Valve Proving - Calculation Of Leakage Rate - Siemens LME7 Series Basic Documentation

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Infrastructure & Cities Sector
Warning!
The OEM must set the evacuation, filling and test times for
atmospheric or mains pressure on every plant in compliance with the
requirements of EN 1643. If not observed, there is a risk of
impairment of safety functions. If this is not observed, there is a risk of
loss of safety functions.
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 the next time it is started
up (only when valve proving is activated). In the case of valve proving, prepurging is
active during 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 pressure switch-
min) opens during 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
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CC1P7105en
29.11.2011