FCU 500, FCU 505 · Edition 02.17
50
Valve proving system
7 .2 .4 Extended valve opening time 1 t
L1
Standard EN 1643:2000 allows a maximum opening
time of 3 s for the tightness test if the main gas valves
are actuated directly. If the gas can flow into the com-
bustion chamber when a valve is opened, the gas vol-
ume must not exceed 0.05% of the maximum flow rate.
If the pre-set opening time t
L
= 3 s is inadequate (e.g. if
slow opening motorized valves VK are used) to build up
or reduce the test volume pressure, bypass valves with
an extended opening time may be used (e.g. VAS 1 or
bypass valves with an additional orifice).
1. Tightness test between 2 gas solenoid valves with
one test volume (parameter 53 = 1):
VK
VK
VAS 1
VAS 1
14
13
57
V1
V2
2. System leak tightness check with one test volume
and pressure reduction using relief valve (parameter
53 = 2):
57
VK
V3
V1
13
VAS 1
15
3. System leak tightness check with two test volumes
and pressure reduction using relief valve (parameter
53 = 3):
57
V3
V1
V2
VAS 1
VAS 1
14
15
13
VK
VK
Current rating of safety interlock output (terminal 57):
max. 0.5 A, see also page 127 (Safety interlock output
in the case of higher power requirement)
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