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6 Leakage Test for Main Gas Valves
6.2 Leakage Test with Ventilation Via Roof
The leakage test checks whether or not the main gas valves are leakproof. For this purpose
the gas pressure of the supply is analysed.
As leakage test section (space between the two main valves) burns empty whenever the burn-
er is switched off, this part is usually pressureless at start-up (gas pressure > min = 0). This is
checked by BurnerTronic. At this point, main gas 1 opens briefly and gas flows into test section
(gas pressure > min switches from 0 to 1). This pressure must remain constantly at least while
leakage test period (P 311) is running. The leakage test is considered complete then.
If leakage test section is not empty at start-up (e.g. resulting from a previous fault shutdown),
main gas valve 2 opens first. The leakage test line is then ventilated (depending on the plant,
either in the combustion chamber or through the roof – for wiring proposition, see chapter 6.3
Exhaust of Test Line Over the Roof). During leakage test period section is checked whether
it remains pressureless or not. Apart from that the process is the same as described above.
The leakage test takes place prior to ignition.
You must connect the pressure monitor for the leakage test line at the “Gas pressure > min”
input on plug X05. It also monitors the minimum pressure during operation. If a different min-
imum pressure should be monitored during operation, the pressure monitor must be inserted
into the safety interlock chain gas or into the controller loop (burner ON). You must assure by
dimensioning the gas line in a way that leakage test control time is sufficient for detecting re-
liably a burner gas consumption leakage of 0.1%, but at least 50 dm
3
/h (at maximum combus-
tion heat output).
NOTICE!
You may only vent 0.05 % of fuel consumption at maximum firing-rate into combustion cham-
ber.
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