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Human-machine combination line of valve: how to connect electric valve
Source: | Author:pmt3e7315 | Published time: 2021-09-12 | 724 Views | Share:

There are two types of power supply for electric control valve. One is three-phase. One is single-phase electricity. Take single-phase power as an example: connect two power lines. Connect with the power terminal of the electric control valve. Four weak current control wires. They are input two and output two. (The most commonly used signals are weak current control signals such as 4 - and 0 -.) The input end of the regulating valve is connected to the control end of the system according to the positive and negative poles. The output end of the regulating valve is connected to the feedback end of the system according to the positive and negative poles.

Man-machine combination line of valve: How are pipes and valves connected together?

How to connect the valve and the common valve connection methods of the pipeline include: flange connection, clamp connection, butt welding connection, screw connection, ferrule connection, clamp connection, self-sealing connection, etc.

1. Flanged connection refers to the connection of flanges at both ends of the valve body, corresponding to the flanges on the pipeline, and installed in the pipeline by bolts. Flange connection is the most commonly used connection type in valves. Flanges can be divided into convex face (rf), plane face (ff) and convex concave face (mf).

2. Wafer connection valve is installed between two flanges. The valve body is usually provided with locating holes to facilitate installation and positioning. The valve and two pipes are directly clamped together by bolts.

3. Welding connection butt welding connection: both ends of the valve body are processed into butt welding groove according to the requirements of butt welding, which corresponds to the pipe welding groove and is fixed on the pipe by welding. Socket welding connection: both ends of the valve body are processed according to the requirements of socket welding, and connected with the pipeline through socket welding.

4. Screw connection Screw connection is a simple connection method, commonly used for small valves. The valve body is processed according to the thread standards, including internal thread and external thread. Corresponding to the thread on the pipe.

5. The ferrule connection ferrule connection has only developed in recent years in China. Its connection and sealing principle is that when the nut is tightened, the ferrule is under pressure, making its edge bite into the outer wall of the pipe, and the outer cone of the ferrule is closed with the inner cone of the joint under pressure, so it can reliably prevent leakage. Such as instrument valve.

6. Clamp connection This is a quick connection method. It only requires two bolts and is suitable for low-pressure valves that are often disassembled. Such as sanitary valve.

7. Internal self-tightening connection All the above connection forms use external force to offset the medium pressure and achieve sealing. The following describes the connection form of self-tightening by using medium pressure. Its sealing ring is installed at the inner cone at a certain angle with the side opposite the medium. The medium pressure is transmitted to the inner cone and then to the sealing ring. On the cone at a certain angle, two components are generated, one is parallel to the center line of the valve body and the other is pressed towards the inner wall of the valve body. The latter component is the self-tightening force. The greater the medium pressure, the greater the self-tightening force. Therefore, this type of connection is suitable for high-pressure valves.

8. Other valve connections

Flange connection

Flange connection is the most commonly used connection form between valve and pipeline or equipment. It refers to the removable connection of flange, gasket and bolt as a group of combined sealing structure.

The pipe flange refers to the flange used for piping in the pipeline device, and the inlet and outlet flanges of the equipment when used on the equipment. The flange connection is easy to use and can withstand large pressure.

Flange connection can be applied to valves of various nominal sizes and pressures, but there are certain restrictions on the use temperature. Under high temperature conditions, flange connection bolts are prone to creep and cause leakage. Generally, flange connection is recommended to be used at ≤ ℃.

According to the shape of the joint surface, it can be divided into the following types:

Smooth type: used for valves with low pressure. Processing is convenient

Concave and concave type: high working pressure, medium hard washer can be used

Tenon and groove type: gaskets with large plastic deformation can be used widely in corrosive media with good sealing effect

Trapezoidal groove type: oval metal ring is used as gasket for valves with working pressure ≥/cm2 or high-temperature valves

Lens type: gasket is in the shape of lens and made of metal. High-pressure valve or high-temperature valve with working pressure ≥ kg/cm2

O-ring type: a relatively new flange connection form, and the sealing effect is more reliable than the ordinary flat washer

Wafer connection

It is a connection form that the valve and two pipes are directly threaded and clamped together with bolts.

Welded connection

Welding connection refers to a connection form of valve body with welding groove and connected with pipeline system by welding.

GB/T,. 34 and other standards stipulate the welding groove

The welding connection between valve and pipeline is divided into butt welding (BW) and socket welding (SW). The socket welding end shall comply with the provisions of JB/T. Butt-welding connection (BW) can be applied to various sizes, pressures and high temperature conditions, and socket welding connection (SW) is generally applicable to ≤ valves.

Threaded connection

This is a simple connection method, which is often used for small valves. There are two situations:

Direct sealing: internal and external threads directly play a sealing role. In order to ensure no leakage at the joint, lead oil, hemp and PTFE raw material belt are often used to fill, among which PTFE raw material belt is widely used.

This material has good corrosion resistance, excellent sealing effect, convenient use and storage, and can be completely removed when disassembling, because it is a non-adhesive film, which is much superior to lead oil and hemp.

Indirect sealing: the tightening force of the thread is transmitted to the washer on two planes to make the washer play a sealing role.

Ferrule connection

The working principle of the ferrule connection is that when the nut is tightened, the ferrule is under pressure, making its edge bite into the outer wall of the pipe, and the outer cone of the ferrule is closely connected with the inner cone of the joint under pressure, so it can reliably prevent leakage.

The advantages of this connection form are:

Small size, light weight, simple structure, easy disassembly;

Strong connection force, wide range of use, and can withstand high pressure (kg/cm2), high temperature (℃) and shock vibration;

A variety of materials can be selected, suitable for corrosion prevention;

The processing accuracy is not high;

Easy to install at height.

At present, the ferrule connection form has been adopted in some small-diameter valve products in China.

Clamp connection

This is a quick connection method, which only requires two bolts, and is applicable to low-pressure valves that are often disassembled.

Internal self-tightening connection

Internal self-tightening connection is a kind of connection form that uses medium pressure for self-tightening. Its sealing ring is installed at the inner cone at a certain angle with the side opposite the medium. The medium pressure is transmitted to the inner cone and then to the sealing ring. On the cone at a certain angle, two components are generated, one is parallel to the center line of the valve body and the other is pressed towards the inner wall of the valve body.

The latter component is the self-tightening force. The greater the medium pressure, the greater the self-tightening force. Therefore, this type of connection is suitable for high-pressure valves. Compared with flange connection, it saves a lot of materials and manpower, but also requires a certain amount of preload, so that it can be used reliably when the pressure in the valve is not high.

The valve made by the principle of self-tightening sealing is generally a high-pressure valve. There are many forms of valve connection, for example, some small valves that do not need to be removed are welded with pipes; Some non-metallic valves adopt socket connection, etc. The valve user shall be treated according to the actual situation. There are many other forms of valve connection, for example, some small valves that need not be removed are welded with pipes; Some non-metallic valves adopt socket connection, etc. The valve user shall be treated according to the actual situation.