Manual Ball Valves



Manual Ball Valves


Ball Valves

 

Ball valves are durable, reliable and securely shut off flow even after sitting idle for long periods of time. Because of this, they are frequently used as fluid and gas flow cut-off valves. Ball valves are also easy to operate. This plus their availability in a range of useful material options has led to their widespread use.

 

The principle of how Ball valves work is the same as any valve in that it controls the flow of water through it and has a handle to stop the flow when required. It is called this because of its ball or sphere closure unit inside the valve which opens and closes when the lever is turned, controlling flow. A ball valve is a form of quarter-turn valve which uses a hollow, perforated and pivoting ball to control flow through it. It is open when the ball's hole is in line with the flow and closed when it is pivoted 90-degrees by the valve handle.

 

So a Ball valve is a quarter turn operated valve. The closure member is a spherical plug with a through hole. When the valve is in open state, the through hole is in-line with the fluid flow and hence, the fluid passes through it. The valve is closed by rotating the globe by 90 Degrees. such that the hole now becomes perpendicular to the flow and hence, stops the flow. 

The seat is usually circumferential, made up of soft materials to offer a tight shutoff. The seat can be made either out of plastic or metals. Ball valves are not recommended to be used in a partially open condition. Due to misalignment between the flow direction and opening of the plug, large pressure drop takes place in partially open condition. 
Due to above specified challenges, ball valves are mostly used in shutoff applications. Ball valves are commonly used in steam, water, oil, gas, air, corrosive fluids. They can handle slurries and dusty dry fluids. Ball valves are not used with abrasive and fibrous materials as it poses risk of damage to the seat and plug surface.

 

 Ball Valves provide tight shut-off and predictable control. They have a high range of use due to the design of the regulating element, without the complications of side loads typical of butterfly or globe valves. Advantages include ease of operation and high flow, high pressure, and high temperature capabilities. Disadvantages include low cleanliness and an inability to handle slurries.