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Ball valve is currently all the valve market, the most widely used a mechanical product, which is mainly composed of valve body, seat, ball, stem and transmission device, through the executive device to drive the ball core rotation, to achieve the function of switching or regulation. In chemical industry, environmental protection, water treatment, urban construction, machinery including food and other industries, widely used, and very popular!

A wide variety of ball valves, through the structure of the form, connection, pressure grade, driving form, etc., can be combined into a variety of different functional products, but from the most basic, ball valves have full diameter ball valves and reduced diameter ball valves of the two major categories of difference. Generally speaking, the ball diameter is less than or equal to the ball port diameter of 85%, that is, reduced ball valve, and ball valve diameter greater than 95% ball port diameter, that is, full diameter ball valve. So what are the differences between the two when choosing or applying them?

 Definition：

1，Full-diameter ball valve for equal width flow channel, that is to say, from the flow into the flow out of the hole size is the same, its size can not be less than the standard value, probably with the specification of nominal diameter, such as DN50 full-diameter ball valve flow channel diameter also need to be about 50;

2，Reduced diameter ball valve flow channel entrance is wider than the flow channel diameter, the actual flow channel diameter is about one smaller than the specification, such as DN50 reduced diameter ball valve flow to the diameter of about 38, roughly equivalent to DN40 specifications. In DN250 and less than one specification, 250-600 two specifications, more than 600 according to the actual situation.

Applicable medium：

1，Full-diameter ball valves are generally used for conveying viscous, slagging medium pipelines. Because of its small fluid resistance, it can be said that there is basically no flow resistance, and it can facilitate the passage of regular wax scraping and purging device.

2，Reduced diameter ball valve is suitable for conveying gas or physical properties similar to water on the pipeline medium, because its weight is about 30% lighter than the full diameter ball valve, and its flow resistance is only about 1/7 of the same caliber globe valve. It is beneficial to reduce pipeline load and reduce cost.

Applicable technology：

1，For pipelines requiring regular pigging, full-diameter ball valves must be used regardless of the medium being transported. Medium through the full diameter ball valve will not reduce the flow, and small flow resistance is an ideal product for pipeline control, especially in strict conditions. Especially in the oil pipeline and gas pipeline in the main line to be buried in the ground, must use full diameter welded ball valve.

2，Reduced diameter ball valve is suitable for some requirements are not high, small convection resistance requirements in the working conditions. When the inner diameter of the valve is more than 80% of the inner diameter of the pipe end, it has little effect on the flow capacity of the pipeline. Many valves have a reduced diameter, generally controlled within 0.8, the reduced diameter on the one hand reduces the flow capacity of the valve, that is, the Kv value of the valve, increases the pressure drop at both ends of the valve, resulting in the loss of energy, for the pipeline, not much impact, may increase the erosion of the pipeline.

Comparison of advantages and disadvantages：

1，Installation space: Reduced diameter ball valves are small, so their installation space requirements are smaller. Because its weight is about 30% lighter than full-diameter ball valves, it is beneficial to reduce pipeline load, reduce transportation load and reduce costs.

2，Cost: reduced diameter ball valve price is lower than full diameter ball valve one grade, taking into account the cost performance, the international general default, adjacent pipe diameter using the same ball diameter valve body. For example, dn32 and dn40, dn50 and dn63, dn90 and dn110, dn160 and dn200, dn250 and dn315 adopt the same sphere.

Note: Because the diameter of the reduced ball valve is small, the torque on the stem is small, which is more suitable for extending the service life of the valve switch. Especially the low torque design of large diameter valves. But the diameter can not be reduced by much, otherwise the system resistance will increase. But if the diameter is not reduced, one is to increase the procurement cost, and will generally reduce the valve control characteristics, so that the adjustment effect becomes worse. For example, if the regulator is always used in small opening, it will reduce the service life of the valve.