One of the things we look for when inspecting indoor and outdoor natural gas appliances is to ensure that the proper gas valves are used.
Gas ball valves require CSA approval in order to be used in combustible gas applications. We will explore more about this rating, testing, and some special features of gas ball valves. The ratings for gas ball valves are set by CSA. There are different ratings depending on installation location (indoor vs. outdoor) and country (Canada vs. USA).
The CSA gas ratings for indoor approvals are 1/2 PSI and 5G. Valves with these ratings can be installed indoors only. Both Canada & the USA use the same ratings for indoor valves. There are two different ratings because they have different applications, the 1/2 PSI rating is used for valves that are at appliances, while the 5G rating is for valves that are used in household piping systems.
For a gas valve to be installed outdoors it must have CAN 3.16 approval in Canada and BRS125G approval in the USA.
Working with combustible gas is not something you want to mess around with. Gas ball valves are no exception, they are tested to 1.5 times the stated working pressure. The one exception to this is the CAN 3.16 valves because they already require much higher pressure. Here is what pressures the valves are tested at for the different ratings:
1/2 PSI - Test Pressure 3 PSIG
5G - 7.5 PSIG
CAN 3.16 125 PSI Valves - 125 PSIG
BRS125G PSI Valves - 188 PSIG (ANSI B16.33)
It is possible for gas valves to have different pressure and temperature ratings under the same CSA approval as per manufacture request, however, all the valves must have met the CSA minimum test parameters with respect to pressure and temperature as outlined in the standard.
Again, if the wrong valve is installed, it will be called out and should always be replaced by a qualified, licensed plumbing contractor.