Solenoid Valves

2/2 Way Solenoid valves for Vacuum.

High and Medium Vacuum solenoid valves come in various sizes and forms or functionality however for vacuum applications you can only use direct acting or assisted lift solenoid valves. Typically you cannot use a servo or pressure assisted solenoid valve, even though you may have a pressure differential due to the vacuum on the outlet port, as this type of pressure assisted solenoid valve requires a positive inlet pressure to operate, you will find that the this type of valve will fail to open if used incorrectly for vacuum applications.

Direct acting and assisted lift (hung diaphragm) solenoid valves do not require any pressure differential and will typically work well on most vacuum applications.

2 way direct Acting Vacuum Solenoid Valve

This is a 2/2 way direct acting solenoid valve schematic, basic direct acting solenoid valves uk1 inlet 1 outlet ON/OFF control. You can clearly see that this solenoid valve directly opens when power is applied.

Good Points: Compact, low cost, low energy consumption.

Bad Points: Low flow (small orifice).

Typical Port sizes from 1/8 through to 1/2" BSP, NPT Thread.

2 way Vacuum Solenoid Valve

This is a 2/2 way assisted lift or hung diaphragm solenoid brass assisted lift solenoid valves ukvalve schematic, basic 1 inlet 1 outlet ON/OFF control. You can clearly see that this solenoid valve is diaphragm assisted open when power is applied the diaphragm is hung or attached to the plunger and assisted open with internal pilot.

Good Points: High Flow.

Bad Points: Can sometimes give poor sealing on slight vacuum, higher energy consumption.

Typical Port Sizes from 3/8 through to 2" thread BSP, NPT or DN25 to DN100 Flange

This is a 3/2 way direct acting coaxial solenoid valve. Also coaxial solenoid valves ukavailable 2/2 way, this valve design allows for diverting from one port to 1 of two other ports i.e. vacuum P to A or vacuum P to R.

Typical port sizes 1/4 through to 2" thread in either BSP, NPT or DN10 to DN80 Flange.

Good points: Compact, high flow, excellent sealing, mounting any direction, manifold options, open and closed position switch and manual over ride options.

Bad Points: Typical more expensive than a solenoid valve.

Materials of Construction.

Solenoid valves for vacuum applications can be made from the same materials as general purpose solenoid valves, typically Brass body, stainless steel internals and NBR seals. The only parameters of concern will be the environment, application temperatures and application requirements . For example for food industry vacuum applications a stainless steel body would be preferred and for high temperature applications PTFE or FKM seals and High a Temperature Class H (180C) or N (200C) rated Coil will be required.

Helpful Hint: Always advise any application environmental and temperature parameters when ordering your vacuum solenoid valve.

How to connect a vacuum solenoid valve.

Solenoid valves ports are usually marked on the ports either in and out or inlet and outlet or even simply 1 and 2, 1 denotes inlet 2 denotes outlet. Remember to connect the vacuum side of the process system to the outlet side of the solenoid valve or port 2, as you will be sucking out not pressurising IN. So connect vacuum to port outlet port 2. (port 1 typically is the pressure or atmosphere inlet)

Typical Industries.

Vacuum solenoid valves are typically found in the Flat panel display, scientific instrumentation, industrial vacuum, process vacuum, research and development, semi conductor, emerging technologies, nanotechnology, steel degassing, lithium-ion and chemical process, vacuum press bagging, Resin infusion, Vacuum distillation and petroleum distillation and Vacuum lifting industries.

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