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Building Technologies Division Basic Documentation LME7... CC1P7105en
Infrastructure & Cities Sector 19 PME73.840... 29.11.2011
19.2.5 Gas valve proving
Valve proving is dependent 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
Step 1: td4 – test space evacuating.
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.
When the gas valve has closed, the gas pressure in the test space
must not drop below a certain level.
Legend
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
Input/output signal 1 (ON)
Input/output signal 0 (OFF)
P LT
7105d68e/1210
P
LT
Figure 80: Valve proving with separate pressure
switch
Input permissible signal 1 (ON) or 0 (OFF)
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.
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