Valve knowledge

Update:28 Mar 2020
1. Difference between gate valve and globe valve:

Both can be turned off, and flow adjustment can be performed in situations where flow linearity is not high. However, due to the structural characteristics of the globe valve, the flow resistance is large, and the gate valve is used a little more where the throttle is required.

2.About check valve

The check valve is a valve that automatically closes by the flow of the medium itself to prevent the medium from flowing backward. Also known as check valve, check valve, reverse flow valve and back pressure valve.

3.About material life

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

The PVDF material is forty years. In general, the life of conventional industrial and mining products is 18 months.

4.About negative pressure

Soft-sealed valves cannot be subjected to negative pressure, and are easy to tear the seal. The sealing material can be used under negative pressure.

5.Skin peeling of PVC products

Due to the poor fusion of the materials of the PVC series products, during the injection molding process, the molding temperature and the 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 cooler for cooling and cooling. However, the injection molding products are affected by temperature, pressure and time: the injection molding time is slightly longer, and the cold material (the raw material that enters the mold cavity for injection molding is heated in the heating coil of the feeding barrel, and the temperature is controlled at about 180 ° C). Excessive material enters the product. The cold material mold itself cannot bear too much cold material. If the excessive cold material enters the product, the cooling time is not enough and the mold temperature is too high. It is also the influencing factor. Therefore, the PVC product after injection molding has a small amount of peeling. inevitable.

6, FRPP grey snow pattern, embossing

When the embossing is pressurized twice, the pressure is too large, resulting in a texture on the product surface. For single-pressurization products, due to the thick body structure of the valve, there are many air holes after cooling, and the valve body is easy to sag. After the second pressurization, the product is stronger and tighter.

FRPP material surface snow pattern

Pure PP material has no such situation. The injection molding of FRPP products is FRPP raw material and reinforced glass fiber particles. After the two are configured in proportion, the glass fiber is unevenly distributed, and the surface of the valve body will form a snow pattern surface. This phenomenon can be avoided if the PP raw material and glass fiber particles are granulated.

7.Metric and English system differences

Metric is measured in meters, centimeters, or millimeters, while English is measured in inches or feet.

Metric threads are represented by the pitch and inch threads are represented by the number of threads in US inches.

Metric threads are 60-degree equilateral teeth, inch threads are 55-degree isosceles, and American threads are 60 degrees.

8.The difference between butterfly valve handle and turbine

The handle butterfly valve handle rod directly drives the clapper, which opens and closes quickly but is laborious. Turbine butterfly valves pass through the turbine transmission flaps, which opens and closes slowly and effortlessly; therefore, handle butterfly valves are particularly laborious when the pressure in the pipe is high.

The butterfly valve commonly used in engineering is generally a turbo butterfly valve, because in addition to saving labor, its seal is better than that of a handle butterfly valve, and its service life is longer than that of a handle butterfly valve in a particularly high switching frequency environment.

9.About gas

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

10. Installation of flange ball valve

The design structure of our judicial blue ball valve is the design principle of the inlet thread, which is convenient for the maintenance of the ball and the valve stem. The valve should be closed when the valve is installed (the valve stem is at 90 ° to the valve body) to avoid the ball from being squeezed by the gasket and causing the ball A series of problems caused by improper installation, such as sliding handles and broken valve stems, caused by pressure not working properly.

According to the operation of the past years, the valve is damaged due to incorrect installation by the user, and the following summary is made:

First, the connection between the flat flange and the flange ball valve is preferred

Second, the preferred full-plane flange rubber gasket

Third, tighten the flange screws when the valve is closed

4. Pay attention to the average force in each direction when tightening the screws. Do not use too much force. The flange surface should not be deformed to the degree. The cut cannot be based on the tightness of the metal valve.