Dear visitors and subscribers!
Today on the agenda of exploitation of ball valves!
In this article, I want to understand why the lion's share of manufacturers of ball valves in the valve prohibits the use of various intermediate positions and strongly recommends that exploit such products only in two: "Open" / "Closed". (These positions are achieved by turning the closure member to the stopper locking devices - the stop, due to which the entire assembly is rotated by 1/4 of its axis, i.e., 90 degrees).
The thing is that most of the ball valves in our market are conventional PTFE ring seal located between the full-bodied ball valve and the housing of the product. These rings are fixed threaded member, which in turn couples the both sides of the valve body.
Ball valve has a small stroke and is not rigidly connected to the rod. Depending on which side there is a pressurized fluid flow, the ball moves and presses on the opposite ring, the thus prevents the exit of hydraulic fluid, in other words fluoroplastic is pressed against the ring gate from the smallest ball pressure. Thus, the tightness is achieved by the device as a whole, and can reliably stop the flow of working fluid without leaking.
Therefore, when the crane slightly parted through the resulting gap with high velocity fluid to create a turbulent flow starts leaking, and high probability of deformation of valve seat sealing ring, as a pressurized stream, pulls not really fixed ring housing.
Besides, working for a long time in an intermediate position (figure above), there is always a probability of the formation of solid deposits on the locking ball (Especially when low-quality water), which may subsequently impair the geometry of the closure element, and therefore leakage of the device.
Moreover, the flow regulation ball valves is not quite exact activity, since the size of the flow cross section is regulated linearly (shaft rotation angle not directly proportional to the change in the flow cross section of the locking element), and to achieve a predictable flow is quite difficult.
As a result, we see that the ball valve - a shut-off valve, it is not designed to regulate the flow due to the vulnerability of structures.
I hope that helped you with this material. That's all and thank you for your attention!
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