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Basic Knowledge of Valve

Apr. 15, 2020

The valve is the control component in the pipeline fluid transportation system. It is used to change the cross-section of the passage and the direction of the medium flow. It has the functions of diversion, cut-off, adjustment, throttling, check, shunt or overflow pressure relief.

The valves used for fluid control range from simple globe valves to various valves used in extremely complex automatic control systems. Their varieties and specifications are wide. The nominal diameter of the valve ranges from very small instrument valves to industrial diameters of up to 10m. Valves for pipelines. The valve can be used to control the flow of various types of fluids such as water, steam, oil, gas, mud, various corrosive media, liquid metals and radioactive fluids. The working pressure of the valve can be from ultra high pressure of 1.3х10MPa to 1000MPa, working temperature From the ultra-low temperature of -269 ℃ to the high temperature of 1430 ℃. The valve can be controlled by various transmission methods, such as manual, electric, hydraulic, pneumatic, worm gear, electromagnetic, electromagnetic-hydraulic, electric-hydraulic, pneumatic-hydraulic, spur gear, bevel gear drive, etc. ; Can be operated according to predetermined requirements under the action of pressure, temperature or other forms of sensor signals, or simply open or close without relying on sensor signals. The valve depends on the drive or automatic mechanism to lift and slide the opening and closing parts Shift, swing, or slewing motion, thereby changing the size of its flow channel area to achieve its control function. Globe valve manufacturer for you to introduce the valve classification in detail.

I. Use of valve

A valve is a pipeline accessory. It is a device used to change the cross-section of a passage and the direction of medium flow and to control the movement of the conveying medium. It has diversion, cut-off, adjustment, throttling, check, shunt or overflow pressure relief Features. Specifically, the valve has the following uses:

1.1 Cut-off valves: connect or cut off the medium in each section of the pipeline. Such as gate valve, globe valve, ANSI ball valve, plug valve, diaphragm valve, butterfly valve, etc.

1.2 Regulating valves: regulating the flow and pressure of the medium in the pipeline. Such as throttle valve, regulating valve, pressure reducing valve, safety valve, etc.

1.3 Diversion valves: change the flow direction of the medium in the pipeline, used to distribute, separate or mix the medium. Such as distribution valves, three-way plug valves, three-way or four-way ball valves, traps, etc.

II Classification of valves

There are many types of valves. With the continuous improvement of the technological process and performance of various sets of equipment, the types of valves are still increasing, but in general they can be divided into two categories:

2.1 Automatic valve

Valves that act on their own depending on the capabilities of the medium (liquid, gas, steam, etc.). Such as safety valves, check valves, pressure reducing valves, steam traps, hydraulic control valves, emergency shut-off valves, exhaust valves, etc.

Forged Steel Globe Valve

Forged Steel Globe Valve

2.2 Drive the valve

Valves operated by manual, electric, hydraulic and pneumatic. Such as gate valve, forged steel globe valve, throttle valve, butterfly valve, ball valve, balance valve, plunger valve, plug valve, etc.

The valve relies on an automatic or drive mechanism to lift, slide, swing or swing the opening and closing parts, thereby changing the size of its flow channel area to achieve its control function.

In addition, the valve has the following classification methods.

2.3 According to structural characteristics

According to the movement direction of the closing and opening piece relative to the valve seat, it can be divided into:

2.3.1 Sectional door shape: The closing and opening part moves along the center line of the valve seat.

2.3.2 Gate shape: The closure member moves in a direction perpendicular to the center line of the valve seat.

2.3.3 Cock and sphere: The opening and closing piece is a plunger or sphere, rotating around its own axis.

2.3.4 Swing shape: The opening and closing parts rotate around the axis outside the valve seat.

2.3.5 Butterfly: The disc of the opening and closing part rotates around the axis inside the valve (center line type) or the axis outside the valve seat (eccentric type)

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