UL 574:2019 pdf download

4.3 A synthetic rubber part in contact with oil shall not show excessive volume change, when consideredon the basis of its intended function, following immersion for 70 hours in lRM oil No.903 (Test Method forRubber Property - Effects of Liquid,ASTM D471-1998).

4.4A change in volume of not more than 25 percent swelling or 1 percent shrinkage is considered asindicating compliance with 4.3.See Volume Change Test, Section 18.

4.5 A part made of synthetic rubber which may be affected by aging shall not crack or show visibleevidence of deterioration following air oven aging.The test time and temperature should be determinedusing the oven aging table in the Standard for Gaskets and Seals, UL 157,based on a servicetemperature as measured during the Temperature Test, Section 17.

4.6 An automatically actuated part of an oil heater shall be made of metal resistant to corrosion or ofmetal protected by a corrosion resistant finish that will not be impaired by exposure,wear, and the like,during the expected service life of the heater.

4.7 Any sheath, caillary, well, or other part shall be resistant to atmospheric corrosion and attack by theoil it may normally contact in service when failure of the part may permit external leakage or result inhazardous operation of the heater.

4.8Uncoated ordinary-ferrous materials are considered adequate for the preceding when made of sheetmetal not less than 0.053 inch (1.35 mm) thick or made of cast metal not less than 178 inch (3.2 mm) thick.Brass alloys in sheet form are not considered resistant to the corrosive effects of fuel oils.

4.9 Cadmium plating shall have a thickness of not less than 0.0003 inch (0.008 mm) and zinc platingshall have a thickness of not less than 0.0005 inch(0.013 mm), except on parts where threads constitutethe major portion of the area, in which case the thickness of the cadmium or zinc plating shall be not lessthan 0.00015 inch (0.0038 mm).

4.10 A part made of drawn brass or machined from brass rod shall be capable of withstanding, withoutcracking, the 10-Day Moist Ammonia-Air Stress Cracking Test, Section 19.

4.11 If warping of a casting can affect the tightness of liquid-confining joints or the necessary fit of parts,the casting shall be stress-relieved to reduce the possibility of warping to a minimum.

4.12 For flat flanges, a plant-fiber gasket shall be not more than 1/32 inch (0.8 mm) thick.Syntheticrubber gasket shall have a thickness of not less than 1/16 inch (1.6 mm) nor more than 3/32 inch (2.4 mm).