Ball valve structure features and characteristics description

Ball valve structural characteristics and characteristics of different types of ball valves

(1) The ball valve has low fluid resistance and has the lowest flow resistance (actually zero)

Ball valves generally have both a reduced diameter and a non-reduced path. Regardless of the structure, the flow resistance coefficient of the ball valve is relatively small. In particular, the so-called full-flow type, that is, the ball valve which does not reduce the diameter, has a channel diameter equal to the inner diameter of the pipe, and the local resistance loss is only the frictional resistance of the pipe of the same length, that is, the flow resistance of the ball valve is the smallest among all the valves. In the rocket launch and its test system, the smaller the resistance of the pipeline is required, the better. There are two ways to reduce the resistance of the piping system: one is to reduce the fluid flow rate, and to increase the diameter of the pipe and the valve diameter, which often has an adverse effect on the economics of the piping system, especially for the low temperature conveying system ( Liquid hydrogen) is extremely unfavorable; first, it reduces the local resistance of the valve, so the ball valve is naturally the best choice.

(2) The ball valve opening and closing switch is quick and convenient.

Since the ball valve only needs to rotate the handle by 90° under normal conditions, the full opening or closing operation is completed, and the quick opening and closing is easy. It can realize fast opening and closing. The opening and closing time of some structures is only 0.05~0.1s, which can be used in the automation system of the test bench. When the valve is quickly opened and closed, the operation is free of impact.

(3) The ball valve has good sealing performance.

At present, the valve seat of most ball valves is made of elastic materials such as Teflon, and the sealing pair composed of metal and non-metal materials is usually called soft seal. In general, the sealing of the soft seal is easy to ensure, and the processing accuracy and surface roughness of the sealing surface are not very high.

(4) The ball valve has a long service life.

Due to the good self-lubricating properties of the PTFE, the friction and wear with the sphere is small, and the roughness is reduced due to the improvement of the sphere processing technology, thereby improving the service life of the ball valve. According to reports, the United States W-K-M company in the test room for the life test of the ball valve, the number of switching more than 100,000 times.

(5) The high reliability of the ball valve is mainly due to:

1The pair of sealing parts of the ball and the valve seat will not cause scratches, sharp wear and other failures, and will not get stuck during operation (in the absence of lubricant), so it can be reliably applied to corrosive media and low boiling point liquids;

2 Built-in valve stem structure eliminates the hidden danger of the valve stem flying out due to the loosening of the packing gland under the action of fluid pressure;

3Adopting anti-static, refractory ball valve, suitable for pipelines conveying oil, natural gas and gas.

(6) The smooth passage in the valve body is more suitable for conveying viscous fluids, slurries, and solid particles.

(7) It can be reliably applied to corrosive media and low-boiling liquids because it will not get stuck during work (in the absence of lubricant).

(8) The ball-type closing member can be automatically positioned in position and can withstand the high pressure difference at the time of closing.

(9) A full two-way seal can be achieved over a wide range of pressures and temperatures.

(10) When fully open and fully closed, the sealing surfaces of the ball and the valve seat are isolated from the medium, so that the medium passing through the valve at high speed does not cause erosion of the sealing surface.

(11) Compact structure and light weight, it can be considered as the most reasonable valve structure for low temperature medium systems.

(12) The valve body is symmetrical, especially when welding the valve body structure, which can well withstand the stress from the pipe.

(13) The ball valve of the all-welded valve body can be buried directly in the ground, so that the valve internals are not eroded, and the maximum service life can reach 30 years. It is the most ideal valve for oil and natural gas pipelines.