How the ball valve works
To understand the principle of operation of a ball valve, it is important to know the 5 main parts of a ball valve and 2 different types of function. The 5 main components can be seen in the ball valve diagram in the figure below. The stem valve (1) that attaches to the ball (4) either works manually or automatically (electrically or pneumatically). The ball is supported and sealed by a ball valve seat (5) and their rings (2) are located around the valve stem. Everyone is inside the valve housing (3). The ball has a hole through it, as shown in the cross-sectional figure in Figure 1. When the valve stem rotates a quarter, the hole either opens to flow and allows media to pass through or closes to prevent media flow. Valve circuit performance, chamber assembly, ball design, and types of operation that all affect ball valve performance are discussed below.
The ball valve may have two, three or even four ports (two-way, three-way or four-way). The vast majority of ball valves are two-way and lever-operated manually. When the valve is opened, the lever is in the direction of the pipe. When closed, the handle is perpendicular to the tube. The direction of flow of the ball valve is simply from one inlet to one for a two-way valve. Hand-held ball valves that can work quickly close, so there is a water hammer with the water sticking at high flow rates. Some ball valves are equipped with a gearbox. Three-way valves have an L-shaped or T-shaped hole that affects the operation of the circuit (flow direction). This ball valve can be seen in the figure below. As a result, different circuit functions such as separating or mixing currents are achievable.
The valve housing assembly can be divided into three common designs: one-piece, two-piece and three-piece chambers. There is a difference in how the valve is assembled and this affects the maintenance or repair facilities. The performance of the valves is the same in each type.
One piece: This is the cheapest type. The two parts that cover the ball are pressed or welded. Valves cannot be opened for cleaning or maintenance. This type is generally used for low demand applications.
Two-piece: Two-piece valves can be separated for cleaning, service and inspection. Most parts are connected via a gear connection. The valve must be completely separated from the pipe to separate the two parts.
Three-piece: More expensive valves are often three-piece. The parts are generally connected by bolt and nut connections. The advantage of this embodiment is that the valve can be serviced without removing the entire valve from the pipeline.
Ball valve design
The most common design is “floating ball design”. The ball is suspended in the fluids and held in place by two sealing rings. Some high quality valves have a mesh ball design. The ball is supported at the top and bottom to reduce the load on the valve seats.
Most ball valves have a floating ball. The ball is supported by a set of taps.
Large diameter valves with high working pressures (eg DN> 100 mm and 30 bar) often have a ternion design. The ball is supported at the bottom and top to reduce the load on the seat rings. In general, the operating torque is lower for a Ternion ball valve.
The ball hole may have different profiles, such as a full bore, a reduced bore, or a V-shaped hole.
Most ball valves have a boron radius. As a result, the valve introduces friction losses into the system. These losses are still relatively small compared to other types of valves.
Full-blown valves have a hole similar to a pipe. The advantage is that no additional friction is lost and the system is mechanically easier to clean (configuration operation). The downside is that the ball and chamber are larger than a regular four-way valve with a small hole. So the cost is a bit higher and for many applications this is not necessary. They are also called full port ball valves.
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