BCU 560, BCU 565 · Edition 02.16
31
6 Valve proving system
The BCU 500..C1 is fitted with an integrated valve proving
system. This allows either the tightness of the gas solenoid
valves and the pipework between them to be checked (tight-
ness test) or the closed position of a solenoid valve (proof of
closure function) to be checked.
Once the test has been carried out successfully, the burner
enable signal is issued.
For details, see pages 31 (Tightness control) and 38 (Proof
6 .1 Tightness control
The aim of the tightness control is to identify an inadmissible
leak on one of the gas solenoid valves and to prevent burner
start. Gas solenoid valves V1 and V2 are tested as is the pipe-
work between the valves.
V2
pu
Vp1
V1
PZ
pu
2
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 tightness control function satisfies the requirements of
EN 1643 (Valve proving systems for automatic shut-off valves
for gas burners and gas appliances).