How Does a Ball Valve Work? Operation & Application Explained

I. What is a ball valve?

A ball valve is a common rotary shut-off valve.
Its core valve element is a perforated sphere.
There is a through hole in the middle of the sphere.

When the direction of the through-hole in the ball body is consistent with that of the pipeline, the medium can pass through and the valve is opened.

When the ball rotates 90° and the through hole is perpendicular to the direction of the pipeline, the medium is cut off and the valve is closed.

So the core action of a ball valve is: the ball rotates 90°

Ball valves are commonly used in:
· Gas pipelines
· Liquid pipelines
· Instrument air supply
· Vent and condensate drains
· On-off shutoffs
· Pneumatic switch valves
· ESD emergency shutoff valves

The biggest features of ball valves are: fast switching, low flow resistance, and good sealing performance.

II. Operating Principle of 90° Rotating Ball Valve

The operating principle of a ball valve is very intuitive. The core is: rotate the sphere by 90° to achieve the switch.

1) When the valve is open and the direction of the through hole in the middle of the ball is aligned with the pipeline, the medium can directly pass through the through hole of the ball.

At this moment, the valve is in an open state.

When the ball valve is fully opened, the flow path is relatively straight. Therefore, the flow resistance of a ball valve is relatively small.

2) When the valve is closed, the through hole of the ball is perpendicular to the direction of the pipeline after the ball is rotated 90°.

At this moment, the medium is blocked by the solid part of the sphere. The valve is closed.
The outer surface of the ball fits tightly with the valve seat to achieve sealing.

3) Although the ball valve in a half-open state can remain in this position, it is not recommended to keep the ordinary ball valve in a half-open adjustment for a long time.

Because when it is half-open, the medium will scour the edge of the ball and the valve seat at high speed.

Long-term half-open may cause:
· valve seat wear
· ball scouring
· sealing surface damage
· valve internal leakage
· switch jamming

Therefore, ordinary ball valves are mainly used for: fully opening or fully closing.

III. Why is a ball valve suitable for quick shutoff?

Ball valves are highly suitable for quick shutoff, primarily due to the following reasons.

1) To rotate the gate valve by 90°, the gate plate needs to move up and down, and the handwheel usually requires many turns.

The globe valve also relies on the lifting and lowering of the valve disc. And the ball valve only needs to be rotated 90°.

The motion stroke is very short, from fully open to fully closed. So the ball valve can be switched quickly.

2) When the ball valve is fully opened, the flow path is relatively straight, and the through hole of the ball aligns with the pipeline. The medium passes through almost straight.

Therefore, the flow resistance is small and the pressure drop is low.

3) Good sealing performance: An annular seal is formed between the ball and the valve seat.

The sealing effect of soft-seal ball valves is particularly good. Suitable for occasions requiring reliable shut-off.

4) It is easy to achieve the 90° rotation action of automatic ball valves, making them highly suitable for equipping with actuators.

Common automatic ball valves include:
· Pneumatic ball valves
· Electric ball valves
· Hydraulic ball valves