Introduction

• A solenoid is a coil of wire that becomes magnetized when electricity is run through it.
• Solenoids often have a hole in the middle and a protruding metal rod that is pushed or pulled by magnetism when power is applied.
• A solenoid valve uses a solenoid to actuate a valve. This lets you control the flow of water, air, or other things with electricity.

There are many different types of solenoid valves available, and many companies that make them.

When selecting a solenoid valve, you must pay attention to:

Valve Types

A two-way valve has two ports.

When power is applied, the pressure flows from one port to the other.

With pressure off, the flow ceases. [Assuming a normally-closed valve, which is almost always the case.]

A three-way valve has three ports.

When power is on, one of the ports is connected to the common port, and pressure flows through to extend the pneumatic cylinder.

When power is off, the other port is connected to the common port, and pressure is exhausted to reset the cylinder.

This is the pneumatic equivalent of a single-pole single-throw electrical switch.

A four-way valve has four ports.

With power on, one set of ports is connected straight through to the other set of ports.

With power off, the connection is reversed.

If a valve has more ports than you need, you can plug them up to get a lesser configuration.

A four-way valve can act as a three-way by plugging one of the ports.

A four-way valve can act as a two-way by plugging two of the ports.

A three-way valve can act as a two-way by plugging one of the ports.

Identification Of Surplus Valves

Importance Of Proper Identification

• If you apply too much pressure, the valve could "stick" - either not opening when desired, or failing to close.
• In cases where the pressure is much greater than the valve is designed of, the valve could fail catastrophically (explode).
• If you use the wrong power, the solenoid coil could burn out, or your power supply could be damaged.
• If the valve is intended for intermittant use, and you turn it on all the time, the solenoid could burn out.

General

• Get as much information as possible when you get the valve.

  Does it come with paperwork? Does the seller have an identical valve that does have paperwork? Even items in a surplus catalog usually have some information.

• Look for specifications marked on the valve.

  Look for an engraved plate somewhere on the valve. Such plates are very common, and usually specify power supply and working pressure.

• Look for manufacturer and model marked on the valve.

  Look for a manufacturer's name and model number. Then contact the manufacturer (search them up on the web) and ask for specifications.

  Note: Very generic information isn't terribly helpful. There must be hundreds of different models of ASCO "Red Hat" solenoid valves, with many different operating specifications.

Wiring

Plumbing

Start by counting the number of "ports" through which air enters and exits the valve. If the valve is relatively new, the ports may be plugged with dust caps. Remove them so you can get a look inside and verify that it is a port. Before removing something, make sure it is a port, and not part of the valve.

The blue plastic bits are plugs that protect ports.

The red plastic bit is part of the valve - leave it alone!

Wiring

Gallery of Assorted Valves

MAC 113B-111BAAA

ASCO "Red-Hat" EF8003G1

(only rated for 50 PSI)

Mead LTV-120

The look of this valve doesn't quite match the specification sheets from Mead, which suggests that this is an earlier model.

Sources