1. The solenoid valve’s composition
There are two main components of a solenoid valve: a solenoid and a valve body (G). A solenoid consists of an electromagnetically inductive coil (A) around an iron core at its center, called the plunger (E).
A solenoid valve controls the automatic on-and-off of refrigerant in a refrigeration system. One type of solenoid valve is a direct acting solenoid valve, while the other is an indirect acting solenoid valve. Generally, solenoid valves used in commercial refrigeration equipment are direct acting.
In general, solenoid valves consist of a valve body and a solenoid head, which are direct-acting. Using a direct opening and closing solenoid valves, the armature in the solenoid controls the opening and closing of the valve hole directly. The aperture is usually between 6 and 22mm.
2. Function and working principle of solenoid valves
The role of solenoid valves:
A refrigeration system is divide into two categories: high and low pressures, liquids, and gases. Solenoid valves prevent high-pressure liquid refrigerant from impacting the compressor after the compressor has been stop. The system pressure is balance when the compressor is start, so there is no impact. The solenoid valves turns on the compressor to begin, and the refrigerant circulates to cool the system.
When the compressor is shut down or the Explosion-Proof Solenoid Valves are quickly shut off after stopping, the refrigerant on the high-pressure side won’t return to the compressor Despite being in the opposite direction, the air will pass through the compressor in the direction of circulation. The entire refrigeration system has slowly been rebalancing with the compressor’s stop pressure.
Principle of operation:
When the refrigeration equipment is turne on, the solenoid coil produces an electromagnetic force that opens the valves. An inductive magnetic field is create by the coil and armature in the solenoid head when the coil is energize. The armature drives the valves needle to move upwards, the valve hole is open, and the fluid flows normally. Once the set temperature is reach, when the solenoid coil is de-energize, the magnetic field disappears, the armature falls by rain and spring force, the valve needle closes the valve hole, and the fluid stops flowing.
3. Selection of the solenoid valves
In general, the solenoid valves with the appropriate port size should be selected based on the flow rate of the system, and the working voltage, ambient temperature, working pressure, and other parameter requirements should also be taken into account. To ensure that the solenoid valves core can move easily up and down, the valve body should be perpendicular to the pipeline when installing the solenoid valves.
The flow direction of the medium in the system should be consistent with the nominal flow direction on the solenoid valve body to ensure tightness when the solenoid valves is closed. To prevent the solenoid valves core hole from being dirty, it is recommended that the front end of the solenoid valves be installed with a filter, and the solenoid valve should be mounted on a unit or bracket to prevent vibration and leakage.
Also, read Introduction of Safety Valves
4. Common problems with solenoid valves
1. It is the wiring of the power supply that is bad, so it just needs to be rewired or connected;
2. In order to restore the rated value of the power supply, it is necessary to adjust the voltage promptly;
3. The moving iron spool or the main spool of the solenoid valve can get stuck due to contamination in the system. The impurities in the system must remove in time, and the solenoid valves must replace.
4. There is a problem with the solenoid valves or its working life is too long, so it needs to replace;
5. The main valves core or the seal of the moving iron core is damage and cannot be close;
6. The solenoid valves spring breaks, and it must replace in time;
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