CSA ANSI NGV 4.7:2020 pdf free download – Automatically pressure operated valves for natural gas dispensing systems
4.1.4 General construction The construction of parts not covered by these requirements shall be in accordance with reasonable concepts of safety, substantiality, and durability. All specifications as to construction set forth herein may be satisfied by the construction actually prescribed or such other construction as will provide at least equivalent performance.
4.1.5 Enclosure protection The mechanisms of valves shall be protected by enclosures so as to prevent interference with the safe operation of the valves.
4.1.6 Pins, stems, or other linkages Pins, stems, or other linkages passing through the valve body or casting shall be sealed to provide gas- tight construction.
4.1.7 Diaphragm valve enclosure Diaphragm type valves in which a flexible non-metallic diaphragm constitutes the only gas seal and which utilize control gas on the atmospheric side of the diaphragm shall have the atmospheric side of the main diaphragm enclosed in a gas-tight casting with means provided for bleeding the control gas.
4.1.8 Diaphragm valve durability Valves in which a flexible non-metallic diaphragm constitutes the only gas seal shall have the atmospheric side of the diaphragm enclosed to limit the leakage to atmosphere in the event of diaphragm rupture to not more than 0.028 m 3 /h (1.0 ft 3 /h) at the maximum pressure rating of the valve when tested with a gas having a specific gravity of 0.55, or shall be provided with means for venting the gas in the event of diaphragm rupture.
4.1.9 Automatic pressure valve clarification An automatic valve, which uses pressure to actuate, may include a means to hold the valve in an open position during pressure failure, provided the means does not affect the intended safety function of the valve.
4.5.1 Material acceptability Materials shall be evaluated and found to be suitable for their intended usage. Compliance shall be deemed met if the materials are successfully tested to the performance section of this Standard (Clause 5) or if the manufacturer supplies evidence acceptable to the testing agency for determining compliance with the performance section of this Standard (Clause 5). Test data based on ASTM or other appropriate test procedures, certifications, or historical data may be submitted for this purpose. The evidence shall show that the materials have been evaluated, as appropriate, for resistance to moisture, corrosion, temperature, the effects of fuel gases, and any other compounds or conditions to which the materials might be exposed. Non-metallic seal materials shall also be suitably resistant to the effects of ozone.
5.5.1.2 Method of test
This test shall be conducted at room temperature on a new sample as follows:
a) The inlet and outlet connections of the valve shall be assembled leak-tight to the appropriate fittings as described in Items i) to iii). Multiported valves shall be tested in all possible configurations. The length of the inlet fitting shall be such that, after assembly, the dimension from the valve inlet to the end of the inlet fitting will be 330 ± 12.5 mm (13 ± 1/2 in). The tightening torque for threaded pipe or tubing connections shall be one-half of that shown in Table 3. i) Pipe threaded connections shall be assembled to Schedule 40 iron pipe, or pipe fitting, using appropriate lubricant, or sealant materials. ii) Tubing connections shall be assembled to steel tubing which conforms to ANSI SAE J525 and has a minimum wall thickness of 0.7 mm (0.028 in), using the attachment means specified by the manufacturer. iii) Connections designed for other than threaded pipe or tubing shall be assembled to test fixture(s) representative of the intended connection means.
b) The valve outlet fitting shall be rigidly supported 25.5 mm (1 in) from the valve outlet, unless the following exceptions apply. When the valve has an integral mounting means independent of the inlet and outlet connections, the valve shall be mounted using the integral mounting means as specified by the manufacturer. When the valve is intended to be mounted by either the integral mounting means or the valve outlet, the mounting means which produces the most severe test condition shall be used.