How to choose the correct description of the solenoid valve

In general, the domestic valve market price is relatively stable, although the slight increase and decrease every year, but the amplitude is very small. The main problems in the valve market are as follows: 1. Some operators purchase valves without factory names, print famous brands and certificates of well-known manufacturers, and pass the certificates.

The reputation of valve companies poses a serious hazard. Second, the renovation of the valve, some operators through the re-painting of the old valve after the second sale, bringing serious safety risks to the project quality. Therefore, care should be taken when selecting the valve that best suits your application. for

To avoid ambiguity, precise rules should be made for each valve. A comprehensive and appropriate description of the required valves should be made at the time of enquiry or order. The valve diameter must be selected to determine the nominal diameter of the pipe to which the valve is connected. Valve material is in the decision

The following factors should be considered when ordering the correct valve material:

· Fluid medium to be controlled by the valve

· Temperature range of the fluid medium

· The pressure range to which the valve is subjected

· climatic conditions that may affect valve operation

· Possible abnormal pressure or stress to be experienced by the valve

· Safety standards or piping procedures to be met

Valve category

What is the control function of the valve? Each valve structure is used to perform a certain function. Don't expect a valve to perform all the functions of the entire piping system.

Pressure-temperature rating. In order to meet the actual needs, please pay special attention to the pressure-temperature rating of the required valve. Pay special attention to the sealing material and the gasket material, which determine the pressure-temperature rating of the valve to a considerable extent. Specify the density according to actual needs

Sealing materials and precipitation materials to meet or exceed actual needs.

Valve and connection method. The integrity of the piping system, future routine maintenance, anti-corrosion factors, on-site assembly, weight and safety are all factors that should be considered in determining the way the valve is connected to the pipe.

Operation mode or operation method Select the appropriate operation mode or operation method according to the valve type, size, pressure, temperature, installation environment and other factors.

Valve order

When ordering valves, please provide the following data to avoid unnecessary repetitions and delays and to ensure that the valve you purchased is indeed the valve you need.

Valve diameter

2. Pressure interface materials: castings and component materials.

3. Valve types: gate valves, globe valves, check valves, butterfly valves, ball valves, etc.

4. Terminal connection method, if the connection method is welding method, also provide the wall thickness of the connecting pipe; if the connection method is flange, provide the flange surface or polishing degree.

5. Any material different from the standard configuration: sealing material, precipitation material, bolt material, etc.

6. Any accessories: acid protection layer, locking device, chain operation, etc.

7. Manual or powered actuator: Please include the required technical details.

8. For ordering convenience, please confirm the specification model.

Valve blank selection principle

Commonly used blanks for machining include castings, forgings, profiles and welded parts. The different blank types and the accuracy, roughness and hardness of the blank have a direct impact on the machining process.

Some factors should be considered when selecting a valve blank:

(1) The material of the part and the organization and performance requirements of the material.

The parts and materials specified on the plan generally determine the type of blank. For example, if the part material is cast iron, the casting method must be used to manufacture the blank. For steel parts, the mechanical properties of the material should be considered when selecting the blank. For example, manufacturing high pressure

Forging parts of valves should generally use forgings or welded parts as much as possible to ensure good mechanical properties.

(2) The structural shape and dimensions of the part.

The structural shape of the piece is an important factor affecting the selection of the blank. For example, a valve body with a complicated structural shape should be selected as much as possible. Large-sized valve bodies are available in sand casting; small sizes are investment-cast.

(3) The size of the production program.

The larger the production program of the parts, the better the economical effect of the high-precision and high-efficiency blank manufacturing method.

(4) Conditions for the manufacture of blanks.

The blank should be selected according to the equipment condition and process level at the site, and the advanced blank manufacturing method should be gradually adopted considering the development prospects.

Main technology of the valve

Intensity

The strength properties of a valve are the ability of the valve to withstand the pressure of the medium.

Seal

The sealing performance of the valve refers to the ability of the sealing parts of the valve to prevent the leakage of the medium. It is the most important technical performance index of the valve.

Flow medium

The pressure loss occurs when the medium flows through the valve, that is, the valve has a certain resistance to the flow of the medium, and the medium consumes a certain amount of energy to overcome the resistance of the valve. In terms of energy conservation, when designing and manufacturing valves, it is necessary to reduce valve convection as much as possible.

The resistance of the moving medium.

Opening and closing force and opening and closing torque

The opening and closing force and the opening and closing torque refer to the force or moment that must be applied when the valve is opened or closed. When designing and manufacturing valves, it is important to reduce their closing force and closing torque.

Opening and closing speed

The opening and closing speed is expressed by the time required for the valve to complete an opening or closing action. In case of accidents, some require a slow shutdown to prevent water hammer, etc., which should be considered when selecting the valve type.

Motion sensitivity and reliability

This refers to the sensitivity of the valve to the corresponding changes in the media parameters. For valves, their functional sensitivity and reliability are important technical performance indicators.

Service life

It indicates the durability of the valve, is an important performance indicator of the valve, and has great economic significance. Usually indicated by the number of opening and closing times that can guarantee the sealing requirements, it can also be expressed by the use time.

Use valve FAQ

1. Why does the double seat valve easily oscillate when working at a small opening?

For a single core, the valve stability is good when the medium is flow-opening; the stability of the valve is poor when the medium is flow-closed. The double seat valve has two spools, the lower spool is closed, and the upper spool is open, so that the spool can be closed when working at a small opening.

It is easy to cause the vibration of the valve, which is why the double seat valve can not be used for small opening work.

2. What is the anti-blocking performance of the straight stroke regulating valve, and the anti-blocking performance of the angular stroke valve is good?

The straight-stroke valve spool is vertically throttled, and the medium flows horizontally in and out, and the flow passage in the valve chamber must turn and turn backwards, making the flow path of the valve quite complicated (the shape is inverted "S" type). In this way, there are many dead zones, which provide space for the precipitation of the medium.

Going, causing a blockage. The direction of the angular stroke valve throttling is the horizontal direction. The medium flows horizontally and horizontally, which makes it easy to take away the dirty medium. At the same time, the flow path is simple, and the space for the medium to precipitate is also small, so the anti-blocking performance of the angular stroke valve is good.

3. Why is the valve stem of the straight stroke control valve thinner?

It involves a simple mechanical principle: large sliding friction and low rolling friction. The valve stem of the straight stroke valve moves up and down, and the packing is slightly pressed tightly, which will tightly seal the valve stem and produce a large backlash. For this reason, the valve stem is designed to be very small and the packing is often

A tetrafluorofill with a small coefficient of friction is used to reduce the backlash, but the problem is that the stem is thin, the bend is easy, and the life of the filler is short. The best way to solve this problem is to use the travel valve stem, that is, the angular stroke type regulating valve, which has a valve stem than a straight stroke valve.

The rod is 2 to 3 times thicker, and the graphite filler with long life is selected. The valve stem has good rigidity and long filler life, and the friction torque is small and the backlash is small.

4. Why does the demineralized water medium use a rubber-lined butterfly valve and a fluorine-lined diaphragm valve with a short service life?

Demineralized media contain low concentrations of acids or bases which are highly corrosive to rubber. The corrosion of rubber is characterized by expansion, aging, and low strength. The butterfly valve and diaphragm valve with rubber lining have poor effect, and the essence is that the rubber is not resistant to corrosion. Backing

The rubber diaphragm valve is improved to a fluorine-lined diaphragm valve with good corrosion resistance, but the diaphragm of the fluorine-lined diaphragm valve can be broken by being folded up and down, causing mechanical damage and shortening the life of the valve. The best way to do this now is to use a special ball valve for water treatment, which can be used for 5 to 8 years.

5. Why should the shut-off valve be hardened as much as possible?

The shut-off valve requires that the leakage is as low as possible, the leakage of the soft-sealed valve is the lowest, and the cutting effect is of course good, but it is not wear-resistant and has poor reliability. From the double standard of small leakage, sealing and reliability, the soft seal cut is not as good as the hard seal cut. Full function

Ultra-light control valve, sealed and protected by wear-resistant alloy, high reliability, leakage rate of 10-7, has been able to meet the requirements of the shut-off valve.

6. Why does the sleeve valve replace the single and double seat valve but does not have the wish?

The sleeve valve that was introduced in the 1960s was widely used at home and abroad in the 1970s. The proportion of the sleeve valve in the petrochemical plant introduced in the 1980s was large. At that time, many people believed that the sleeve valve could replace the single and double seat valves. Become a second generation product. Until now, this is not the case

Single seat valves, double seat valves, and sleeve valves are equally used. This is because the sleeve valve is only improved in throttling form, stable ** and better than single seat valve, but its weight, anti-blocking and leakage indicators are consistent with single and double seat valves. How can it replace single and double seat? Valve

So, they can only be used together.

7. Why are piston actuators used more and more in pneumatic valves?

For pneumatic valves, the piston actuator can make full use of the air supply pressure, making the actuator smaller in size than the diaphragm type, and the thrust is larger. The O-ring in the piston is also more reliable than the film, so its use will become more and more many.