Five big differences between trunnion ball valve & floating ball valve

Five big differences between trunnion ball valve & floating ball valve

This page will tell you the difference between the trunnion ball valve and floating ball valve in sealing surface, look, application, working principle and features.

Sealing area

As the ball valve is floating, so under the force of the center, the ball will action and in opposition to the downstream set,. So the floating ball sea valve belongs to the one-side seal. The trunnion ball valve cannot be shifted, so the 2 sides of the ball trunnion valve both must be preserved.

Since the sealing rule is diverse, the needs of the 2 ball valve on the sealing area material are special, mainly the sealing area of the ball floating valve must be capable to face the force leaded by the floating ball.


The floating ball valve is perfect for low and medium force and generally has a little diameter. The ball trunnion valve can be applied in top force conditions and the size can be up to sixty inches.

The trunnion ball valve is a type of DBB valve, while the floating ball valve just seal the downstream area. The trunnion ball valve can stop downstream and upstream media. And when the force in the center cavity is bigger than the seat spring force, the seat will be pushed to open to release the force inside the chamber to make sure safety.

Working principle

The floating ball valve just has upper stem and the ball have a slim displacement, so it is known as floating ball valve. The ball trunnion valve has another stop at the base to fixed the ball position, so the ball cannot move.

The sealing of the floating ball is realized by the force of the medium, when the ball valve is closed, the floating ball is forced against the sealing surface under the action of force to realize sealing. When the trunnion ball valve is clogged, the ball does not generate dislocation, but the floating seats will shift and force against the ball within the action of the media force to realize sealing.


To the floating ball valves, the ball trunnion valves are generally used longer, has little size and simpler to operate.

also has the function of mechanical release force, when the medium temperature in the valve increases and causes abnormal force rise, the trunnion ball valve can mechanically release the force without a relief valve. This is very vital to make sure the safety of industrial production.


The trunnion ball valve and the floating ball valve are simple to distinguish in look. If the valve body has a fixed shaft on the bottom, it must be the ball trunnion valve.

If the ball valve has a gadget for injecting grease it, it is generally a trunnion ball valve. Anyway, if there is no injecting gadget, we say it must be a floating ball valve?
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