Covers power-operated pumps for anhydrous ammonia and liquefied petroleum gas (LP-Gas) for use in liquid transfer operations in nonrefrigerated systems in installations covered by the following Standards: Safety Requirements for the Storage and Handling of Anhydrous Ammonia, ANSI/K61.1. Storage and Handling of Liquefied Petroleum Gases, ANSI/NFPA No. 58. SUMMARY OF CHANGES TO UL 51 UL 51 was originally listed for comment in the February 16, 1996 issue of Standards Action. Only the revised text outlined below is being resubmitted due to substantive changes in the text. The revisions include: changes based on the replacement of the Mercurous Nitrate Immersion Test with a 10-Day Moist Ammonia Air Stress Cracking Test; changes due to the replacement of the oxygen bomb test with the air-oven aging test; reinstatement of requirements for production tests. (Revised) 5.11 A part made of drawn brass or machined from brass rod shall be capable of withstanding, without cracking, the 10-Day Moist Ammonia Air Stress Cracking Test, Section 19A. (Deleted Section) 19 Mercurous-Nitrate Immersion Test (Added) 19A 10-Day Moist Ammonia Air Stress Cracking Test 19A.1 After being subjected to the conditions described in 19A.2 C 19A.4, a brass part containing more than 15 percent zinc shall show no evidence of cracking when examined using 25X magnification. 19A.2 Each sample is to be subjected to the physical stresses normally imposed on or within a part as the result of assembly with other components. Such stresses are to be applied to the sample prior to and maintained during the test. Samples with threads, intended to be used for installing the product in the field, are to have the threads engaged and tightened to the torque specified in Table 14.1. Teflon tape or pipe compound is not to be used on the threads. 19A.3 Three samples are to be degreased and then continuously exposed in a set position for ten days to a moist ammonia-air mixture maintained in a glass chamber approximately 12 by 12 by 12 inches (305 by 305 by 305 mm) having a glass cover. 19A.4 Approximately 600 ml of aqueous ammonia having a specific gravity of 0.94 is to be maintained at the bottom of the glass chamber below the samples. The samples are to be positioned 1-1/2 inches (38.1 mm) above the aqueous ammonia solution and supported by an inert tray. The moist ammonia-air mixture in the chamber is to be maintained at atmospheric pressure and at a temperature of 34 "2EC (93 "3.5EF). (Revised) 20.1.3 A part made of synthetic rubber shall not crack or show visible evidence of deterioration following exposure for 70 hours to a temperature of 100 "2EC (212 "3.5EF) in an air-circulating oven. (Revised) 21.2 Each pump is to be operated and determined to be in condition before shipment.