Piston Digital Control Valves

Piston Digital Control Valve is an electrically actuated, hydraulically operated multi-function control valve. It can be used for local as well as remote controlled batching operations with electronic batch controller. The valve also offers an in-built flow governing function.


  • Fail-safe design : the valve is held closed upon loss of electric supply and/or line pressure
  • Positive shut-off : meets ANSI Class VI for bubble-tight closure
  • Multi-stage opening and closing : avoids static charge generation due to splashing of product in the beginning and foaming / overflow at the end, resulting in accurate delivery
  • Low pressure drop
  • Rectangular ports : for uniform valve response and linear control
  • Built-in flow rate control : no need of external pilots for flow rate control, when used with electronic batch controller
  • No diaphragm


The Alma Piston Digital Control Valve works on the principle of “balanced piston”.

Piston is always exposed to high upstream pressure from its bottom side, whereas pressure in the piston chamber can be varied with the help of solenoid valves. When pressure in the piston chamber is equal to the high upstream pressure, the top spring acts as a differential force, pushing the piston down on the valve seat and the valve is held tightly-closed.

When pressure in the piston chamber is relieved with the help of solenoid valves, a differential pressure is created across the piston. The high upstream pressure below the piston overcomes the top pressure plus the spring force and pushes the piston up, resulting in valve opening and the flow starts.