BS ISO 6182-6:2015 pdf download – Fire protection — Automatic sprinkler systems — Part 6: Requirements and test methods for check valves
4.3.2 The rated working pressure shall be specified by the manufacturer.
4.3.3 Inlet and outlet connections shall be permitted to be machined for lower working pressures to match installation equipment provided the valve is marked with the lower working pressure.
4.4 Bodies and covers
4.4.1 Bodies and covers shall be made of a material having corrosion resistance at least equivalent to cast iron.
4.4.2 Cover fasteners shall be made of steel, stainless steel, titanium, or other materials with equivalent physical and mechanical properties.
4.4.3 Non-metallic materials other than gaskets, diaphragms and seals or metals with a melting point less than 800 °C shall not form part of the valve body or cover.
4.4.4 For valves with a cover plate, it shall not be possible to assemble the valve with the cover plate in a position which either improperly indicates flow direction or prevents proper operation of the valve.
4.5 Strength (see 6.3)
4.5.1 An assembled valve, with the sealing assembly blocked open, shall withstand, without rupture, an internal hydrostatic pressure of four times the rated working pressure for a period of 5 min, when tested as specified in 6.7.
4.5.2 If the test in accordance with 6.7 is not done with standard production fasteners, the supplier shall provide documentation showing that the calculated design load of any standard production fastener, neglecting the force required to compress the gasket, does not exceed the minimum tensile strength specified in ISO 898-1 and ISO 898-2 when the valve is pressurized to four times the rated working pressure. The area of the application of pressure shall be calculated as follows.
a) If a full-face gasket is used, the area of application of pressure is that extending out to a line defined by the inner edge of the bolts.
b) If an “O”-ring seal or ring gasket is used, the area of application of force is that extending out to the centre line of the “O”-ring or gasket.
4.6 Access for maintenance Means shall be provided to permit access to working parts and removal of the sealing assembly.
4.7 Components
4.7.1 Any component which is normally disassembled during servicing shall be designed so that it cannot be reassembled improperly without providing an external visual indication, when the valve is returned to service.
4.7.2 With the exception of valve seats, all parts intended for field replacement shall be capable of being disassembled and reassembled using tools normally employed by the trade.
4.7.3 All components shall be non-detachable during normal operation of the valve.
4.7.4 Failure of the sealing assembly diaphragms or seals shall not prevent the valve from opening.
4.7.5 Sealing surfaces of sealing assemblies, including the sealing assembly seat ring, shall have corrosion resistance equivalent to brass or bronze and have sufficient width of surface contact to withstand ordinary wear and tear, rough usage, compression stresses and damage due to pipe scale or foreign matter carried by the water.
4.7.6 Springs and diaphragms shall not fracture or rupture, when tested in accordance with 6.2.
4.7.7 There shall be no sign, on visual examination, of damage to the sealing assembly after testing for the operational requirements in accordance with 6.1 0.
4.7.8 When wide open, the sealing assembly shall bear against a definite stop. The point of contact shall be located so that impact or reaction of the water flow will not permanently twist, bend or fracture valve parts.
4.7.9 Where rotation or sliding motion is required, the part or its bearing shall be made of a corrosion resistant material. Materials lacking corrosion resistance shall be fitted with bushings, inserts or other parts made of corrosion resistant materials at those points where freedom of movement is required.
4.7.10 The sealing assembly shall close towards the seat when water flow ceases. Springs shall be permitted to ensure full and proper seating. 4.8 Leakage (see 6.4)
4.8.1 There shall be no leakage, permanent distortion or rupture of a valve when an internal pressure of twice the rated working pressure is applied for 5 min with the sealing assembly open in accordance with 6.6.1 .
4.8.2 There shall be no leakage, permanent distortion or rupture of a valve at an internal pressure of twice the rated working pressure applied to the downstream side of the sealing assembly for 5 min with the upstream end vented in accordance with 6.6.