UL 51:2013 pdf download – Power-Operated Pumps and Bypass Valves for Anhydrous Ammonia,LP-Gas, and Propylene.
13 Guards
13,1 A gear, belt, pulley, or other rotating part shall be enclosed in a metal guard to reduce tile risk of unintentional contact, unless the construction of the part is such that the risk of injury to persons is of a negligible degree, or unless the pump assembly is furnished with an enclosure.
14 Pipe Connections
14.1 Pipe threads shall be in accordance with the Standard for Pipe Threads. General Purpose (Inch),
ANSI,ASME Bt.20.1.
Exception. Pumps ard bypdss valves nitended lui use xi installations where ppe httirigs incorporate other than NPT type threads shall be permitted to be provided with pipe threads complying with a national pipe thread standard compatible with those fittings. The pipe thread type shall be identified in accordance with 25.5.
14.2 Flanges of flange-type pumps or bypass valves shall comply with the respective American National Standard for pipe flanges and flanged fittings covering the material from which they are made.
15 General
15.1 A representative sample of each size and specific design of pump or bypass valve is to be subjected to the tests described in these requirements. Additional samples of parts constructed of nonmetallic materials are generally required for physical and chemical tests.
15.2 Water or other liquid is to be used in developing the required pressure in a leakage or hydrostatic pressure test. All hydrostatic pressures are to be maintained for at least 10 minutes.
15.3 The investigation of a pump or bypass valve is to be limited to the service conditions for which it is recommended, such as speed, maximum differential pressure at specific flow capacity, and liquid to be handled.
15.4 Pressure-measuring devices shall be calibrated over the range that they are used. The test pressure measured shall be not less than 20 percent or more than 80 percent of the full-scale reading of the device used.
Exception: The test pressure is allowed to be less than 20 percent and more than 80 percent of the full-scale reading of the measuring device, when calibration ind,cates that there is no loss of accuracy in the measured value.
18 Endurance Test
18.1 A drive shaft seal shall not leak after tile pump has been subjected to the endurance test described in 18.2 and 18.3.
18.2 This test is to be conducted on a pump sample previously subjected to the Deformation Test, Section 16. and the Leakage Test. Section 17. The test pump is to be connected to an electric motor of sufficient power rating to permit continuous operation of the pump for a total of 300 hours without causing the motor to overheat as follows:
a) 250 hours at pressure differential of 25 psi9 (170 kPa) and
b) 50 hours at the maximum pressure differential for which the pump is rated.
18.3 During this test, operating parts of a pump are to be kept “wets’ by a continuous flow of a suitable
test liquid. Other conditions of the test are to simulate, insofar as practicable, those of actual service.
18.4 A Leakage Test, Secton 17. on the drive shaft seal is to be conducted immediately after completion
of this endurance test.
19 DifferentIal Pressure Test
19.1 This test shall be conducted on a representative sample of each size pump or bypass valve. The test procedure for a pump only, or a pump with integral bypass valve is described in 19.2 and 19.3, The test procedure for a separate bypass valve is described in 19.2 and 19.4. One of the following results shall be obtained:
a) For a pump only. or a pump with integral bypass valve:
1) The differential pressure at specified flow rate shall not exceed the limit for the
minimum service pressure of the pump for which it is rated in accordance with 1.3 or
2) The pump shall be marked as required by 25.2 or 25.6.
b) For a separate bypass valve, the measured flow capacity shall be equal to or greater than the manufacturer’s rated flow capacity for the minimum service pressure and differential pressure rating in accordance with 1.3.
19.2 This test shall be conducted with each sample installed in a piping crcuit that includes a supply of lijid, pressure gauges, shutoff valve(s), tlowmeter, and container(s). The piping system shall be of the same pipe size as the samples being tested. The test shall be conducted with the liquefied gas for which the sample is intended, Stoddard’s Solvent, or other suitable liquid.