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What is an Indirect Acting Solenoid Valve?

24 April 2020

Indirect acting solenoid valves use the pressure energy of the operating fluid to open and close the valve seat and therefore needs a pressure differential to operate (minimum 0.1bar). The pilot system functions as a booster, so that even with a solenoid of lesser magnetic force (than that of a directly actuated valve), fluids flowing at higher rates under high pressures can be controlled. Both pistons and diaphragms are used as sealing elements for the main seat.

What is an Indirect Acting Solenoid Valve?

What are the benefits of Indirect Acting Solenoid Valves?

Suitable for high flow rates (up to 16 bar)
Media pressure assists valve opening allowing for a smaller coil
Less power consumption
Available in compact 2/2 way normally open or normally closed versions
Includes Click-onTM solenoids that can be replaced without tools
Anti-water hammer feature as standard
Suitable for liquids or gas

Where are they used?

Most suited to the process industry, these valves are used in applications that always contain media pressure in the pipeline.

Cooling systems
Water control systems
Isolation systems

How do they work?

Solenoid de-energised and valve is closed

The sealing element is directly connected to the plunger. When the solenoid is de-energised, the spring force presses the plunger on to the seat sealing the orifice. The plunger is only moved by energising the solenoid.

Solenoid energised and valve is open

When the solenoid is energised the magnetic force raises the core from the vent. When the core is raised, the pressure above the diaphragm is relieved through the vent. The downstream fluid pressure, which is now greater than the closing force exerted by the media above the diaphragm, lifts the diaphragm (or piston) off the seat to open the valve.