In the face of so many valve classification and such a complex variety of conditions, to choose the suitable valve products for pipeline system installation, we should first understand the characteristics of the valve; Secondly, the steps and basis for selecting the valve should be mastered; Furthermore, the principle of selecting valves for the petroleum and chemical industries should be followed. The principle of choosing the valve in the petroleum and chemical industry: the flow channel is a straight-through valve, whose flow resistance is small, and the valve is usually selected as a cut-off and opening medium; Valves that are easy to adjust the flow rate are used to control the flow rate; Plug valves and ball valves are more suitable for reversing shunt; The sliding valve with wiping action along the sealing surface [] is suitable for medium with suspended particles.

01. Valves for closing and opening media

The flow channel is a straight-through valve, whose flow resistance is small, and the valve is usually selected as a cut-off and opening medium. Downward closed valves (globe valves, plunger valves) are less used because of their tortuous flow channels and higher flow resistance than other valves. In allowing a higher flow resistance

On occasions, closed valves can be selected.

02. Valve for flow control

Usually choose a valve [] that is easy to adjust the flow rate as the control flow. Downward closing valves, such as globe valves, are suitable for this purpose because their seat size is proportional to the stroke of the closing member. Rotary valves (plug valves, butterfly valves, ball valves) and torsion

Curved body valves (clamp valves, diaphragm valves) can also be used for throttling control, but usually only in a limited valve J diameter range. Gate valve is a disc-shaped gate to the circular seat mouth to do cross-cutting movement, it can only be close to the closed position, in order to better control the flow, so it is usually not used for flow control.

03. Valve for reversing and diverting

The valve may have three or more channels, depending on the need for reversing shunt. Plug and ball valves are more suitable for this purpose, so most valves used for reversing shunt choose one of these types of valves. But in some cases,

Other types of valves, as long as two or more valves [] are properly connected to each other, can also be used for reversing shunt.

04, with suspended particles medium valve

When there are suspended particles in the medium, it is suitable for the valve with wiping effect by sliding its closing parts along the sealing surface. If the closure is vertical in the back and forth movement of the seat, it may clamp the particles, so the valve [door] is only suitable for basically clean media unless the sealing surface material can allow embedding particles. Ball valves, plug valves, butterfly valves have a wiping effect on the sealing surface during the opening and closing process, so it is suitable for use in media with floating particles.