5.1.4

1. 5.1.4 Applying Propane Pump Operating Characteristics & Selecting the Dispenser Pump Selecting the pump for a propane dispenser should include a complete understanding of how the dispenser will be operated, and the functions that the dispenser must fulfill. In this module you will learn to: • Identify the operating characteristics of propane pumps • Select the dispenser pump

2. Identifying the operating characteristics of propane pumps Regenerative turbine pumps Courtesy of Corken Pump Div. of IDEX Figure 1. Regenerative Turbine Pump

3. Positive displacement pumps Courtesy of Blackmer Div. of Dove r Figure 2a. Sliding Vane Pump

4. Positive displacement pumps Courtesy of Smith Precision Products Figure 2b. Gear Pump (Coupling Shield Removed for Illustration)

5. Selecting the dispenser pump Dispenser application and operating requirements What containers will be filled? If the dispenser will be primarily used to fill smaller cylinders, with larger containers filled only occasionally, a pump with minimal gallon per minute rating should be selected. The primary consideration in this case is minimizing the risk of over filling small cylinders. If the installation is primarily used to fill larger, vehicle-mounted mobile or motor fuel tanks, a higher volume pump should be considered to reduce filling time and minimize operator waiting that could contribute to lack of attention during the filling operation.

6. Selecting the dispenser pump Dispenser application and operating requirements What is the expected volume of daily usage? Does the installation location present particular limitations? If the power supply at the site will only support low-voltage, single-phase electric motors, the pump size and volume must be matched to the limitations of the power supply. If site requirements or jurisdictional authority approval mandates the use of a buried or mounted underground supply tank, the pump selection should be made after consulting the pump manufacturer or distributor.

7. Pump rating Manufacturers’ propane pump ratings are generally shown in relation to differential pressure. Differential pressure is the difference between the pressure at the outlet side of the pump and the pressure at the inlet side of the pump.

9. Motor Selection Three factors must be known to verify that the explosion-proof motor is appropriate for the dispenser installation and pump: • The pump’s horsepower and revolutions per minute (rpm) requirements • The installation’s available electrical power supply voltage and phase • The motor frame style required; the frame style refers to how the motor is mounted and how the pump is driven by the motor

10. Figure 3b. For Pumps Up to 80 GPM Courtesy of Corken Pump Div. of IDEX Figure 3a. For Pumps Up to 40 GPM • Pump protection devices • Proper bypass valve and system

11. Courtesy of Dover Corp., Blackmer Pump Div. Figure 4. Automatic Bypass Valve & Adjustment Mechanism NOTE: For LP-gas installations, Underwriters Laboratories, Inc. listing and NFPA 58 allow a maximum differential of 125 psig. If the pump is equipped with an internal bypass (sometimes called a pump “relief valve”), check its pressure setting on the rating plate attached to the pump or in the manufacturer’s IOM instructions.The internal bypass valve pressure must be set according to manufacturer instructions, typically at least 10-25 psig higher than the external bypass valve setting.

12. Pump protection devices • Verify that a flexible connector for piping stress relief is provided in the pump inlet piping, and if needed, in the pump outlet piping. Figure 5. Stainless Steel Flexible Connector • Flexible sections of the proper length must be selected, and should be installed so that they are as close as practical to a straight line. • They should never be used in place of pipe fittings to make turns or bends. Improper installation may result in damage to the reinforcement braids and complete failure of the connector.

13. Figure 6a. Improperly Installed Flex Connector Figure 6b. Reverse Side Damage to Stainless Steel Reinforcement Webbing

14. Figure 7. Inline Strainer Body (Note Flow Direction Arrow, L to R) • The pump should be protected by the installation of an inline strainer upstream of the pump inlet. Pump manufacturer IOM instructions give strainer screen size specifications for protecting the pump from debris that could damage internal components.

15. Time to See If You Got the Key Points of This Module… • Complete the Review on pages 8 & 9. • See if you are ready for the Certification Exam by checking off the performance criteria on page 10.