The Differences between Solenoid Valves and Motorized Valves

Figure 1: Comparison of the motorized valve and the solenoid valve.

The solenoid valves is an industrial equipment controlled by electromagnetic, which is the basic component of automation used to control fluid. It belongs to actuators, not limited to hydraulic and pneumatic. It adjusts the direction, flow rate, speed and other parameters of the medium in the industrial control system. The solenoid valve can be matched with different circuits to achieve the desired control, and high control accuracy and flexibility are guaranteed.

The motorized valve, also called an electric motorized valve, uses an electric actuator to control the valve to open and close the valve. The valve stem is driven by the motor to drive the spool to move.

The motorized valve is divided into a shut-off valve and a regulating valve. The shut-off valve is a two-position type, that is, fully open and fully closed. The regulating valve is a positioner installed on the motorized valve, which can dynamically stabilize the valve in one position through closed-loop adjustment. The motorized valve can be divided into upper and lower parts, the upper part is the electric actuator, and the lower part is the valve.

Solenoid valves and motorized valves are different in usages, ways of switching, working styles, and special applications. The following will focus on these aspects in detail.

Different Usages

The solenoid valve: used for switch control of liquid and gas pipelines, two-position digital output (DO) control, generally used for the control of small pipelines, commonly found in pipelines of DN50 and below.

The motorized valve: It is used for analog regulation of medium flow in liquid, gas and wind system pipelines. It is analog input (AI) controlled, and can also be controlled by DO or analog output (AO). It can also be used for two-position switch control in large valves and wind systems.

Different Ways of Switching

The solenoid valve is driven by a coil, which can only be opened or closed, and the action time is short when switching.

Figure 2: Components of a solenoid valve and how it works.

The motorized valve is generally driven by a motor. It takes some time to complete the opening or closing action.

Different Working Styles

Solenoid valves generally require a small flow coefficient and a small working pressure difference. For example, the flow coefficient of the general 25-caliber solenoid valve is much smaller than that of the 15-caliber electric motorized ball valve. The solenoid valve is driven by a solenoid coil and is relatively easy to be damaged by voltage shocks. The role of the solenoid valve is equivalent to a switch, that is, on and off. The switching speed is faster. Solenoid valve can generally be reset after power off.

The motorized valve is generally driven by a motor, which is relatively resistant to voltage shocks. It is mainly used on the occasion of large diameter and large flow rate. Its switching action is much slower than that of the solenoid valve. However, the degrees of opening of the motorized valve can be controlled, namely open, closed, half-open and half-closed, so as to control the flow rate of the medium in the pipeline. In order to reset in case of power failure, the motorized valve needs to be equipped with a reset device.

Different Applications

The solenoid valve can meet some special requirements, such as special fluid media. Hence the price is higher.
The motorized valve is generally used for adjustment, including on-off adjustment, such as used at the end of a fan coil unit.

Figure 3: 2 way and 3 way motorized valves for heating applications.

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