Valve knowledge
Release Date: 2020-03-11

1. Difference between gate valve and stop valve:

Both of them can be closed, and the flow can be adjusted in the case of low demand for flow linearity. However, due to the structural characteristics of the stop valve, its flow resistance is large, so the gate valve is used a little more where there are requirements for throttling.

2. About check valve

Check valve is a valve that automatically closes by the flow of medium itself to prevent the backflow of medium. It is also called check valve, single direction valve, counter flow valve and back pressure valve.

3. About material life

FRPP, PPH, UPVC, CPVC and other materials are properly maintained, and their service life is five to six years without pollution.

PVDF material is 40 years. In general, the service life of products put into use in conventional industries and mines is 18 months.

4. About negative pressure

Soft seal valve can not be subject to negative pressure, easy to tear the seal, so the sealing material can be used under negative pressure.

5. Peeling on the surface of PVC series products

Due to the poor fusion of PVC series products, in the process of injection molding, the molding temperature and decomposition temperature are close to each other, and the requirements for temperature control are extremely high. Therefore, each injection molding machine is equipped with a cooling fan for cooling. But the injection products are affected by temperature, pressure and time: the injection molding time is a little longer, the cold materials (the raw materials entering the mold cavity for injection, heated in the electric heating ring of the feeding barrel, and the temperature is controlled at about 180 ℃) will have redundant materials entering the products, the cold material mold itself can not bear too much cold materials, the redundant cold materials entering the products, the cooling time is not enough, and the mold temperature is too high, which is also the reason Influence factors, so injection finished PVC products have a small amount of peeling phenomenon is inevitable.

6. FRPP grey snow pattern, embossing

When the embossing is supercharged twice, the pressure is too large, resulting in the product surface texture. For single pressurization products, due to the thick structure of the valve body, there are many air holes after cooling, and the valve body is easy to sink. After the second pressurization, the product is more solid and tight.

Snowflake pattern on FRPP material surface

Pure PP material has no such situation. The injection molding of FRPP product is FRPP raw material and reinforced glass fiber particles. After the two are configured in proportion, the injection molding production will be conducted. The glass fiber distribution is uneven, and the snow pattern surface will be formed when the valve body surface is gathered. If PP raw materials and glass fiber particles are granulated, this phenomenon can be avoided.

7. Difference between the British and the British

The metric system is measured in meters, centimeters or millimeters, while the English system is measured in inches or feet.

Metric thread is represented by pitch, while British thread is represented by the number of thread threads in American inch.

Metric thread is 60 degrees of equal profile, English thread is 55 degrees of equal waist profile, American thread is 60 degrees.

8. The difference between butterfly valve handle type and turbine

The handle of butterfly valve directly drives the disc, which can be opened and closed quickly but laboriously. The turbine butterfly valve is driven by the turbine disc, which is slow to open and close but labor-saving; therefore, the handle butterfly valve is particularly laborious when the pressure in the pipe is large.

The butterfly valve commonly used in the project is turbine butterfly valve, because in addition to saving labor, its sealing is better than handle butterfly valve, especially in the environment of high switching frequency, the service life is longer than handle butterfly valve.

9. About gases

Our valve is mainly used for liquid, air molecules and water molecules with different densities. Butterfly valve is not recommended for over gas. In addition, our company has 5 kinds of materials. It is not recommended to use gas if the air tightness is not strong.

10. Installation of flange ball valve

The design structure of our judicial blue ball valve is the design principle of water inlet thread, which is convenient for the maintenance of the ball and the valve rod. Such valves should be in the closed state (the valve rod is 90 ° to the valve body) during installation, so as to avoid a series of problems caused by improper installation, such as the pressure of the ball caused by the compression of the gasket and the abnormal operation of the ball, the handle slipping and the valve rod fracture.

According to the operation over the years, the valve damage caused by incorrect installation of users is summarized as follows:

1、 Preferred connection of plane flange and flange ball valve

2、 Preferred full face flange rubber gasket

3、 Tighten the flange screws when the valve is closed

4、 When tightening screws, pay attention to the average force in each direction. Do not use excessive force. Take the flange surface not deformed as the degree. Do not use the tightness of metal valve as the standard.

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