In this article, we’ll explain what a solenoid valve is and how it works. This is a common valve used in a variety of applications, and understanding how it works is essential for knowing how to use it.
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Solenoid valves are used to convert electrical energy into mechanical energy. Solenoid valves have quite distinctive look about them as they have the valve body but on top they have a block which will have some cables coming out. Once the valve is installed this top part is the solenoid and the bottom part is the valve, therefore making a solenoid valve, why do we use solenoid valves?
Well these valves allow engineers to autonomously remotely control the flow of fluid within a system. This fluid can be a liquid or a gas for example water, air, gas, oil, steam and refrigerant etc, the list goes on.
The solenoid coil on the top is used to operate the valve by passing an electrical current through it to create an electromagnetic field and operate the valve. This means if its connected to a controller it can be autonomously and remotely by a computer without the need for engineers to physically run around opening and closing valves. This allows systems to run much more efficiently and safely.
With the direct operated valve we have the solenoid on top which is basically a coil of wire. As you may have seen in our electrical articles and videos, when you pass an electrical current through a coil we generate an electromagnetic field. This magnetic field is what we will use to control the valve. We have two types of valve- the normally open and normally closed type.
Lets look at the normally closed type first. So inside the valve we have the armature. The solenoid is placed over this and completely surrounds the armature so that its at the centre of the magnetic field. Inside the cylinder of the armature is the plunger and spring. The spring pushes the plunger down in a normally closed type valve. Because the plunger is pushed by the spring it will sit in the down position to close the valve indefinitely. But if the coil receives an electrical current then it will generate an electromagnetic field and this magnetic field passes through the plunger and will cause it to move upwards against the spring, therefore opening the valve.
At the centre of the coil the magnetic field lines are the most compact and therefore the strongest. This is why we place the plunger in the centre. Once the electrical current is stopped, then the magnetic field disappears and the spring will force the plunger down again to close the valve.