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Valve selection basis and selection guide

September 18, 2020

How to select the righty type of valve? the following article will give you an idea how to choose the right structure/type valve.

Nowadays, there are more and more valves on the market, the types of valves are particularly complex, and the

ball valve working diagram-3D GIF animated presentation

structures and materials are all different. The selection of valves is very important for the long-term operation of the device in working conditions. Improper selection of valves and users’ ignorance of valves are the source of accidents and safety threats. Nowadays, the demand for valve products in the social industry is becoming more and more extensive, and users should have a further understanding and cognition of knowledge about valves and other aspects.

There are generally two types of valve characteristics, use characteristics and structural characteristics.

Use characteristics of the valve: It determines the main use performance and use range of the valve. The

butterfly valve working diagram-3D GIF animated presentation

characteristics of the valve use include: valve category (closed circuit valve, regulating valve, safety valve, etc.); product type (gate valve, globe valve, butterfly valve, ball valve) Etc.); the materials of the main parts of the valve (valve body, bonnet, valve stem, valve disc, sealing surface); valve transmission mode, etc.

The structural characteristics of the valve: it determines the structural characteristics of the valve installation, repair, maintenance and other methods. The structural characteristics include: the structural length and overall height of the valve, the connection form with the pipeline (flange connection, threaded connection, clamp Connection, external thread connection, welding end connection, etc.); the form of the sealing surface (inlaid ring, threaded ring, surfacing, spray welding, valve body); valve stem structure (rotating rod, lifting

gate valve working diagram-3D GIF animated presentation

rod), etc.

Valve selection steps:
1. Clarify the purpose of the valve in the equipment or device, and determine the working conditions of the valve: applicable medium, working pressure, working temperature, etc.
2. Determine the nominal diameter and connection method of the pipe connected to the valve: flange, thread, welding, ferrule, quick installation, etc.
3. Determine the method of operating the valve: manual, electric, electromagnetic, pneumatic or hydraulic, electrical linkage or electrohydraulic linkage, etc.
4. Determine the material of the valve housing and internal parts according to the medium, working pressure and

globe cut-off valve working diagram-3D GIF animated presentation

working temperature conveyed by the pipeline: gray cast iron, malleable cast iron, ductile iron, carbon steel, alloy steel, stainless acid-resistant steel, copper alloy, etc.
5 Select the type of valve: closed circuit valve, regulating valve, safety valve, etc.
6. Determine the valve type: gate valve, globe valve, ball valve, butterfly valve, throttle valve, safety valve, pressure reducing valve, steam trap, etc.
7. Determine the parameters of the valve: For automatic valves, first determine the allowable flow resistance, discharge capacity, 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: structural length, flange connection form and size, valve height dimension after opening and closing, connecting bolt hole size and number, overall valve outline size,

tilting disc swing check valve working diagram-3D GIF animated presentation

etc.
9. Use existing information: valve product catalog, valve product sample, etc. to select appropriate valve products.

Basis for valve selection:
1. The purpose, operating conditions and operation control mode of the selected valve.
2. The nature of the working medium: working pressure, working temperature, corrosion performance, whether it contains solid particles, whether the medium is toxic, whether it is flammable or explosive medium, the viscosity of the medium, etc.
3. Requirements for valve fluid characteristics: flow resistance, discharge capacity, flow characteristics, sealing level, etc.
4. Requirements for installation dimensions and external dimensions: nominal diameter, connection to the pipeline and connection dimensions, external dimensions or weight restrictions, etc.
5. Additional requirements for the reliability and service life of valve products and the explosion-proof performance of electric devices. (Note when selecting parameters: If the valve is to be used for control purposes, the following additional parameters must be determined: operation method, maximum and minimum flow requirements, pressure drop for normal flow, pressure drop when closed, maximum and minimum inlets of the valve Pressure.)

According to the above-mentioned basis and steps for selecting valves, the internal structure of various types of valves must be understood in detail when selecting valves reasonably and correctly, so that the correct choice can be made on the preferred valve. The ultimate control of the pipeline is the valve. The valve opening and closing parts control the flow mode of the medium in the pipeline. The shape of the valve flow channel makes the valve have a certain flow characteristic. This must be considered when selecting the most suitable valve for the pipeline system.

Valve flow characteristic curve and classification

September 18, 2020

The flow characteristic of the valve is the relationship between the relative flow of the medium flowing through the regulating valve and its opening under the condition that the pressure difference between the two ends of the valve remains constant. Flow characteristic is an important technical index and parameter of regulating valve. It is very important to make the correct selection in the application process of the control valve.

Flow characteristics of regulating valve

Valve flow characteristics can be defined as: the relative flow of the controlled medium flowing through the valve, and the relationship between the relative opening (relative displacement) of the valve is called the flow characteristics of the regulating valve. Generally speaking, it is divided into four types: straight line, equal percentage (logarithm), parabola and quick opening! The specific description and advantages are as follows:

1. The linear characteristic refers to the linear relationship between the relative flow of the valve and the relative opening, that is, the time constant of the flow change caused by the change of unit opening. The relative stroke of the linear characteristic is linear with the relative flow. The flow change caused by the change of unit stroke is constant. When the flow is large, the relative value of the flow changes little, and when the flow is small, the relative value of the flow changes greatly.

2. the equal percentage characteristic (logarithm) means that the relative flow change caused by the change of the unit opening is proportional to the relative flow at that point, that is, the amplification factor of the regulating valve changes, and it increases with the increase of the relative flow. The relative stroke and relative flow of equal percentage characteristics are not in a linear relationship. The change in flow caused by the change of unit stroke at each point of the stroke is proportional to the flow at this point, and the percentage of flow change is equal. Therefore, its advantage is that when the flow rate is small, the flow rate changes small, and when the flow rate is large, the flow rate changes greatly, that is, it has the same adjustment accuracy at different opening degrees.

3. the parabolic characteristic means that the relative flow change caused by the change of the relative opening of the unit is proportional to the square root of the relative flow value at this point. The flow rate changes in proportion to the two sides of the stroke, and generally has an intermediate characteristic between linear and equal percentage characteristics.

4. the quick opening flow characteristic means that there is a larger flow when the opening is small. With the increase of the opening, the flow can reach the maximum quickly, and then the opening is increased, and the flow change is small, so it is called For quick opening characteristics.

The flow characteristic of the diaphragm valve is close to the quick opening characteristic, the flow characteristic of the butterfly valve is close to the equal percentage characteristic, the flow characteristic of the gate valve is the linear characteristic, the flow characteristic of the ball valve is linear in the middle opening and closing stage, and the equal percentage characteristic in the middle opening.

Globe valve (9)

Under normal circumstances, ball valves and butterfly valves are usually not used for adjustment. If they are used for adjustment, they are only used for adjustment when the opening is small. Generally, they can be classified as quick-opening, and they are really used for adjustment. Most of them are basically cut-off valves (globe valve). The valve head is processed into a parabolic cone, spherical shape, etc., and different curve characteristics are used. Generally speaking, as an adjustment, the basic percentage characteristic is used more.

TH Valve is a professional manufacturer of butterfly valve, gate valve, check valve, globe valve, knife gate valve, ball valve with API, JIS, DIN standard, used in Oil, Gas, Marine industry, Water supply and drainage, fire fighting, shipbuilding, water treatment and other systems, with Nominal Diameter of DN50 to DN1200, NBR/EPDM/VITON, Certificates & Approvals: DNV-GL, Lloyds, DNV, BV, API, ABS, CCS. Standards: EN 593, API609, API6D

installation principle and setting of the bypass valve

September 17, 2020

Whether the valve needs to be installed with the principle and setting of the bypass valve.
We occasionally see relatively large valves in some pipelines and always install bypass valves. Why is this? What is its main function? Under what circumstances does it need to be installed? And what is the size of the bypass valve of the corresponding equipment?

bypass valve installation

In fact, by setting a bypass valve in the pipeline, its role can be divided into two major points in general: one is to protect (balance the pressure at both ends), and the other is to make emergency use!
First, the protective effect can also be said to be a protective measure for the main valve to prevent the large opening resistance caused by the excessive pressure difference between the front and rear of the valve and the difficult opening of the valve, especially in some large diameter or high pressure pipeline. Before the high-pressure pipeline is opened, the pressure is released through the bypass valve to avoid the sudden influx of high pressure and impact on the pipeline below the valve. Or the pressure difference between the two ends of the valve is too large, and the opening torque is too large. In order to avoid torsion damage to the valve, the valve should be opened after bypassing and releasing the pressure.

butterfly valve and bypass valve

Second, the emergency function, used as a backup pipeline, the biggest advantage is that when the main valve fails or needs maintenance, it can flow through the bypass valve without affecting normal production.
Whether the valve needs to be installed with the specific requirements and settings of the bypass valve: (for reference only)
2.5MPa level, above DN400; 4.0MPa level, above DN250; 6.4MPa level, above DN200; 10MPa level, above DN150; For valves from DN100 to DN200, the bypass pipe and bypass valve are DN20;
For valves from DN250 to DN600, the bypass pipe and valve are DN25; for valves above DN600, the bypass pipe and valve are DN40.

TH Valve is a professional manufacturer of butterfly valve, gate valve, check valve, globe valve, knife gate valve, ball valve with API, JIS, DIN standard, used in Oil, Gas, Marine industry, Water supply and drainage, fire fighting, shipbuilding, water treatment and other systems, with Nominal Diameter of DN50 to DN1200, NBR/EPDM/VITON, Certificates & Approvals: DNV-GL, Lloyds, DNV, BV, API, ABS, CCS. Standards: EN 593, API609, API6D

The difference of cryogenic valve and ordinary temperature valve

September 17, 2020

Cryogenic valves, as the name implies, are valves that can work in cryogenic and cryogenic conditions. The operating temperature is demarcated. Valves with operating temperatures below -40°C are usually called cryogenic valves, which are mainly used for gas liquefaction, For separation, transportation and storage equipment, the operating temperature can reach below -270℃. Currently, there are butterfly valves, check valves, gate valves, globe valves, ball valves, and throttle valves.

In recent years, ultra-low temperature valves have been used more and more widely, and they are one of the

lug type butterfly valve, ductile iron, center lined,

indispensable important equipment in petrochemical, air separation, natural gas and other industries. The working medium is not only low in temperature, but most of them are toxic, or flammable and explosive. , And strong permeability, so it determines many special requirements for valve materials and design. It is not only required to work normally at the set temperature, but also to ensure the working performance at room temperature.

Compared with the normal temperature valve, the low temperature valve has a higher packing part and uses an extended stem. Its purpose is to reduce the heat transferred from the outside into the device; to ensure that the temperature of the stuffing box is above 0℃, so that the stuffing can work normally; to prevent the valve stem and the upper part of the valve cover at the stuffing box part from being too cold The parts are frosted or frozen.

The design of the long-neck bonnet is mainly the design of the neck length L. L refers to the distance from the bottom of the stuffing box to the upper surface of the upper sealing seat. It is related to the thermal conductivity of the material, the thermal conductivity area, the surface heat dissipation coefficient, and the heat dissipation area. , The calculation is relatively cumbersome, and it is generally obtained by experimental methods.

Ferritic stainless steel can be used when the temperature is higher than -100℃, austenitic stainless steel can be used when the temperature is lower than -100℃, copper alloy or aluminum alloy can be used for low pressure and small diameter valves, and the valve body should be able to withstand temperature changes sufficiently. The expansion and contraction, and the structure of the valve seat part will not be permanently deformed due to temperature changes.

Valve installation instructions and process precautions

September 17, 2020

Valve is a kind of mechanical product that is widely used in the construction of national economy. In the current market, the more commonly used valve types are butterfly valves, check valves, ball valves, globe valves, gate valves and regulating valves. For the correct installation method of the valve, the user should understand the following introduction.

ductile iron, DI, butterfly valve, manufacturer, center line, TH valve

1. Valve installation
Valves should generally be positioned before pipeline installation. The piping should be natural, and the position should not be hard to avoid leaving pre-stress. During installation, it is recommended to install with a lifting ring. When installing with a chain, pay attention to protective measures for the outer coating of the valve. When the valve is equipped with a bracket or transmission mechanism, the sling should be fixed on the valve hoist ring, and the sling should not be placed on the transmission mechanism; the sling or hoisting chain should not squeeze the external parts of the valve and its extension rod to avoid damage to the valve actuator , Causing the valve to be unable to switch or difficult to switch.

2. Welding of the valve

double plate check valve body

(1) After the valve is in place, the valve should be placed in the fully open position when preheating and welding the valve, otherwise, during the welding process, the ball of the ball valve and the gate plate of the gate valve will be stained with welding slag and put into production At this time, these attached welding slag will scratch the valve seat seal and cause internal leakage of the valve. In severe cases, the valve will fail.
(2) The valves must be supported on their respective bases or separately.
(3) After the valve is welded, if the valve needs to be rotated, a manual grease gun should be used to fill in grease. (4) Confirm that the sewage outlet and pressure outlet are closed.
(5) General ball valve installation has no directionality, but attention should be paid to the position of the operating side. Some ball valves are directional when installed, so they must be installed in accordance with the arrow mark on the valve body and cannot be reversed. For example, the inlet and outlet sides of some of the ball valves of the crude oil and product oil yards of the Western Pipeline use two types of valve seat sealing, one end uses a double piston effect valve seat, and the other end uses a self-draining seal valve seat. If installed in reverse, After commissioning, the valve will automatically release the pressure and a pipeline accident will occur.

3. Requirements after valve welding
(1) The valve should be filled with grease before pressure test after welding to ensure that the sealing surface of the valve is filled with grease, and the impurities attached to the sealing surface of the valve seat during welding are discharged with grease.
(2) Check the condition of the valve to ensure that all external joints are locked and not loose; confirm that the sewage outlet and pressure outlet are in a tightly locked state to prepare for pressure test.
(3) Operate the valve according to the pressure test plan and keep the valve in the specified position.
A valve is a device used to control fluid flow, pressure and direction. The fluid to be controlled can be liquid, gas, gas-liquid mixture or solid-liquid mixture. In oil, natural gas, coal, metallurgy and ore mining, processing and pipeline transportation systems; in petrochemical, chemical products, medicine and video production systems; in hydropower, thermal power and nuclear power generation systems; in urban construction In water supply and drainage heating and gas supply systems; in metallurgical production systems; in fluid systems of ships, vehicles, aircraft, aerospace and various sports machinery; in national defense production and new technology fields; in agricultural irrigation and drainage systems,, A large number of new varieties of valves are used.

Code of valve sealing or lining material

September 16, 2020

The sealing surface of the valve mainly refers to the contact surface of the valve disc and the valve seat. The sealing

marine valve seat

element plays the role of cutting off and connecting, adjusting and distributing, separating and mixing the medium on the valve passage, and improving the quality and service life of the valve sealing surface. Appropriate sealing surface materials and reasonable sealing structure must be selected. Valve sealing ring materials are mostly mixed materials, and seals of different components have different effects. When selecting valves, customers should choose corresponding seals according to the actual conditions of the medium, temperature and pressure.

code	sealing material/lining material
T	Copper alloy
X	Rubber
N	Nylon plastic
F	Fluoroplastic
B	Babbitt alloy
H	Alloy steel
D	Nitrided steel
Y	Hard alloy
J	Lining
Q	Lead lining
C	Enamel
P	Boronized steel

Note:

1. The code of the valve seat sealing material directly processed by the valve body is coded by “W”.
2. When the sealing materials of the valve seat and the valve disc (valve plate) are different, it is indicated by the code of low hardness material (except for diaphragm valves).

Types and selection of electric valves

September 16, 2020

Types of electric valves:
Electric valves are valves driven by electric energy, mainly composed of electric actuators and various types of valves.

double eccentric butterfly valve (2)

Because the electric valve is easy to use and can be operated when the power is turned on, it is the longest-used type of automatic control valve. There are many types of electric valves. Commonly used are electric control valves, electric ball valves, electric butterfly valves, electric gate valves, and electric globe valves. Different types of electric valves have different applications.

1. The electric control valve can choose different valve structures and spool types according to the working conditions of the medium. It is mainly suitable for high, medium and low pressure pipelines with various media to adjust pipeline parameters. With the increasing requirements in the field of modern industrial automation, electric control valves are becoming more and more widely used. Different materials can be used to use various liquid and gas media pipelines.

2. Electric ball valve and electric butterfly valve are the most widely used electric valve models, equipped with different actuators, which can not only realize the two-position cut-off of the pipeline, but also can be used for occasions where the linearity requirements are not too strict. Electric butterfly valves There are two connection methods: wafer type and flange type. Normal pressure and large diameter pipes are mostly used. Electric ball valves and electric butterfly valves are similar in use, but they use more pressure than electric butterfly valves.

3. Both the electric gate valve and the electric shut-off valve have a blocking function in the pipeline, but it should be noted that these two types of valves cannot be used for adjustment. It is suitable for all kinds of large diameter, high, medium and low pressure medium working conditions.

Electric valve selection:
Electric valves are usually valves that are driven by a motor. Because the motor needs to be decelerated to drive the valve to open and close, it is generally not recommended to use electric if it is required to close and open the valve quickly. Basically, you can choose electromagnetic quick-closing valve, pneumatic or hydraulic quick-closing valve. Close the valve. But if necessary, you must choose an electric type of quick-closing valve, then you should choose an electric butterfly valve or an electric ball valve, because this type of valve has a short switching stroke.

Lining material and its application scope of fluorine lined valve

September 16, 2020

Description of lining material of fluorine-lined valve
With the maturity of the fluorine lining process, the varieties of fluorine lining valves are becoming more and more

U type flange butterfly valve (3)

abundant, including fluorine diaphragm valves, fluorine butterfly valves, fluorine ball valves, fluorine check valves, fluorine globe valves, and fluorine filters. The biggest advantage of fluorine-lined valves is to control strong corrosive media, with a pressure rating of 0.6-1.6Mpa, which is suitable for working conditions with a temperature within 150°C. However, there are many types of lining materials for fluorine-lined valves, and different materials are suitable for different media and temperatures. Users should choose the correct type according to the actual working conditions.

	Fluorine-lined valve lining material applicable table
Polyperfluoroethylene FEP (F46)	Applicable medium: any organic solvent or reagent, dilute or concentrated inorganic acid, alkali, ketone, aromatic hydrocarbon, chlorinated hydrocarbon, etc.　　 Operating temperature: -85~150℃ Features: The mechanical, electrical properties and chemical stability are basically the same as F4, but the outstanding advantage is high dynamic toughness, excellent weather resistance and radiation resistance.
Polytrifluoroethylene PCTEF(F3)	Applicable medium: various organic solvents, inorganic corrosive liquids (oxidizing acids) 　　 Operating temperature: -195~120℃ Features: heat resistance, electrical properties and chemical stability second only to F4, mechanical strength, creep properties, hardness Better than F4
Polypropylene RPP	Applicable medium: aqueous solutions of inorganic salts, dilute or concentrated solutions of inorganic acids and alkalis. Operating temperature: -14~80℃ Features: one of the lightest plastics, its tensile and compressive strength at yield, hardness is better than that of low-pressure polyethylene, outstanding rigidity, good heat resistance, easy to form, and cheap. After modification, it has dynamic impact, fluidity and bending elasticity.
Rigid PVC	Applicable medium: water resistant, concentrated alkali, non-oxidizing acid, chain hydrocarbon, oil and ozone, etc.　　 Operating temperature: 0-55℃ Features: high mechanical strength, excellent chemical stability and dielectric properties, good oil resistance and aging resistance, easy welding and bonding, and low price.
Polytetrachloroethylene PTFE (F4)	Use medium: strong acid, strong base, strong oxidant, etc.　　 Operating temperature: -200~180℃ Features: Excellent chemical stability, high heat resistance, cold resistance, low friction coefficient, it is an excellent self-lubricating material. But the mechanical properties are low, the fluidity is poor, and the thermal expansion is large.
Polyvinylidene chloride PVDF (F2)	Use medium: resistant to most chemicals and solvents, operating temperature: -70~100°C Features: tensile strength and compressive strength are better than F4, bending resistance, weather resistance, and radiation resistance. Light resistance and aging, etc., the biggest feature is good toughness and easy forming.
Polyolefin PO	Applicable medium: various concentrations of acid-base salts and certain organic solvents.　　 Operating temperature: -58~80℃ Features: It is the most ideal anti-corrosion material in the world at present, and it has been widely used in the lining of large-scale equipment and pipe fittings of rotational molding.

TH Valve is a professional manufacturer of butterfly valve, gate valve, check valve, globe valve, knife gate valve, ball valve with API, JIS, DIN standard, used in Oil, Gas, Marine industry, Water supply and drainage, fire fighting, shipbuilding, water treatment and other systems, with Nominal Diameter of DN50 to DN1200, NBR/EPDM/VITON, Certificates & Approvals: DNV-GL, Lloyds, DNV, BV, API, ABS, CCS. Standards: EN 593, API609, API6D

Classification and selection of fluorine-lined valves

September 16, 2020

Fluorine-lined valves, anti-corrosion valves, corrosion-resistant special valves

Introduction to fluorine-lined valves and corrosion-resistant valves:
Fluorine-lined valve, also known as fluorine-lined plastic corrosion-resistant valve, is a method of molding (or inlaying) polytetrafluoroethylene resin and placing it on the inner wall of the valve pressure part or the outer surface of the valve inner part. (The same method applies to all The lining of similar pressure vessels and pipeline accessories), using its unique performance in resisting strong corrosive media, is made into a special corrosion-resistant valve. Simply put, fluorine-lined valve is to use the lining process for all the places in the valve body that the medium can reach.

The lining material of fluorine-lined valves generally adopts FEP (F46) and PCTFE (F3) and other fluoroplastics,

double eccentric butterfly valve (6)

which can be applied to various concentrations of sulfuric acid, hydrochloric acid, hydrofluoric acid, aqua regia and various organic acids, strong acids, strong oxidants and others Corrosive media and other pipelines, but fluorine-lined valves are relatively limited by temperature, and are only suitable for media between -50°C and 150°C.

Classification of fluorine-lined valves and corrosion-resistant valves:
Common fluorine-lined plastic valves are: fluorine-lined butterfly valves, fluorine-lined ball valves, fluorine-lined globe valves, fluorine-lined diaphragm valves, fluorine-lined gate valves, fluorine-lined plug valves, etc.
1. Fluorine lined ball valve
The ball valve with fluoroplastic lining layer has extremely high chemical stability and is suitable for any strong corrosive chemical medium. The structure is a full-pass floating ball valve structure. The element leakage closes in the entire pressure range, which is convenient for the pipeline system to pass Ball sweep line and pipeline maintenance.
2. Fluorine-lined butterfly valve
Used in occasions requiring reliable sealing and good adjustment characteristics. The valve body of the fluorine-lined butterfly valve adopts a split type, and the sealing of the current end of the valve shaft is controlled by adding fluorine rubber to the rotating base surface between the butterfly plate and the valve seat, so as to achieve compact structure, beautiful appearance, reasonable process and reliable performance. The fluorine-lined butterfly valve ensures that the valve shaft does not contact the fluid medium in the cavity. It is very convenient to replace the valve shaft. The fluorine-lined butterfly valve can be completed without removing the pipeline.
3. Fluorine lined gate valve
One of the most common open-close valves, which use wedge-shaped gates sealed on both sides to connect or cut off the medium in the pipeline. The wedge gate valve does not allow a small amount of opening to be used as a throttling device in the pipeline to avoid high-speed flow The medium erodes and accelerates the damage of the sealing surface.
4. Fluorine-lined plug valve
The structure is compact and reasonable, the internal cavity space of the valve is minimal, and the medium retention is reduced. In addition, the special molding process makes the sealing surface dense, and the combination of herringbone ring PTFE packing enables the valve to achieve zero leakage; this series is for various It is designed for automatic opening and closing control of the pipeline of strong corrosive medium.
5. Fluorine-lined globe valve
The valve can be unblocked or blocked by lifting the valve flap. The valve flap and the inner side of the valve body are all made of fluoroplastic lining. It has the advantages of light switch, small size, reliable sealing, simple structure, convenient maintenance and wide range of use.
6. Fluorine-lined check valve
The fluorine-lined check valve only allows the medium to flow in one direction and prevents the flow in the opposite direction. Usually this fluorine-lined check valve works automatically. Under the pressure of one direction, the valve flap opens and the liquid flows in the opposite direction. There are liquid pressure and the weight of the valve flap, and the closing valve flap acts on the valve weight to cut off the flow. Fluorine-lined check valve includes lift check valve, swing check valve, wafer check valve and so on. H41F46 fluorine-lined check valve is suitable for various concentrations of aqua regia, sulfuric acid, hydrochloric acid, hydrofluoric acid and various organic acids, strong acids, and strong oxidants at -50℃～150℃. FEP is also suitable for various concentrations of strong alkali Use on pipelines of organic solvents and other corrosive gases and liquid media.

The difference and selection of electric valve and pneumatic valve

September 15, 2020

With the progress and continuous reform of the times, my country’s valve products have also been innovated with the change of the times. At present, in the valve market where environmental protection and safety are increasingly

ductile iron, DI, butterfly valve, manufacturer, center line, TH valve

demanded, the use of automatic control devices such as electric valves and pneumatic valves is gradually becoming impossible Optional. The use of self-control valves is more energy-saving, safer and more reliable. Compared with the traditional manual valve, the movement speed is faster than the ordinary valve, which not only reduces the manpower, but also greatly improves the work efficiency.
Compared with the pneumatic valve, the electric valve has a simple structure and reliable operation, and its power source (power source or air source) is easy to solve for the remote operation point. The disadvantage is that the price is higher and the explosion-proof requirements are also higher. When selecting, comprehensive consideration should be given to factors such as the

electric ball valve

availability, price and control requirements of the power source. The selection of the valve generally first confirm the valve material, valve diameter, medium type, pipeline pressure, connection mode, control mode, medium temperature etc.

Electric valve selection: When electric valve is selected (the control mode of electric actuator is generally divided into on-off type and regulating type), in addition to the basic valve body diameter, pressure, material and other requirements, the following parameters should be provided:
1. Power supply parameters (including voltage, number of phases and frequency);

pneumatic ball valve

2. Running time and form of electric actuator;
3. Whether explosion-proof and explosion-proof grade are required;
4. Atmospheric protection level;
5. Overload protection requirements, such as over travel protection, over torque protection, etc.;
6. Local operation requirements, such as whether to bring a local operation handwheel;
7. Operation instruction requirements.
Pneumatic valve selection: When selecting pneumatic valves (the operating principle of pneumatic actuators can be divided into single-acting and double-acting), in addition to determining specific parameters such as valve body diameter, pressure, and material, the following parameters should also be provided:
1. Air source parameters (including air source pressure range, whether to bring your own gas storage tank, etc.)
2. Running time and form of pneumatic actuator
3. Whether explosion-proof and explosion-proof grade are required;
4. Atmospheric protection level;
5. Overload protection requirements, such as over travel protection, over torque protection, etc.;
6. Local operation requirements, such as whether to bring a local operation handwheel;
7. Operation instruction requirements.
As the level of industrial automation requirements has increased significantly, the demand for electric (pneumatic) valves is also increasing, and the control requirements for electric (pneumatic) valves have become more and more detailed and complex. For the correct selection of electric (pneumatic) valves, it not only involves the correct use of the product, but also may affect the safety of the entire pipeline system. Users should understand and understand the relevant selection knowledge.

TH Valve is a professional manufacturer of butterfly valve, gate valve, check valve, globe valve, knife gate valve, ball valve with API, JIS, DIN standard, used in Oil, Gas, Marine industry, Water supply and drainage, fire fighting, shipbuilding, water treatment and other systems, with Nominal Diameter of DN50 to DN1200, NBR/EPDM/VITON, Certificates & Approvals: DNV-GL, Lloyds, DNV, BV, API, ABS, CCS. Standards: EN 593, API609, API6D

Posts

Valve selection basis and selection guide

Valve flow characteristic curve and classification

installation principle and setting of the bypass valve

The difference of cryogenic valve and ordinary temperature valve

Valve installation instructions and process precautions

Code of valve sealing or lining material

Types and selection of electric valves

Lining material and its application scope of fluorine lined valve

Classification and selection of fluorine-lined valves

The difference and selection of electric valve and pneumatic valve

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