Valve interlock

Abstract

It is conventional to supply current to an electromagnet from thermally responsive means including a thermocouple near a standing pilot to hold a safety valve open. Failure of the pilot then causes the safety valve to close, shutting off all combustible gas to the system. Unfortunately, many manual valves may be shut off and turned on a short time thereafter. This permits the pilot to go out and a dangerously large amount of unburned but combustible gas to collect within the combustion chamber. This disclosure includes an interlock located between the safety and manual valves. The interlock does not permit the manual valve to be opened immediately after closure thereof. Reopening of the manual valve is permitted preferably only at or after the closure of the safety valve. Combustible gas thus cannot collect in the vicinity of the main burner if an attempt is made to close and then immediately thereafter to reopen the manual valve. This is true because the interlock prevents the manual valve from reopening after it has been closed.

Dependencies are inferred from the claim text.