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Externally controlled valves

  • externally controlled valves
  • electro-pneumatic valves
  • air-controlled valves

The raising of the sealing element is done with compressed air, directly via an externally controlled actuator. In single-acting actuators there is a pressure spring for the return to the rest position, taking away the control air.

We distinguish between

  • externally controlled poppet valves
  • externally controlled coaxial valves.

Externally controlled poppet valves:

The standard functions are: 'Closed with spring force and medium flow' or 'Closed with spring force against medium flow'.
In liquid-carrying pipelines, valves that close 'against the medium flow' are used for shut-off in order to reduce the water hammer.
The valves are controlled by a pilot valve, typically 3/2-way or 5/2-way.
Pilot-operated valves are suitable for controlling gaseous, highly viscous, conditionally contaminated and aggressive media. The drive (control) chamber is separated from the main medium.

Coaxial valves, externally controlled:

The switching process with this type of control takes place almost without friction and without differential pressure. This design allows any flow direction. NO- with spring force open is possible as well as the standard function NC- with spring force closed. The control air connection is realised by a Namur interface.

The following applies to externally controlled valves:

  • Control pressure 3-8 bar is required
  • Control medium preferably air
  • fast opening and closing time with high repeat accuracy.
  • Any installation position


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