requirements.

When handling liquid / vapour mixtures, the pumps behave as though they were handling liquid with lower weightcorresponding to the specific gravity of the mixture. Characteristic curves for different mixtures are indicated by dottedlines in the above diagram.

Vapour separated in the inlet area is re-condensed in the pump so that vapour-free LPG can be discharged.

to the consumer

differencein static height


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2.2 CEH pumps for positive suction head operation

Sterling SIHI pumps of the CEH range have been developed with special consideration being given to thepumping conditions of LPG.

They guarantee:

1. Handling entrained vapour at normal duty without interrupting flow.

2. Very low suction heads for trouble-free operation.

3. Characteristic curves which guarantee that the equipment will continue to pump without trouble in the event ofincreased differential pressure.

The pumps are of segmental design, and have end section discharge branch pointing radially upwards. An inducer isfitted on the suction side making it possible to achieve the favourable suction heads indicated. The side channel stagesare arranged in series.

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On the discharge side, the shaft is sealed by means of a robust mechanical seal of well-proven design, internallyflushed by the pumped liquid and therefore absolutely maintenance-free. On the suction side there is an internalsleeve bearing product lubricated. The nominal casing pressure is 40 bar.

This CEH is also available with a retaining stage, the CEH/7. This retaining stage offers a protection against dry runningby controlling the liquid level in the pump.

CEH/5 for positive suction operation with mechanical seal

CEH /7 for positive suction operation and magnetic coupling

Offering the highest degree of safety with CEH/6, this unit is sealless and is drived by a magnetic coupling. The motortorque is transmitted by a maintenance-free magnetic coupling. The nominal casing pressure is 25 bar (or 40 bardepending on the desing).


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2.3 Rating of pumps and aspects of installation

Pumps can be selected in accordance with the characteristic curves. Specific data, especially with regard to the requiredmotor, will be given in our quotation.

When selecting a pump size, it must always be borne in mind that vapour-free inflow can not always be guaranteed. Inpractice, it is always very important to design an installation in accordance with the state of the art (e.g. see installationdrawing below) in order to minimalize vaporisation and headlosses. If not, some safety factors need to be incorporatedin the determination of the pump design.

The influence of specific gravity on the power absorbed is determined by the following formula:

Aspects on installation (general)

1. The suction pipes must be configured such that there is a minimum of resistance. There should be no bends, filtersetc. which could impact high frictional loses and hinder the flow to the pump.

2. Suitable measures must be taken to maintain the necessary pumping capacity.3. Bypass pipes from discharge side to inlet or suction side are not allowed. The bypass backflow from the

relief valve must be fed back to the storage tank.

4. If one pump has to fill several tanks with different LPG mixtures at different vapour pressures, efficient non-returnvalves or other suitable shut-off devices are required at the discharge side to avoid any service liquid blowing outduring the change-over process.

5. All relevant regulations are to be observed (e.g. VBG 16, TRB 801).

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Aspects on installation of a CEH for positive suction head operation

1. The net positive suction head (NPSHa) must be higher than the required NPSH (NPSHa).

2. A 1 to 2 pipe should be fitted going from the suction line, close to the suction, branch to the vapour phase ofthe storage tank. This allows vapour to escape instead of entering the pump.

3. The diameter of the feed pipe has to be equal to the nominal bore of the pump.

Installation example

P1 = 1P2 2

P = power absorbed by the pump (kW)= specific gravity (kg /m 3)

Observe safety regulations and operating instructions!


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The filling valve must have relatively short closing periods to comply with the relevant instructions for cylinder filling. Thiscauses pressure fluctuations in the system, which could be detrimental to the pumps. This is particularly important whenfilling small bottles.

Pressure shocks can be absorbed by installing a bypass from the discharge side of the pump to the storage tank. Thereturn of heated liquid will cause a slight increase in vapour pressure in the feed tank. This will considerably improvesuction head conditions.

An expansion tank filled with inert gas can also be installed in the discharge line to reduce the pressure shocks.

2.5 Commissioning

The training of personnel working on LPG installations is most important. Mistakes made when starting up can result indry-running and subsequent problems caused by damaged pump components.

1. The pump must only be started when the pump is correctly vented and filled with liquid.

2. Do not operate against closed discharge valve. Fit a by-pass valve.

3. Ensure that the vapour return line from the suction line to the tank always remains open.

4. Do not operate the pump outside its range.

5. Check direction of the motor when uncoupled from the pump.

6. When draining the tank ensure that the pump is switched off (a level monitor or dry-running protection isrecommended).

See the operating instructions for further information .

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Cylinder filling plant with a CEH/5 with positive suction head operation

2.4 Cylinder filling


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. 6 L P G p u m p s

f o r p o s

i t i v e s u c

t i o n

h e a

d o p e r a

t i o n -

P u m p p r o g r a m

C E H / 5 -

C E H / 6 -

C E H / 7

1 9


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3.1 General

Space restrictions and technical safety regulationsincreasingly require the installation of undergroundtanks or surface-mounted tanks covered with earth.

Such applications require pumps operating under

suction lift operation which causes severe demandson the pumps. Sterling SIHI pumps CEH/ 6 andCEH/ 7 in conjunction with PC systems can meetthese demands.

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Due to their capability of handling large quantities of vapour and their low NPSH, these pumps have the advantage that theycan be used without having to fit moving components or assemblies inside the pressurised tank.

The operating principle of PC systems can be understood using the pressure / temperature diagram below.

By the exhausting of vapour and re-vaporization during the suction phase, heat is drawn from the liquid in the suctionpipe. The pressure difference generated against the constant tank pressure causes the liquid to rise up to the pump andthe pumping commences.

At the same time, an energy-bearing partial flow is returned to the vapour phase of the tank and continues to producethe differential pressure to overcome the suction lift required.

The relatively high consumption of energy caused by partial recirculation, sets an economic limit for this system atsuction lifts of Hs < 4 m and tank volumes of V < 200 m 3 for propane and propane/butane mixtures with at least 20% ofpropane.

pressure/ temperature course at suction lift operation

3- PC units operating on suction lift (top-off loading)


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3.2 Installation for PC-plants on suction lift operation

1. The static suction lift must be limited to the absolute minimum.

Hstat. 4 m

2. On initial start up, the discharge end of the pump should be provided with a facility for venting to the atmosphere.

3. In order to guarantee a reliable suction lift operation, a gas separator must be installed at the discharge end. A by-pass and a gas separator balancing line must be led back from the separator into the vapour phase of the tank.

4. In the retaining stage, the pump has two connections for an explosion proof level switch, making it possible to ensurethat the pump can only run when it contains sufficient liquid.

5. A delayed release timer relay set to 30 sec. must be installed to allow for a decrease in level within the retaining

stage during the suction phase.6. The Sterling SIHI PC plant complies with all the above requirements.

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Twin PC-plants at National Oil Company Petronas in Malaysia

CEH/7 with retaining stage for suction lift opreration


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1 2 3

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l a n

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r o g r a m

P C p

l a n

t f o r s u c

t i o n

l i f t o p e r a

t i o n

f r o m

u n d e r g r o u n

d t a n

k s -

L P G p u m p s p r o g r a m

C E H / 6 -

C E H / 7

1 3


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4- Vertical tank pumps (top-off loading)

4.1 General

In storage tanks with diameters not exceeding 6 m, tank pumps with externallymounted motors can be used as an alternative. These vertical pumps aremounted inside the storage tank and are designed to suit a specific tank.

The first pumping stage is located at the bottom of the tank by means of theextended shaft design and operates under positive suction head conditions.

The following pump types are available dependent on the operating range:

1. Up to 35 m 3/h: CEB-Side channel combination pumps using thehydraulics of the CEH pumps

2. Up to 100 m 3/h: ZEB-Centrifugal pumps using the hydraulics of the ZEApumps and the low NPSH impeller

3. Booster pumps with a low NPSH impeller to increase for inlet pressure.

All pumps are equipped with a magnetic coupling and are therefore totally leak-free. Stringent safety regulations and environmental considerations have been

taken into account in the design.

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ZEB booster pump installed in the dome pit


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4.2 Vertical booster pumps CEB/ZEB with combined external pressure generating pump

Booster pumps are mainly used whereit is essential to have as few moving partsas possible inside the pressurized tank.The single NPSH impeller of this pump isfixed on the shaft and is extremelyresistant to wear and operates effectivelyunder unfavourable conditions.

The main pressure increase is achievedby means of an externally mounted pumpallowing easy maintenance.

This solution has proved successfulwhere different applications have to becombined, e.g. where two pressuregenerating pumps of different sizes are tobe fed by only one feeder pump with dualspeed motor to suit different operatingconditions.

Booster pump ZEB

External pressure generating pumps for bottling and road tanker filling


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4.3 Installation

Installation for CEB/ ZEB pumps

When adjusting the min. level switch in the storagetank, it is important to take into consideration therequired positive suction head.

During standstill, differences in temperature betweenstorage tank and external pump parts may cause theliquid to be forced out of the pump. The installation ofbalance lines or vapour eliminating by-pass valvesguarantees a permanent liquid level in the pump.

If the pump is equipped with a foot valve then a safetyrelief valve is required (included in the scope ofsupply).

The pump must be protected against dry runningoperation and extreme temperature increases bysuitable monitoring instruments (e.g. flow indicator,

load detector, PT 100 etc.).

The installation and operating instructions must alwaysbe observed.

Care must the taken to ensure that both maximum andminimum flow rates are not exceded. Suitable regulationmust be incorporated.

Such devices include orifice plates or permanant by-passtires.

Installation of a ZEB pump for road tanker loading

Installation example


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Installation for booster pumps with pressure generating pumps

1. Provision must be made in the installation to ensure that both pumps can be started successively.

2. Both pump systems must be individually protected against dry running and increase in temperature.

3. The technical aspects regarding vertical tank pumps and LPG pumps operating under suction head operation, alsoare to be taken into consideration.

4. Documentation for plant design and installation have to be available.

4.4 Operation (start up)

The training of operating personnel on LPG plants is of considerableimportance. Mistakes in start up result in dry running and subsequentoperating troubles caused by damaged components in the pump.

The following must therefore be noted:

1. The pump must only be started when the pump is correctlyvented and filled with liquid.

2. Do not operate against closed discharge valve. Fit an overflow

valve.3. Ensure that the vapour return line from the suction line to the tank

always remains open.

4. Do not operate the pump outside its range.

5. Check direction of the motor when uncoupled from the pump.

6. When draining the tank ensure that the pump is switched off (alevel monitor or dry-running protection is recommended).

For other information see the operating instructions.

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Booster pump CEB with pressure generating pump AEH


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1 9

4 . 5

L P G v e r t

i c a

l t a n k

p u m p s

f o r

t o p - o

f f l o a

d i n g o u

t o

f u n

d e r g r o u n

d t a n

k s -

L P G p u m p s p r o g r a m

C E B a n

d Z E B


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5- Multistage segmental pump UEA for large flows (bottom-off loading)

5.1 General

To handle large flow economically multistage segmental type pumps are preferable.

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In order to meet the requirements of pumping LPG, these horizontal end section pumps are fitted with a low NPSHimpeller. The low NPSH required by this series of pumps guarantees operation in many different applications withoutcavitation and other problems.

The UEA-pumps can leavealone with 2 or 4 pole motors andare available with mechanicalseal or with magnetic couplingdepending on the application.

The UEA range has anintegrated side channel stagewhich is especially suitable forhandling vapour.

At standstill, increased ambienttemperature may cause vapo-rization in the suction line.The design of the suction stageensures that vapour bubbles aredrawn out of the suction line andvapour.

UEA pumps for road tanker filling

UEA-pump with integrated side channel stage


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5.2 Installation of UEA pumps

1. Install a straight section of pipe in the suction line of the same bore as the suction pipe and 10-20 x the diameter.

2. Protect the pump against dry running and extreme increase in temperature (magnetic drive) by using a suitablemonitoring instrument (e.g. flow indicator, overload detector, PT 100 etc.).

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3. Fill the pump up to theshaft centre line.

4. After start up, the vapour in the suction line must not be pumped against a higher differential pres-sure. It isrecommended that a temporary by-pass is fitted to the storage tank.

5. The return line from the suction pipe to the storage tank must be kept open at all times.

6. Avoid the operation against a closed discharge by installing a relief valve and return line to the storage tanks.

UEA pumps in bulk plant of Esso, Australia


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2 2

2 3

5 . 3

L P G p u m p s

f o r h

i g h e r

f l o w r a

t e s a n

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L G P p u m p s p r o g r a m

U E A


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latent heat at 0 C kJ /kg 379 385

viscosity at 0 C Pa s 127 214

critical temperature C 96.8 152.1

critical pressure bar 43.4 38.8

melting point C 188 131

propane n-butaneGeneral physical data for LPG

6- General data

6.1 general physical data for LPG


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Data n-butane propaneC4 H10 C3 H8

flash point t crit. C 152 97

C ignition temperature 365 470

ignition group (acc. to VDE) G 2 G 1

explosion class (acc. to VDE) 1 1

dangerous materials class (acc. to VbF)

explosion limit inferior vol. % 1.5 2.0 2.1

in air superior vol. % 8.5 9.5

max. explosion pressure, bar 8.6 8.6

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Technical safety data

For definition of the data, determination of the values and for detail of further influential values, please see:Nabert/Schn Technical safety data of combustible gases and vapours, 3 rd edition, pages 31-35.

6.2 Technical safety data


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7- Selection

As well as the fundamental properties of LPG pumps, namely

low NPSH

capability to handle vapour mixtures

safety of the shaft sealing

self priming

proven material design

the correct selection of the pump size is anessential factor to ensure an economicalsystem together with good operatingreliability.

The determination of the desired outputcomes mainly from the required dischargerate or filling capacities. However, the

maximum limits are not necessarilydetermined by the pump performance but byphysical limitations or by the geometry of theother components in the system.

The nominal output rating can be found in thecapacity curve of a filling carroussel for LPGcylinders. This nominal output rating, withregard to a constant filling pressure, shouldbe increased by an additional, by-passquantity led back to the feeling tank via apressure sustaining valve.

The additional quantity is normally from 20 to50 %, depending on the size of the fillingsystem.

The differential pressure to be generated by the pump depends on the frictional characteristics (system curve) of theLPG plant and the flow rate.

Whilst the static head may often be neglected, the flow losses (dynamic head) of the components in the system can becalculated accurately with the aid of standard tables and empirical values.

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Total System Head

Capacity curves for filling carousels


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Uncertainty often arises when calculating thesystem head which in LPG plants results mainlyfrom pressure differences are highly dependantupon temperature changes. The seasonaltemperature changes and thus the change in thepressure differential must also be consideredespecially at the discharge side.

The pressure difference can be determined by

means of the vapour pressure curve for the mediabeing pumped. The use of the pressure gradientof the liquefied gas could also been used. Thispressure gradient indicates the pressure changeper C and guarantees a fast and accuratecalculation of the differential pressure during thedesign stage.

However it must be realized that, if extremefactors are taken into consideration, the resultantselection will be an oversized pump.

Thus the high cost of both the pump and theoperation under the partial load, will produce anuneconomic solution and unfavourable operatingconditions.

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Sterling SIHI LPG pumps guarantee reliable filling when moderately rated because of their steep and stable

characteristics and also because of their capability of operating under extreme conditions for a short time.The higher differential pressure, necessary to overcome a counter pressure depending on the temperature, is reducedimmediately at the beginning of the filling procedure and makes the temporary reduction of the pumping capacitynegligible.

Carousel filling plant for small cylinders (Siraga)

Pressure gradient of liquid gas


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8- Application examples

8.1 Industrial plants

The industry uses LPG in different applications e.g.

Welding soldering Municipal gas production

Double-Duro hardening Automotive fuel

Drying ovens Building construction

Combustion chambers Heating of railroad yards

Hot-water preparation FuelHeating of buildings Destroying of weeds

For all pumping plants the instructions for installation and start up must be observed.

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Rail tanker off-loading pumps type CEH/6 with magnetic coupling


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8.2 Off-loading of rail tankers

During off-loading rail tankers, troubles may occur if the existing static suction heads are considerably reduced by

pressure losses caused by the installation of armatures or extremely long feed lines. Furthermore, it has to be noted thatwhen connecting a number of rail tankers to a common line unequal emptying of the rail tankers will not lead tointerruption of the regular flow by vapour locking (dry running of the pump).

The installation of the pressure balance line between storage tank and rail tanker is essential.

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LPG bulk filling station for rail tankers equipped with a Sterling SIHI pump type CEH


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8.3 Automotive refuelling with positive suction head operation

The installation of above ground or mounted tanks with free front side is advantageous for inspection, but requires a large

area because of the necessary safety zones. In these cases low suction heads are important in order to keep theinstallation costs low. The Sterling SIHI CEH/ 5 pumps comply reliably with these requirements. It is recommended toinstall a level switch in the feed line which will avoid vapour formation due to a decrease in suction head below theminimum.

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LPG plant with above ground storage tank positive suction head operation


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8.4 Automotive refuelling with a suction lift operation

Lack of space and the requirements for technical safety make underground installation of LPG storage tanks necessary.In this case the pump has to operate under suction lift operation. Because of the physical properties of LPG the reliableoperation of the refuelling plant using a SIHI CEH/ 7 pump, is only possible by using a special arrangement of thepipework or a Sterling SIHI PC plant.

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Suction lift operation out of underground tank (PC plant)


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SIHI Service Capabilities

SIHI Pumps Asia established throughout the Asia / Pacific region a strong localservice network of sales and service offices, authorized repair centers andcarefully selected business partners. All our service facilities supply qualityrepairs and maintenance with genuine spare parts and trained personnel close toour customers. We are working according to high quality standards and sharinga common knowledge base to assure customer satisfaction.

Our LPG services: Consultancy System Optimization Installation & Commissioning Pump Alignment Training & Seminars Spare Part Kits Service Contracts

Our service contracts for LPG cover the following: Correct Installation and Alignment

LPG is sometimes very dirty, especially after first commissioning vessels pipes are full of rust and weldingparticles normally a change of seal is required. Fully covered by contract Yearly Service Check / Performance Check 5 Years Guarantee on All Parts (including wear parts normally change every 3 years) 24 Hours Response (via Swap Pumps strategically located for quick response )

Benefits: Quick Response / Very limited down time 5 Years product guarantee! Fixed cost per year No need for stock / standby (spare parts / pumps) Save money on equipment, correct installation, guaranteed performance and no loss of production

Contact our local representative / SIHI Pumps Asia office for more information.

Contact Addresses Asia

SIHI Pumps (Singapore)Singapore

Tel.: (65) 656 283 00Fax: (65) 656 283 08

Email: [email protected]

SIHI Pumps (Australia)Knoxfield

Tel.: (61) 3 9800 6200Fax: (61) 3 9801 4011


SIHI Pumps (China)Shanghai

Tel.: (8621) 621 880 68Fax: (8621) 621 780 86


SIHI Pumps (Malaysia)Selangor Darul Ehsan

Tel.: (60) 3 89426877Fax: (60) 3 89428599


SIHI Pumps (Thailand)Bangkok

Tel.: (66-2) 319 2567Fax: (66-2) 319 2573/4


SIHI Pumps (Taiwan)Taipei County 251Tel.: (886) 2 2808 4675Fax: (886) 2 2808 4552


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100 Hp Sihi Pumps