ANSI/IAS NGV 4.6-1999,CSA 12.56-M99-1999 Manually Operated Valves For Natural Gas Dispensing Systems.

1.1.1 These requirements apply to manually operated valves for high pressure natural gas.
1.1.2 These requirements do not apply to cylinder shut-off valves.
1.1.3 A valve that complies with the requirements for a Class A valve may be used for a Class B valve application, however, a Class B valve may not be substituted for a Class A valve. (See Part IV Definitions.)
1.2.1 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.
1.2.2 Valves shall be provided with means to compensate for manufacturing tolerance variations, displacement of lubricants, and for wear which may occur.
1.2.3 For Items Unique To One Country (Canada) see Exhibit A.
1.2.4 All references to psi throughout this document are to be considered gauge pressures unless otherwise specified.You can download CSA 12.56-M99 here.