Trunnion mounted ball valve
The trunnion ball valve design works almost the same method as the ball floating but the seats are spring packed against the ball and the ball does not pivot. The ball just rotates on its axis in this design.
In this design, the ball uses a next shaft and bearing on the base of the ball. This post or stem grips the bottom of the valve in location. The top of the ball is not slotted and the upper stem is rigidly linked to the ball. This stops the ball from moving into the downstream seat.
Since the ball does not go into seats, the seats must go towards the ball. Spring behind the seat force them strongly into the ball in order to make the seal.
Trunnion valves are extremely amazing at closing off extremely low force that would be powerful enough to go a floating ball into the downstream seat. They are also needed on big diameter valves and top-force valves. The factor for this is the contact area of the seats in floating ball is pretty little. The pressure on the downstream seat in a floating ball is derived from the process force in the pipe upstream forcing on the powerful area of the ball in the closed position. If the force is high or the area is large, the downstream seat will be damaged.
The tradeoff is those trunnion valves are much more costly than floating ball designs.
Both trunnion and floating ball designs are accessible as different port valves by using complex flow paths in the path and further ports in the body.
Floating ball valve
A ball valve floating design sandwiches the vacant ball between 2 or more cupped seats that makes a strong seal between the ball and the body at the inlet and outlet ports of the valve body.
The ball is turn around (commonly ninety degrees) by a shaft that stick outer surface of the valve body is linked to some type of operator. For this factor, most ball valves are known to as area turn valves. This shaft is not rigidly linked to the ball in order for the ball to pivot on the shaft end as it turn around on the ball axis.
When in the open angle, the flow path in the ball is in line with the body flow path. The openings in the ball are associated with the opening in the ports of the body. This permits flow from the upstream port to move via the balls flowpath and out to the downstream pipe.
When the ball is in the closed angle, the flow path in the ball is perpendicular to the flow path in the body and valve. The strong parts of the ball cover both downstream and upstream cupped seat openings. The force in the pipe upstream https://www.italvalvinox.com/trunnion-ball-valve/ pushes against the strong part of the ball which shifts on its pivot point and is forced strongly against the seat downstream. This close off flow.