Proof of Closure in a gas valve: how to confirm that the valve has truly closed

Proof of Closure is the confirmation that a safety valve is actually in the closed position before the next step of a sequence is permitted.

What is checked

An end switch or position switch confirms the mechanical position of the valve and sends a relevant signal to the BMS or the safety circuit.

Why it is important

The “close” command does not in itself prove that the valve has closed completely. Proof of Closure provides independent position confirmation.

What it does not check

Confirmation of the closed position does not prove that the seat is perfectly tight. Valve proving may be used separately for this purpose.

Functional check

During commissioning or a proof test, it is confirmed that the change in valve position correctly corresponds to the electrical feedback.