FCU 500, FCU 505 · Edition 02.17
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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 746-2 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
pu
Vp1
V1
PZ
pu
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
Vp1
pu
pu
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
pu
Vp1
PZ
pu
2
V1
V2
PZ
Vp2
The valves and the pipework between the valves are
tested.