Although pneumatic solenoid valves are very reliable and safe, sometimes they can cause complexities due to some carelessness. So, to keep you away from any hassle, this article will present how pneumatic solenoid valve works, and how to wire, clean and check them properly. So, keep learning!

Figure no 1 Pneumatic solenoid valve

1) What is a pneumatic solenoid valve?

“A pneumatic solenoid valve is an apparatus designed for controlling the airflow and gases within the circuitry of the pneumatic systems.”

Its operation is determined by an electromagnetic solenoid. It is used to either cut off or permit the flow of compressed air by opening or shutting a valve respectively. Such valves are important in regulating the supply of air in machines and systems enabling processes in different industries to be automated.

Figure no 2 Foye Solenoid valve

 

Pneumatic solenoid valves are common components in industrial automation and manufacturing plants. These are incorporated in such activities as the control of air cylinders, operation of pneumatically driven tools, and air drive function control systems. In the factory data, they serve the purpose of operating packaging machinery, conveyor belts and robotic arms. Whilst, automotive applications include air-brake controls and other controlling tasks.

Depending on how many ports there are for controlling airflow, the valves with solenoids are made into two-way, three-way, or four-way types. This allows them usable for any application including accurate air distribution, quick toggle operation, as well as the safe termination of systems.

2) How does a pneumatic solenoid valve work?

The most basic pneumatic valve solenoid may consist of the following basic parts:

• The solenoid coil: It is the element of the valve that creates the magnetic field.

• Plunger: A plunger can occupy the space of the coil and can move in or out of the coil depending on the magnetic field.

• Valve body: The internal parts are kept and secured by the valve body. And, also they have in and out ports from which compressed air can come in and go out.

• Airports: The ports allow the valve to direct air to different pneumatic parts of a system.

• Working Procedure:

Step 1) Original state: While at rest, which is when the solenoid valve plate is not charged (energized), the plunger is held at its natural position. This could be either allowing air to flow or blocking flow depending on the design of the valve. In a normal close valve, where no power is supplied to the valve, the plunger will remain in the position and there will be no flow of air. In the normally open position, air can flow into the valve until the valve is supplied with electric power.

Figure no 3 De-energized states of valve

Step 2) Supply of electric power: After the supply of electrical power to the solenoid is done, the coil creates magnetic forces.

Figure no 4 Energized state of valve

Step 3) The plunger’s movement: Depending on the configuration of the valve, either the plunger will be pulled upwards or the plunger will be pushed downwards.

• For a normally closed valve, pulling the actuator in the direction of the flow vertically lifts the coil plunger from its seated arrow. It will open the way for transportation of the compressed air.

• While in the normally open valve, when the electrical power is supplied in order to energize the valve, the plunger is occupied and the airflow is blocked in the cavity.

Step 4) Air entrance: The air into the valve enters through the chosen ports. And, it will be distributed through the specifically arranged vessels for pneumatic actuators air cylinders or other parts within the system.

Step 5) Cut off power supply: Also, when the electrical current is no longer supplied, the magnetic field disappears. Now, the valve plunger is urged by a spring back to its original position, either blocking airflow or allowing it again.

These straightforward on-off features give pneumatic solenoid penumatic valves high precision and rapid speed.

3) How to wire a pneumatic solenoid valve?

Wiring a solenoid valve is rather an unenviable task. It entails the proper connection of electrical devices so that the solenoid can influence the working of the valve. It is also advisable to cross-check if the solenoid operates on the same power supply as expected, AC or DC. Standard voltages include 24V/110V/220V, and the use of excessive voltage may burn the valve or render it ineffective for its intended use.

• How to Wire a Pneumatic Solenoid Valve:

Step 1) Switch off power: Diligently ensure that the power supply is switched off before messing up with any electrical component to avoid injury or electric shock.

Step 2) Secure wiring terminals: The solenoid valve pneumatic should have two, three or more wiring block terminals where wires are connected. These are most of the time screws or clamps formulated to fit the wires tightly.

Step 3) Connecting wires: Generally, polarity does not matter for AC solenoids but in some cases where DC solenoids are used, appropriate colours should be used, i.e. connect the positive wire (red) to the positive terminal with the positive wire of the power supply. And, the negative wire (black) to the negative terminal.

Figure no 5 Wiring a pneumatic solenoid valve

Step 4) Sealing the joints: This helps to complete the electrical connections either by tightening the terminals or by securing the connectors. Poor connections may affect the operation and lead to arcing.

Step 5) Earthing: Some solenoids might need to be earthed, particularly in AC applications. If this is the case, attach the earth wire to the valve on the earth point.

Step 6) Secure the system: When all the accessories are connected, switch on the power and switch the solenoid valve on. Check that the valve turns on and off properly based on the control signal.

Correct wiring is essential in ensuring that the pneumatic solenoid valve is safe and functions optimally.

4) How to properly clean a pneumatic solenoid valve?

Cleaning of the air pneumatic solenoid valve is important because it can improve performance, which will also increase service life. However, if the valve is used for an extended period of time, it gets dirty inside and there will be simply no way to operate it. Here are some practical steps that will help you clean the valve in a safe manner.

• Proper Cleaning of a Pneumatic Solenoid Valve:

• Turn off the power and air supply: First, make sure the electric supply to the valve solenoid is turned off to avoid accidents. Ensure the air supply is disconnected and relieve any pressure that may be in the system to avoid the risk of injuries.

• Bring out the solenoid coil: Detach the sylphon spring or any mechanical parts that are manufactured with the solenoid coil. With patience, detach this coil from the valve body to access the inner parts of the valve. Avoid breaking the coil or its wiring during this process.

• Disassemble the valve: Using a screwdriver, unscrew and detach the valve body so as to view the internal petal assembly. The assembly consists of the plunger, seals, springs and their cavities. Take notes of the arrangement of the parts as it will help in reconstructing them in the proper way.

• Vacuum cleaning: From the stuffing box and the duct located on the upper part of the housing, vacuum off the internal valve sections with a soft gauze cloth. Stubborn stains may require either compressed air or some cleaning agents. Do not use very strong chemicals that can attack any seals or internal parts.

• Damaged component recovery: During the cleaning exercise, examine seals, springs, and plungers for any wear or damage. If one part appears to be damaged and cannot be used, replace it with another before putting the valve back together.

• Put together the valve: After cleaning and performing all the basic inspections, the valve can now be assembled making sure that all the parts are returned to their accurate places.

• Run the valve: When the assembly is complete, the air and power supplies can be connected. Follow with an operation of the valve to check for operational integrity.

Frequent cleaning of pneumatic solenoid valves enhances the performance of the components making them work effectively.

5) How to check a pneumatic solenoid valve?

Checking a pneumatic solenoid valve is essential to ensure the proper functionality of the system. Below is a step by step procedure on how to check a pneumatic solenoid valve.

Figure no 6 Check the solenoid valve

• Procedure for Inspection of Pneumatic Solenoid Valve:

i) Switch off the System: Alright, so the first step is switching off the power supply and depressurizing the pneumatic system. This will help in avoiding risks or destruction of materials during the check.

ii) Visual Inspection: Begin with the visual examination of the Component solenoid valve. Assess the valve body and all of its connections for cracks, leakages or any wear and tear.

iii) Check the electrical supply: A multimeter is used to check that the correct voltage is being applied to the solenoid coil. Turn the multimeter in voltage position and place its sounding probes at the terminals of the valve. Make sure you take note of the voltage which is displayed on the meters. Now, compare it to what should be on the valve which ranges from 24V 110V or 220V according to specifications.

iv) Listen for operational sounds: Let the valve be energized and hear for the clicking sound produced when the solenoid attracts. If no sound is heard this time, it could have been the case that the coil went defective or the plunger has gotten stuck.

v) Check for airflow: When the valve is activated, observe whether air is passing through the particular valve appropriately. This can either be done by feeling the escaping air from the valves or by employing the use of a pressure gauge.

vi) Test the coil resistance: Change the setting of the multimeter so that it reads resistance (ohms) for determining the solenoid coil. If the resistance is very high or even reaches zero, then the coil is faulted and requires replacing.

6) Final words

If you want your pneumatic solenoid valve to work properly, it is necessary to regularly check and clean it. Following the recommendations in this article protects the valve system from short life span and ineffective operations.

Foye also specializes in providing such precision pneumatic components, including solenoid valves and other control elements. By using advanced CNC machining and innovative designs, Foye provides safe custom pneumatic systems for different industries like automotive, medical, food packaging, etc. To learn more, please visit our website, Foye Pneumatics.