UL-1739:2017 pdf free download – STANDARD FOR SAFETY Pilot-Operated Pressure-Control Valves for Fire-Protection Service.
10 Materials
10.1 A part that bears against, rotates within, or slides on stationary parts, and that moves during valve operation, shall be either:
a) Made of corrosion-resistant material; or
b) Fitted with bushings, inserts, or other parts made of corrosion-resistant material at those points where freedom of motion is required.
10.2 An interior bolt or screw shall be made of bronze or other material having at least equivalent resistance to corrosion.
10.3 An internal spring shall be made of material having corrosion resistance at least equivalent to that of phosphor bronze and shall be resistant to stress corrosion.
10.4 A seat ring shall be made of brass, bronze, or a material having at least equivalent resistance to corrosion and shall be held in place by screw threads, cold swaging, or the equivalent.
11 Body-Seat Rings
11.1 A body-seat ring shall have a smooth, machined surface capable of complying with the Seat
Leakage Test specified in 20.2.
11 .2 A seat ring of an iron-bodied valve shall be made of a material having corrosion resistance
equivalent to brass or bronze and shall be held in place by screw threads, cold swaging, or the equivalent.
12 Valve Mechanisms
12.1 An internal working part that is removed during intended maintenance shall be removable without damaging the valve. The removal shall require the use of ordinary tools only, such as pipe wrenches, flat-blade or cross-point screwdrivers, pliers, and the like.
12.2 A part that is disassembled in field servicing shall be of a construction that will permit its accurate reassembly.
12.3 A part within the valve shall be secured to resist separation during intended use.
12.4 If an orifice with a diameter less than 3/16 inch (4.8 mm) is used in the trim or operation of a valve, a screen or strainer with corrosion resistance equivalent to brass shall be provided. The total area of the openings in the screen or strainer shall be not less than 20 times the cross-sectional area of the opening that the screen or strainer is intended to protect. The largest dimension of the screen or strainer openings shall not exceed 1/32 inch (0.8 mm) less than the diameter of the protected orifice. The strainer shall be constructed such that the screen is capable of being cleaned without removing the strainer from the pilot piping.
12.5 The pilot trim line used in a pressure control valve shall not incorporate a manual shutoff valve that could affect the proper operation of the valve unless the shutoff valve has provisions to be locked in the open position.
13 Clearances
13.1 Clearances shall be provided between working parts and between working and stationary parts so that corrosion or deposits of foreign matter within an assembly will not result in impaired operation of the valve.
13.2 The clearance between a valve disc or a part attached thereto and the inside walls of an iron body casting shall not be less than 1/2 inch (12.7 mm) for every position of the disc except fully open. This clearance shall not be less than 1/4 inch (6.4 mm) for valves having bodies of bronze or equivalently corrosion-resistant material.
14 Valve Adjustment
14.1 A valve shall be provided with a means such as a fastening nut to secure the intended setting.
PERFORMANCE
15 General
15.1 Representative samples of each size valve shall be subjected to the tests described in Sections 16 — 22. Additional samples of parts constructed of nonmetallic materials, such as rubber seal rings, are to be used for the Elastomeric Parts (Except Gaskets) Test, Section 17.