5.3 Gas valve proving
Valve proving system is carried out with pressure switch that supervises piping section
between valves. Burner control opens and closes gas valves during proving according
to the programmed times. If leak is detected, gas valve proving function prevents gas
valves from opening, and ignition from beginning. Safety shutdown activates. Burner
control display shows the leaking valve.
Gas valve proving is carried out during normal burner shutdown, between phases 62
and 70. If the previous shutdown was not normal, for example, because lockout or
burner control has been de-energized, it takes place during next start-up sequence,
during pre-purge period, between phases 30 and 32.
Valve proving sequence phases are 80... 83.
Phase 80:
Evacuate. Gas valve V2 on burner side is opened to
bring test space to atmospheric pressure. Valve V1
on gas network side stays closed.
Phase 81:
Atmospheric pressure test. Both gas valves are
closed. Gas pressure may not exceed the preset limit
of the valve proving pressure switch during test.
Phase 82:
Fill. Gas train is filled by opening gas valve V1 on gas
network side. Gas valve V2 on burner side is closed.
V1
V2
PS-VP
t80
t81
t82
t83
V1
V2
PS
VP
TIIVIYDENTESTAUSPAINEKYTK ver. 3
Phase 83:
Pressure test. Both gas valves are closed. Gas
pressure may not drop below the preset limit of the
pressure switch valve proving pressure switch during
test.
5.4 Legend to time sequence diagrams
Phases:
00 Lockout phase
50 2nd safety time
01 Safety phase
52 Interval 2 (ti2)
10 Homerun
54 Low-fire position
12 Standby (stationary)
60 Operation 1 (stationary)
21 Shutoff valve ON (start release)
62 Operation 2
Low-fire position
22 Fan motor ON
70 Post-combustion time
24 Prepurge position
72 Postpurge position
94 (129)
M5178 1647EN
Summary of Contents for GKP-350 M
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