The Differences Between A Solenoid Valve And A Motor Operated Valve

What is a motor operated valve?

motorised valve

In general, a motor operated valve is using an electrical actuator to control on and off. Typically, an electrically operated valve is composed of two parts: the upper section,  where a motor is mounted, and the lower section, the valve.

By working pattern, the motor operated valve has two types: one is called angular travel valve, in which an angular electric actuator works with an angular valve so that the fluid can be controlled in a 90 degree range; the other is called linear controlled valve in which a linear actuator is used to control the up and down motion of valve plate. Usually, the type of valve can be seen in the highly automated system.

 

What is a solenoid valve?

solenoid valve

A solenoid valve is also an actuator which is used for fluid control. It is widely applied in the hydraulic and pneumatic system. A solenoid valve is controlled by a solenoid coil, when the coil is energized, the valve switches it’s on and off due to the electromagnetic force. There is single direction solenoid valve, safety solenoid valve, directional control solenoid valve, speed control solenoid valve and so on.

The differences

1. Cost

The control of a solenoid valve is realized solely the electromagnetic coil. The structure is simple and the price is cheaper.

While a motor controlled valve needs a motor to control the valve rod and to control the valve plate further. There are shutdown valve and adjustment valve. The structure is more complex and the price is higher.

2. Purpose

The solenoid valve is mainly used for on-off control of liquid and gas pipeline. It belongs to digital output control (DO). It always has only on and off switch valve. The solenoid is only suitable for small size pipe control, e.g. below pipe size of NG50. It is very rare to use a solenoid valve to control fluid larger than DN50.

The motor operated valve is used to control the medium fluid in liquid, gas and air system. It belongs to analog input (AI). This type of valve is always used for large pipeline.

For more information of DO and AI signal, check this article.

3. The on-off pattern

For solenoid valve, there is only on and off. The switching time is short. While the motor operated valve is controlled by a motor which takes time to execute the witching motion. However, this also enables adjustment possibility.

4. Working environment

With a tiny flow efficient, the solenoid valve is working under a minor pressure. For example, the flow efficient of a DN25 solenoid valve is greatly smaller than that of a NG15 motor driven ball valve. And because the solenoid valve is controlled by electromagnetic force, meaning that it may be damaged by electric shock.

However, a motor operated valve has a better electric shock resistance property due to the motor it is using. The valve can switch to on, to off or even to half on.