How A Solenoid Works

We will look into solenoids and how they work, look at permanent magnet, cut a real-world solenoid/cut one open, and look at the basic solenoid. The problem with a standard conventional magnet is that the magnet cannot easily be turned on or turned off. Opposites attract in 2 of these magnets. Moving a compass in the magnet, the compass face will rotate the opposite end of the magnet, and follows the magnetic field lines. Permanent magnets are always on, and unfortunately can't easily or practically be turned off or controlled. 

However, we can control an electromagnetic field and generate it with a standard wire. If I place a compass near the wire, with a power source, as soon as I pass a current through the wire, current places an electromagnetic field. If I reverse the direction of the current, then we change the direction of the field. The compass will rotate to align with magnetic field, and the magnetic poles will reverse. Electrons flow from negative to positive but for our application we will assume that it flows from positive to negative. The north pole will be on the positive end, whereas the south pole will most likely be on the negative end. 

We use these valves to autonomously control the amount of fluid in a system. The core on the top is used to pass electrical current to have an electromagnetic field in the valve, to allow the systems to operate without physically opening the valves. 

Solenoid valves are found in everything from washing machines to rockets. We will certainly find at least one solenoid valves in each system. The air handling unit has a cooling coil. The top expansion valve and cooling valve depends on cooling coil. Solenoid valves can isolate valves when cooling is needed. Another application is to control the flow of refrigerant. Moisture frees and gets ice, and opens the valves to send refrigerant through the compressor instead of the condenser. Valves can also clothes to shut leaks and part of production line to protect manufacturing equipment. 

There are a few variations in how the valve operates. 

The direct operated valve has a solenoid on top. You generate an electromagnetic field. We have normally open and normally closed valve. Inside the valve, we have armature and solenoid surrounds the armature and we have plunger and spring inside of the armature. If a coil receives current, it generates a field and passes thorough plunger and cause it to move upwards.