00 Lockout phase
● Servomotors run to stand-by position.
● Burner failure activates.
● Requires manual reset.
5.8 Gas valve proving
The system performs gas valve proving using a pressure switch or transmitter that
monitors the section of pipe between the valves. During gas valve proving, burner
control opens and closes gas valves at programmed intervals. If a leak is detected, the
gas valve proving function prevents gas valves from opening and the ignition phase
from starting. Safety shutdown is activated. The control unit display indicates which
valve is leaking.
Gas valve proving is carried out during a normal burner shutdown, between phases 62
and 70. If the previous shutdown was not normal, for example, because of a lockout or
because burner control has been de-energized, it will take place during the next start-
up sequence (during the pre-purge period) between phases 30 and 32.
Valve proving sequence phases are 80... 83.
Phase 80:
Evacuate. Gas valve V2 on the burner side is opened
to bring test space to atmospheric pressure. Valve V1
on the gas network side stays closed.
Phase 81:
Atmospheric pressure test. Both gas valves are
closed. During the test, gas pressure may not exceed
the preset limit for the pressure switch used for valve
proving.
Phase 82:
Fill. The gas train is filled by opening gas valve V1
on the gas network side. Gas valve V2 on the burner
side is closed.
Valve proving ver. 4
Phase 83:
Pressure test. Both gas valves are closed. During
the test, gas pressure may not drop below the preset
limit for the pressure switch used for valve proving.
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M4248 2316EN
