Protective valves in our lives are ubiquitous. In any house, in any plant, gas station, oil well, farm, boiler room, and even when entering water into an apartment, check valves are used everywhere to protect the system and equipment from the reverse flow of water, gas, fuel and many other fluids.

We welcome our reader and bring to your attention an article on a variety of protective fittings for pipelines.

Wafer type check valve - protecting networks and equipment.

Check valve - protective pipe fittings that allow fluid flow in one direction and block the movement of the medium in the opposite direction. It is a direct-acting valve; it is triggered automatically when the working medium returns.

By design, check valves are divided into:

• on ball or receiving;
• back gates;
• interflange;
• combined (combined with valves).

Wafer products are characterized by their compact size and installation method - in flange ruptures of pipelines.

Appointment and scope

Using reverse valves, they protect piping systems, equipment, pumps, heating boilers, automation from water hammer; in case of leakage or destruction of part of the system, they reduce leakage.

In technological schemes check valves are used:

• in closed systems for recharge;
• after installation of meters and other instrumentation;
• in systems with several pumps;
• in heating systems at the jumper between the supply and return pipelines;
• in all kinds of supply pipelines where the movement of the medium in one direction is required;
• in ventilation systems;
• in filtering systems, treatment facilities - to ensure the movement of fluid through the filter or in only one direction;
• in everyday life - in wells together with a deep-well submersible pump, in quick-disconnect couplings of irrigation systems, in thermostatic fittings of heating systems in private houses.

The scope of application of protective valves - in all areas of industry, mining, household, agriculture, transport, gas transmission system.

Check valves are used in systems with both liquid and gaseous media.

Management and specifications

Type of connection

Wafer type check valves can be installed in the pipeline both vertically and horizontally.

A design feature of connecting such valves is that they do not have flanges for installation in the pipeline - they are clamped between the pipeline flanges.

Device

Wafer designs are characterized by the absence of flanges. In the case they have a working body - a disk, sashes, which, when the medium current changes to the reverse, block the passage and do not allow the reverse flow of gases and liquids.

Operating principle

The principle of operation of reverse valves is based on the fact that in the absence of a medium flow, the working body (disk, spool, ball) moves under the action of its own weight and additional devices to the “closed” position (it sits in the saddle of the body).

When a flow occurs, the valve moves under its pressure to the “open” position and opens the passage through the seat. If the flow of liquid or gas reverses its position, it stops, the shutter moves to the closed position, then the pressure of the liquid or gas additionally presses the spool, ball or disk - the passage is reliably closed.

The non-return valve is activated automatically by the action of the moving medium, without additional control and regulation.

Types and designs

Structurally, wafer type check valves are double-leaf and spring-loaded disk.

Spring-loaded disc models (they are sometimes called single-leaf) have a shutter in the form of a flat disc, which in the closed position is pressed against the housing saddle by a spring.

A thin disk takes up little space in the case, which greatly reduces the weight and construction length of the mechanism. The use of a spring and the light weight of the disc makes it possible to install the fittings in both vertical and horizontal positions.

Such models are installed on pipelines with a working diameter of 15-200 mm.

Double-wing models are more reliable than disk ones and are used in more complex and larger systems with working diameters from 50 to 700 mm.

In a double-leaf check valve, the shutter elements are two flaps (segments or petals) fixed on an axis. The axis passes through the center of the aisle, and springs are attached to it.

In large hydraulic or pneumatic systems, dangerous hydraulic shocks often occur (in emergency situations, shutting down pumps, etc.). In such cases, valves with shock absorbers are used, damping sharp pressure surges in the hydraulic system.

Check valves for the material from which they are made are:

• from structural alloyed steel;
• from stainless steel;
• from brass and bronze;
• from cast iron;
• from titanium;
• from aluminum;
• from bronze;
• combined.

In the marking in second place are letters that indicate the material.

Differences between flange and interflange valves

Flange models differ from interflange:

• construction length - in flange models it can be 6-8 times longer than in interflange models;
• the mass of flanged models can be 5 times more;
• according to the installation method: flange mounted in the pipeline using flanges;
• interflange clamped between the flanges of the pipeline.

Advantages and disadvantages

Benefits:

• small dimensions, including construction length;
• light weight;
• affordable price;
• the ability to install on vertical and horizontal sections of the pipeline;
• simple construction;
• reliability;
• maintenance free
• good maintainability.

A significant drawback of interflange products is a significant loss of pressure on the valve (since there is a working body in the aisle - shutters with an axis, a disk). When installing in large hydraulic systems, it is necessary to take into account the pressure loss in the calculations of the system parameters. Disk models inhibit the current of the medium more strongly than the casement ones. Disk models do not work well in conditions where there are impurities in the liquid, such as sand.

It should be borne in mind that check valves do not replace conventional shut-off valves and gate valves.

In almost everyday life, we may encounter the installation of a clutch check valve (clutch lock) after the water meter and at the input of the heating system. Choosing a shutter for the meter makes almost no sense - they are sold everywhere and are available in every region. technology and design are also the same everywhere. The material is brass. The main thing is to buy in a store, with a check, a guarantee and inspect visually. The most important thing is that the conditional diameter matches the diameter of the water meter!

Work on the input of the heating system must be carried out by public utilities. But it is likely that under certain conditions, the residents of the house will still have to buy and choose components for the input node. The most important thing is a purchase in a construction hypermarket, with a guarantee, of the required nominal diameter. The choice of materials is very important: the ideal, but expensive option is stainless steel or brass.

The best option in terms of price / quality ratio - structural steel with a working body made of stainless steel - also works well and takes a long time.

Rules for installation and operation of the device

Necessary tools and materials

For the water meter you need: the valve itself, gaskets of the desired diameter (preferably made of silicone), two adjustable spanners, FUM tape.

Wiring diagram

The valve is installed immediately behind the meter.

During installation, make sure that the direction of the water flow coincides with the arrow on the device.

Progress

Installation Order:

• a water meter pipe with a union nut is disconnected from the water meter;
• the pipe thread of the apartment or house network and the water meter pipe are carefully wrapped with FUM tape;
• screw the nozzle into the valve;
• screw the valve onto the thread of the internal network, the arrow of the direction of the water flow should be directed from the meter;
• a gasket is installed in the union nut;
• screw the nut onto the meter connecting pipe;
• they let water in and test the connection; if there is a leak, tighten the connections.

We suggest watching the installation of a non-return valve on a water meter in the video:

Common installation errors and problems

There can be only one mistake: installation is not in the direction of movement of water. And there may be leaks.

When installing the valve in the opposite direction, water will not flow into the meter and the apartment - you will have to unscrew it and mount it again. When leaking, tighten the connections.

When installing a water metering unit, especially in a steel water supply system, it may be inconvenient to carry out installation - there will not be enough space to wind up a union nut at the last moment. In this case, it is worth supplementing the metering unit with another union nut - “American” on the valve side (such as “nut-fitting”).

In any systems, the design of which provides for the presence of the pipeline, it is provided that the working medium is transported in one direction. In order not to encounter a change in the direction of its movement, which can lead to failure of the entire system, various technical devices are used, one of which is an interflange check valve. They are equipped with pipelines used by oil refining and chemical industries, through which both liquid and gaseous working media are transported.

Wafer type check valve - stainless steel “flap” for operation in various aqueous environments

Design features and specifications

The interflange valve, like all non-return valves, is used to block the flow of a gas or liquid medium if it starts to move in the wrong direction. In other words, this is a kind of locking device. Check valve flanges, unlike many others, can be installed both in horizontal and vertical position. Depending on the features of their design, they can be:

1. spring loaded;
2. pneumatic made of stainless steel;
3. clamshell made of cast iron;
4. rotary type made of stainless steel.

The installation process for wafer closures of all the above categories is the same and does not cause any difficulties.

Among the advantages possessed by check valves related to the wafer type, compact dimensions should be noted, which makes it possible to use them in cramped conditions, where it is not possible to use other valve products. Thanks to the use of such compact valves, it is possible to reduce the length and other parameters of the mounted system, which is important in many situations.

There are several of the most common modifications of the wafer type check valves, each of which differs in certain technical characteristics. So, if we talk about models of such devices, then among them should be highlighted:

• 19С53НЖ - devices that are simple to operate and maintain;
• 16CH42R - reverse type interflange valves, which are made of especially durable materials;
• RU16 - models that are characterized by high reliability of the connection created with their help.

Main varieties

If you review the most popular valve devices of the reverse type, then you should start with rotary models, in particular with the DU150 wafer valve. DU150, like other models, passes the flow of the working medium through itself in only one direction. If the direction of flow of the working fluid changes, the valve is automatically blocked, and its shutter closes.

Among the check valves belonging to the class of rotary valves, there are:

• simple;
• unstressed.

The shut-off element of the rotary type check valves is a spool, which allows them to be used even when working with a heavily polluted working environment. In addition, the design features of such valve devices make it possible to use them for pipelines of even a significant diameter (from fifty to one hundred and fifty millimeters).

Rotary check valves, the structural elements of which are made of brass, are used to equip heating systems, as well as water and heat supply systems. The design of such valves, working mainly with a liquid working medium, includes a mesh that performs the function of a filter element.

Depending on their design, rotary check valves can be of one of three types:

• coupling;
• flanged;
• interflange.

Interflange devices, in turn, are divided into check valves of the following types:

• stainless steel back wafer lock;
• double-leaf wafer type check valve;
• cast iron inverted butterfly valves.

Popular models of non-return valve interflange devices, for the manufacture of which steel alloys are used, are also DN25, 32, 50, 80, 110. The most significant advantages of these valve devices are their compact size and affordable cost. Meanwhile, when using interflange valves in the pipeline, a significant pressure loss of the transported working medium occurs.

Among the many non-return valves offered by modern manufacturers, one should single out a lifting flange valve ДУ150 and model ДУ100, which are installed and successfully used on pipelines for various purposes. Mention should also be made of a brass non-flange check valve with two wings fixed on one axis. Valve devices of this type, which are unpretentious in the installation, are used to equip pipelines whose diameter is in the range of 50–80 mm.

Flanged valve devices according to the material of manufacture are divided into products of the following types:

• back wafer steel valve with a protective mesh;
• cast iron check valve, also equipped with a mesh that acts as a filter element.

Valves made of cast iron or steel alloy are distinguished by their large size and weight, which somewhat limits the scope of their application.

In order not to lose much of the pressure of the working medium transported through the pipeline, it is possible to use spring-type check valves for its equipment, which can be made of both cast iron and brass alloy. Flanged check valves are also equipped with a spring, the most popular models of which are DN50, 80, 110. Their great advantage is that they can be installed both in horizontal and vertical position. In addition, interflange spring check valves are able to successfully resist the phenomenon of water hammer.

Closing the shutter in non-spring check valves is ensured by the force of gravity that the shutter possesses. Their installation can be carried out both in horizontal and vertical position, but only if the flow of the working medium transported through a vertical pipeline is directed from the bottom up.

Today, ventilation systems are also equipped with reverse air locks, which is necessary in order to prevent polluted air from getting back into the ventilated room. Such devices can be found in ventilation systems serving not only industrial, but also office and household premises (kitchens, sanitary facilities, etc.). In addition, ventilation systems that are installed in public buildings - shopping and entertainment centers, shopping malls, etc. are equipped with check valves.

The design of check valves installed in ventilation systems forms a rotating axis, on which special blades are fixed. These blades can cut off the air flow due to a special spring or gravity.

Another type of such devices is a poppet (or disk) check valve, the locking element of which is a disk located in the seat with a sealing element. The locking element in the disk check valve is fixed on the stem, which is able to move freely in the device. Disk type check valve can be interflange and coupling. It is used to equip both pipelines through which gas fluids are transported, and ventilation systems.

Check Valve Modifications and Manufacturers

Among the popular manufacturers of reverse valve devices, the following companies can be distinguished:

• Tecofi (France);
• FAF (Turkey);
• FERRO (Poland);
• Westshintorg (Republic of Belarus).

If we talk about the most popular models, then they are valves DU32, 50, 80, manufactured by the French company Tecofi. These models, for the manufacture of which stainless steel is used, are practical, highly reliable and have a long service life, which makes them so popular among domestic consumers.

The main parameters that affect the cost of reverse-type valve devices are:

1. appointment;
2. constructive design;
3. material of manufacture;
4. the dimensions of the valve and the cross section of its mounting holes.

A brief overview of the main technical characteristics of the most popular models of check valves will provide an opportunity to get an idea about these devices.

  DN50

The check valve body of this model (16CH42R) is made of cast iron, and its closure part is made of brass. Due to the manufacture of the gate part ДУ50 of stainless material, it can be used to equip pipelines through which water and steam are transported. The check valve of this model can operate at a temperature of the working medium exceeding 225 °, and at a pressure of 1.6 MPa.

Such a check valve is installed on both horizontal and vertical pipelines. Moreover, on vertical pipelines it is located with the inlet pipe down, and on the horizontal axis of rotation of its flaps should be in a horizontal plane.

  DN80

Wafer type check valve ДУ80, the casing of which is made of galvanized steel or cast iron, and the sealing element is made of rubber, can be used for installation on pipelines that transport hot and cold water. The maximum temperature of the working medium that the DN80 can withstand is + 90 °, and the maximum pressure is 1.6 MPa.

  DN100

This disk-type check valve has elements made of electroplated steel. DU100 can be used in pipelines that transport cold and hot water and steam, is able to withstand a pressure of 1.6 MPa and a temperature of + 130 °.

  DN150

The body of the interflange check valve of this model, used to equip pipelines for various purposes, is made of cast iron, and the locking elements, which are two spring-loaded valves, are made of stainless steel. DU150 is also used to equip pipelines through which oil products are transported, and can be installed both in horizontal and vertical position. The operating pressure at which the check valve of this model can be operated is 1.6 MPa.

As a rule, non-return valves can be conditionally divided into two categories, depending on the particular connection with the pipeline - flange or interflange connection.

What is a flanged check valve

For example, flanged check valve  actively used in the water supply system, thereby preventing possible water hammer or the appearance of a reverse water flow. Such a device does not belong to the group of valves. According to its own design features, this model can be of several types: spring, ball or lifting.

The presented device is used to pass various liquids exclusively in one specific direction, and a special flange connection is used as a mount.
  In general, the flange is the corresponding connecting part of the pipeline system, which is a disk or a small frame with special holes for bolts.
  Such a valve is mounted on horizontal pipes in order to automatically shut off the flow of water or other working fluids that are transported through the pipeline. These devices can be considered a regulatory mechanism.

What is an interflange check valve

As for the second type of connection, it is customary to use interflange models for installation on appropriate technical pipelines for high-quality protection and quick shut-off of the water flow in automatic mode. The wafer type check valve is used for all kinds of liquids, including gas or steam. Due to certain design features, such devices are characterized by maximum tightness and can completely eliminate the possibility of even the smallest water hammer.

Unlike flanged models, flange valves  can be installed absolutely in any convenient position - horizontally or vertically. During installation, such a valve will be firmly fixed between the two flanges (hence the name). It is important to note the fact that the flow of incoming fluid should go towards the valve disc itself, where a special arrow will indicate.

In heat and water supply systems it is customary to use thermal shutoff wafer devices that guarantee high quality protection for any pipeline.

Where can I buy both types of pipe fittings

You can order and purchase on our official website right now.

The interflange check valve will help to reduce damage from accidents in the water supply system, restrain water hammer, and give stability to pressure. This shut-off element in the pipeline performs the following functions:

• prevents the fluid flow from reversing. A similar danger arises from a drop in pressure, its drops;
• equalizes the flow head in case of water hammer, emergency.

Mount shut-off devices in plumbing, heating mains, sewage.

Benefits of Locking Modules

Wafer type reverse locking devices are popular with consumers due to the following advantages:

• suitable for installation at any point on the highway;
• can serve both horizontal and vertical pipelines;
• have small dimensions, lengthening pipelines only slightly;
• cost little.

Specificity of the dangers against which the non-return valve protects

Fluid flow in technical lines can change direction due to various reasons. For example, in the pipes of the heating system, the heat-carrying liquid must flow continuously, which is ensured by the operation of special pumps. Pumps direct pressure to the flow so that it moves. If a malfunction occurs in one of the pumps and it stops, a vortex type funnel forms in the pipe, and the pressure difference provokes a reverse flow in the opposite direction.

Water hammer is a shock wave that has arisen due to a sharp change in pressure in the pipeline. Such a wave has sufficient strength, runs along the entire length of the pipe. Strong areas stand in front of it, worn areas can be seriously damaged.

Water hammers in water mains occur with a certain periodicity, therefore, locking interflange mechanisms are mounted in them, which protect the pipes from premature wear and accidents. Constipation on both sides isolates the pipe section where the pressure drop occurs, do not allow the shock wave to spread along the highway, damage it.

Functionality, technical parameters, basic information

The locking device operates according to a simple principle. A valve installed in the direction of flow passes fluid through itself. This occurs when a pressure of sufficient force presses on the valve flaps, thereby opening them. If the pressure decreases, the flaps close, hermetically blocking the channel.

Wafer-type valves differ from standard ones in the absence of mating flanges in the design, which must connect the valve to the pipe. The installation of the mechanism in the pipe is made by simply clamping it between its flanges. Because of this feature, the design is compact, has reduced dimensions, five times less weight, eight times less building length in comparison with shutters of other designs. All this significantly reduces the cost of acquisition, installation.

The dimensions of the valves, the gasket material must correspond to the magnitude of the flow of the working fluid, its properties. Most often, sealing surfaces are made of rubber, brass, bronze. They may be fused with steel or alloys that are resistant to corrosion. These gaskets provide the tightness of the shutter element shutter. Install non-flange check valves without using a threaded connection, and insulating rubber gaskets serve as a sealant.

The sealing material may be paronite. It is made of several components (rubber, asbestos powder, powder fillers), a mixture of which is vulcanized to a flat web, then rolled. Paronite gaskets are able to seal even aggressive liquids of high temperatures under strong pressure (water heated to a temperature above 100 degrees, liquids containing alkalis, salts, acids, etc.).

Cases of devices are made of cast iron, brass, alloys, less often - stainless or ordinary steel. Cast iron mechanisms with stainless steel dampers are universal, suitable for work in highways for various purposes.

The double-wing interflange check valve, depending on the model, can have a diameter of 50-700 mm. The most popular non-return valve for water is 150 mm wafer.

Lining (inner lining) of locking devices can be:

• anticorrosive;
• rubber (for technical fluids);
• plastic (for drinking water).

The inter-flange spring check valve has a spring as a clamping element, and the plate (disk) performs the shutter function. This allows the valve to be lighter, have a small construction length. Such devices are usually used for trunks of small diameters (15-200 mm). Spring models often have special threaded holes that remove the charge of static electricity, which is especially important for the production of chemical explosive substances.

Usually, shutoff valves withstand the temperature of the working medium (water) up to 120-225 degrees Celsius. Products with a rubber seal can withstand not too high temperatures.

Double-wing interflange check valve: types, features

By the number of valves, a single-leaf interflange and double-leaf valve is distinguished. Devices with two shutters can be equipped with a spring, optimal for installing pipes with a diameter of 5-8 cm.

By the type of locking mechanism, there are different gate modules.

1. Lifting. Its design is simple: the fluid flow lifts the spool vertically along its axis, when the flow force weakens, the sash lowers into the hole due to its weight, blocking it.
2. Spring: the spring presses on the leaf, if the opposed pressure of the jet is insufficient to withstand its force, the flow is blocked.
3. Check valve disk interflange. It is usually made of electroplating. Suitable for servicing pipes with water of any temperature (up to 130 degrees and above) under pressure up to 1.6 MPa.
4. Swing check valve interflange (shock, unstressed). Acts like a spool device, equipped with a filter (mesh). The flow is controlled by a flap closing on a spring. Indispensable for communications of large diameters (up to 15 cm), pipelines transporting contaminated liquid. Most often it is used for high temperature flows (heating communications, water supply branches supplying hot water). Their most popular diameter is 5-11 cm.

Installation of valves in the pipeline: features, process description

When installing the valve, additional components are required:

• rubber gaskets (both DN-40, 50, 80, 100, 150, 200);
• bolt M16 * 70, 20 * 90;
• nut, washer, stud, all in size M16, 20.

Seals made of paronite before installation, it is useful to treat with graphite powder to prevent sintering them with pipeline elements.

Installation procedure

First of all, the technical characteristics of the locking element, the documentation for it, are carefully studied. An external examination is carried out to detect damage, if any. Flawed valves are not suitable for installation in the pipeline. Operating parameters during operation must comply with those specified in the accompanying instructions.

Product labeling

Shut-off valve models are indicated by two abbreviations that tell the user their main characteristics.

In the article "RU" the working pressure is encrypted at which the shutter can work. Most often, this figure is 16 atmospheres.

The parameter "ДУ" (or "DN") denotes the diameter of the nominal bore, that is, the internal diameter of the part in millimeters, usually has a value of 40-600 mm.

Mounting

Install the valve, guided by several principles.

1. The place for installation is determined in advance. It is desirable that access to the selected point be free. If the constipation needs to be installed in the area of \u200b\u200bthe pipe bend, it is mounted in the direction of flow in a straight section, slightly departing from the bend, and not immediately after it. This is explained by the fact that in the inner region of the “knee” the fluid flow is the smallest, it may not have enough force to open the damper, some distance is required to stabilize the flow.
2. The diameters of the locking mechanism and pipe must match.
3. When assembling the system, the locking device is mounted in series. When it is installed in an existing system, part of the pipe is cut out and a valve is fixed to this place.
4. In horizontal pipes, the valves are fixed so that the axis of the valves is horizontal, in vertical pipes, with the inlet down.
5. Collar flanges are attached to the pipe, a locking mechanism is inserted between them. The distance between the flanges must absolutely exactly match the size of the valve so that the connection is tight.
6. Upon completion of installation, the operation of the system is checked. Before starting the pipe work, it is useful to purge it to eliminate mechanical litter.

During installation, the shutter mechanism is oriented in the direction of flow, for this there is a special pointer in the form of an arrow or hook on the lock.

After installation, the locking module functions independently; it does not need any maintenance.

How to choose and buy locking elements

In order to correctly select the interflange reverse locking devices for the parameters of a particular pipeline, the following aspects are clarified:

• type of working medium, its temperature, pressure;
• optimal design of the locking mechanism;
• dimensions, valve material.

All these indicators affect the final cost of products.

The company Techarmatura presents for sale an interflange valve of various diameters. The products are capable of working with process media with temperatures from 120 to 225 degrees Celsius. The proposed valves can serve different types of media: drinking water, industrial, hot, cold.

The quality, reliability of locking valves is confirmed by their guarantee, quality certificates. The level of shutter quality is determined by a double check: water flow, air stream.