UL 79 2021 pdf download – Power-Operated Pumps for Petroleum Dispensing Products.
5.2 With reference to the requirement in 5.1, an elastomeric part used in contact with liquid or vapor shall have the following properties when tested as specified in the Standard for Gaskets and Seals, UL 157: a) Those properties relating to minimum tensile strength and elongation after oven aging, as specified in UL 157. The service temperature used to determine the conditioning time and temperature for oven aging is to be 140°F (60°C), unless the product is designated for use at a higher temperature, or the temperature of the component measured during the temperature test is higher. b) Low temperature rating of minus 20°F (minus 29°C). c) Volume change and extraction as specified in the requirements for UL 157, for end-use applications of gasoline, gasoline/alcohol blends up to 15% Ethanol, gasoline/alcohol blends up to 15% Methanol, diesel fuel, fuel oil, and lubricating oil. Other end-use applications, when marked on the pump, shall use the fluids marked for exposure. Exception No. 1: Polytetrafluoroethylene (PTFE) is considered to comply with the requirements of this paragraph. Exception No. 2: When an elastomeric part does not comply with the requirements described in (a) – (c), the pump assemblyshall be evaluated in accordance with 5.5. Exception No. 3: Testing with methanol is only required when the product is specifically rated formethanol blend use. 5.3 An elastomeric part forming a part that is depended on for protection of electrical components from rain or submersion in water shall have the following physical properties when tested as specified in the Standard for Gaskets and Seals, UL 157: a) Those properties relating to minimum tensile strength and elongation after oven aging, as specified in UL 157.
5.4 The Standard for Gaskets and Seals, UL 157, provides for the testing of either finished elastomeric parts, or sheet or slab material. Sheet or slab material is to be tested when the elastomeric parts are O- rings having a diameter of less than 1 inch (25.4 mm). The material tested is to be the same as that used in the product, regardless of whether finished elastomeric parts, or sheet or slab material is tested. 5.5 When the limits for tensile strength and elongation, volume change or extraction, aging, or low temperature are exceeded, the gasket material may be retested in the complete pump assembly after conditioning as outlined below. 5.6 When the limits for tensile strength, elongation, volume change or extraction are exceeded, the complete assembly constructed with the gasket installed as intended shall be filled with the appropriate test fluid for 70 hours at room temperature, and then shall comply with the requirements for the Leakage Test, Section 43 and the Hydrostatic Strength Test, Section 49. 5.7 Where the oven aging results are not in accordance with 5.2(c), the complete assembly with the gasket installed as intended, shall be placed in an air oven for the same duration and at the same temperature used when testing the gasket material, and then shall comply with the Leakage Test, Section 18, and the Hydrostatic Strength Test, Section 49, while at the test temperature.