Gas Valve Proving; Valve Proving With Separate Pressure Switch - Siemens LME7 Series Basic Documentation

P LT
Fig. 24: Valve proving with separate pressure
switch
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12.2.3 Gas valve proving

Valve proving is dependent on parameter 241. It is employed to detect leaking gas
valves and, if necessary, to prevent the valves from opening or ignition from being
switched on. Lockout is initiated.

Valve proving with separate pressure switch

P Step 1: td4 – test space evacuating.
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Gas valve on the burner side is opened to bring the test space to
atmospheric pressure.
Step 2: td1 – test atmospheric pressure.
When the gas valve has closed, the gas pressure in the test space
must not exceed a certain level.
Step 3: td3 – test space filling.
Gas valve on the mains side opens to fill the test space.
Step 4: td2 – test gas pressure.
7105d68e/1210
When the gas valve has closed, the gas pressure in the test space
must not drop below a certain level.
Legend
td1
td2
td3
td4
V...
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) and P241.01 = 1

Note!
If valve proving is parameterized to take place on startup and shutdown,
the gas valves must run through additional switching cycles. As a result,
strain (wear) on the gas valves and the relay increases.
Basic Documentation LME7...
12 PME71.901...
Test atmospheric pressure
Test gas pressure
Test space filling
Test space evacuating
Fuel valve
Pressure switch valve proving
Input/output signal 1 (ON)
Input/output signal 0 (OFF)
Input permissible signal 1 (ON) or 0 (OFF)
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CC1P7105en
29.11.2011