What kind of valve is a trunnion valve?

For your reference: A trunnion ball valve features a mechanical mechanism for securing the ball at the top and bottom; this design is typically used in larger valves operating under higher pressures

It refers to a fixed valve; it’s an explanation of a fixed ball valve as mentioned above. This post was last edited by liguofu0 on 2009-3-5 at 22:07.]

Here are some relevant materials for your information; please check out this topic! Explanation of Trunnion Design… http://www.connectworld.net/plast/trunnion.gif Trunnion design involves the use of upper and lower supports to hold the ball in place under pressure. Named after the “trunnion” used historically to support cannons, the trunnion in a ball valve essentially doubles its safety and usability. This feature is common in many higher-quality metal ball valves, but among plastic ball valves it is found only in Plast-O-Matic True Blue brand valves. It enables the valve to be installed in either direction, as the trunnion prevents the ball from shifting—or worse, breaking free—under pressure. This feature, along with the ability to install the valve in either direction, means that the True Blue Ball Valve can indeed be used in applications with reverse flow. Another advantage of the trunnion design is that it allows the True Blue Ball Valve to function as a true union valve: the downstream piping can be disconnected even when there is full pressure in the upstream pipeline (the user is responsible for ensuring that the downstream piping is empty of liquid and that the valve is properly closed and secured to the upstream piping). Many plastic ball valves claim to be “true union” valves due to their union fittings, but they cannot actually be disconnected in this manner. http://www.connectworld.net/plast/film.gif Click here to watch a video demonstration of the trunnion design; left-click to play, right-click to download. The trunnion in a two-way ball valve functions in a similar way to the stem at the top of the valve, by holding the ball in place. In a three-way ball valve, the trunnion has a different design, resembling a supporting ring, but it still provides the same function and level of stability.