A ball valve, invented in the 1950s, is a valve with a spherical disc. With the rapid development of technology and the ceaseless improvement of processing technique and product structure, the ball valve has been one kind of main valves in recent years. Now it is applied with an increasing speed at home and abroad. The ball valve is widely used in different industries, such as petroleum refining, long-distance transport pipes, chemical, paper making, pharmacy, water treatment system, electricity and so on.
A ball valve, one type of quarter turn valve, is quite literally a ball placed in a passageway through which fluid flows. The ball has a hole, by which the valve opens and closes. When the ball is positioned in this way where the hole runs the same direction as the passageway, the fluid simply flows through the hole, and the valve is open. However, when the ball is positioned in this way where the hole is perpendicular to the passageway, the fluid cannot pass through, and the valve is closed. The ball is controlled from outside of the valve, often with a handle that can be turned 90 degrees, or a quarter turn, back and forth for opening and closing the valve. Therefore, ball valve is an excellent choice for shutoff applications.
But with the development of technology, it also has the functions of throttling-control and fluid-control.
The ball valve has the following main features. What comes first is that the it is very versatile because it supports pressures up to 700 bars and temperatures up to 200°C and sizes typically range from 0.5 cm to 30 cm. secondly, the ball valve has such a simple structure that it is easy to operate and repair.
Thirdly, the seal and the ball are often in close state so that the ball valve is very reliable and not easy to be eroded by the working medium. Last but not least, with the PTFE valve seat ring the ball valve is quite durable and usually work to achieve perfect shutoff even after years of disuse. As for the types, there are five general body styles of ball valves: single body, three-piece body, split body, top entry, and welded. The difference among them is based on how the pieces of the valve-especially the casing that contains the ball itself-are manufactured and assembled. The valve operation is the same in each case.
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