Determination Of Vp Leakage Rate - Siemens LMV51 Series Basic Documentation

Recommendation
Determination of VP
leakage rate
Legend
Examples
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It is possible to parameterize whether gas valve proving shall be performed. Also, the
time can be set. Gas valve proving can be carried out during startup, shutdown, or in
both phases.
Perform gas valve proving during shutdown.
Parameter: ValveProvingType (No VP / VP startup / VP shutdown / VP stup/shd)
The evacuation and filling times as well as the test times at atmospheric pressure or
mains pressure must be set by the OEM, for each individual plant and in accordance
with the requirements of EN1643.
Parameter: VP_EvacTme
Parameter: VP_TmeAtmPress
Parameter: VP_FillTme
Parameter: VP_Tme_GasPress
In particular, it must be ensured that the 2 test times will be set correctly. It must also be
checked whether - on the specific application - it is permitted to introduce into the
combustion chamber the gas required for testing.
The test times are safety-related.
After a reset, or in the event gas valve proving has been aborted or prevented, the
burner control will carry out gas valve proving during the next startup sequence (only if
gas valve proving is activated).
Examples of aborted gas valve proving:
When the safety loop or the start prevention input for gas (containing Gpmin) opens
during gas valve proving.
If gas valve proving is parameterized with «startup and shutdown», the gas valves must
perform additional switching cycles. This means that wear and tear of the gas valves will
increase.
(P G - P w ) • V • 3600
¾¾¾¾¾¾¾¾¾
Q Leakage =
Q Leakage in l / h
P G in mbar
P W in mbar
P atm in mbar
V in l
t Test in s
Refer to chapter «Commissioning instructions for LMV51... system» / gas valve proving /
leakage test.
Basic Documentation LMV51...
3 Burner control
P atm • t Test
Leakage rate in liters per hour
Overpressure in the piping section between the valves to be tested, at the
beginning of the test phase
Overpessure adjusted on the pressure switch (normally set to 50 %
of the gas inlet pressure)
Absolute air pressure (1,013 mbar normal pressure)
Volume in the piping section between the valves to be tested, including the
volume in the valves themselves, plus any pilot section (Gp1)
Test time
CC1P7550en
29.05.2002