Siemens LME7 Series Basic Documentation page 76

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It must be ensured that the 2 test times are correctly set. It is to be checked whether
the gas required for the test may be fed into the combustion chamber (on the relevant
application). The test times are safety-related. After a reset and in the case of aborted
or prevented valve proving, the unit will perform valve proving on the next startup (only
when valve proving is activated). In the case of valve proving, prepurging is active dur-
ing the startup phase, even if it has been deactivated.
Examples of aborted valve proving:
When the safety loop or the start prevention input for gas (containing Pmin) opens dur-
ing valve proving.
Valve proving – calculation of leakage rate
(P G - P w ) V
• •
t Test = ⎯⎯⎯⎯⎯⎯⎯⎯⎯
P atm Q Leck
•
Q in l / h Leakage rate in liters per hour
Leck
P in mbar Overpressure between the valves at the beginning of the test phase
G
P in mbar Overpressure set on the pressure switch (normally 50%
W
of the gas inlet pressure)
P in mbar Absolute air pressure (1013 mbar normal pressure)
atm
V in l Volume between the valves (test volume) including valve volume
and pilot pipe, if present (Gp1 mod)
t in s Test time
Test
Basisdokumentation LME7...
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24.09.2009