check valves. Check valve (flanged, wafer) Flanged check valve

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. A prerequisite is the vertical position 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:

high 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. As a clamping element, a spring is used that presses the ball to the seat. Such valves are usually made for small diameter pipelines and are used as domestic plumbing fixtures. 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.

The main task that the flanged check valve, installed on pipelines, solves for various purposes, is to ensure the movement of the transported medium in one direction. The design features of the check valve, for 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 be performed in the wrong direction. check valves 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 in the opposite direction. 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 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 of the 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 its 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, however, such devices are very effective and are able to provide reliable protection for 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. Choice of flanged valve with certain type 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 a 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, then the most significant of them is that they rotary mechanism at the moment of closing, the locking disc slams too hard, which eventually leads to wear of the seat. Such a disadvantage are deprived of rotary check valves, equipped with a special mechanism that ensures smooth closing of the locking disc. However, these improved flanged 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 such valves, due to the peculiarities of their design, can only be installed in 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 size its locking elements - sashes - are very compact in size.

Check valves, the design of which is additionally equipped with a strainer, 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, whose 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 its placement in special seats, which are equipped with sealing elements, the flanges are pulled together using 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 joints. 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, the internal elements of 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 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 in flanged shockless type valves 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 given parameter 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.

Check flange valve - a kind of protective pipe fittings. It differs from other modifications in the type of connection (flange). Refers to types of fittings direct action With automatic control- allows the flow of the working medium in one direction. When the direction is reversed, the valve automatically closes the flow 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. The internal design is determined by the type of bolt 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, the normally closed position of the gate is maintained 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.

As a rule, check valves can be conditionally divided into two categories, depending on the specific connection to the pipeline - flanged or wafer connection.

What is a Flanged Check Valve

For example, flange check valve actively used in the water supply system, thereby preventing possible water hammer or the appearance of a reverse flow of water. This device does not belong to the group stop valves. According to 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 fastener.
In general, a flange is a corresponding connecting part of a pipeline system, which is a disk or a small frame with special holes for bolts.
This 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 a wafer check valve

As for the second type of connection, it is customary to use wafer models for mounting on appropriate technical pipelines for high-quality protection and quick shutdown 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 allow you to completely eliminate the possibility of even the slightest water hammer.

Unlike flange models, wafer valves can be installed absolutely in any convenient position - horizontally or vertically. During installation, such a valve will be securely fixed between two flanges (hence the name). At the same time, it is important to note the fact that the flow of incoming fluid must go towards the disk of the valve itself, where a special arrow will point.

In heat and water supply systems, it is customary to use thermal shut-off devices that guarantee high quality protection for any pipeline.

Where can I buy both types of pipeline fittings

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

Ball check valve type 012F (flanged, cast iron body)

Ball check valve is another type of Dendor Valve Industrial check valve.

The check ball valve for protecting the pipeline from the backflow of the working medium is also called the "check valve for sewage". The backflow restrictor is a steel ball coated with protective layer. It is used in a wide variety of industries - but most wide application he got into sewer installations.

The sewer check valve is installed in both horizontal and vertical positions. In a vertical position, the flow must be directed exclusively from the bottom up. The check ball valve is attached to the pipeline using flanges. For correct operation valve, the direction of flow of the medium must match the direction indicated on the valve.

Ball check valve

check valve ball- a type of pipeline fittings that provides a one-way flow of working media in various engineering systems. Due to its special design, such a valve allows the medium to pass in one direction and prevents its reverse movement. This principle of operation allows you to secure systems operating under pressure. Installation of ball valves is most in demand in systems of hot and cold water supply, water disposal, water treatment. They are also indispensable in the arrangement of storm drains and sewer systems.

Features of design and use

The body of this product is made of cast iron treated with epoxy powder coating. Other structural advantages of the check ball valve include:

the locking element is made in the form of a steel ball, on the surface of which an elastomeric coating is applied;
for ease of installation of the valve, an arrow is marked on its body according to the direction of movement of the flow of the working medium;
the product is equipped with a cover that allows you to inspect and repair it without dismantling it from the pipeline.

Flanged Ball Check Valve can be installed in a horizontal and vertical position, included in the system using flange connections.

You can buy a high quality ball check valve from us by placing an order on the website or by contacting us by phone.