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TYPE OF BALL VALVES - Coggle Diagram
TYPE OF BALL VALVES
HOUSING ASSEMBLY
One Piece Ball Valve
- a single-piece cast body that houses the internal components.
- eliminate the risk of leakage of the fluid
- cheapest ball valves and always reduces bore
Split Body Ball Valve
Two piece ball valve
- housing is divided into two pieces that are fitted together.
- the main piece contains the ball and a connection to one end, and the other piece holds the internal components together and has a connection to the other end.
Three piece ball valve
- housing for the internal components of the valve which are fitted and held together by bolt connections to its two ends.
- used for applications that rely heavily on valves, that their maintenance activities must frequently be done.
- can be cleaned and serviced easily and their seats and seals can be routinely replaced by just taking the valve body out without disturbing the two ends.
Top Entry Ball Valve
- access to the internals of the valve by simply removing the bonnet on top of the valve.
- allows in-line maintenance activities (i.e., dismantling, cleaning, inspection, and repairing the valve) without removing the ball valve from the main pipe.
BALL DESIGN
Floating Ball Valves
- ball is suspended inside the valve and free to move in a lateral direction when the valve is in a closed position.
- It is sandwiched between two seats that support the valve and hold it in place.
- ball is connected to the shaft in a slot on one end while the other end is free. When the valve is in an open position, the shaft connection to the slot at the top of the ball prevents the ball from moving laterally.
Trunnion Ball Valves
- ball is supported by an additional shaft at its bottom which is called the trunnion.
- The inlet fluid pressure activates the springs towards the ball held by the trunnion, which creates a tight sealing.
- can operate efficiently in a wide range of pressures and they are ideal for high-pressure applications since the fluid pressure is also dissipated to the trunnion and the springs of the seats.
Vented Ball Valves
- constructed and operates in the same way as a standard ball valve, except that the vented ball has small orifices drilled into its side.
- drilled hole is used to vent trapped gases which causes a build-up of internal pressure inside the valve, to prevent leaking, valve failure, and explosion.
BORE PROFILE
Full Bore Ball Valve
- flow area for the fluid for full bore valves remains constant, therefore the flow resistance offered by this type is very low.
- bore diameter should be equal to the pipe size, it requires a larger ball size and housing which makes it more expensive than a reduced bore.
- A spherical or cylindrical device called pigs is allowed to flow in the pipes to detect and remove any build-up without interfering with the fluid inside the pipeline.
Reduced Bore Ball Valve
- flow area for the fluid becomes narrower at the downstream outlet, therefore there are frictional losses that are introduced which result in a pressure drop.
- reduced bore is less expensive than a full bore since it requires a smaller ball size and housing.
Segment Ball Valve
- has a V-shaped notch on its ball.
- A segmented ball valve has good flow rate control which depends on the ball rotation.
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