You will also need to know the inlet and outlet pressures, which will allow you to determine the pressure dro across the solenoid. For pilot operated solenoid valves, the pressure dro must be at least equal to the minimum differential pressure required for proper system operation.
Then you will need to know the diameter of the inlet and outlet pipes (in inches or millimeters) and the type of connection (threaded or flange mounted).
The choice of the number of solenoid valve ports (2, 3, 4 or 5) depends on its purpose.
The two-way solenoid valve is mainly used to supply power directly to the circuit
The three-way solenoid valve is mainly used for regulating the circuit. Three-way solenoid valves generally use two inlet lines and one outlet line to ensure that the two fluids are mixed at a constant flow rate. They can also be used with one inlet tube and two outlet tubes to regulate the flow at one of the outlets by diverting the fluid to the second outlet.
Four-way solenoid valves are equipped with two inputs and two outputs, for example, for reverse circulation of heat pumps.
Finally, you have to pay attention to the voltage rating of the solenoid.
Note that some pneumatic or hydraulic directional valves may be similar to solenoid valves, but work differently. They mainly appear on pneumatic or hydraulic circuits to control actuators.
How to calculate the size of the solenoid valve? - Zorgon (Zhejiang) Automation Technology Co.,Ltd. (cnzorgon.com)
www.cnzorgon.com/how-to-calculate-the-size-of-the-solenoid-valve.html
