Siemens LDU11.523A27 Gas valve proving system

Automatic gas valve proving system for gas burners.

Automatic gas valve proving (leakage test) based on the pressure proving principle.
Used in connection with 1 or 2 commercially available pressure switches, valve proving is
automatically initiated with every burner startup, either
– prior to burner startup
– during the prepurge time if it lasts a minimum of 60 seconds
– immediately after a controlled shutdown, or
– on completion of the burner control’s control sequence, e.g. at the end of the
postpurge time