Dry goods: Large collection of valves, classification, characteristics, selection, must see

Dry goods: Large collection of valves, classification, characteristics, selection, must see

In the fluid pipeline system, the valve is the control element, and its main function is to quarantine equipment and pipeline systems, regulate flow, prevent return, regulate and excrete pressure.

Valves can be used to control the flow of various types of fluids such as air, water, steam, various corrosive media, mud, oil, liquid metal and radioactive media. Because the pipeline system is very important to choose the most suitable valve, it is also important to understand the characteristics of the valve and the steps and basis for choosing valves.

1. Classification of valves

There are two categories of valves: two categories:

1. Automatic valve

Valves that rely on medium (liquid, gas) themselves to move by themselves.

Such as the return valve, safety valve, regulating valve, hydrophobic valve, pressure reduction valve, etc.

2. Driving valve

With the help of manual, electric, hydraulic, and pneumatic valves.

Such as the gate valve, the deeper valve, the throttle valve, the butterfly valve, the ball valve, the rotor valve, etc.

According to the structural characteristics, according to the direction of the closing part relative to the valve seat movement:

Crossing the door: Close parts move along the center of the valve seat;

Gate shape: Close parts move along the center of the vertical valve seat;

Capital and spherical: The closed piece is a plunger or ball, rotating around the central line of itself;

Rotating: Close the parts around the axis outside the valve seat;

Disc shaped: The disc’s disc, turning around the axis in the valve seat;

Slide valve shape: Close pieces slide in the direction vertical in the channel.

According to the purpose, according to the different uses of the valve, it can be divided into:

Open disconnection: It is used to connect or cut off the pipeline medium, such as the deeper valve, gate valve, ball valve, butterfly valve, etc.

Turbus: It is used to prevent the medium from flowing, if the return valve.

Adjustment: It is used to regulate the pressure and flow of the medium, such as regulating valve and pressure reducing valve.

Distribution: It is used to change the direction of the medium and allocate medium, such as three -way rotation, distribution valve, slide valve, etc.

Safety valve: When the medium pressure exceeds the specified value, it is used to discharge excess media to ensure the safety of the pipe system and equipment, such as safety valves and accident valves.

Other special purposes: such as hydrophobic valves, empty valves, sewage valves, etc.

According to the driver, it can be divided into:

Manual: With the help of hand wheels, handles, leverage or splin wheels, there are manpower drives, and the strong torque fashion has a snail wheel, gear and other deceleration devices.

Electric: Drive by motor or other electrical devices.

Liquid: Drive with the help of (water, oil).

Pneumatic: Drive by compressed air.

Pressing the pressure, according to the nominal pressure of the valve, it can be divided into:

Real vacuum valve: Absolute pressure <0.1MPa is a valve with a height of 760mm Hg, and usually uses MM Hg or MM water column to indicate pressure.

Low pressure valve: nominal pressure PN ≤ 1.6MPa valve (including steel valve with PN ≤ 1.6MPa)

Middle pressure valve: nominal pressure PN2.5-6.4MPa valve.

High -pressure valve: nominal pressure PN10.0-80.0MPa valve.

Ultra -high pressure valve: nominal pressure PN≥100.0MPa valve.

According to the temperature of the medium, the medium temperature according to the valve work can be divided into:

Ordinary valve: It is suitable for valves with a medium temperature of -40 ° C to 425 ° C.

High -temperature valve: It is suitable for valves with a medium temperature of 425 ° C to 600 ° C.

Heat -resistant valve: It is suitable for valves with a medium temperature above 600 ° C.

Low -temperature valve: It is suitable for valve valves with a medium temperature of -150 ° C to -40 ° C.

Ultra-low temperature valve: It is suitable for valves below the medium temperature of -150 ° C.

According to the nominal diameter, according to the nominal diameter of the valve, it can be divided into:

Small diameter valve: nominal diameter DN <40mm valve.

Middle caliber valve: nominal valve with DN50 to 300mm.

Large -caliber valve: nominal valve with DN350 ~ 1200mm.

Extra -diameter valve: nominal valve with DN≥1400mm.

According to the pipeline connection method, the connection method of the valve and the pipe can be divided into:

Flat connection valve: valve body with flange, valve connecting the French connection with the pipeline.

Thread connection valve: The valve body has an internal thread or external thread, and the valve connected to the thread connection with the pipeline.

Welding connection valve: The valve body has a welding port, and the valve is used to connect to the pipeline.

Pyrant connection valve: The valve has a clamp on the valve body, and the valve connected to the pipeline is connected to the pipeline.

Card cover connection valve: use the valve connected to the pipeline.

Second, the characteristics of the valve

There are two types of valve characteristics, with characteristics and structural characteristics.

1. Use characteristics

It determines the main use performance and scope of the valve, which belongs to the characteristics of the valve:

Category of valves (closed circuits, regulating valves, safety valves, etc.);

Product type (gate valve, deeper valve, butterfly valve, ball valve, etc.);

Materials of the main parts of the valve (valve body, valve cover, valve stem, valve flap, cover);

Valve transmission method, etc.

2. Structural characteristics

It determines some structural characteristics of the valve installation, maintenance, maintenance, maintenance, etc., which belong to the structural characteristics:

The structural length and overall height of the valve, the connection form of the pipeline (flange connection, thread connection, hinge connection, outer thread connection, welding end connection, etc.);

The form of the cover (inlaid, thread ring, heap, welding, valve body);

Structure forms (rotation rods, lift rods) and so on.

3. Steps and basis for selecting valves

1. Select steps

(1) Clarify the purpose of the valve in the device or device, and determine the working conditions of the valve: applicable medium, work pressure, work temperature, etc.

(2) Determine the nominal diameter and connection method of the connection pipeline with the valve: flange, thread, welding, etc.

(3) Determine the method of operating valve: manual, electric, electromagnetic, pneumatic or liquid, electrical linkage or electrical linked.

(4) Determine the shells and internal materials of the selected valve according to the medium, work pressure, and work temperature transported by the pipeline: gray cast iron, forged cast iron, ball ink cast iron, carbon steel, alloy steel, stainless acid steel, copper alloy, etc. Essence

(5) Choose the type of valve: closed valve, adjustment valve, safety valve, etc.

(6) Determine the type of valve: gate valve, deeper valve, ball valve, butterfly valve, throttle valve, safety valve, pressure reduction valve, steam hydrophobic valve, etc.

(7) Determine the parameters of the valve: For automatic valve, determine the allowable flow resistance, emissions, back pressure, etc. according to different needs, and then determine the nominal diameter of the pipeline and the diameter of the valve seat hole.

(8) Determine the geometric parameters of the selected valve: structure length, flange connection form and size, size and size and quantity of connected bolt holes in the height of the valve, the size and size of the entire valve.

(9) Use existing data: Valve product directory, valve product samples, etc. to select appropriate valve products.

2. The basis for selecting valves

While understanding the selection valve steps, you should also further understand the basis of the selection valve.

(1) The purpose of the selected valve, the conditions of use, and the manipulation control method.

(2) The nature of working medium: work pressure, working temperature, corrosion performance, whether it contains solid particles, whether the medium is toxic, whether it is flammable, explosive medium, the viscosity of the medium, and so on.

(3) Requirements for valve fluid characteristics: flow resistance, emissions ability, traffic characteristics, sealing levels, etc.

(4) Installation dimensions and shape size requirements: nominal diameter, connection method and connection dimension, shape size or weight limit of the pipeline, etc.

(5) Additional requirements for reliability, service life, and explosion -proof performance of valve products.

Pay attention when selecting parameters:

If the valve is used to control the purpose, the following additional parameters must be determined: operation method, maximum and minimum traffic requirements, normal flow pressure drop, pressure drop when closed, maximum and minimum import pressure of the valve.

According to the basis and steps of the above selection valve, when selecting the valve reasonably and correctly, the internal structure of various types of valves must be fully understood in order to make the correct choice of valves that are preferred.

The final control of the pipeline is the valve. The valve opening closure controls the streaming method of the medium in the pipeline. The shape of the valve runner makes the valve have a certain flow characteristics. When selecting the valve that is most suitable for installation of the pipe system, this must be considered.

The principle that the valve should follow:

1. Valves for cutting off and open medium

The runner is a direct valve, and its flow resistance is small. It is usually selected as a valve for cutting off and open media. The downward closed valve (cut -off valve, plunger valve) is less used than other valves than other valves, so it is rarely used. A closed valve can be selected on the occasion where there is a higher flow resistance.

2. Control the valve for traffic

Valves that are easy to adjust flows are usually selected for control flow. The downward closed valve (such as the deeper valve) is suitable for this purpose, because its valve seat size and closing the itinerary are proportional. The rotating valve (rotor valve, butterfly valve, ball valve) and the deflection valve (clamping valve, diaphragm valve) can also be used for reunification control, but it can usually only apply within a limited valve diameter range. The gate valve uses a discs to do horizontal cutting of the circular valve seat mouth. It can only control the traffic only when it is close to the closure position, so it is usually not used for traffic control.

3. Valle

According to the need for diversion, this valve can have three or more channels. The rotor valve and the ball valve are more suitable for this purpose. Therefore, most of the valves used for diversion are selected in this type of valve. However, in some cases, other types of valves can be replaced with diversion as long as two or more valves are connected to each other.

4. The medium with suspended particles for the valve

When there is a suspended particles in the medium, the sliding valve with a wiping effect is most suitable for the sliding of its closure. If the back and forth movement of the valve seat is vertical, the particles may be held at the end, so this valve can allow embedded particles except for non -sealing materials, otherwise it is only suitable for basic cleaning medium. The ball valve and the cyclone valve have a wiper effect on the cover surface during the opening and closing process, so it is suitable for the medium with suspended particles.

Fourth, valve selection instructions

1. Selection of the gate valve

Under normal circumstances, the gate valve should be preferred. In addition to the medium such as steam and oil products, the gate valve is also suitable for valves containing granular solids and large viscosity, and is suitable for valve valves to be empty and low vacuum systems. For medium with solid particles, one or two sweeping holes should be brought on the gate valve body. For low temperature media, low -temperature special gate valves should be selected.

2. Selection instructions for cut -off valve

The cut -off valve is suitable for pipelines that are not strictly required for fluid resistance, that is, the stress loss is not considered, and the pipeline or device of high temperature and high -pressure medium is suitable for DN <200mm steam and other media and other media pipes. Valves, such as needle -shaped valve, instrument valve, sampling valve, pressure meter valve, etc.; Cut off valve has flow adjustment or pressure regulation, but the regulatory accuracy is not high, and the diameter of the pipeline is relatively small. Valves; for the toxic media, the cut -off valve sealing the ripple tube should be selected; but the cut -off valve should not be used for the medium with a large viscosity and a medium containing granules that is easy to precipitate, nor should they be used as a valve and a low vacuum system valve.

3. Selection of the ball valve

The ball valve is suitable for low temperature, high pressure, and viscosity medium. Most ball valves can be used in the medium with suspended solid particles, and can also be used for powder and granular medium according to the sealing material requirements.

全通道球阀不适用于流量调节,但适用于要求快速启闭的场合,便于实现事故紧急切断;通常在密封性能严格、磨损、缩口通道、启闭动作迅速、高压截止(压差大)、 In the pipelines with low noise, gasification, small operating torque, and small fluid resistance, the use of ball valves is recommended;

The ball valve is suitable for light structure, low -voltage cutter, and corrosive medium; the ball valve is still the most ideal valve with low temperature and deep -cold media, and the low -temperature media and device with low temperature media should be selected.

When the floating ball valve is selected, the valve seat material shall be carried out of the load of the sphere and the working medium. The large -caliber ball valve needs a large force during operation. In the case of high pressure; in addition, the ball valves for high -quality materials and flammable pipelines should have a fire and anti -static structure.

4. Selection instructions for the throttle valve

The throttle valve is suitable for occasions with low temperature and high pressure. It is suitable for parts that need to adjust flow and pressure. It is not suitable for medium with large viscosity and solid particles. It should not be used as a partition valve.

5. Instructions for Selection of the Cetener Valve

The rotor valve is suitable for the occasion that requires fast opening and closing. Generally, it is not suitable for medium with higher steam and high temperature. It is used for medium with low temperature and large viscosity. It is also suitable for medium with suspended particles.

6. Selection of butterfly valve selection

The butterfly valve is suitable for occasions with large caliber (such as DN> 600mm) and short structure length requirements, as well as fast occasions that need to be adjusted and closed -closing requirements. Generally, water, oil and compression of water, oil and compression with pressure ≤80 ° C, pressure ≤ 1.0MPa Air and other medias; because the butterfly valve has a large pressure loss compared to the gate valve and ball valve pressure, the butterfly valve is suitable for the strict pipeline system with strict pressure requirements.

7. Stop back valve selection instructions

The stop valve is generally applicable to a cleaning medium, and it is not suitable for the medium with a large solid particles and a large viscosity.

When DN ≤ 40mm, a lifting and stopping valve should be used (only allowed to be installed on a horizontal pipe);

When DN = 50-400mm, a rotary lift and stop valve should be adopted (it can be installed on the horizontal and vertical pipes. If it is installed on the vertical pipe, the medium flow should be from the bottom);

When DN≥450mm, a buffer -type stop valve should be used;

When DN = 100 ~ 400mm can also be used for clamping valve;

The spin -off -type stop valve can be made in high work pressure. The PN can reach 42MPa. The material of the shell and sealing parts can be applied to any working medium and any working temperature range. The medium is water, steam, gas, corrosive media, oil, drugs, etc. The operating temperature range of the medium is between -196 and 800 ° C.

8. Selection instructions for septum valve

The diaphragm valve is suitable for oil, water, acidic medium and medium containing suspended substances with a working temperature of less than 200 ° C and less than 1.0MPa. To choose a weir diaphragm valve, refer to its flow characteristics table; viscous fluid, cement slurry, and precipitated medium should be used to use a direct diaphragm valve; except for specific requirements, the diaphragm valve should not be used on vacuum pipes and vacuum equipment.

Valve applications, operating frequency and services are ever -changing. It is necessary to control or eliminate the fear of low leaks. The most important and most critical device also counts valve.It is important to learn the valve correctly.

Product Recommendation: butterfly flange valve