UL 331:2017 pdf download – Strainers for Flammable Fluids and Anhydrous Ammonia
UL 331:2017 pdf download – Strainers for Flammable Fluids and Anhydrous Ammonia.
8.5 A flat gasket employed with a bolted cover shall be cemented to the cover or body unless the construction is such that the gasket will be retained by either the body Or cover wi’en the cover is removed.
Exception: Cementing or retaining of the gasket is not necessary provided a complete set of new gaskets is furnished with each replacement cartridge for a strainer that employs a cartridge-type filtering element.
8.6 A plant fiber gasket shall not be less than 1/32 inch (0.8 mm) thick.
8.7 A cork gasket shall be graphited on one side, and when high pressures are involved, the other side
shall be cemented In place so the gasket will not be blown out.
9 Stuffing Boxes
9,1 If packing is used to prevent leakage around a stem, and the construction Es such that it is necessary for the user to adjust or renew the packing during usage or as wear occurs, a stuffing box complying with the requirements in 9.2 — 9.8 shall be provided.
9.2 A stuffing box shall be provided with a removable, shouldered, unthreaded follower gland, and shall have a nut or other means for adjusting the gland to maintain pressure on the packing.
9.3 A stuffing box gland shall be made of corrosion-resistant material.
9.4 A stuffing box shall be fully packed prior to shipment of the strainer
9.5 A spring-loaded follower gland shall employ a spring made of corrosion-resistant material, or of material provided with a corrosion-resistani protective coating.
9.6 If corrosion of a stem will cause damage to a packing or seal material and result in leakage, the stem shall be of a corrosion-resistant material.
9.7 A stem shall be constructed so that it cannot be completely withdrawn from the strainer by reverse rotation, Threads 01 a stem shall not enter a stuffing box recess.
9.8 A stem shall be of sufficient length to permit repacking the stuffing box without requiring the strainer to be dismantled.
12.3 With reference to the requirements in 12.1, the change in volume shall not be more than 25 percent swelling (40 percent in Reference Fuel C or Fuel C blends) or 1 percent shrinkage, and the weight loss (extraction) shall not be more than 10 percent.
Exception: If the limits for volume change or we,ht loss are exceeded, a complete strainer assembly Es to be filled with the appropriate test liquid for 70 hours and then shall comply with the requirements for the Deformation and External-Leakage Test. Section 13, and the Hydrostatic-Strength Test, Section 14.
12.4 Synthetic rubber part that is in contact with fluids, shall not crack or show visible evidence of deterioration following exposure for oven aging. as specified in the requirements in the Standard for Gaskets and Seals, UL 157. The maximum service temperature used to determine the conditioning time and temperature for oven aging is to be 6OC, unless the product is designated for use at a higher temperature.
12.5 The GasketsStandard for and Seals, UL 157. provides for the testing of either finished elastomeric parts, sheet, or slab matenal, Sheet or slab material is to be tested when the elastomenc parts are o-nngs 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 elastomenc parts, sheet, or slab material is tested.
13 DeformatIon and External-Leakage Test
13.1 When tested as specf led in 13.2 — 13.6, a strainer shall not leak, nor shall there be evidence of damage resulting from:
a) The application of 1-112 times maximum rated pressure for 1 minute.
b) The tightening of threaded parts used for care and servicing, and
C) The turning effort exerted on openings threaded for piping.
13.2 Representative strainer assemblies are to be ngidly supported. Any bolts, pipe plugs, or threaded parts detached for care and servicing of the strainer are to be tightened with a torque wrench to the value specified In Table 13.1 or 13.2.