Valve type

(1) Close the valve

This kind of valve is used for opening and closing. Standing on the inlet and outlet of cold and heat sources, equipment and pipeline branches (including risers), it can also be used as a drain valve and a vent valve. Common cut-off valves are gate valves, globe valves, ball valves and butterfly valves.

Gate valves can be divided into exposed and hidden rods, single and double rams, wedge rams and parallel rams. The sealing performance of gate valve is not good, and it is difficult to open large-diameter gate valve; The size of the valve body along the water flow direction is small, the flow resistance is small, and the nominal diameter span of the gate valve is large.

Cut-off valves are divided into three types according to the flow direction of the medium: straight-through, right-angle and direct-flow, and also divided into open-stem and hidden-stem. The sealing performance of globe valve is better than that of gate valve, with long valve body, large flow resistance and maximum nominal diameter DN200.

The valve core of the ball valve is a sphere with an opening. Move the valve stem so that the ball hole is fully open when facing the pipeline axis, and fully closed when turning 90. The ball valve has certain adjustment performance and is tightly closed.

The valve core of the butterfly valve is a circular valve plate, which can rotate along the vertical axis perpendicular to the pipeline axis. When the plane of the valve plate is consistent with the axis of the pipeline, it is fully open; When the gate plane is perpendicular to the pipeline axis, the gate is completely closed. Butterfly valve body has small length and low flow resistance, which is higher than gate valve and globe valve. [ 1]

(2) Check valve

This kind of valve is used to prevent the medium from flowing backwards. It opens itself by using the kinetic energy of the fluid and closes automatically when it flows backwards. Stand at the outlet of the water pump, the outlet of the steam trap and other places where the fluid is not allowed to flow backwards. Check valves are divided into swing type, lift type and clip type. For swing check valves, the fluid can only flow from left to right, and automatically closes when it flows in the opposite direction. For the lift check valve, when the fluid flows from left to right, the valve core is lifted to form a channel, and when the fluid flows in the opposite direction, the valve core is pressed against the valve seat and closed. For the wafer check valve, when the fluid flows from left to right, the valve core opens to form a channel, and when the fluid flows reversely, the valve core presses on the valve seat and closes. Wafer check valves can be installed in multiple positions, with small volume, light weight and compact structure. [ 1]

(3) Control valve

The pressure difference before and after the valve is constant. When the opening of ordinary valve changes in a large range, its flow rate changes little, but when it reaches a certain opening, the flow rate changes sharply, that is, the regulation performance is not good. The regulating valve can change the resistance of the valve by changing the stroke of the valve core according to the direction and magnitude of the signal, so as to achieve the purpose of regulating the flow. Regulating valves are divided into manual regulating valves and automatic regulating valves. Manual or automatic regulating valves are divided into many types, and their regulating performance is also different. Automatic control valves include self-operated flow control valves and self-operated differential pressure control valves. [ 1]

(4) vacuum class

Vacuum category includes vacuum ball valve, vacuum baffle valve, vacuum inflation valve, pneumatic vacuum valve, etc. Its function is to change the direction of air flow, adjust the size of air flow and cut off or connect the pipeline in vacuum system, which is called vacuum valve.

(5) Special purpose category

Special purpose categories include pigging valves, exhaust valves, sewage valves, exhaust valves, filters, etc.

Exhaust valve is an indispensable auxiliary component in pipeline system, which is widely used in boilers, air conditioners, oil and gas, water supply and drainage pipelines. It is often installed at commanding heights or bends to remove excess gas in the pipeline, improve the efficiency of the pipeline and reduce energy consumption.

According to the main parameters

At nominal pressure:

(1) vacuum valve: refers to the valve whose working pressure is lower than the standard atmospheric pressure.

(2) Low pressure valve: refers to the valve with nominal pressure PN ≤ 1.6Mpa.

(3) Medium-pressure valves: refer to valves with nominal pressure PN of 2.5Mpa, 4.0Mpa and 6.4Mpa.

(4) High-pressure valve: refers to the valve with the nominal pressure PN of 10.0 MPa ~ 80.0 MPa.

(5) Ultra-high pressure valve: refers to the valve with nominal pressure pn ≥ 100.0mpa. ..

Depending on the operating temperature:

(1) ultra-low temperature valve: used for working temperature t of medium.

(2) Normal temperature valve: used for medium with working temperature of -29℃

(3) Intermediate temperature valve: used for working temperature of medium of 120℃

(4) High temperature valve: used for working temperature of medium t >；; 425℃ valve.

According to the driving mode:

According to the driving mode, it can be divided into automatic valve, electric valve and manual valve.

diameter

(1) Small valves: valves with nominal diameter DN≤40mm.

(2) Intermediate diameter valve: a valve with a nominal diameter DN of 50 ~ 300mm.

(3) Large-diameter valves: valves with a nominal diameter DN of 350 ~ 1200mm.

(4) Extra-large-diameter valves: valves with nominal diameter dn ≥1400 mm.

According to the structural characteristics

Structural characteristics of valves

The structural feature of the valve is that according to the movement direction of the closing part relative to the valve seat, it can be divided into:

(1) truncated door shape: the closing piece moves along the center of the valve seat; Such as stop valves

(2) cock and ball: the closing part is a plunger or ball, which rotates around its own center line; Such as plug valves, ball valves

(3) gate shape: the closing piece moves along the center of the vertical valve seat; Such as gate valves, gates, etc.

(4) Swing shape: the closing part rotates around the shaft outside the valve seat; Such as swing check valves.

(5) Butterfly: the disc of the closing part rotates around the shaft in the valve seat; Such as butterfly valves and butterfly check valves.

(6) Slide valve shape: the closing piece slides in the direction perpendicular to the channel. sly/tricky

According to the connection method

(1) Threaded connection valve: The valve body has internal thread or external thread, which is connected with the pipeline by thread. ..

(2) Flange valve: The valve body is connected by flange and connected with the pipeline flange.

(3) Welding connecting valve: The valve body has a welding groove and is welded with the pipeline.

(4) Clamp connection valve: The valve body has a clamp and is connected with the pipe clamp.

(5) Socket-type connecting valve: connected to the pipeline through a ferrule.

(6) Clamping valve: a connection form that directly clamps the valve and two pipelines together with bolts.

According to the valve body material

(1) metal valve: Its valve body and other parts are made of metal. Such as cast iron valves, cast steel valves, alloy steel valves, copper alloy valves, aluminum alloy valves, lead alloy valves, titanium alloy valves, Monel alloy valves, etc.

(2) Non-metallic valve: Its valve body and other parts are made of non-metallic materials. Such as plastic valves, enamel valves, ceramic valves, FRP valves, etc.