Types and functional features of the check flanged valve. Check valve (flanged, wafer type) Horizontal flanged valve

Flanged check valve Granlok RD30 is designed to protect pipelines from the reverse flow of the working medium. Designed for pipelines transporting technical hot, cold water, steam, neutral media.

Installation

check valve swivel can be installed both in horizontal and vertical position. Installation to the pipeline is carried out using flanges. The direction of medium flow must match the direction indicated on the valve. The valve is installed on a horizontal pipeline so that the axis of the disc is higher than the axis of the pipeline and is located in horizontal plane. On a vertical pipeline, valves are installed with the inlet pipe down so that the axis of the disk is in a horizontal plane

Specifications

Flange connection according to DIN 2501 (DIN 2633 at PN 1.6 MPa) / EN1092-2.

Mating flanges available Russian production according to GOST 12820-80, 12821-80 for PN 1.6 MPa.

Specification

Overall dimensions and parameters

In the lift check valve, the shut-off element is the lift spool. Under the action of water pressure, the spool rises, passing the flow. When the pressure drops, the spool drops onto the seat, preventing the flow from flowing back. Such valves are installed only on horizontal sections of pipelines. Required condition– vertical arrangement of the valve axis.

Valves are divided into four groups according to the method of attachment:

• Butt Weld Attachment: The check valve is welded to the pipeline. It is used when working in aggressive environments.
• Flange mounting: the check valve is connected to the pipeline through sealed flanges.
• Coupling: The valve is attached to the pipeline through a threaded coupling. Used in systems large diameter.
• Wafer fastening: the check valve does not have its own fastening unit. Clamped between pipeline flanges. It is applied on sites with restriction on dimensions.

Lift check valves with a protective mesh at the inlet and designed to be installed at the beginning of the suction pipeline are called foot valves.

Advantages of check valves:

• simplicity of design;
• reliable tightness;
• possibility of repair without dismantling the entire valve.

Disadvantages of check valves:

• big hydraulic resistance;
• the possibility of jamming the shutter in the guide part of the cover when using the valve in systems with a contaminated working environment;

Ball check valves

In a ball check valve, a ball element serves as a shutter. A spring is used as a clamping element, pressing the ball to the seat. Such valves are usually made for pipelines of small diameters and are used as household plumbing equipment. The check ball valve loses to the spring disc valve in dimensions.

Check valves, principle of operation:

In this design, the locking element is a spool - "slam". The axis of rotation of the "flap" is above the through hole. Under the action of pressure, the "clap" leans back and does not prevent the passage of water. When the pressure drops below the permissible value, the spool falls and slams the through passage. In large diameter check valves, swipe spool on the seat, which leads to a quick failure of the structure. During further operation, this provokes the occurrence of water hammer when the check valve is activated. Therefore, rotary check valves are divided into two groups: Simple - valves with a diameter of up to 400 mm. They are used in systems where impact phenomena cannot seriously affect the operation of the hydraulic system and the valve itself. Impactless - valves with devices that ensure a smooth and soft landing of the spool on the seat. The advantage of rotary valves is the ability to work in systems large sizes and low sensitivity to environmental pollution.

Check flange valve - a kind of protective pipe fittings. It differs from other modifications in the type of connection (flange). Refers to the types of direct acting valves with automatic control- allows the flow of the working medium in one direction. When the direction is reversed, the valve automatic overlap passage section. For this, the force from the gravity of the shutter, from the spring, from the lever-load mechanism is used.

Using Flanged Valves

The placement of check valves prevents the occurrence of emergency situations in pipeline systems during an emergency pressure drop. Flanged check valves are installed on pressure sections of pipelines (according to the number of pumps connected in parallel), on pipelines after a counter (flow meter), in complex systems heating, water supply, other working medium in areas that require movement in only one direction (make-up valves of closed systems; valves before cleaning filters).

Advantages

Flange design slightly increases the value connection size. This feature is offset by ease of installation, maintainability of the valve, unpretentiousness in operation (no need Maintenance). In addition, flanged check valves are reliable in operation and provide complete shut-off of the return flow of the working medium. It is possible to choose a full-bore valve design with a minimum of hydrodynamic losses.

Design features

Flanged valves have a cast metal (more often cast iron) body. Mounting flanges are provided on both sides. Internal construction determined by the type of shutter mechanism used. The most common types of mechanisms: lifting, ball, disk, rotary.

Installation of flanged valves

All types of flanged check valves are installed in the pipeline, taking into account the direction of direct flow. In lift-gate valves, normal closed position the shutter is supported by a spring. When the flow moves under the shutter, the valve opens. Mount such a valve on vertical, inclined, horizontal sections.

In ball valves, a locking element in the form of a metal ball is used. In the absence of flow or in the opposite direction, the ball under its own weight closes the through hole. The installation of such a flanged valve is carried out with the orientation of the ball chamber upwards.

The main task that the flanged check valve, installed on pipelines for various purposes, solves is to ensure the movement of the transported medium in one direction. Design features check valve, for the installation of which a flange is used, allow such a device to automatic mode stop the movement of the transported medium at the moment when such movement begins to be carried out in the wrong direction. Check valves of flange type are installed mainly on pipelines through which liquid media are pumped.

Features and applications of check valves

Check valves various types(including flanged ones) are used to protect the pipeline from:

• the occurrence of reverse flows of the working environment in it;
• hydraulic shocks.

The reverse flow in pipelines, as is clear from its name, is the movement of the working medium into opposite side. This can happen, in particular, when the pump that provides the supply of the working medium and its movement is switched off. If for heating systems such a phenomenon as reverse flow is not particularly critical, then in sewer and plumbing systems, as well as in pipelines through which oil products and other media are transported, its occurrence cannot be allowed. That is why the use of check valves in such pipeline systems is a mandatory requirement.

Another undesirable phenomenon, from the consequences of which pipeline systems are able to protect a flanged, wafer-type check or any other valve, is water hammer. It is characterized by the fact that in the pipeline there is sharp drop pressure of the transported medium, which leads to the formation of a shock wave passing along the entire length pipeline system.

Water hammer can eventually lead to the destruction of individual sections of the pipeline and the failure of the elements that are used to ensure it. normal operation. With the help of check valves installed by means of flanges or in any other way, the system is divided into separate isolated sectors, which makes it possible to effectively protect it from the effects of water hammer.

Operating principle

The principle by which check valves work is quite simple, meanwhile, such devices are very effective and are able to provide reliable protection parts of pipeline systems. Any check valve, regardless of the type, is made up of a body (steel or cast iron) and a locking element located in it. The locking mechanism works due to the pressure of a special spring, the rigidity of which can be adjusted.

The spring, which is equipped with non-return valves, ensures the opening of their locking elements only in one direction - in the direction of the correct movement of the transported medium. By exerting pressure on the locking element held by such a spring, the liquid or gas pumped through the pipeline opens it and begins to move in the required direction. As soon as the pressure of the working medium in the opening direction of the valve begins to fall, the locking element closes, preventing the liquid or gas from moving in the opposite direction.

Types and properties

The design of the shut-off elements of check valves, for the installation of which flanges are used, may be different. The choice of a flanged valve with a certain type of locking element depends on the tasks for which such a device is intended.

So, depending on the design of the locking element, there are:

• rotary valve;
• lift type check valve;
• non-return valve with ball locking element;
• double-leaf check valve;
• receiving check valve equipped with a grid.

The rotary check valve is locking device, the main part of which is a steel slamming disk fixed on a spring-loaded axle. At the moment when such a check valve is open, the disk in its inner part is parallel to the movement of the working medium, and when it is closed, it is perpendicular. Flanged swing check valve has a simple structure and, accordingly, low cost. If we talk about the disadvantages of check valves of this type, the most significant of them is that their rotary mechanism at the moment of closing, the locking disc slams too hard, which eventually leads to wear of the seat. Rotary check valves, equipped with a special mechanism that ensures smooth closing of the locking disc, are deprived of such a disadvantage. Meanwhile, such advanced flange rotary valves are more expensive, which somewhat limits their application.

In flange-type lifting check valves, a special spool is used as a shut-off element, which, under the pressure of the working flow, rises along the vertical axis, and when the pressure decreases, it falls to its seat, blocking the movement of the medium transported through the pipeline. It should be borne in mind that due to the peculiarities of their design, such valves can only be installed in a vertical position.

Ball check valves, as their name implies, use a spool made in the form of a ball as a shut-off element. Big size does not allow them to be used as wafer locking devices.

The double-leaf check valve, which is produced mainly in a wafer design, involves the use of two slamming flaps in its design at the same time. Each of them is connected to a spring, which regulates the force of their resistance to the pressure of the working flow. Wafer type butterfly valve due to small sizes its locking elements - sashes - are very compact in size.

Check valves, the design of which is additionally equipped with strainer, are used for installation on pipeline systems for pumping oil, gas or water from underground sources. Such devices are most popular model which is 16Ch42R, simultaneously solve two important tasks: their locking mechanism does not allow liquid or gas to return back to the source, and the mesh protects the pipeline from large debris entering it.

Model 16Ch42R, which body is made of steel or cast iron, is highly versatile and can be installed on pipelines or pumps used for pumping both liquid and gaseous media.

Flanged vs Wafer Check Valves: Differences

Check valves that use flanges for installation in piping systems can be one of the following types:

• flanged;
• interflange.

On flange-type devices, the flange on the supply part and the return flange are welded to the valve body and form an integral whole with it. Flanged check valves are mainly used to equip large-diameter pipes, with the help of which the transport of working media is carried out on an industrial scale.

There are virtually no fasteners in wafer type check valves. This type of installation, as mentioned above, is very often used for the installation of double-leaf check valves. In this case, the valve itself (in particular, a double-leaf wafer valve) is installed between two flanges fixed at the ends of the connected pipes. After being placed in special seats, which are equipped with sealing elements, the flanges are pulled together with threaded studs. Despite the apparent unreliability of such a connection, if it is done correctly, the wafer check valve is fixed with the same reliability as any other type of device.

Check valves can be installed on pipeline systems using not only flanges, but also couplings or welded joint. However, if we talk about pipelines of large diameter, such valves are installed on them only using flanges.

Advantages and disadvantages of flange type check valves

Since flange type check valves are most often used to equip pipelines through which the working medium is transported with high intensity, internal elements such devices (in particular, the locking mechanism) experience significant shock loads during operation. In addition, the flange-type check valve, due to its significant dimensions, is itself the cause of water hammer. In the process of closing the valve flaps in the pipeline in which it is installed, the pressure inevitably increases, which leads to the formation of a water hammer.

In those pipeline systems in which water hammer is not able to have a significant impact on performance as individual elements, and the system as a whole, check valves are used simple type. The diameter of the latter, as a rule, does not exceed 400 mm. In other cases, non-impact type check valves are used. Smooth and soft closing of the locking element in flanged valves of the non-impact type can be provided by special weights or hydraulic dampers. Meanwhile, when choosing non-impact type check valves for equipping a pipeline system, it should be borne in mind that they can only be installed in horizontal sections.

Some of the most significant benefits of flanged check valves include:

• compact dimensions, which allows you to install such devices on almost any part of the pipeline system;
• possibility effective work even in those systems in which the working environment is characterized by severe pollution;
• the possibility of installation on pipelines with a large diameter.

Features of choice

The main parameters that you should pay attention to when choosing a check valve (including a flanged one) are:

• operating pressure at which such a device can operate;
• conditional diameter.

You can find out what operating pressure the check valve corresponds to by marking the device, in which this parameter is denoted by the letters RU. The numbers in the marking after such letters indicate the working pressure for which the device is intended. For example, the designation RU16 indicates that a flanged valve can operate at a pressure of 16 bar without being subject to excessive wear.

The nominal diameter, on which it depends on which pipeline a flange-type valve can be installed, is indicated by the letters DN. Accordingly, the numbers following these letters in the marking indicate the nominal diameter of the check valve in millimeters. When choosing a check valve for this parameter, keep in mind that such a product can only be mounted on pipeline elements that have the same dimensions. In other words, model DU80, for example, can only be installed on pipes or other elements of the pipeline system, the bore diameter of which corresponds to a value of 80 mm.

When installing flanged check valves, the following rules must be strictly observed.

• Installation must be carried out by specialists who have previously been trained and received permission to perform work of a similar plan.
• The part of the pipeline system where installation is performed is completely disconnected from the supply of the working medium.
• Before starting installation, make sure that the product to be installed fully complies with those climatic conditions in which it will be used.
• If a wafer check valve is installed, then its flange part is first mounted, and only then it is fixed in it.
• Before supplying the pipeline with the flow of the working medium, it is necessary to check again that the check valve is installed securely and all the required connections are made.

In conclusion short video with a visual demonstration of the principle of operation of a rotary check valve.