Having the answers will make it much easier for the solenoid supplier to provide the correct type for a particular application. What is the ambient temperature the solenoid will see?.Does the solenoid need to be explosion proof or just watertight?.What materials of construction do I need the solenoid made from?.What port size do I need in my solenoid body?.Do I want a direct mount or remote solenoid?.What do I want my actuator to do if I lose power to my coil?.What type actuator do I have (fail open or fail closed)?.Solenoid questions to answer: When picking a solenoid valve, be sure to ask these 11 questions: Normally open solenoids allow an open path for the air supply to reach the actuator when the coil is de-energized. A normally closed solenoid will block the air supply from the actuator when the coil is de-energized. Normally-closed or normally-open refers to the position of the solenoid when the coil is de-energized. Generally, you will need normally-closed solenoids for automating your actuators. This configuration will duplicate the operation of a dual coil solenoid. If you do not have a 4-way or 5-way solenoid readily available, the user can use two 3-way solenoids to control each side of a double acting actuator independently. Dual coil solenoids will cause your actuator to remain in place if there is a loss of power. Single coil versions will cause your actuator to be fail closed or fail open on loss of power. Four-way and 5-way solenoids may have either one or two electromagnetic coils. They allow you to pressurize and vent each side of the actuator’s pistons. 4-way and 5-way solenoids are primarily used on double acting actuators. A 5-way solenoid is similar to the 4-way except they have one inlet pressure port, two outlet pressure ports, and two independent exhaust ports. The spring return actuator usually has a built-in vent for the non-pressure side of the piston(s) or diaphragm.įour-way solenoids have one pressure inlet port, two pressure outlet ports and share an exhaust port for both sides of the actuator piston. 3-way solenoids only pressurize and vent one side of the actuator’s pistons. Three-way solenoids are used primarily on spring return actuators. For example, a 3-way solenoid has one pressure inlet port, one pressure outlet port that goes to operate the pneumatic actuator (coil energized), and it has an exhaust port to vent pressure from the actuator’s pressure side when the coil is de-energized. These ports direct your air supply as well as the actuator’s exhaust when the electric coil is energized or de-energized. The terms "3-way," "4-way," and "5-way" refer to the port configurations inside the solenoid valve body. Remote mount solenoids are useful if the actuator is in a harsh or hot environment that might affect the operation of the solenoid’s electronics. Remote mount solenoids can be mounted on or near the actuators and require the air to be piped to the actuator. Modern rack and pinion actuators have a universal NAMUR supply port configurations that allow the use of special direct mount solenoids to eliminate the need for tubing or fittings. You must also vent the pressure side of the piston(s) or diaphragm as the actuator is returning to its normal position. If you do not vent the actuator, it will not completely stroke the valve. When you add air to one side of the piston(s) or diaphragm, the user must vent air from the opposite side in order for the piston or diaphragm to move and operate the valve. Spring return actuators have springs on the ends of the pistons that return the pistons to a specific position when the air is removed from the actuator. There are also diaphragm actuators that utilize a rubber diaphragm with a spring attached to a rod, which operates the valve. Many pneumatic actuators consist of either one or two pistons inside a cylinder that connects to a rod or pinion which operates your valve. Most pneumatic valve actuators fall into one of two categories: Double-acting (fail in place) or spring return (fail-open or fail-closed).