Vertical flanged check valve. Flanged check valve. Disadvantages of check valves

A flange check valve is a type of protective pipeline fitting. It differs from other modifications in the type of connection (flange). Refers to types of fittings direct action With automatic control– passes the flow of the working medium in one direction. When the direction is changed to the opposite, the valve automatically closes the flow area. For this purpose, 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 in the event of 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 the meter (flow meter), in complex systems heating, water supply, and other working media in areas that require movement in only one direction (feeding valves of closed systems; valves in front of cleaning filters).

Advantages

The flange design slightly increases the size of the connecting size. This feature is compensated by the ease of installation, maintainability of the valve, unpretentiousness in operation (no need for Maintenance). In addition, flanged check valves are reliable in operation and provide complete shutoff of the reverse flow of the working medium. It is possible to select a full bore valve design with a minimum of hydrodynamic losses.

Design Features

Flanged valves have a cast metal (usually cast iron) body. There are connecting flanges on both sides. The internal design is determined by the type of bolt mechanism used. The most common types of mechanisms are: 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 forward flow. In valves with a lift-off mechanism, the normal closed position of the valve is maintained by a spring. When flow moves under the valve, the valve opens. Such a valve is mounted on vertical, inclined, and horizontal sections.

Ball valves use a locking element in the form of a metal ball. In the absence of flow or in the opposite direction, the ball, under its weight, blocks the passage hole. Installation of such a flanged valve is carried out with the ball chamber oriented upwards.

A check valve is a safety valve that is installed on a pipeline. the main task details - prevent reverse stroke substances in the event that the pump is switched off or fails, the pipeline breaks. Simply put, a valve is a safety device that activates automatically.

What is special about a check valve?

An element such as a check valve protects pipelines, equipment and the pumps themselves during emergency situation. At the same time, the valve is used to combine the activities of several pumps into one line. The main task of the valve in this case is to protect devices from excessive pressure.

The mechanism of action of the device is simple. If there is no flow of the working medium, the flap is in the closed position under the influence of its own weight. If the working medium moves through the pipeline, then the seat opens under its weight. But as soon as the substance changes direction, the flap returns to its original position.

All check valves are divided into two categories:

check valves - made of steel and cast iron. The main areas of application are water supply and heating systems, water distribution and pumping stations. There are rotary, lifting, spring, coupling and reverse;
check valves - the valve is made in the shape of a disk.

Return products are most often installed on horizontal sections of pipelines.

Five benefits of safety valves:

simplicity of structure - makes it possible to easily and quickly maintain and repair parts;
small stroke - to completely block the passage, only 0.25 Dу is required;
compact dimensions and low weight;
additional regulatory functions;
the ability to operate the pipeline at high operating pressures and significant pressure drops.

The PASADOR company offers to buy check valves of various modifications according to attractive prices. We supply products to all regions of Russia.

Pipeline fittings of this type are used to prevent the reverse movement of the working medium (water hammer or back pressure). Our range includes threaded, flanged and wafer products designed for industrial and household use and designed for long service life.

The advantages of check valves are:

automatic operation without additional energy consumption;
reliability;
performing functions both in normal and emergency operating conditions;
no significant impact on the pipeline capacity.
opening the valve at a minimum pressure of 0.5 bar (gravity).

From us you can buy check valves for domestic and process water supply, heating, steam systems, oil and chemical industries, sewerage at reasonable prices. The products can be used in pipelines for transporting non-aggressive liquids and gases.

The catalog presents check valves with threaded, flange and wafer mounting in a body made of cast iron, carbon and of stainless steel, brass, bronze. Most models are designed for horizontal and vertical installation.

The design consists of a body and a shutter, the mechanism of which is a spool. In the absence of flow, fittings of this type are in a closed state. Under the influence of a moving working environment, the shutter automatically opens and closes when it stops. The spool only opens in one direction, so reverse flow environment is excluded.

Types of check valves

We offer ball and straight line check valves with various types fastenings

Regular walk-through models are designed for horizontal installation only. Ball check valves can be installed in horizontal and vertical positions, since they use a ball element as a valve. These types of fittings are available with threaded and flange mounting.

Wafer check valves are installed in flanged pipe breaks. They can be mounted in vertical and horizontal positions. A flat disk is used as a shutter. Designs with double-leaf valves are equipped with damping elements to successfully resist water hammer.

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

Features and applications of check valves

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

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

Reverse flow in pipelines, as is clear from its name, is the movement of the working medium in the opposite direction. This can happen, in particular, when the pump that supplies the working fluid and moves it is turned off. If for heating systems such a phenomenon as reverse flow is not particularly critical, then in sewer and water supply systems, as well as in pipelines through which petroleum 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 which pipeline systems can be protected by a flanged, wafer check or any other valve is water hammer. It is characterized by the fact that a sharp pressure drop of the transported medium occurs in the pipeline, which leads to the formation of a shock wave passing along the entire length pipeline system.

Water hammer can, over time, lead to the destruction of individual sections of the pipeline and the failure of elements that are used to ensure its normal operation. With the help of check valves installed using flanges or any other method, 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 operate is quite simple, yet such devices are very effective and are able to provide reliable protection parts of pipeline systems. Any check valve, regardless of type, consists of a body (steel or cast iron) and a locking element located in it. The locking mechanism operates due to the pressure of a special spring, the rigidity of which can be adjusted.

The spring with which check valves are equipped ensures that their locking elements open in only one direction - in the direction of the correct movement of the transported medium. By exerting pressure on the shut-off 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 direction of opening the valve begins to fall, the shut-off 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 installation of which flanges are used, can be different. Selecting a flanged valve with a certain type locking element depends on what tasks such a device is intended to solve.

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

rotary valve;
lift type check valve;
check valve with ball shut-off element;
double-leaf check valve;
intake check valve equipped with a mesh.

A rotary check valve is locking device, the main part of which is a steel slamming disk fixed on a spring-loaded axis. At the moment when such a check valve is open, the disk in its inner part is located parallel to the movement of the working medium, and when closed, it is perpendicular. The flange check valve has a simple design and, accordingly, low cost. If we talk about the disadvantages of check valves of this type, then the most significant of them is that their swivel mechanism at the moment of closing, the locking disc slams too hard, which over time leads to wear of the seat. Rotary check valves, equipped with a special mechanism that ensures smooth closing of the locking disc, do not have this drawback. Meanwhile, such advanced flange rotary valves They are more expensive, which somewhat limits their use.

In flange-type lift 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 lowers to its seat, blocking the movement of the medium transported through the pipeline. It should be borne in mind that such valves, due to their design features, can only be installed in a vertical position.

Ball check valves, as their name suggests, use a ball-shaped spool as a shut-off element. Big size does not allow their use as wafer locking devices.

A double-leaf check valve, which is produced mainly in a wafer design, involves the use of two slamming flaps simultaneously in its design. Each of them is connected to a spring, which regulates the strength of their resistance to the pressure of the working flow. The wafer-type double-leaf valve, due to the small size of its shut-off elements - the flaps - is characterized by very compact dimensions.

Check valves, the design of which is additionally equipped mesh filter, are used for installation on pipeline systems for pumping oil, gas or water from underground sources. Such devices, the most popular model of which is 16CH42R, simultaneously solve two important problems: their locking mechanism prevents liquid or gas from returning back to the source, and the mesh protects the pipeline from large debris entering it.

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

Flanged and Wafer Check Valves: Differences

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

flanged;
wafer

On flange-type devices, the supply flange and the return flange are welded to the valve body and form a single unit with it. Flanged check valves are used primarily for fitting pipes large diameter, with the help of which the transportation of working media is carried out on an industrial scale.

Wafer check valves have virtually no fastening elements. This type of installation, as mentioned above, is very often used for installing 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 its placement in special seats, which are equipped with sealing elements, the flanges are tightened together using threaded rods. Despite the apparent unreliability of such a connection, if it is made correctly, the wafer check valve is fixed with the same reliability as devices of any other type.

Check valves can be installed on pipeline systems using not only flanges, but also couplings or a welded connection. However, if we talk about large-diameter pipelines, 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 fluid is transported with high intensity, the internal elements of such devices (in particular, the shut-off mechanism) experience significant shock loads during operation. In addition, a flange-type check valve, due to its significant dimensions, itself causes water hammer. During the process of closing the valve flaps, the pressure in the pipeline in which it is installed 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 the performance of both 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 during flanged valves shockless type can be provided by special weights or hydraulic dampers. Meanwhile, when choosing non-impact type check valves to equip a pipeline system, you should keep in mind that they can only be installed in horizontal sections.

The most significant advantages of flanged check valves include:

compact dimensions, which allows the installation of such devices in almost any area of the pipeline system;
opportunity efficient work even in systems where the working environment is highly polluted;
Possibility of installation on pipelines with large diameters.

Features of choice

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

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

You can find out what operating pressure the check valve corresponds to by looking at the device’s marking, in which this parameter is designated by the letters RU. The numbers in the marking after such letters indicate the operating 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, which determines which pipeline a flange-type valve can be installed on, is indicated by the letters DU. Accordingly, the numbers following these letters in the marking indicate the value nominal diameter check valve in millimeters. When choosing a check valve according to this parameter, keep in mind that such a product can only be mounted on pipeline elements that have the same dimensions. In other words, the DU80 model, for example, can only be installed on pipes or other elements of the pipeline system, the mounting diameter of which corresponds to 80 mm.

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

Installation must be carried out by specialists who have previously been trained and have received permission to perform work of this kind.
The part of the pipeline system where installation is carried out is completely disconnected from the supply of the working medium.
Before starting installation, you should make sure that the installed product’s characteristics fully comply with the climatic conditions in which it will be used.
If a wafer check valve is installed, its flanged part is first mounted, and only then is it fixed in it.
Before introducing a flow of working fluid into the pipeline, you should once again make sure that the check valve is installed securely and all required connections are made.