The Difference Between The Floating Ball Valve And The Trunnion-mounted Ball Valve

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The content will explain the main difference between the floating ball valve and the trunnion-mounted ball valve in their apperance, sealing surface, working principle, application and characteristics.


1.Appearance

The floating ball valve and the trunnion ball valve are simple to find out by look at them . When the valve body includes a fixed shaft at the bottom part, it should be the trunnion ball valve.

When the ball valve body includes a device for injecting grease,it's essentially a trunnion ball valve.However, if there's no injecting device,are we able to say it should be a floating ball valve? This really is incorrect, because small size for example 2 "150LB trunnion ball valves are often not full of injecting device either.

2. Sealing surface

Because the ball from the floating ball valve is floating, so underneath the pressure from the medium, the floating ball will move and from the downstream seat., therefore the seal from the floating ball valve is one of the single-side seal.The ball from the trunnion ball valve can't be moved, therefore the two sides from the trunnion ball valve both should be sealed.

Because the sealing principle differs, the needs of these two ball valves around the sealing surface material will vary, particularly the sealing top of the floating ball valve must have the ability to bear the pressure brought on by the floating ball.

3. Working principle

The floating ball valve has only upper stem and also the ball may have a slight displacement, so it's known as floating ball valve.The trunnion ball valve ball has another stem at the end to fixed the positioning of the ball,therefore the ball can?ˉt move.

The sealing from the floating ball valve is recognized through the pressure from the medium,once the ball valve is closed, the floating ball is pressed from the sealing surface under the act of pressure to understand sealing.Once the trunnion ball valve is closed, the ball doesn't produce displacement, however the floating seats will move and press from the ball under the act of the press pressure to understand sealing.

4. Application

The floating ball valve is appropriate for medium and occasional pressure in most cases includes a small diameter.The trunnion ball valve may be used in high pressure conditions and also the size can depend on 60 inches.

The trunnion ball valve is a type of double-block-and-bleed(DBB) valve, as the floating ball valve only seal the downstream side.The trunnion ball valve can block both upstream and downstream media. So when the pressure in the centre cavity is more than the seat spring pressure, the seat is going to be pressed available to release the pressure within the chamber for the utmost safety.

5.Characteristics

Towards the floating ball valves,the trunnion ball valves are often used longer,has smaller sized size and simpler to function.

The trunnion ball valve also offers the part of automatic release pressure, once the medium temperature within the valve increases and results in abnormal pressure rise, the trunnion ball valve can instantly release the pressure with no relief valve,This will be relevant to guarantee the safety of pipeline and its production.




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