FCU 500, FCU 505 · Edition 02.17 34
Valve proving system
7.1 Tightness control
The aim of the tightness control is to identify an in-
admissible leak on one of the gas solenoid valves
and to prevent burner start. European standards
EN 7462 and EN 676 stipulate tightness controls for
capacities over 1200 kW (NFPA 86: from 117 kW or
400,000 Btu/h).
The FCU offers several ways of testing tightness:
1. Between 2 gas solenoid valves with one test volume
(parameter 53 = 1):
V2
p
u
V
p1
V1
PZ
p
u
2
2. The system tightness of a complete gas inlet section
with one test volume and pressure reduction using a
relief valve (parameter 53 = 2):
V1
PZ
V
p1
p
u
p
u
2
V3
3. The system tightness of a complete gas inlet section
with two test volumes and pressure reduction using a
relief valve (parameter 53 = 3):
V3
DG
V3
p
u
V
p1
PZ
p
u
2
V1
V2
PZ
V
p2
The valves and the pipework between the valves are
tested.
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