Siemens LME7 Series Basic Documentation page 75

Building Technologies
HVAC Products
14.2.5 Valve proving of gas valves
Valve proving is depending on parameter 241. This is valve proving designed to detect
leaking gas valves and, if necessary, prevent the valves from opening or ignition from
being switched on. Lockout is initiated.
Valve proving with separate pressure switch (P LT)
P
LT
P LT
7113d11e/1009
Figure 39: Valve proving with separate pres-
sure switch (P LT)
Valve proving can be parameterized to take place on startup, shutdown, or both.
Recommendation:
Perform valve proving on shutdown.
No. Parameter
241.00 Valve proving
0 = Off
1 = On ¹)
242 Valve proving test space evacuating
243 Valve proving time test atmospheric pressure
244 Valve proving test space filling
245 Valve proving time test gas pressure
¹) Valve proving during postpurging, if P234 >0 (postpurge time (t8)) and P241.01 = 1
Caution!
If valve proving is parameterized to take place on startup and shut-
down, the gas valves must run through additional switching cycles.
As a result, strain on the gas valves (wear) increases.
Caution!
The OEM must set the evacuation, filling and test times for atmos-
pheric or mains pressure on every plant in compliance with the re-
quirements of EN 1643.
Basisdokumentation LME7...
14 PME73.820A2
When performing valve proving, the gas valve on
the burner side is opened first to bring the test
space to atmospheric pressure. Then, the valve is
closed whereupon the pressure in the test space
must not exceed a certain level. Then, the gas val-
ve on the mains side is opened to fill the gas pipe.
When the gas valve is closed again, the gas pres-
sure must not drop below a certain level.
td1 Test atmospheric pressure
td2 Test gas pressure
td3 Test space filling
td4 Test space evacuating
V... Fuel valve
P LT Pressure switch valve proving
Signal ON
Signal OFF
Permissible signal
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CC1P7105de
24.09.2009