Solenoid valves are electromechanical valves used to control the flow of liquids or gasses. By opening and closing, valves dose, release, shut off, distribute, or mix fluids and gasses. Because of the advantages they offer in the way of safe and rapid switching, reliability, long service life, and compact design, they are very popular in a variety of industries. However, they’re most frequently employed in the residential, appliance, industrial, and commercial industries.
Solenoid valves function using two main components: a solenoid coil and a valve. The coil is a magnetized wire coil that comes alive from a series of electrical charges and then emits a current flow. This current flow generates a magnetic field that converts electrical energy into mechanical to move the actuator. The actuator is an extension of the valve; it, along with an attached string, is responsible for moving the valve from an opened to closed position. Read More…
Solenoid valves are generally built as either normally closed (NC) or normally open (NO) devices. Normally closed valves operate with an inner plunging rod or pin, called a plunger, held in place by the solenoid coil, that blocks current flow. To activate flow in an NC valve, an electromagnetic charge must be sent through the coil, which will then lift the plunger out of the way to allow flow. NO valves, on the other hand, are the opposite. They will close when the solenoid is activated.
Solenoid valves are either pilot-operated or direct-acting. A pilot-operated solenoid valve, which is a combination of either a hydraulic valve or a pneumatic valve and a smaller solenoid valve, uses a diaphragm rather than a plunger to create differential pressure and thereby control flow. A direct-acting solenoid valve uses a plunger that has direct contact with the in-flow valve body opening, called an orifice. In this case, the plunger opens and closes the orifice to control flow.
Some solenoid valves are better suited to certain applications than others. For example, because stainless steel is corrosion and abrasive resistant, stainless steel solenoid valves work well with chemical processing applications, which require outstanding control of bases, acids, and analytical reagents. Likewise, high-pressure solenoid valves are excellent resources for flow control in areas that are incompatible with other valves, like in work areas that engage with dangerous machinery or inaccessible lines. Another example is miniature solenoid valves, which are the perfect size for delicate medical equipment like biotechnology equipment, portable medical devices, and gas analyzers.
Solenoid valves are defined by three general components, to help manufacturers select which valve may be best:
- Material being controlled, like solenoid water valves and solenoid air valves
- Valve construction/design, like proportional solenoid valves, 3-way solenoid valves and plastic solenoid valves
- How they are powered, like 12-volt solenoid valves and pneumatic solenoid valves
Solenoid water valves, also called hydraulic solenoid valves, direct water flow with pilot-operated, normally open valves. Solenoid air valves, also called gas solenoid valves, air valves or pneumatic solenoid valves, regulate air and gas flow with diaphragms and gas pressure. They are able to maintain both regular pressures, like those maintained for home heating and cooling, and extremely high pressures, like those regulated for power tool operation. Proportional solenoid valves work like regular pneumatic valves, aside from the fact that they operate with more advanced flow control capabilities, which allow them to establish variable flow, proportionate to the valve’s electrical control signal. Twelve-volt solenoid valves carry 12 volts, supplied by its DC power source. (Twelve volts are standard.)
Manufacturers have a wide variety of materials available to them with which to construct their solenoid valves. Valves may be made from both plastic and metal materials, such as PVC, natural polypropylene, PTFE, PVD, CPVC, stainless steel, bronze, aluminum, and brass. Additionally, customers may choose from valves with either two connection areas and one orifice or three connection areas and two orifices.
There are many reasons to purchase a solenoid valve over others. With fewer moving parts than other valves, solenoid valves are comparably low-maintenance. They are also operable by remote devices, which is an invaluable feature for hazardous applications. In addition, they can be made portable. Finally, solenoid valves are flexible; able to use either hydraulic or pneumatic power.