CSA ANSI Z83.4A-2004 pdf download American National Standard/ CSA Standard For Non-Recirculating Direct Gas-Fired Industrial Air Heaters ANSI Z83.4a-2004 CSA 3.7a-2004 Part I: Construction
1.14 Automatic Valves and Safety Shutoff Valves
1.14.3 All gas to the main burner(s) shall pass through at least two valves in series that may or may not be in a single control body. Both valves shall be automatic valves (see Part IV, Definitions) and serve as operating valves and safety shutoff valves (see Part IV, Definitions).
One safety shutoff valve incorporating valve seal overtravel (proof of closure) interlock meets this requirement for appliances having an input rate of 10,000,000 Btu/h (2 930 71 2 W) or I ess.
1.16 Dischage Air, Purge, Limit Controls And Interlocks
1.16.11 A heater design that includes a gas valve with valve seal overtravel interlock shall:
Prevent the start of an ignition cycle when the valve seal overtravel interlock switch verifies that the valve is in the open position; and
Allow the gas valve to be energized during the flame establishing period and while the automatic gas ignition system proves the supervised flame or ignition source.
1.22 Operating And Installation Instructions
1.22.10 Adequate instructions shall be provided for checking the gas tightness of the safety shut-off vaive(s) on at least an annual basis.