The Viking model DRV-1 dry valve is a latching differential valve used to separate the water supply from the dry pipe sprinkler system. The valve head provides a positive mechanical seal within the valve, separating the supply water pressure from the air in the system. The differential design allows a low system air pressure to control a higher water supply pressure. When the air pressure in the dry pipe system is lowered sufficiently to destroy the pressure differential - due to a sprinkler activation and subsequent loss of air pressure in the piping - the valve opens allowing water to enter the dry pipe system.

The valve is also designed to operate a water motor alarm and/or an electric pressure alarm switch. The Viking model D-2 accelerator can be used to speed up the operation of the valve on large capacity systems or where faster action is required.