Ball valve is currently the most widely used mechanical product in all valve markets. It is mainly composed of valve body, valve seat, ball, valve stem and transmission device. The actuating device drives the core to rotate to achieve the function of switch or adjustment. In the chemical, environmental protection, water treatment, urban construction, machinery, and food industries, it is widely used and very popular!

There are many types of ball valves, which can be combined into various products with different functions through differences in structure, connection, pressure registration, and drive mode. But from the most basic point of view, ball valves are divided into two categories: full bore ball valves and reduced diameter ball valves. Generally speaking, when the inner diameter of the valve ball is less than or equal to 85% of the inner diameter of the ball valve port, it is called a reduced diameter ball valve, and when the inner diameter of the ball valve is greater than 95% of the inner diameter of the ball valve port, it is called a full-bore ball valve. So what is the difference between the two in the selection or application?

一. Definition:

1. The full-bore ball valve has equal-width flow channels, that is to say, the size of the orifices from inflow to outflow is the same, and its size cannot be less than the value specified by the standard, which is roughly equivalent to the nominal diameter of the specification, such as DN50 full-bore The diameter of the ball valve flow path also needs to be about 50mm;

2. The inlet of the reduced diameter ball valve is wider than the diameter of the flow channel, and the actual diameter of the flow channel is about one specification smaller than this specification. For example, the diameter of the DN50 reduced-diameter ball valve is about 38mm, which is roughly equivalent to the DN40 specification. Reduce one specification within DN250 and reduce two specifications from 250-600. Above 600 depends on actual conditions.

二. Applicable medium:

1. Full-bore ball valves are generally used for conveying viscous and slagging media pipelines. Because of its low fluid resistance, it can be said that there is basically no flow resistance, which can facilitate the passage of regular wax scrapers.

2. Reduced diameter ball valve is suitable for conveying gas or pipelines with physical properties similar to water. Because its weight is about 30% lighter than a full-bore ball valve. And its circulation resistance is only about 1/7 of the same diameter globe valve. It is helpful to reduce the pipeline load and reduce the cost.

三. Applicable process:

1. For pipelines that need to be pigged regularly, no matter what kind of medium is being transported, full bore ball valves must be used. The medium passing through the full-bore ball valve will not reduce the flow, and the flow resistance is small, which is an ideal product for pipeline control, especially for strict working conditions. Especially when the main line in the oil pipeline and gas pipeline needs to be buried underground, full-diameter welded ball valves must be used.

2. Reduced diameter ball valve is suitable for some working conditions such as low requirements and small convection resistance. When the inner diameter of the valve is greater than 80% of the inner diameter of the pipe end, it has almost no effect on the pipe fluid passing capacity. Many valves have a reduced diameter, generally controlled within 0.8. On the one hand, the reduced diameter reduces the flow capacity of the valve, that is, the KV value of the valve, and increases the pressure drop at both ends of the valve, causing energy loss. That said, there is not much impact, and it may increase the erosion of the pipeline.

四, comparison of advantages and disadvantages:

1. Installation space: The reduced diameter ball valve is small in size, so its installation space requirements are smaller. Because its weight is about 30% lighter than a full-diameter ball valve, it is beneficial to reduce the pipeline load, reduce the transportation load, and reduce the cost.

2. Cost: Reduced-diameter ball valves are one grade lower in price than full-diameter ball valves. Considering the cost performance, it is generally accepted internationally that adjacent pipe diameters use the same ball diameter valve body. Such as DN32 and DN40, DN50 and DN63, DN90 and DN110, DN160 and DN200, DN250 and DN315 use the same sphere.

Note: Since the inner diameter of the reduced-diameter ball valve is small, the torque on the valve stem is small, which is more suitable to extend the service life of the valve switch. Especially the low-torque design of large-diameter valves. However, the diameter cannot be reduced too much, otherwise the system resistance will increase. However, if the diameter is not reduced, the purchase cost will be increased, and the valve control characteristics will be reduced, making the adjustment effect worse. For example, if the regulating valve is always used at a small opening, the service life of the valve will be reduced.