VALVE PROVING SYSTEM SIEMENS LDU11
The LDU11... gas valve proving system is designed for use in gas-fired
plant equipped with two safety shutoff valves. During each startup cycle,
the control unit automatically programs the valve proving test and, in the
event of a leak, prevents burner startup.
The LDU11… control unit is designed to provide automatic gas valve pro-
ving (leakage test) based on the pressure proving principle. It is for use in
gas-fired plant with or without vent pipe to the atmosphere. For plants
without vent pipe, where DIN/DVGW regulations apply, refer to the hints
given on "Connection examples with vent pipe to the
atmosphere".
Gas valve proving is initiated automatically with every burner startup
using one or two standard pressure monitors, either
z
prior to burner startup,
z
during the pre-purge time, if it lasts at least 60 s,
z
immediately after the controlled shutdown, or
z
on completion of the burner control's control program, e.g. on comple-
tion of the post-purge time
The valve proving test is based on the two-stage pressure proving princi-
ple: first, the valve on the mains side is tested by evacuating the test
space and by monitoring the atmospheric pressure in it. Then, the valve
on the burner side is checked by pressurizing the test space and by moni-
toring the gas pressure. If the pressure increases excessively during the
first test phase (Test 1), or decreases excessively during the second test
