The structure of a water valve. Functions and types of valves

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Functions and types of valves

Victor, Krasnoyarsk asks a question:

Among the huge number of shut-off valves on the market, I need to choose a valve for the water supply system. Please tell me what types of valves exist and what type of these locking devices is better to choose?

The expert answers:

The valve is installed in the water supply system to tightly shut off the water flow if necessary. Depending on the type of valve, it can perform the following functions:

Valves for water supply are used to tightly shut off the access of water.

• regulate water flow;
• serve as shut-off valves on water pipelines;
• serve as a shut-off and control device on pipelines intended for other purposes.

A device for hermetically shutting off flows has its pros and cons, which are taken into account when completing a water supply project and when installing all types of valves. In addition to water supply, these units are used in energy, gas transportation systems, heating, and air conditioning.

According to the valve design, flow control valves can be parallel or wedge. The O-rings of parallel models are located parallel to each other, and in wedge versions they are located at an angle and form a wedge. These types of valves are characterized by the following modifications:

• with wedge gate;
• with gate;
• with a device adapted for connection to a hose.

Wedge models are capable of providing a high level of tightness, but they are very sensitive to temperature changes.

Parallel modifications are single-disc or double-disc; they work well at elevated temperatures. Their place of application is metallurgy and energy.

Shut-off units differ in the way their bodies are manufactured. The device body is made using:

• casting;
• welding;
• stamping;
• combinations of different manufacturing methods.

The classification of products for starting and regulating flows according to the sealing elements of moving parts is as follows:

• stuffing box;
• siphon;
• self-sealing.

Locking products also differ from each other in the nature of the transmission of force to the gate; they are equipped with a translational or rotational drive.

The shut-off valves are started:

• in manual mode from the flywheel;
• in manual mode through a gearbox;
• from the work environment;
• using hydraulic drive;
• from electric drive;
• using pneumatics.

In addition to those listed above, there are other types of classifications of products for opening, closing and manually adjusting the supply of flows of various liquids, steam, and air.

Good day, dear reader! Water supply networks are a complex system that requires careful regulation, periodic repair or replacement of taps, pipe sections, water meters and other elements that make up the system. It is to control the flow of water or stop it completely that they are used.

Gate valves are a common type of shut-off valves used to completely block the movement of the medium for carrying out repair work in the system or maintenance of plumbing fixtures. They are equipped with almost any pipelines with a diameter from 15 mm to 2 m in hot/cold water and oil products supply systems operating with constant high-speed movement of the medium under pressure up to 25 MPa. They have a relatively simple design, short overall length, low hydraulic resistance, are suitable for operation in conditions of varying complexity, and can be operated manually.

To shut off gas equipment, Ludlo type valves with a retractable spindle are most often installed.

If valves are mainly used as shut-off devices, then water stops perform both functions of pipeline fittings. They have the ability not only to stop the flow, but also to regulate the flow of water. However, they are limited in terms of the permissible operating pressure - up to 2.5 MPa.

Design and principle of operation

The design of a water valve consists of three main components:

1. A housing with a lid, in the cavity of which locking parts are located and a certain part of the working substance is held under pressure. The body is a hollow, solid or collapsible structure made of steel, cast iron or non-ferrous metals. All its surfaces are protected from corrosion by epoxy resin. The housing has two pipes (inlet and outlet) with which the device is connected to the pipeline.
2. A locking unit consisting of two seats and a bolt. The seats have a parallel or angular arrangement with respect to each other; when the valve is actuated to close, the sealing part is pressed against their sealing surfaces. Centering of the lock is ensured by guides in the form of vertical cylinders with grooves, made of wear-resistant plastic or being a protruding part of the inner surface of the body. The lock itself, depending on the modification of the valve, can have the shape of a wedge, one or two disks;
3. Control node. It consists of a screw rod (spindle), a flywheel and a threaded bushing, with the help of which the torque is converted into translational movement of the shutter part. The running unit can be located in the upper part of the cavity of the device body or located outside it. The hole through which the spindle exits the housing is sealed with a special seal that operates on the principle of a bellows or oil seal.

The principle of its operation is as follows:

• the flywheel is driven manually or electrically;
• the force is transmitted through a threaded connection to the rod, which moves the valve along the guides perpendicular to the flow;
• the shut-off part is pressed tightly against the seats and stops the movement of fluid flow in the pipeline.

To open the valve, the flywheel is turned in the opposite direction.

Water supply valves

In a water pipeline valve, the shut-off element is made in the form of a disk, the diameter of which is equal to the size of the internal diameter of the pipe. When the valve opens and closes, the disk rotates around an axis perpendicular to the direction of flow.

The valve body has a shortened cylindrical shape, it can be collapsible and monolithic (all-welded construction). It is made of cast iron alloys, different types of steels, non-ferrous metals, composite polymers. In its cavity there is a locking organ, represented by a movable part - a flat or biconvex disk and a fixed part - a saddle. Elastic rubber rings are used as seals.

Types and classification of water valves

According to the design of the shut-off body, valves for plumbing systems are divided into:

• wedge;

• parallel;

• gate;

• hose

Wedge valves are equipped with a cone-shaped gate, which, in the “closed” position, fits tightly into the space between the seats. The wedge can be of different types:

• rigid, having the shape of a solid plate narrowed towards the bottom. It smoothly descends into the lower part of the device and blocks the through holes of the saddles in the perpendicular direction, thus interrupting the movement of the working medium. A stiff wedge securely seals the bore, but is more prone to rust and harder to fit to saddles. Therefore, in such devices there is a danger of jamming and difficulties arise in raising the wedge during sudden temperature changes;
• two-disk - consisting of two disks, which are movably fastened together at an angle to each other. When the valve is actuated to close, both elements rotate relative to each other and close the through holes in the saddles, firmly pressing against their sealing surfaces. When opened, they move away from the saddles, freeing the passage for the working substance. This design of the locking element provides a good level of tightness, reduces the risk of jamming and increases the working life of the entire device;
• elastic, the two disks of which are connected to each other by an elastic rubber part. It is able to bend under the influence of water pressure, thus providing a tighter pressing against the sealing materials of the saddles. Gate valves with a rubberized wedge require less effort to operate, have smooth passage surfaces that reduce friction and wear of the shut-off body elements.

Parallel valves include devices in which the sealing surfaces of the shut-off or control body are located in parallel planes to each other.

For stove chimneys, which includes a frame and a metal plate with a handle. When the valve is opened, the plate moves out of the frame, when it is closed, it returns to its original position.

Gate valve selection criteria

To correctly select a water valve, it is necessary to perform a thorough analysis of the initial requirements for its technical characteristics, as well as compare prices for products from different manufacturers.

This analysis is performed in the following sequence:

• determination of the purpose and operating conditions of the valves (properties of the working medium, the value of the maximum operating pressure and temperature range);
• determination of the nominal size of the conditional diameter (DN);
• choosing a device control method;
• selection of material for body parts;
• clarification of the function (locking or regulation);
• choice of design modification of the product;
• final determination of the geometric parameters of the device (construction length and height, dimensions of connecting ends, method of connection to the impulse line, number of fastening elements, etc.);
• selection of the appropriate model according to the range of valves produced.

Cast iron fittings for heating and water supply systems have recently been used less frequently; mainly steel devices are used here. Cast iron shut-off valves are often installed in sewers, in systems for supplying compressed air, steam and bulk materials.

Pipeline connection and installation

The connecting ends of the valves can be flanged, coupling or welded. The method of carrying out the installation process depends on this factor and the type of pipe in the system.

Connection to metal water pipes

Installation of valves in a water supply system made of metal pipes is carried out as follows:

• cut out a section of pipe at the installation site equal in length to the size of the device body;
• clean the edges;
• depending on the type of connection to the process of the selected valve, either threads are cut on the edges of the pipes or counter flanges are welded to them;
• perform sealing of joints: flanged - sealed with rubber rings, threads - with linen thread;
• fix the valve on the pipeline: the flanges are fastened with bolts and washers or the connecting pipes are screwed onto the prepared thread.

Installation in a plastic pipe system

When installing a valve on a plastic pipe:

• cut out a section of pipe of the required length;
• both ends are put on the nozzles of the welding machine heated to 260ºС;
• after heating, the connecting pipes of the device are inserted into them;
• keep the joints stationary for several minutes until the plastic has completely hardened.

Features of installation on chimneys

The stove valve is installed on the chimney at the stage of its construction:

• lay a row of bricks according to the order;
• cut out a recess on top of the brick that matches the thickness of the valve frame and a groove on the side for the handle;
• place the gate in the prepared recess in cement mortar;
• lay the next row of bricks.

There are a number of rules that must be followed during installation, namely:

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• Kinds
• Choice
• Installation
• Finishing
• Repair
• Installation
• Device
• Cleaning

Features of valves of various modifications

The same tasks can be performed by various types of valves, characterized by different principles of valve design. Thus, according to the valve principle, the following main types of pipeline fittings are distinguished: valves, gate valves, faucets, dampers, hose valves, diaphragm valves, level, flow and pressure regulators.

The wedge valve is intended only to block the flow of the working substance; it cannot be used to regulate the pressure.

Valves are an integral part of the water supply system. There are different types of valves, each of which has its own characteristics, advantages and weaknesses.

Functional purpose

Depending on the type of product, it can be used to perform various functions:

• as a regulator of the flow of the working environment;
• as pipeline shut-off valves;
• as pipeline shut-off and control valves.

The main purpose of valves is their use as shut-off valves - devices necessary to shut off the flow of a working medium with a certain degree of tightness.

Their similar use allows for discrete (two-position) regulation of the flow of the working medium.

In some cases, short-term use of valves to perform the functions of shut-off and control valves is allowed.

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Structural features of valves

Diagram of the main elements of the valve.

Each type of valve differs from other types of products according to a number of criteria. Depending on the design of the valve, designs are divided into parallel and wedge.

The difference between wedge modifications is that their sealing rings are located at a certain angle, forming a wedge, while for parallel valves such rings are located parallel to each other.

Wedge models are made with a solid (elastic or rigid) wedge or a double-disk composite wedge formed by 2 disks located at a certain angle to each other.

A parallel valve can have a valve in the form of 1 sheet or disk, or in the form of 2 disks with a spacer spring or spacer wedge located between them.

Parallel valves are made of cast iron. They are used as control and shut-off valves for steam, gases and water. The fittings are connected to the pipeline using flanges and bolts. Parallel valves with rising stems are shut-off valves and can at the same time be used as a gate to regulate the volume of water supplied. They are installed on pipelines with a diameter of at least 50 mm.

Shut-off valves can be with a non-retractable (rotating) or retractable spindle. In the first case, when opening and closing the valve, the spindle performs only rotational movement. The running thread is in contact with the working medium. In the second case, when opening and closing the valve, the spindle makes a translational movement. The running thread and nut are located outside the valve cavity.

The shut-off valves are controlled using an electric or manual drive. On large-diameter manually operated valves, a gearbox with spur, bevel or worm gears is used to reduce the required force on the manual drive flywheels.

As a rule, such shut-off valves are made full bore, that is, the diameter of the valve passage is almost the same as the diameter of the pipeline. In some cases, to reduce dimensions and weight, reduce moments and forces required to control shut-off valves, “bell-shaped” (narrowed) valves are used.

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Structural modifications and main types of valves

Gate valve drive diagram.

Valves come in various types. Thus, according to the type of valve, the following shut-off valves are distinguished:

• with a wedge locking element (wedge);
• with parallel locking element (gate);
• with elastic deformation of the valve channel under the working medium (hose).

In turn, wedge modifications can be with a composite wedge, with an elastic wedge and with a solid wedge.

Gate valves are a type of shut-off valve in which the sealing surfaces of the valve elements are located parallel to each other. Such fittings also have a number of modifications. Thus, single-disc gate models are equipped with 1 disk, which is pressed by the sealing surface to the surface of the housing seat. In the center of the disk there is a hinge, through which force is transferred from the rod to the disk. The compression can be carried out using wedge spacers installed in the housing.

Double-disc gate products can be either with wedge or spring spacers.

According to the method of movement of the gate valve, shut-off valves can be rotary type or reciprocating type. In gate valves, sealing along the gate is carried out using spring-loaded movable seats. There are modifications of the rotary type, which are equipped with 2 fixed disks with holes, between which a movable disk is placed. When this disk is rotated, the working medium is blocked.

The use of elastic elements guarantees the necessary fit of the contacting surfaces of the disks.

Depending on the type of body shaping, the product can be:

• cast;
• welded;
• forged or stamped;
• combined.

Scheme of types of valves.

When choosing a method for manufacturing the product body, the following factors are taken into account:

• production program and technological capabilities of product production;
• resistance of the shut-off valve body to the working environment;
• restrictions depending on the conditions of use of the product (temperature, pressure, corrosion resistance, etc.);
• quality characteristics of the material used to make the case.

In the manufacture of metal locking structures, the main type of shaping of the product body is casting. But with high requirements for strength, stamping, forging, or a combined method of manufacturing the body are more preferable.

There are other classifications of locking products. So, according to the type of sealing of moving parts, they are divided into:

• self-sealing;
• bellows;
• stuffing box

Stuffing box valves - the tightness of the moving parts (stem, spindle) in relation to the external environment is ensured using a stuffing box seal. In bellows modifications, the tightness of moving parts is ensured using a bellows - an elastic corrugated shell that maintains strength and density under high-cycle deformations.

Depending on the nature of the transmission of control force to the valve gate, there are:

• with linear drive;
• with a rotary drive.

By type of control:

• from the work environment;
• from hydraulic drive;
• from a pneumatic drive;
• from electric drive;
• manual via gearbox;
• manual from the flywheel.

where they are used, advantages and disadvantages

Flange valves are installed to regulate pressure in communication and industrial water and gas pipeline systems. Shut-off valves are always installed on pipelines for any purpose. This article provides information on the design features of flanged valves, applications, and typical advantages and disadvantages. Such pipeline elements do not have a complex design, are reliable, affordable, and have a long service life. Such mechanisms are installed to block and open the flow of pipeline contents.

What types of valves are there?
Design Features
Housing and locking assembly
Characteristic indicators
Expert assessment
Advantages and disadvantages

What types of valves are there?

The design of flanged valves can be of several types:

1. Wedges.
2. Parallel.

Wedge valves block the passage opening by moving the valve element perpendicular to the direction of water flow. Features of parallel valves include parallel placement of built-in sealing surfaces. The designs of such elements can consist of one or two disks. Valves are divided into several main types based on the type of movement. Large dimensions are the main distinguishing feature of such elements.

The second type of valve involves the use of a non-retractable spindle. The size of such products is much smaller. Such devices are best suited for pumping aqueous media, various petroleum products and other materials that do not contribute to the formation of corrosion. There are steel and cast iron valves. Steel fixtures are mostly used for gaseous and liquid working media. Cast iron valves are necessary to completely shut off the moving flow. The maximum permissible temperature for operation is 225 degrees.

In horizontally located systems, cast iron valves are equipped, in which a retractable spindle is installed in a vertical position. This spindle can be controlled in automatic and manual modes. The use of an actuator to control the operation of the valve is highly practical.

Design Features

Despite the impressive number of manufactured models available on the market, the structure of a flanged valve is almost always the same, regardless of what product will be installed on the pipeline. The main operating tool is a steel disk or wedge located at right angles to the water flow. When the valve closes, the disc is clamped by two seats, and the flow of liquid or gas is completely blocked and the required tightness is restored.

When the valve is turned, the steel disc is moved back with the help of the rod, and the lumen of the pipeline is cleared.

The wedge design in different models may have some differences:

• A sufficiently high level of tightness can be achieved due to the rigidity of the wedge and the high accuracy of matching of the seats and the disk;
• Double-disc wedges are constructed from several tightly connected components. This makes it possible to minimize the chances of the element jamming, while the structure remains completely sealed;
• A modified version of the double-disk element is the so-called elastic wedge. An elastic elastic material is inserted into the locking part. This makes it possible to increase the resistance to temperature changes and reduce the likelihood of defects in the housing;
• A special protective EPDM layer is used to treat the disc, which significantly increases the corrosion resistance of the internal elements of the valve. The tight adhesion of the wedge to the two seats results in good tightness;
• The valve can be controlled manually or using some kind of drive, which makes it possible to control the pipeline from a distance.

Such an elementary design of the valve makes it possible to meet all the functional requirements of the system in question; repair and maintenance of the element is not particularly difficult.

Housing and locking assembly



There is no thread at the main ends of such a valve; in these places there is a special flange, the design features of which are approved by GOST 12819-80. This technology makes it possible to install a wedge-shaped valve in pipelines with a possible increase in pressure level up to 200 atmospheres. The diameter of the hole in the pipe with such indicators should not be more than 400 mm. The conditional passage must correspond to at least 15 mm.

The upper end of the housing can be equipped specifically for a flange connection with a built-in locking device system. The dimensions of the top flange are determined by standards established separately for each industry. The body elements of such shut-off valves are cast in specially manufactured molds. Steel and cast iron are considered the main materials for the manufacture of valves. Wedge valves are designed in the same way as cast iron valves.

A rigid shutter is characterized by relatively large valves. It is these devices that are used on pipelines with a relatively high internal pressure. Thanks to the rigid shutter, complete tightness of the closed passage opening is ensured. The operation of such valves has certain features. When the ambient temperature decreases, the shutter device may jam in the frame itself. Only the double-disc shutter does not have this drawback. These locking mechanisms consist of several discs assembled into a V-shaped structure.

Thanks to this form of the mechanism, the body seat does not need to be subjected to ultra-precision machining. Thus, the total cost of the shutter is reduced, and the cost of funds for production is significantly reduced. The valve control device consists of the following components:

1. A rod attached to a butterfly valve.
2. A flywheel that facilitates the rotation of the rod.

The main distinguishing feature of such a device is high reliability. For this reason, such valves are used in the equipment of industrial pipelines.

Characteristic indicators

The valves are characterized by the following indicators:

• The working environment with which the valve can interact is diverse;
• The maximum temperature of the working environment is 450 degrees;
• The pressure indicator can reach 25 MPa;
• The diameter can range from 50 to 1200 mm.

Installation of valves on a pipeline system is carried out using standard types of flanges or welding machines. The method of fastening valves using welding is highly reliable, especially relevant when interacting with aggressive materials and at high pressure in the working environment. The tightness of such devices is always at a high level, so the possibility of leakage is practically eliminated. The disadvantages of this method of fastening include the relative complexity of the dismantling procedure in a situation where repairs are required.

Expert assessment

Flange connections are very popular and are installed at industrial facilities in a wide variety of industries. This type of connection involves the use of bolts; elastic gaskets are pre-installed between the flanks.

Depending on the pressure indicators of the operating working environment and the diameter of the product, several main varieties can be distinguished:

• Welded flat products without protrusion, made of steel. The elementary structure is made using simple sheet steel. Such devices are installed in the narrowest pipeline systems. There are both factory-made devices and handicraft valves on the market;
• Welded lip valves are used for medium diameter systems;
• Valves made of gray cast iron with a recess or projection provided. Such devices can be manufactured if the necessary equipment is available. A sufficient indicator of tightness is ensured by the connection technology, in which a counter protrusion enters the recess of the flange;
• Gate valves with a grooved or tenon connection can be manufactured exclusively in the factory. The required sealing rate is ensured by the insertion of the tenons into the grooves.

The absence of any protrusions in the design of welded flange valves and coverage of the entire surface by an elastic layer when clamping. When using flat flanges, it is advisable to use special elastic gaskets with a low material rigidity.

The presence of scratches and minor damage on the flange impairs the quality of the tightness and tightness of the connection. Since there are no protruding surfaces on the flange, the slip of the gasket is increased, while the likelihood of it slipping increases. It is thanks to these characteristics that the possibility of operating such devices is completely excluded.

Advantages and disadvantages



The advantages of flange connections include:

• Reliability;
• Comparative ease of installation;
• Possibility of repeated dismantling;
• The flow of the substance used can be launched in any direction;
• Simplicity of design and quality of materials ensure a long service life;
• Low hydraulic resistance.

The disadvantages of such connections include:

1. High production cost due to the need to use large amounts of metal. The increase in price is due to an increase in the mass of the flanges, as well as their thickness, the number of bolts used for fixation, and the use of thick sheet metal.
2. To produce large flanges, you have to use large lathes, which not every manufacturer can afford.
3. It is impossible to regulate the intensity of the medium flow using such a mechanism. The valve must be fully open or closed.
4. The gap takes a long time to open and close.
5. The construction height of the devices is very large. This is especially true for mechanisms with a retractable wedge. This makes installation much more difficult.

The main features of installing such valves should also be mentioned. The diameter of the flanges on the pipes and the valve must match. The counter flanges are attached to the pipe using a welding machine. A special elastic sealing ring is placed between the connected elements.

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Gate valves - types and description

The gate valve is a fitting on a pipeline with a control element. It is a widespread type of stop valves and is mainly used in housing and communal services, in transport pipelines, in water and gas supply, in the energy sector, in technological pipelines, etc. avk flanged valves are installed on those water supply systems, through which neutral liquid is mainly transported. Its temperature should not exceed 70 degrees Celsius. The devices are made of high quality stainless steel with the addition of auxiliary materials. Thanks to surface treatment with a synthetic primer and mica-containing paint, the valve is provided with anti-corrosion protection.

Advantages of the devices:

• simple design
• optimal face-to-face length
• operation in different conditions
• minimal hydraulic resistance, which allows their use in powerful main pipelines.

The disadvantages of this type of fittings include rapid wear of the seals, as well as difficulties in repairing devices, especially during operation. A certain type of valve serves only as a shut-off valve, that is, adjusting the flow of the medium in this case is impossible.

When manufacturing valves, the diameter of the pipeline itself is taken into account, which equal to the diameter of the reinforcement, that is, its passage opening. In order to somehow reduce the torque and reduce wear on the seals, slightly narrowed valves began to be used. At the same time, a slight increase in resistance, in this case, has almost no effect on the operating process of the system. Meanwhile, it is not recommended to use this type of valves on those main pipelines that have a large diameter.

Valves that are controlled by a steering wheel as if manually are widely used. and electric drives. It is also possible to use pneumatic or hydraulic drive. If the valve is manually operated and is large in size, it is more advisable to install a gearbox on it, which significantly reduces the resistance of the valve.

Gate valves differ in the design of the shut-off body and therefore are of the following types:

• wedge gate valves
• parallel valves
• gate valves
• pinch valves

Wedge gate valves

The first type of valve has seats located in the body in such a way that a small angle is formed between them. The gate of such a valve is made in the form of a wedge, which in turn can be elastic, with two disks, or rigid. It can fit tightly between the saddles in the "closed" position. The choice of wedge type depends on the operating conditions.

Hard wedge

To ensure high tightness of the stopcock, it is recommended to use hard wedge. But at the same time, it is important to require increased accuracy when processing the wedge, which will allow the angle between the saddles to be aligned without interference with the angle of the wedge itself. Meanwhile, it should be noted that when using a hard wedge, danger of shutter jamming, sometimes there are problems opening the valve due to temperature fluctuations, when signs of corrosion or wear of the seals appear.

Wedge with two discs

As the name suggests, this wedge consists of a pair of discs tightly fastened together and at an angle. The self-installation feature allows avoid sealing problems in the closed position of the valve. The possibility of the shutter jamming is also reduced due to the double-disc design of the device. The wear of seals is also reduced, the tightness is increased, and less force is used to close.

Elastic wedge

As for the elastic wedge, the discs connected by the elastic element are able to bend, thereby increasing the density between the seals in the closed position. However, in an elastic wedge, the self-alignment of the disks is somewhat reduced, but to some extent there is ability to compensate for minor body deformations, which appear due to atmospheric temperature fluctuations or loads on the pipeline. The advantages of using an elastic wedge on pipelines include the absence of the need for problematic fitting of the valve to the body. The simple design of the fittings is also noteworthy. We can say that the elastic wedge combines the advantages of the two above-mentioned valves.

Parallel gate valves

The name clearly conveys the design and location of the sealing surfaces in the housing. Here, too, there are two disks, which are pressed against the saddles with a wedge fungus to block the working medium.

Gate valve

The main difference between the gate valve is the design and execution of the locking element. The presence of a metal plate allows cutting the inclusion in the liquid flowing in the valve. The gate valve is used in vacuum technology, since there is a wide possibility of making any sections on the device, even with a minimum length. Inside the pipe in the “open” position no valve elements protrude. This nuance minimizes gas resistance and increases the efficiency of creating a vacuum. This type of valves is also used in the oil and gas industry, in sewer systems, as well as in those pipelines in which there are media contaminated with mechanical elements. By the way, for the destruction of some particles in the pipeline, the gate valve is made in the form of a knife.

pinch valve

The hose valve has a slightly different design, with a body without seats and a valve without seals. The working environment is passing through the pipe. The latter is located in a housing and is able to isolate metal parts from the working environment. To block the passage, the spindle acts on the hose, which is completely pinched. Hose valves are installed on pipelines transporting viscous media and aggressive liquids.

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Design features of water supply valves, their classification. Installation Guide.

Design and principle of operation

In order to find out which type of fittings is best to choose, you need to know its main advantages and operating principle. The cost and design dimensions depend on the diameter of the pipes, purpose and material from which the valve is made.

Gate valves of any type consist of a body and a cover, which form a space (working area) in which the valve is located. There are two ends on the body with which the part is connected to the pipeline. These elements can be coupling, threaded, or welded. The body design contains protrusions called saddles. When closing the valve, the sealing parts of the valve are pressed against the seats, preventing the liquid from passing through the working area.

The element that helps move the shutter is called the spindle. The mechanism for moving the spindle along the threaded nut is:

• manual
• automated (using an electric drive).

For large diameter pipes, valves with an electric motor are used exclusively. This provides additional security to the locking system.

Types of valves for water pipes

Wedge

They stop the flow of liquid using valves - cone-shaped disks adjacent to two saddles located at an angle. When the flywheel is activated, the spindle moves the disk by rotating in the threads of the nut. The tight fit of the disc to the body protrusions is due to its wedge-shaped shape and the sealing surfaces of the shutter. This and similar types of valves are used for pipelines transporting water, ammonia, steam, gas, oil products and other substances.

Types of wedges and their features:

• rigid wedge – has increased tightness, which somewhat complicates the conditions for maintenance and operation of the valves;
• double-disc wedge - a sophisticated design increases wear resistance of sealing surfaces, improves sealing and reduces the required force to open or close the valve;
• elastic wedge - a modified and simplified device allows for effective operation in a wide temperature range, compensating for housing deformations caused by loads on the pipeline.

Parallel

Such valves differ significantly in their design from those described above. The shutter in them consists of two disks connected by a spacer spring or wedge. When the valve is inserted into the “closed” position, the discs are pressed against the seats and stop the flow. The main advantage of parallel shut-off valves is their high reliability: the valves shut off the flow almost perfectly and therefore can operate in any temperature regime.

Installation of valves for water supply

There are different ways to connect fittings to pipes: flange, coupling, socket and welded. The latter is the most reliable and convenient. Also, certain types of valves tend to be fixed to pipes without the presence of separate connecting elements.

When installing shut-off valves, it should be remembered that valves are installed exclusively with the flywheels facing up in order to avoid hydraulic fluid leakage or gas leakage. It is also necessary to ensure that the flange connection (if any) is made smoothly and without bending.

The widespread use of valves in water supply systems is explained by the fact that they have a simple design, short overall length and are easy to operate. Due to their structural features, they are used in a variety of conditions, and also have low hydraulic resistance, which allows them to operate at high speeds of the transported medium.

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Application of valve devices for wedge-type pipelines: features, device, types

In water supply and heating systems, wedge valves are a fairly frequently used element. Their main purpose is to shut off water, wastewater and neutral liquids. It is worth noting that these elements are used in many areas. In addition to the housing and communal services sector, such valves are widely used in gas supply systems, for energy oil pipelines, etc. In order not to make a mistake with the choice of shut-off valves of this type, a decision must be made taking into account such parameters as the operating temperature of the medium flow, pressure level and operating mode .

Advantages and disadvantages of wedge valves

If we consider the features of shut-off valves, we can highlight a number of its characteristic advantages:

• a simple device that minimizes the likelihood of their failure;
• versatility of application - allows the use of these shut-off valves at facilities with various conditions, where they are able to cope with the effects of any pressure temperatures;
• low level of hydraulic resistance;
• wide variety of standard sizes. Due to this, the consumer has the opportunity to find a product that is most suitable for a specific type of pipe;
• the design of such fittings allows it to pass the work flow in different directions.

At the same time, wedge valves have a number of disadvantages that must be taken into account at the selection stage:

• the process of opening/closing valves takes a long time;
• the presence of a large building height, which is primarily relevant for shut-off valves equipped with a retractable spindle;
• low level of maintainability, which is primarily observed in situations where the service life of the sealing materials used has expired.

Gate valve types

Gate valve– a type of pipeline fittings, the shut-off or control element of which moves back and forth perpendicular to the direction of flow of the working medium.

Functional purpose of valves
As a pipeline shut-off valve
As a two-position regulator of the flow of the working medium.
As shut-off and control pipeline valves.

The main application of gate valves is their use as shut-off valves, i.e. devices designed to shut off the flow of the working medium with the required degree of tightness. This use of valves allows for two-position (discrete) regulation of the flow of the working medium.

In some cases, short-term use of valves as shut-off and control valves is allowed (with the permission of the valve developer).

In addition to the main function (blocking the flow), valves also have an important function - providing throughput, which is determined by the conditional diameter of the valves taking into account the resistance coefficient.

Structural modifications of valves.
1. By shutter type:
gate valves with a wedge locking element (wedge gate valves);
gate valves with a parallel locking element (gate valves);
valves with elastic deformation of the channel for the working medium (hose valves).

1.1 Wedge valves

These are valves in which the sealing surfaces of the valve are located at an angle relative to each other. The locking or regulating element is made in the form of a wedge.

Wedge valves are:
valves with solid wedge;
valves with elastic wedge;
gate valves with a composite wedge;

a) Wedge valves with a solid wedge have a rigid and reliable design that allows them to achieve a high degree of tightness.

However, such valves also have disadvantages:
require high-precision equipment during manufacturing;
prone to jamming at high temperatures;
Low maintainability (requires removal from the pipeline and the use of special equipment).

b) Wedge valves with an elastic wedge - eliminate the possibility of jamming when the temperature of the working medium fluctuates.

c) Wedge valves with a composite wedge are divided into:
double-disc valves without a cage (the discs are connected using simple spacer elements);
double-disc valves with a cage (the discs are inserted into the cage and movably attached to it).

d) Wedge valves with a composite wedge:
do not require special high-precision equipment during manufacturing;
ensure a tight fit of the sealing surfaces of the discs to the valve body seats (tightness according to class A);
They have good maintainability.

1.2 Gate valves (with parallel closing element)

Gate valves are valves in which the sealing surfaces of the valve elements are mutually parallel.

Gate valves have modifications:
Single disc gate valves have one disc. It is pressed by the sealing surface against the sealing surface of the housing seat. In the center of the disk there is a hinge, with the help of which force from the rod is transmitted to the disk. The compression can be done using wedge spacers located in the housing.
Double-disc gate valves can be manufactured with either spring or wedge thrusters.

According to the method of moving the gate valve, there can be:
reciprocating type;
rotary type.

In gate valves, sealing on the gate is performed using movable spring-loaded seats. There are rotary gate valves, which have two fixed disks with holes, between which a movable disk is installed. When this disk is turned, the working medium is blocked.

Guaranteed fit of the contacting surfaces of the disks is ensured by the use of elastic elements.

1.3 Hose valves

2.By type of body shaping:

a) cast valves;
b) welded valves;
c) stamped or forged valves;
d) combined valves;

When choosing a method for manufacturing a valve body, take into account:
technological production capabilities and valve production program;
resistance of the resulting valve body material to the working environment;
quality characteristics of the valve body material;
restrictions on applicability depending on the conditions of use of the valve (pressure, temperature, corrosion resistance, etc.)

When manufacturing valves from metal, the main type of shaping of the valve body is casting. However, if there are high requirements for the strength of the valve body, forging, stamping or a combined method of manufacturing the valve body (forging, stamping and subsequent welding) are more preferable.

3. According to the type of sealing of the moving parts of the valves:
stuffing box;
bellows;
self-sealing.

3.1 Stuffing box valves– the tightness of moving parts (spindle, rod) relative to the external environment is ensured using an stuffing box seal (oil seal).
3.2 Bellows valves- the tightness of moving parts (spindle, rod) relative to the external environment is ensured using a bellows.
The bellows is an elastic corrugated shell that maintains density and strength under high-cycle deformations.

4. By type of transmission of control force to the locking element:

with rotary drive;
with linear drive.

5. By type of valve control:
manual from the flywheel;
manual via gearbox;
from electric drive
from a pneumatic drive;
from hydraulic drive;
from the work environment.

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