Singer Model 106 EPDV-A-10506A Pneumatic/Electric Solenoid control valve is based on the Singer Model 106 PG-UL Deluge main valve.
The solenoid pilot provides on-off position operation. The solenoid, using an independent air supply, either admits inlet pressure into the main valve operating chamber from the inlet of the main valve via a high capacity relay valve or releases pressure from the relay valve and therefore the main valve operating chamber. This either opens or closes the main valve. The pilot system is usually piped to discharge to drain (atmosphere).
The 106 EPDV-A-10506A is available with the main valve closed when the solenoid is de-energized (NC- normally closed; this refers to the main valve, not the solenoid).