autogas 150 series pumps installation … · corken, inc. • a unit of idex corporation • p.o....

CORKEN, INC. • A Unit of IDEX Corporation • P.O. Box 12338, Oklahoma City, OK 73157 • Phone (405) 946-5576

A Unit of IDEX Corporation® Application Bulletin

No. 13June 2001

AUTOGAS 150 SERIES PUMPS INSTALLATION GUIDELINESFOR UNDERGROUND TANK APPLICATIONS


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BACKGROUND:Because of the environmental problems caused bytraditional fuels such as gasoline and diesel, theuse of alternative fuels, like LPG, are rapidlyincreasing worldwide. To reduce air pollution, manygovernments are adopting energy policies thatpromote the use of autogas. Since autogas istypically used in highly populated cities with airpollution problems, special safety measures andtechniques have been implemented to improve theintegrity and safety of the LPG dispensing stations.One of the techniques widely implemented is theuse of underground storage tanks.

THE CHALLENGE OF PUMPING LPG:The pumping of boiling liquids, like LPG, offers aunique set of challenges to the manufactures andusers of LPG pumps. Since LPG is stored at exactlyits boiling point, any increase in temperature, as wellas any decrease in pressure, will cause the productto boil and form vapor.

To limit the amount of vapor formation at the pump’sinlet port, the design of the suction piping system, isan important aspect. For boiling liquids, the netpositive suction head available (NPSHA) of aninstallation is reduced to the height of the liquid levelabove the pump (net static suction head) minus thefrictional losses. For an underground tank where thepump is located above the liquid level, the net staticsuction head becomes the net suction lift, which isnegative, not positive. This means that foraboveground pumps pumping from underground

tanks, the installation NPSHA will always benegative, and the pump will always handle vapor inthe liquid stream.

Over the years, several methods have been used,but each one of them not only complicated thepumping system, but also in many cases contributedto cavitation in the pump. Some examples are:

1.0 The use of a “foot-valve”, or a backpressurecheck valve at the end of the suction dip tube.

This method is ineffective: eventually vapor willbe formed in the dip tube when the pump isshut-off. Upon starting the pump, this vapor willbe drawn into the pump, causing cavitation.

2.0 The “Parkhill-Wade” method developed in the1940’s, using a small receiver tank with an eductorat the pump’s discharge port.

Since this system must use a pump with ahigher capacity than what the applicationrequires, the pump cavitates continuously.

3.0 Padding the storage tank using a compressor, ora “blanket” of an inert gas.

4.0 Blowing down the vapor in the pump until thepump is primed with liquid.

This requires venting product to the atmosphere,which is not a safe practice.

Special design criteria must be incorporated in thedesign of LPG pumps, so the pump can effectivelyhandle a certain amount of vapor, without sufferingthe destructive effects of cavitation.


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TYPES OF LPG PUMPS:Submersible Pumps:Although these types of pumps have been used withsome degree of success in the LPG industry, thereare many disadvantages.

• Requires a special construction storage tank

• More expensive pump

• Special and costly protection system to avoidrunning the pump dry. Dry-run tolerances arevery limited.

• Many of these pumps cannot be repaired (i.e.,throw-away pumps)

• The pump’s well must be evacuated in order toremove the pump for repairs or to be replaced.

• Due to its weight, the use of a crane is typicallyrequired to remove the pump from the tank’s wellbefore servicing the pump.

• Since some of the submersible pumps are integralpump/motor units, neither the pump nor theelectric motor can be replaced separately. Thecomplete assembly must be replaced.

Positive Displacement (PD) Pumps:Positive Displacement (PD) pumps such as pistonpumps, gear pumps and sliding-vane pumps arewidely used in the LPG industry due to their goodsuction characteristics and their vapor handlingcapability. However, when positive displacementpumps run dry, severe wear, increased noise andvibration will occur.

Regenerative Turbine Pumps:Unlike the positive displacement pumps, there isonly one moving part, its impeller, which floatsfreely without metal-to-metal contact. Although thistype of pump does not have the vapor handlingcapability of positive displacement pumps, they domove vapor more readily and have an excellenttolerance level for running dry without noise andvibration. Since a pump for an underground tankapplication will run dry until they are primed withliquid, these characteristics make the regenerativeturbine pump, the pump of choice for anunderground tank application.

INSTALLATION DESIGN CRITERIAFOR UNDERGROUND TANKS’APPLICATIONS:

• Minimize suction frictional losses:

- Pump should be as close as possible to thetank’s liquid outlet connection.

- No strainer necessary since the tank itself actsas a sump to collect foreign materials.

- Use of full-port ball valves, or low restrictive valves.

- Use a 2-inch (51 millimeters) pipe.

• Minimize the net static suction lift, to approximately14 feet (4,267 millimeters) maximum.

• Use vapor eliminator valves.

• Use of back-pressure check valves downstreamthe pump.

• Limit the capacity of the pump to a maximum of1.5% of the tank’s capacity. For example, with a1,000-gallon (3,785 liters) tank, limit thecapacity of the pump to 15 gallons per minute(56.8 liters per minute).


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5 feet (1,524 mm)maximum

Underground tank

9

6

7

10

2

1

3

4

11

55

Approximately14 feet (4,267 mm)maximum

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Minimum liquid level of12 inches (304 mm)

above endof dip tube

1.0 UNDERGROUND TANK APPLICATION


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REF. NO. DESCRIPTION REMARKS

1 2”, schedule 80 pipe

2 Man way Cover Existing

3 2 ball valve, full port Manual or remote control

4 Corken 150 Series pump With 7.5 HP (5.5 KW) electric motor

5 1/4” NPT pressure gauge 0-400 PSIG (0-28 Bar-g)

6 Corken B166 By-Pass Valve 1 inch NPT With spring code C

7 1/4” NPT hydrostatic relief valve Set at 450 PSIG (31 Bar-g)

8 In-line excess flow valve Closing flow of 10-15 GPM (37-57 LPM)

9 Back pressure check valve Like Corken’s Flo-Chek valve

10 By-pass return line’s valve Existing

11 2” x 1-1/2” eccentric reducer

BILL OF MATERIALS

WARNING:1.0 No excess flow valves on the tank’s liquid outlet connections are shown in these schematics. If local

regulations require the use of excess flow valves, its closing flow should be approximately 1.5 timeshigher than the pump’s rated capacity for the operational conditions.

2.0 Periodic inspection and maintenance of Corken products is essential.

3.0 Only experienced, trained and qualified personnel must make inspection, maintenance andinstallation of Corken products.

4.0 Maintenance, use and installation of Corken products must comply with Corken instructions,applicable laws and safety standards such as NFPA 58 for LP-Gas and ANSI K6.1-1972 forAnhydrous Ammonia.

5.0 Transfer of toxic, dangerous, flammable or explosive substances using Corken equipment is at theuser’s risk. Only qualified personnel should operate Corken equipment according to the applicablelaws and safety standards.


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Minimum liquid level of12 inches (304 mm)

above endof dip tube

5 feet (1,524 mm)maximum

Underground tank

9

4

8

13

11

3

1

2 10

1214

76

55

Approximately14 feet (4,267 mm)maximum

2.0 UNDERGROUND TANK WITH MANIFOLD FOR SUBMERSIBLE PUMP


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BILL OF MATERIALS

REF. NO. DESCRIPTION REMARKS

1 2”, schedule 80 pipe

2 5” manifold Existing

3 2” ball valve, full port Manual or remote

4 Corken 150 Series pump With 7.5 HP (5.5 KW) electric motor

5 1/4“ NPT pressure gauge 0-400 PSIG (0-28 Bar-g)

6 Corken B166 By-pass Valve 1” NPT With spring code C

7 1/4“ NPT hydrostatic relief valve Set at 450 PSIG (31 Bar-g)

8 In-line excess flow valve Closing flow of 10-15 GPM (37-57 LPM)

9 Back pressure check valve Like Corken’s Flo-Chek valves

10 2” ball valve Existing

11 2” x 1 1/2” eccentric reducer

12 5” flange Existing

13 Pressure equalizing line Part of existing 5” manifold.Must be open for pump to operate properly.

14 By-pass return line’s valve Existing

WARNING:1.0 No excess flow valves on the tank’s liquid outlet connections are shown in these schematics. If local

regulations require the use of excess flow valves, its closing flow should be approximately 1.5 timeshigher than the pump’s rated capacity for the operational conditions.

2.0 Periodic inspection and maintenance of Corken products is essential.

3.0 Only experienced, trained and qualified personnel must make inspection, maintenance andinstallation of Corken products.

4.0 Maintenance, use and installation of Corken products must comply with Corken instructions,applicable laws and safety standards such as NFPA 58 for LP-Gas and ANSI K6.1-1972 forAnhydrous Ammonia.

5.0 Transfer of toxic, dangerous, flammable or explosive substances using Corken equipment is at theuser’s risk. Only qualified personnel should operate Corken equipment according to the applicablelaws and safety standards.


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0 50 100 150 200 2500

50

100

150

200

0

2.5

5.0

7.5

10.0

12.5

15.0

0

2.5

5.0

7.5

10.0

12.5

15.0

0

3.0

5.0

7.5

10.0

15.0

20.0

GPMCAPACITY

LPM

HP

KW

DIF

FE

RE

NT

IAL

PR

ES

SU

RE

PS

I

BA

R

Curves based on LPG*Capacity

Power required

0 10 20 30 40 50 60

0

0 10 20 30 40 50 60

50 100 150 200 2500

50

100

150

200

250

0

2.5

5.0

7.5

10.0

12.5

15.0

17.5

0

2.5

5.0

7.5

10.0

12.5

15.0

17.5

0

3.0

5.0

7.5

10.0

15.0

20.0

GPMCAPACITY

LPM

HP

KW

DIF

FE

RE

NT

IAL

PR

ES

SU

RE

PS

I

BA

R

Curves based on LPG*Capacity

Power required

Example @ 2880 RPM

DIFFERENTIAL PRESSURE10.0 Bar

145.0 PSI

FLOW85 LPM

22.5 GPM

POWER REQUIRED5.1 KW6.8 HP

Example @ 3450 RPM

DIFFERENTIAL PRESSURE10.0 Bar145.0 psi

FLOW128 LPM33.8 GPM

POWER REQUIRED6.3 KW8.4 HP

PERFORMANCE CURVES:

*The performance curves are based on aboveground LPG installations. Performance curves for underground LPGtanks will vary based on the specific installation. Consult factory.

autogas 150 series pumps installation … · corken, inc. • a unit of idex corporation • p.o....

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