Solenoid valves convert electrical energy to mechanical energy, which causes a magnetic response. The solenoid activates when an electrical current comes through the wire coil. When activated, solenoids in hydraulic valves and pneumatic valves control the flow of fluid when a fluid power system is in motion. Many different types of solenoid valves are available, though direct-acting and pilot-operated valves are the two main categories. When selecting a solenoid valve, it is important to answer questions about the application and ensure that you are choosing a suitable valve.
These are questions that you need to answer to select the types of solenoid valves that will be the right fit for your application.
TYPE – 2-way, 3-way, or 4-way
OPERATION – Is it a Normally Open (N/O), Normally Closed (N/C), or Universal (U) operation?
MEDIA
What is going through the valve? Air, gas, water, something else?
What is the source of the fluid?
What is the temperature of the fluid?
Is the fluid clean?
Is the fluid being heated, cooled, or treated before it reaches the valve?
SIZE
What is the port size at the inlet and outlet of the valve?
What is the flow capacity?
PRESSURE – The pressure of the line helps the valve open
What is the maximum pressure?

What is the differential pressure? Inlet pressure compared to the outlet pressure. Upstream pressure, the pressure of the fluid between its normally open solenoid valve, compared to its downstream pressure after it leaves the valve. The answer
ATMOSPHERE
Where will be valve be installed? When the valve goes into service, you want to make sure it won’t be affected by the environment like moisture, heat, freezing temperatures, etc.
What is the range of the ambient temperatures?
What type of NEMA enclosure does the valve require?
VOLTAGE – Ask the customer what the voltage will be for the valve.
EXTRAS – Are there any special options needed by the customer? The sealing material may be one extra specification