Before valves are quite obvious, but despite this, some enterprises continue to use wedge valves, citing several reasons.

Some engineers at enterprises believe that a valve made of steel is more reliable ball valve, and with its help it is possible to regulate the flow of the medium. However, engineers from leading companies producing pipeline fittings clearly state: wedge valves are in no way intended to regulate the flow of a medium, unlike the same ball valves.

Features of wedge valves

Practical application shows that when used valve As control valves, valves quickly fail, ceasing to keep the flow of the medium closed, that is, they do not even perform their direct function.

It should be noted that we are talking about steel valves, because cast iron valves are not even considered here. The main problem is that cast iron injection molding machines are extremely demanding in terms of operating conditions.

For example, cast iron valves cannot be used at temperatures above +350 degrees and below -20 degrees (here we are talking about best brands cast iron) on the Celsius scale. There are also restrictions on the type of pumped medium (cast iron injection molding machines are almost impossible to safely use in some types of gas pipelines), pressure, bore diameter, etc. Although valves are still the most common type of injection molding machines on various pipelines, in Lately There is a trend towards replacing gate valves with ball valves in many systems.

Main reasons for replacement:

Valves require constant monitoring technical condition(for example, cleaning oil seals),

Valves perform poorly in emergency situations that require quickly shutting off the flow of the working medium.

In addition, the design of the valve does not provide good tightness, and this applies to almost all elements: both the valve itself and the body. Further, we note that wedge valves have considerable weight and substantial dimensions, and also often break, which leads to regular emergency situations.

Features of ball valves

Ball Valves compared to wedge valves are a newer type of shut-off valve, although ball valve designs are over a hundred years old. From the name it is easy to understand that the main shut-off element in these taps has the shape of a ball. The practical application of this design shows itself to be much more advantageous than a gate valve. It should also be noted that modern ball valves are much more airtight than wedge valves. The fact is that manufacturers managed to solve the problem of all ball valves of the past (insufficient tightness), when using modern materials. Saddle modern ball valve is made from polymer compositions, and not made of metal, as it was before. In addition, this solution made it possible to simultaneously and significantly simplify the control of the crane, since now it is not necessary to make significant efforts to change the position of the shut-off element. The next feature of ball valves is compact design, which also distinguishes a ball valve from a wedge valve. This is especially true for systems housing and communal services However, even in fairly large pipelines, ball valves are significantly superior in size to wedge valves. On this moment Manufacturers offer ball valves made of steel, cast iron, brass and other materials.

Brass taps cannot be used in systems where the ambient temperature exceeds +100 degrees and they do not perform very well even at sub-zero temperatures. In addition, brass ball valves are made small in diameter (usually no more than 50 mm).

Steel ball valve will cope with temperatures of +200 degrees and will operate at -50 degrees Celsius, which makes it indispensable in media pumping systems in northern conditions. The advantages of steel reinforcement include the increased diameter of the passage hole. But there is one drawback - the price of the ball valve. In a budget-conscious situation, there is a great temptation to make a choice based on price. But even in this case, a rational comparison should not be based on the purchase price, but on the “total cost of ownership” of the equipment, in our case a ball valve or gate valve. If the cost of a ball valve is on average 2 times higher than the cost of a gate valve of the same diameter, then its full service life is 4 times higher.

Which ball valve to choose?

Despite all the advantages of modern fittings, a very important factor is how interchangeable the outdated ones are cast iron valves And ball valve. To avoid creating difficulties in the future pipeline operation How quickly and efficiently is it possible to replace valves? Therefore, it is important to understand which ball valves are better than valves, that is, what properties the valves should have in order to replace old valves with existing pipelines? Let's look at these properties:

1. Construction length of the ball valve (L=....mm)

When repairing a pipeline where steel or cast iron valves, plays an important role face-to-face length of ball valve. If you choose the right ball valve, you can get rid of additional installation work, which are not always convenient or impossible due to the characteristics of technology and security conditions. Used in Russia face-to-face length standards for gate valves and ball valves vary, the construction lengths of ball valves of various domestic and foreign manufacturers. But optimal choice still exists - some Russian manufacturers take into account " national characteristics» utility pipelines and produce ball valves based on face-to-face length standards for valves (for example equal port valves LD, collapsible cranes LD 11s67p or TEMPER gate valves" ). These cranes are completely correspond to the valve being replaced. When installing a new pipeline, the choice of the construction length of the crane is more independent. But it doesn’t hurt to be sure that the face-to-face length of the fittings used is not exclusive, and if replacement is necessary in a few years, you won’t have to look for one single manufacturer of a ball valve with a unique construction length. When using a ball valve, very often the face-to-face length turns out to be closely dependent on another important parameter fittings - conditional diameter.

2. Full and incomplete (standard) passage

Choice full or incomplete (standard) passage ball valve depends on the operating conditions of the structure in the pipeline system and its permissible hydraulic resistance. Two most typical cases can be distinguished: when the structure is installed on a main line with a high flow rate of medium, it is necessary to have fittings with low hydraulic resistance in order to avoid high energy costs for transporting the medium, especially liquid, but in dead-end positions it is permissible to use fittings with an increased coefficient of hydraulic resistance .

The greatest energy losses will occur in pipelines in which liquids move at high speed. Under these conditions, it is necessary to use cranes with low hydraulic resistance coefficient values. Approximate coefficient values ​​for various types taps: full bore - 0.1-0.4; partial bore - 0.4-1.6.

Most ball valves known foreign brands are manufactured to standards that differ from the reinforcement standards used in Russia and CIS countries. It is the construction length of the crane that is the first and most obvious honors- Ball Valves foreign production with face-to-face length "locked" can be manufactured by the manufacturer only to order. The cost and duration of such an order inevitably increases. The next significantly different characteristic of imported fittings is the effective passage of the crane. Most foreign-made ball valves have reduced (standard) in relation to the connecting diameter, the diameter of the effective passage.

Advantages of ball valves over wedge valves

Ball valves can be manufactured to fit almost any diameter;
- ball valves are able to withstand a significantly higher level of pressure;
- the operating temperature range of ball valves is significantly greater than that of wedge valves;
- ball valves have practically no jamming and are much easier to control, while gate valves jam quite often, especially after long time are in open or closed position;
- higher tightness of ball valves;
- ball valves are universal, while wedge valves in most cases are used only for water;
- ball valves, in comparison with wedge gate valves, have more compact dimensions and lighter weight;
- ball valves last much longer, fail much less often and are more reliable than wedge valves;
- wedge valves require regular inspection and maintenance, ball valves do not require constant condition monitoring;
- wedge valves can only be used as shut-off pipeline valves, and ball valves can be used as shut-off and shut-off and control valves.

For specialists working on industrial enterprises, it is important to know the differences between a faucet and a valve.

general information

A valve is a drive fitting used for the manufacture of a pipeline, where the gate valve rotates around its own axis in a perpendicular direction. The element includes two components:

• Movable type cork;
• Static body.

Fig 1. How the structure is arranged

A valve is a drive-type fitting where the structure moves along the flow and fits onto the seat. Designed for direct opening or closing, regulating the flow of any medium.

What are the main differences

It is customary to distinguish three types of fittings depending on their purpose:

1. Driven.
2. Regulating.
3. Constipated.

Some classifications add a safety group.

Considering the main differences between a valve and a ball valve, it is worth noting that in the first mount it is possible to adjust the fluid flow. The ball valve is not able to perform this task. Based current rules, controlling and changing the flow of liquid using a ball valve is strictly prohibited by safety precautions. This is primarily due to the limited functions, since the regulator can only open or close the flow.

With the help of a valve, changes in the operating pressure are allowed due to the water pressure in the pipelines.

This is all due to design differences that determine the functions and use of elements. Considering the main elements of the fixed valve body, the shutter mechanism in it “sits” on the seat. Its movement is carried out in the direction of the flow.

When operating a crane, turns are carried out around its own axis. If needed additional elements, plumbers use ball elements. When the ball begins to rotate, the diameter in the hole automatically changes.

The valve is equipped with a ground box. When the stems are screwed in/out, the valve moves up and down.

Comparing both designs, several conclusions can be drawn:

1. The valve is in the closed and open positions.
2. The valve is also capable of regulating the pressure.
3. To visually recognize whether it is a valve or a faucet, just pay attention to the handle. The faucet's structure is quite simple, unlike the valve (here it is presented in the form of a lamb).

When considering the main types of shut-off valves, it is recommended to consider another popular element - the valve.

There are several types of cranes, based on the body of rotation:

• Conical. Visually resembles the shape of a truncated cone. The hole can be seen as rectangular or round shape. Most often used in gas supply. Popular due to its price.

Fig 2. Cone

• Cylindrical. Chief regulator of the heating system. Can perform vertical movement to regulate fluid flow.

Fig 3. Cylindrical

• Ball. No plumber can do without it. The hole is made in a round shape through which the medium passes.

Fig 4. Ball

Why do you need a valve, the main advantages and nuances

A type of fitting where the adjustment part moves in a perpendicular position, moving in the direction of flow. Among representatives of this category, the valve is considered more relevant.

Fig 5. Gate valve

The tool is popular in use:

• Transport activities, where the diameter of products ranges from 15-2000mm;
• In creating water and gas supply;
• In the housing and communal services sector;
• Oil production.

The prevalence of the use of valves is due to the following aspects:

• Easy to operate;
• Small sizes;
• Allowed for use in different conditions;
• There is a slight resistance in the hydraulics.

The last aspect is important when constructing highways. Constantly carried out in an environment characterized by high speed.

The mechanism is not without serious nuances. Experts in choosing necessary tools and materials, it is not recommended to use designs where the spindle is retractable. The shutter stroke is at least one diameter.

It is customary to distinguish two types of valves:

• Full bore.

Fig 6. Full bore

• Narrowed.

Fig 7. Narrowed

The first one is the most common. In it, the full bore diameter is equated to the value of the pipeline on which the tool is installed. To reduce the amount of torque, valves are used to control the control of valves, including reducing the wear rate of other pipeline components.

There are several principles for controlling valves:

• Manually;
• By means of an electric drive system;
• By means of a pneumatic drive system;
• Through a hydraulic drive system.

Considering comparative characteristics between a tap and a valve, we can conclude that both elements have a number of similar features and differences.

comparison table

Criterion	Gate valve	Tap
General signs	They are used to create tightness during the movement of liquid and gas flow in a pipeline. Ideally suited for structures with high pressure
What are the differences	The movement of the main element (partition) is carried out in all directions: right, left, up and down	The shutter acts as the main element. It can make movements around its own axis, and also place the channel at different angles relative to the fluid flow
	Wear occurs intensively with constant use	Less wear and tear even with constant use
	It is necessary to calculate additional space outside the pipeline creation to accommodate part of the partition	It is necessary to calculate additional space only for the placement of regulatory elements
	In practice, installation and operation of the device is most often found as a locking element, in the open or closed position.	As a traffic controller. At any time, it is enough to set the required intensity to ensure uniform motion flow
	Rarely used as a component in a mixer	Acts as one of the main elements in the mixer.

The tap and valve are very tight. This is why plumbers use them during plumbing repairs. However, the crane is characterized by less wear than that of gate valves. They can be used longer only if the following basic conditions are met:

• high-quality periodic maintenance,
• optimal lubrication.

Based on this table, we can conclude that the main differences between the two mechanisms can be traced in the following indicators:

1. How quickly parts wear out.
2. The amount of free space that will be needed outside the pipeline structure.
3. Where can it be used?

The tap copes well with the role of a regulator, and can also act as an auxiliary element in regulating the supply of water or gas at high pressure. Therefore, when creating a pipeline, taps are often found at the end sections. Since the rotating element moves around its own axis, it does not require much space. But the control mechanisms will require space to place the valves.

A distinctive characteristic of mechanisms is the type of main mechanism. This is a system that moves in a perpendicular direction in a pipeline. The main element in the tap is a special valve. If it is placed parallel to the flow or small angle, the intensity of the movement of liquid or gas increases; with a perpendicular arrangement, the intensity decreases.

A flange valve is installed on pipelines to provide the ability to quickly shut off the liquid supply and subsequent drying of the medium. To increase the level of security, these elements are located in all parts of the network.

Description

A flanged valve acts as a shut-off valve and has a simple design, despite its high efficiency. It belongs to the category of household shut-off taps and has a special blocking part in the center of the structure; its design depends on the type of valve itself. The most widely used are disc shut-off, wafer wedge and ball rotary elements.

The flanged valve gets its name due to the special flange rings located along the edges. They are used to provide quick access to the system and the ability to remove the fixture for replacement or repair work. It is worth noting that the dimensions of the counter flange element must correspond to the main plate. Otherwise, the connection will not have the proper quality or will become impossible.

Advantages and disadvantages

Among the main positive aspects The following are worth noting:

• enable quick repair or replacing the device with a new one;
• simple design;
• long service life;
• low degree;
• reliability.

The main disadvantage is the large mass. This leads to a high cost of elements, especially large ones, since their production requires a large number of material. It is also worth noting the rapid wear of the seals.

Varieties

The cast iron flanged valve is produced in various options. Devices are divided into types according to the direction of action - parallel and perpendicular. The last option is stationary and extends perpendicular to the main flow. Parallel devices are installed with a zero angle and are not an obstacle to the flow, provided they are in standard mode.

There is also a division according to design features - these are gate, ball and wedge-shaped elements. The latter are shut-off valves standard view. They are quite effective, have a perpendicular type of blocking, but are heavy.

The ball design is similar to shut-off valves household items similar type. DU 50 devices have become most widespread due to their relatively low cost. The flange valve DU 100 has a special disk element that closes the pipeline using a powerful spring. As a rule, it is installed on oil pipelines and gas networks.

Classification by control method:

• Handheld devices. This type is controlled manually by turning a special handle or valve. Despite the need for significant physical effort, they do not require maintenance and rarely fail.
• Electric drive fittings. Has a built-in electric motor for control. The system is blocked autonomously after pressing a button.

Working conditions

The flanged valve operates in various pressure ranges, the maximum level can reach hundreds of units. The operating temperature ranges from +200 to -50 degrees. Cast iron parts have advanced characteristics, in particular, work with gaseous substances can occur at +400 degrees, and the transported liquid medium can have a temperature of +270 degrees Celsius.

The clinker flanged valve is made mainly from materials such as cast iron and steel. This parameter is located in the device labeling. Any products equipped with flanges must be carefully selected according to dimensions, which are regulated by special documents. First of all, the diametrical size of the nominal diameter is taken into account. If there are any discrepancies with this criterion, the connection becomes impossible. If a flanged steel product with size DN 80 or DN 50 is used for installation, the flange going to the adjacent pipeline must have the same parameters. At the same time, a flanged valve, the sliding spindle of which produces a rotational-translational movement when opening, can be produced in various sizes. Maximum size can reach up to 1500 mm, the smallest fittings have a diameter of 25 mm.

Scope of application

Elements DN 80 and DN 50 have become most widespread in secondary pipelines and side branches of systems. In addition, they are used on large systems household use, bends and in boiler rooms. The flanged valve 100 has much larger dimensions and is installed on the main heating and water supply pipelines. DU 200 products are used only in industrial conditions on pressure main systems, and large special bolts are used for their installation. The cost of fittings depends on both dimensions and design features. The price of the material used in production also matters.

Installation

Installation of products is carried out according to standard scheme. At the same time, work is simplified by welding flanges to pipes or shut-off valves. Otherwise, workers would have to independently connect the valves to additional details and weld individual elements pipes This process requires large financial and time costs, and is also characterized by some difficulties, the failure of which can lead to problems during operation. This is of particular importance in the industrial sector.

The element increases the tightness. It is installed in a channel located on the flange plate. On front side the plates must be free of abrasions and any other damage, otherwise there is a risk of depressurization and breakthrough of the system. When working with high pressure pressure, this is fraught with serious consequences.

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Comparative characteristics of shut-off valves

General characteristics of different types of shut-off valves

Shut-off valves are used in the construction of gas and sewer systems. It can be seen on general purpose pipelines, industrial type, industrial pipelines with special operating conditions, sanitary pipelines and many others. They are designed to block any water or gas flows.

Gate valves, faucets, gates, valves, and other locking mechanisms are used for these purposes. Household plumbing cannot do without such mechanisms, but few people understand the difference between a faucet and a valve. Without this it is simply impossible to connect household appliances, fix the leak, turn off the gas or change the mixer. Plumbing surrounds us all around us, and shut-off valves are an integral part of it.

In fact, it has significant differences, both design and operational, although any constructive solution This type of valve always works in two positions: closed and open.

But, based on their functional characteristics and scope of application, one or another type of device is selected. For the right choice you should know how the principle of their operation may differ, and what function each of them performs.

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Operating principles of taps, valves and gate valves

Design solutions for shut-off valves are taps, valves and gate valves. How are they different from each other?

Gate valves are the most common and most popular locking devices. Their design implies that the locking element is in the closed and open position. The flow of the working medium is blocked due to the fact that the locking element moves perpendicular to its axis. Gate valves can be used exclusively as locking valves. They are parallel, wedge and gate.

A valve or valve is capable of blocking the flow of the working medium due to the fact that the device moves parallel to the axis of its movement. It, unlike valves, can be used not only as a shut-off device, but also as a regulating device due to the fact that its design will allow you not to completely block the flow of the medium, but partially.

A significant drawback is the valve’s inability to respond to changing speed and pressure in the system. Therefore, its scope of application is pipelines with a relatively constant flow and pressure of the working medium. In addition to regulatory and locking devices, there are bypass, mixing, and distribution structures of these mechanisms.

A faucet is another type of shut-off valve. It can be used as a shut-off or a regulating device. It functions like this: the locking element, rotating around its axis, moves in a direction perpendicular to the movement of the medium flow. The locking element has the shape of a disk. Due to its rotation around its own axis, the liquid overlaps in a perpendicular direction.

Modern plumbing offers various design solutions for shut-off valves that have own characteristics. Of course, this entails distinctive advantages and disadvantages that manifest themselves in different conditions. Therefore, in order to choose the right shut-off valve, it is necessary to take into account the design features of the pipeline, as well as the conditions of use and requirements for a specific device. To do this, you need to understand the difference between, for example, a faucet and a valve, because the difference between them is not so obvious.

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Comparative characteristics of tap and valve

The main difference between a faucet and a valve is the adjustment of the pressure of the working medium. The valve can make such adjustments, but the faucet cannot. Moreover, taking into account the operating rules of taps, it is strictly prohibited to regulate the pressure using them. The tap has only two functions: open and close the flow of the medium. But the valve can easily regulate the pressure of liquid or gas.

This difference is due to design. The shut-off element in this device moves in the direction of flow and eventually sits on the seat. In cranes, it rotates around its axis. In addition, there are ball valves. In their design, the shut-off element is a ball that rotates perpendicular to the flow, as a result of which the diameter of the pipe changes. But the valves are equipped with a ground axle box. This design solution implies that by moving the axlebox rod, the valve, which is attached to the rod, is raised or lowered. Thus, the opening or closing of the hole that is located in the saddle occurs.

Visually, it is easy to distinguish a valve from a faucet. If the shut-off valve has a simple handle, and the end of this handle is attached to the stem, then it is a faucet. If there is a thumb in place of the handle on the rod, it is a valve.

A gate valve is a type of shut-off valve used to shut off or change the flow volume of the transported working medium in technological, industrial and sanitary pipelines.

This article presents flanged valves. We will consider wedge, parallel, clinket, gate and hose modifications, and study design features fittings and its operational characteristics.

Contents of the article

Functional purpose and design features

Steel flanged valves differ from other types of pipeline fittings in that the locking mechanism in them moves perpendicular to the movement of the working medium. Such structures are produced in diameters of 15-2000 mm, they are intended for installation on pipelines, working temperature in which it does not exceed 600 degrees with a pressure of up to 25 MPa.

Gate valves are widely used in all areas of industry:

• water supply systems and heating communications of housing and communal services;
• oil and gas transport systems;
• main pipelines of the energy industry.

The spread of this type of pipeline fittings is due to the following operational advantages:

• simplicity and maintainability of the design;
• minimum construction length;
• reliability in difficult conditions operation;
• low level of hydraulic resistance.

Gate valves also have disadvantages, the main one of which is the large overall height of the structure, which is especially typical for products with a sliding-type spindle, in which the stroke of the rod must be equal to the full diameter of the passage opening. Also a disadvantage is the long opening time and the tendency to operational wear of the sealing elements, as a result of which the valves require periodic maintenance and.

Note that the design features of the valves do not imply their use as control valves - during operation the locking mechanism must be in the extreme open or closed position, and not in the intermediate.

Almost all types of valves are produced in a full-bore configuration - the cross-section of their passage opening is identical to the diameter of the pipes on which the product is installed. Reducing valves (with a narrowed cross-section of the passage opening) are also produced, but they have a narrow scope of use - they are installed only on pipelines, in order to control the valves on which it is necessary to reduce the torque exerted by the working medium.

The control mechanism in shut-off valves is a hand wheel; there are also designs equipped with hydraulic or electric drives, less often with a pneumatic drive. Large-sized valves that implement manual control, to facilitate opening efforts, they are equipped with a gearbox.

Manufacturing technology and materials used

Valves, depending on the manufacturing method, are classified into cast and welded. The casting method produces steel, aluminum and, using welding joints, titanium and some varieties steel products. In terms of strength and reliability, welded structures are practically not inferior to their cast counterparts.

The sealing elements of the fittings can be made of fluoroplastic, brass or rubber. Elastic materials (rubber and synthetic rubber - EPDM) are most often used in production (where the walls are covered with rubber locking mechanism) and hose structures (a pinch hose is made of rubber).

The valves have a type marking unified according to GOST No. 9698 30nzh42p du50, wherein:

• 30 - nomenclature of fittings (number 31 can also be used);
• nzh - designation of the material from which the structure is made, in this case nzh - stainless steel(s - carbon steel, ls - alloy steel, h - cast iron, tn - titanium);
• 42 — model number;
• p - material for manufacturing the sealing elements (p - plastic, br - bronze or brass, p - rubber, p - plastic);
• DN50 - diameter 50 mm (varies between 15-2000 mm).

Installation of flanged valve DN219 (video)

Operating principle and varieties

The operating principle of all types of valves is similar to each other. The body and cover of the valve form a cavity in which the shut-off unit is located. The body has flanges through which the valve is connected to the pipeline. Depending on the type of connection, the design can be flanged or wafer, which is clamped between the flanges of adjacent sections of the pipeline (a wafer valve has significantly smaller dimensions.

Inside the body, next to the locking element, there are two seats (parallel or at a certain angle to each other). The shutter is adjusted by rotating the actuator, to which the locking mechanism is connected via a rod. Depending on the principle of movement of the rod, the valve can be retractable (the rod performs a rotational-translational movement when closing) or rotary (exclusively rotational movement).

The rod is installed inside running nuts, this unit is called a threaded pair. The nut, when the drive rotates, ensures the movement of the locking element in a given direction. When the valve is moved to the closed position, its walls are pressed against the sealing surfaces of the seat, while in the open position the valve is completely out of the body bore.

The main classification of fittings is carried out depending on the type of locking mechanism, according to which valves are divided into:

• wedge;
• parallel;
• gate;
• hose

The shutter has a conical shape; when closed, it fits into the saddles located under given angle to each other and blocks the passage hole. Wedge, depending on design, can be hard or clinket.

A rigid wedge (steel) ensures maximum tightness in the closed position, however, the operation of such a design may be accompanied by a number of problems associated with jamming of the valve due to temperature fluctuations or damage to the sealing surfaces due to corrosion.

A flanged clinker gate valve has a gate consisting of two valves placed at an angle to each other, which are rigidly connected to each other. This design is characterized by increased reliability - it does not jam, the seals are subject to minimal wear, and changing the position of the shutter requires much effort. less effort. The flanged clinker valve is the most common type of ship fittings.

The valve consists of two disks that move between sealing seats located parallel to each other. A variation of the parallel design is, in which the locking unit has a similar design, but the shutter consists of 1 disk.

Gate valves are installed on pipelines with one-way movement of the working medium. Due to the simplicity of the design, it is not capable of ensuring maximum tightness of the ceiling, however, the gate valve is repairable, which allows the use of such structures in waste and sewer systems transporting liquid with a high content of mechanical particles.

Hose-type valves are fundamentally different from the previously discussed analogues. There are no sealing seats in their design - the working flow circulates inside an elastic rubber hose, which completely isolates the internal surfaces of the housing from the transported liquid. The flow is blocked by pinching the hose with a rod.

Such structures are intended for installation on pipelines transporting viscous substances and chemically aggressive liquids, under the influence of which accelerated corrosion of steel occurs - rubber is a material resistant to most chemical compounds. Operation of these valves is possible at temperatures up to 110 degrees and working medium pressure up to 1.6 MPa.