Pneumatic & Electric Ball Valve - How They Work

A ball valve is a quarter-turn valve that controls the flow of a media by having a hollow rotating ball, as seen in Figure 2. The figure shows the main components of a manual ball valve in a sectional view. When the hollow portion of the ball is in line with the flow (pipe or hose), the valve is open and the media can flow through. The valve closes when the solid portion of the ball is in line with the flow, which is done with a 90-degree rotation (hence the name quarter-turn valve) of the ball.

It is also possible to position the valve between fully open and fully closed, which allows you to regulate the flow more precisely. Typical ball valves have two ports, one for an inlet and one for an outlet. However, three ports (L or T) are also available, and depending on how the valve is assembled and installed will determine how the 90-degree rotation of the ball directs the media flow. Four-port ball valves are possible but rare.

ball valve have a valve stem, which is attached to the ball and controls its rotation. In Figure 2, the valve stem is connected to a manual handle to actuate the valve. However, the valve stem can also be connected to a pneumatic or electric rotary actuator to spin the stem to open and/or close the ball valve automatically and/or remotely.

ball valve can be combined with a pneumatic actuator (pneumatic ball valves) or an electric actuator (electric ball valves) for automation and/or for controlling remotely. Depending on the application, automating with a pneumatic actuator vs an electric one may be more advantageous, or vice-versa. In this article, we will compare the two options.

Difference between Electric ball valve and Pneumatic Ball Valve

The essential difference between electric ball valves and pneumatic ball valve is the use of different actuators. Generally, different actuators are selected according to the requirements of working conditions. For example, in chemical and other occasions where explosion-proof is required, pneumatic valves are most used because they are cheap and easy to operate. It also has a smart locator that meets high security requirements.

Pneumatic ball valves have more force than electric ball valve. The opening and closing action and speed of the pneumatic valve can be adjusted. Simple structure, easy to protect. Due to the buffering properties of the gas itself, it is not easy to be damaged due to blockage during operation. However, it requires an air source and its control system is more complicated than an electric ball valve. The pneumatic ball valve is flexible, safe and reliable. Many places with high control requirements have set up compressed air stations with pneumatic external control components. The power source of the pneumatic actuator is the air source, and the electric control signal is converted into a pneumatic control signal through the positioner to drive the pneumatic actuator to adjust the valve position.

The power supply of the electric valve actuator is the power supply, and its circuit board or motor is prone to sparks, so it is generally used in places with low environmental requirements and no risk. Pneumatic ball valves are faster than electric ball valves. Under normal circumstances, the opening and closing time of the pneumatic ball valve is about 6 seconds, while the opening and closing time of the electric ball valve is generally 15-20 seconds.

All in all, pneumatic ball valve are better than electric ball valves. The electric ball valve acts quickly and is suitable for places without external air source, but its safety function is poor, and it is not easy to be used in flammable and explosive places with high explosion-proof requirements. During operation, the performance of the electric ball valve is not as stable as that of the pneumatic ball valve, and the cost and maintenance cost are high. But the pneumatic ball valve can fully meet the control requirements, and the device is easy to use. Its safety function is relatively high, and it is suitable for places with high explosion-proof requirements such as flammable and explosive.

The advantage of electric ball valve is that it has good effect on liquid medium and large-diameter gas, and is not affected by weather or compressed air pressure. Disadvantages are high cost and poor performance in wet environments. The advantages of pneumatic ball valve are good effect on gaseous medium and small diameter liquid, low cost and convenient protection.