A ball valve is a type of quarter-turn valve that uses a hollow, perforated, and pivoting ball (often referred to as a "floating ball") to control the flow of fluid through it. The ball has a hole, or port, through the middle so that when the port is in line with both ends of the valve, the valve is fully open. When the valve is closed, the hole is perpendicular to the ends of the valve, and fluid flow is blocked. Here are the main parts of a typical ball valve:

1. Body:

   • The body is the main outer casing of the valve, which contains the internal components and provides the primary structure of the valve. It is usually made of metal (such as brass, stainless steel, or cast iron) or thermoplastics (such as PVC or CPVC).

2. Ball:

   • The ball is the central component of the ball valve. It has a hollow core with a hole (port) through the middle, allowing fluid to flow through when the valve is open. The ball rotates within the valve body to control the flow of fluid.

3. Seat:

   • The seat is the sealing surface that forms a tight seal around the ball when the valve is closed. It prevents fluid from leaking through the valve when it is in the closed position. Seats are typically made of resilient materials such as PTFE (Teflon), nylon, or elastomers.

4. Stem:

   • The stem is the shaft that connects the actuator (handle, lever, or gearbox) to the ball. It transmits the rotational motion from the actuator to the ball, allowing the operator to open or close the valve. The stem is usually made of metal, such as stainless steel, and extends through the valve body to connect to the ball.

5. Actuator:

   • The actuator is the mechanism used to operate the valve. It can be a handle, lever, gear operator, pneumatic actuator, electric actuator, or hydraulic actuator, depending on the size and application of the valve. The actuator controls the rotation of the ball to open or close the valve.

6. Stem Seal:

   • The stem seal provides a secondary sealing barrier around the stem to prevent leakage of fluid through the valve stem. It ensures that the valve remains leak-tight even under high-pressure conditions. Stem seals are typically made of materials such as PTFE (Teflon) or graphite.

7. Body Seals:

   • Body seals are gaskets or O-rings that provide a seal between the body and the end connections of the valve, preventing fluid leakage at the valve joints. They are typically made of elastomeric materials such as Nitrile (Buna-N), Viton, or EPDM.

These are the main components of a typical ball valve, though variations may exist depending on the specific design and application requirements. Ball valves are widely used in various industries for their reliability, ease of operation, and versatility in controlling the flow of fluids.