Spring valve. Reverse water valve: principle of operation, design and varieties. Disadvantages of spring valves

With a pressure above the installed. The valve must also provide a discontinuation of the medium to restore the operating pressure. Safety valve is reinforcement direct action operating directly from the working medium, along with most of the designs of the protective reinforcement and the pressure regulators of direct action.

Dangerous excess pressure may occur in the system as as a result of third-party factors (incorrect operation of equipment, heat transfer from third-party sources, incorrectly assembled thermal mechanical scheme, etc.), and as a result of internal physical processes, due to a certain source event, not provided for normal Operation. PC Mounted everywhere where it can happen, that is, almost on any equipment, but in particular they are important in the field of exploitation of industrial and household vessels working under pressure.

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Why the safety valve in the hijacggo water supply system

Safety valve design (in stereo-format anaglyph)

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Operating principle

When the safety valve is closed, the force from its sensitive element operating pressure In the protected system, seeking to open the valve and the power from the deposit that prevents the discovery. With the occurrence of perturbations in the system, causing an increase in pressure over the worker, the magnitude of the plugging force of the spool to the saddle decreases. At that moment, when this force becomes equal to zero, an equilibrium of active forces comes from the exposure to the pressure in the system and the parameter on the sensitive element of the valve. The locking body begins to open if the pressure in the system does not stop increasing, the working medium is reset through the valve.

With a decrease in pressure in the protected system caused by resetting medium, indignant effects disappear. The valve locking body under the action of effort from the master closes.

The closing pressure in some cases is 10-15% lower than the operating pressure, this is due to the fact that to create the tightness of the shut-off body after the operation, an effort is required, much greater than, which was sufficient to maintain the valve tightness before opening. This is due to the need to overcome when planting the force of the clutch of the molecules of the medium passing through the slot between the sealing surfaces of the spool and the saddle, to oust this medium. Also, a decrease in pressure contributes to the retardation of the closure of the locking body associated with the impact on it of dynamic effort from the passing environment of the medium, and the presence of friction forces requiring additional effort for its complete closure.

Classification of safety valves

According to the principle of action

direct valves - usually these devices are meant when the phrase uses safety valvethey open directly under the action of the pressure of the work environment;
indirect valves - valves with control by using an extraneous pressure source or electricity, the generally accepted name of such devices Pulse safety devices;

By the nature of the climbing organ

proportional valves (used on incompressible environments)
two-position valves

In height of the climbing organ

low-way
middle-seen
four-dyed

In view of the load on the spool

cargo or lever-cargo
spring
arm-springs
magneto-spring

Differences in structures

Safety valves usually have an angular housing, but may also have a passage, regardless of this valves are installed vertically so that when the rod closes it down.

Most safety valves are made with one saddle in the housing, but there are designs and with two sides installed in parallel.

Lovely called safety valveswhich in which the height of the lifting of the locking element (spool, plates) does not exceed 1/20 diameter of the seat, full-dimensional valves, in which the lifting height is 1/4 of the saddle diameter and more. There are also valves with a lifting height of 1/20 to 1/4, they are usually called mid-lining. In the low-lifted and mid-circuit valves, the rise of the spool over the saddle depends on the pressure of the medium, so they are conditionally called valves proportional actionAlthough the rise is not proportional to the pressure of the working environment. Such valves are used, as a rule, for liquids, when a large bandwidth is required. In full-dimensional valves, the discovery occurs immediately to the complete plate of the plate, so they are called valves two-position action. Such valves are high-performance and are used both on liquid and gaseous media.

The greatest differences in the designs of the safety valves are the types of load on the spool.

Spring valves

In them, the pressure of the springs compression is counted in them. The same spring valve can be used for various limits for setting the trigger pressure by the configuration by various springs. Many valves are manufactured with a special mechanism (lever, fungus, etc.) of a manual undermining for a valve control purge. This is done in order to verify the performance of the valve, since during operation there may be various problems, such as harnessing, sample, adhesion of the spool to the saddle. However, in some industries under conditions of aggressive and toxic media, high temperatures and pressures, the control purge can be very dangerous, therefore, for such valves, the possibility of manual purge is not provided and is not even prohibited.

Most often, the springs are exposed to a working environment that is reset from the pipeline or capacitance when triggered, special coatings of springs are used to protect against weakly aggressive media. Single seal in such valves is absent. In cases of work with aggressive media in the chemical and some other installations, the spring isolate from the working medium using a seal along the slicer with a slurry device, a bevelon or an elastic membrane. The bellows seal also applies in cases where the leakage of the medium into the atmosphere is not allowed, for example, at nuclear power plants.

Lever-car valves

In such valves, force on the spool from the pressure of the working medium opposes the power from the load transmitted through the lever to the valve rod. Setting such valves for opening pressure is made by fixing the cargo of a certain mass on the arm of the lever. The levers are also used for manual valve purge. Such devices are forbidden to use on mobile vessels.

For sealing, large diameters sealing are required by significant weights of the loads on long levers, which can cause strong vibration of the device, in these cases the hulls are used inside which the reset cross section is formed by two parallel sodes, which overlap with two spools with two levers with loads. Thus, two parallel working shutters are mounted in one case, which allows to reduce the weight of the cargo and the length of the levers, ensuring normal valve operation.

Magneto-spring valves

In these devices, an electromagnetic drive is used, that is, they are not direct valuable revenue. The electromagnets in them can provide additional pressing of the spool to the saddle, in which case, when the signal pressure is reached on the signal from the sensors, the electromagnet is turned off and the pressure opposes only the spring, the valve starts working as a normal spring. Also, the electromagnet can create an opening effort, that is, to counteract the spring and to open the valve. There are valves in which the electromagnetic drive also performs additional pressed, and the opening force, in this case the spring is used to damage to the case of termination.

For reset overpressure The atmosphere applies valves Safety springs, which are special pipe fittingsproviding reliable protection Pipeline from malfunctions and mechanical damage. The device is responsible for automatic reset of excess fluids, steam and gas from vessels and systems until the pressure is normalized.

Purpose of spring valve

Hazardous exceeding pressure in the system arises as a result of external and internal factors. In addition, it leads to the incorrect collection of heat-mechanical schemes, causing failures in the functioning of equipment, heat in the system from extraneous sources and intrasystems of physical processes that are not provided for by standard operating conditions periodically arising in the system.

Safety products - a mandatory part of any household or industrial system operating under pressure. Installation of safety mechanisms is carried out on pipelines in compressor stations, on autoclaves, in boiler rooms. Valves perform protective functions on pipelines for which not only gaseous, but also liquid substances are transported.

Device and principle of spring valves

The valve consists of a steel housing, the lower fitting of which is used as a connecting element between it and the pipeline. If the system increases pressure, the reset of the medium occurs through the side fitting. Adjected depending on the pressure in the spring system ensures the pressing of the spool to the saddle. The spring adjustment occurs by means of a special sleeve, which is screwed into the upper cover located on the device case. The hollows placed in the upper part is designed to protect the sleeve from destruction as a result of mechanical effects. The presence of a special ears for sealing allows you to protect the system from foreign intervention.

For valves, in which the spring, the spring is performed, the effort of the worker is selected. If the parameters are selected correctly, at the normal state of the system, the spool that is responsible for the release of excessive pressure from the pipeline must be pressed to the saddle. When the performance indicators increases to a critical level depending on the type spring device The spool moves up at a certain height.

Safety spring valve, providing a timely discharge of pressure, is made from different materials:

Carbon steel. Such devices are suitable for systems, the pressure in which dwells in the range of 0.1-70 MPa.
Stainless steel. Valves out of stainless steel Designed for systems, the pressure in which does not exceed 0.25-2.3 MPa.

Classification and characteristics of spring valves

The valve safety spring is available in three versions:

Lightweight devices Suitable for gas pipelines and steam pipelines, the pressure in which does not exceed 0.6 MPa. The height of the lift of such a valve does not reach more than 1/20 diameter of the seat
Mid-lining devices, in which the height of the lifting of the spool is from 1/6 to 1/10 from the nozzle dimer.
Full-dimensional devicesin which the lifting height of the valve reaches up to ¼ from the saddle diameter.

Known classification of valves based on the method of their opening:

Reverse spring valve. To control inverse spring valves, an indirect foreign source of pressure is involved. Reverse spring valves that are called pulsed safety devices can operate by exposure to electricity.
Direct valve. In devices direct type The operating pressure of the medium has a direct effect on a spool, which rises with the increase in pressure.

Highlight valves open and closed type . In the case of using a direct type device when the valve is opened, the medium is reset directly into the atmosphere. Closed-type valves remain completely sealed with respect to environmentdropping pressure into a special pipeline.

Benefits

Highlight different kinds Equipment for resetting overpressure from the system, but safety sprocket valves are popular due to the presence of important advantages:

Simplicity and reliability of the design.
Easy to configure operating parameters and ease of installation.
A variety of sizes, types and constructive versions.
Installation of the safety product is possible both in horizontal and vertical position.
Relatively small overall dimensions.
A large passage section.

By the cons of safety valves include the presence of restrictions in the height of the lifting of the spool, increased requirements for the quality of the manufacture of spring for safety valves, which may fail when working under the aggressive medium or constant exposure to high temperatures.

How to choose a spring valve?

When choosing a fuse should be based on several important principles, on which the uninterrupted operation of the system and the ability to execute the necessary functions are depends on:

Safety spring valves have the smallest dimensions compared to other types of fuse valves of waste, so they should be chosen in cases where free space is not enough.
The features of the application of valves are associated with the presence of increased vibrations that adversely affect performance features Devices and can quickly lead it into disrepair. For example, lever-cargo type devices are more susceptible to breakdowns due to the effects of vibrations due to the presence in the design of a long lever with weight and hinges. Therefore, for systems in which significant vibrational impacts are observed, it is worth choosing a safety spring valve.
Depending on the design features of the device, the spring can change the pressure force over time. This is due to the fact that the constant rise of the spool causes changes in the structure of the metal.

Nuances of Montaja

Spring-type safety valve is installed at any point of the system that is exposed. increased pressure And it is threatened to obtain mechanical damage. The device does not require the presence of a large free space, which is a significant advantage compared to other types. safety devices.

In order to avoid troubleshooting before the safety valve, you should not install any locking reinforcement. To reset the gaseous medium, special devices are installed or the discharge occurs directly into the atmosphere. To alert personnel, together with spring valves, a special whistle is assembled, which is placed on a dumping nozzle. When the valve is triggered, the whistle signal will flow, meaning that the system has increased pressure and the valve opened to reset the medium.

Possible causes of safety valve breakdowns

Safety valves are strong and reliable devices that provide constant protection of systems from exceeding pressure. Direct or reverse spring valve fail for several reasons:

The presence of increased vibrations;
Continuous impact of the aggressive environment on a safety choke.
Incorrect installation of a safety spring choke or valve.

In order to avoid accidents and malfunctions in the operation of systems, safety valves pass periodic verification for problems. Valves are tested for strength and density before commissioning. Periodic checks are carried out in order to determine the tightness of the sealing surfaces and the sloping compounds.

With the correct choice of safety devices, taking into account the parameters of the system, conducting periodic inspections and timely troubleshooting safety sprocket valves will ensure reliable operation of the system and trouble-free protection against excess pressure over a long time.

The company "Nemen" sells safety valves designed to work in various environments. We offer, which can be installed vertically on the pipeline area or boiler aggregates.

Appointment of safety reinforcement

The safety valve is a form of fittings that is designed to automatically protect pipelines and equipment from exceeding pressure over a certain, predetermined value by resetting overweight working media. The valve also provides a discharge stop when restoring normal operating pressure. Safety valve is a direct valve fittings directly from the energy of the working medium.

Principle of operation of the safety valve

When the safety valve is in a closed state, the power pressure of the reinforcement is affected by the power pressure in the pipeline, which seeks to open the valve, as well as preventing the discovery force from the deposit. In the event of an occurrence in the system of perturbations provoking the increase in pressure of the medium over the worker, the prulchery force of the spool to the saddle decreases. When its value is zero, there is an equilibrium of active forces from the valve and the pressure of the medium simultaneously affecting the valve. If the pressure in the system continues to increase, the locking body opens and reset the excess medium through the valve. Reducing the volume of the medium leads to normalization of pressure in the system and disappearing of perturbing effects. When the pressure level falls below the maximum permissible, the locking body returns to its original position under the influence of force from the depositter.

Safety spring valves

In such safety valves, the springs compression force is used as counteraction of the pressure of the working medium. Due to the installation of various springs, the same safety spring valve can be used for several limits setting the maximum allowable pressure. In spring valves there is no seal on the stock. If the valve is installed in systems with an aggressive working medium, the spring is isolated using the glands, an elastic membrane or a bellows. The bellows seal is used in cases when the leakage of the working medium from the pipeline is unacceptable.

Safety valves apply to industrial scale and are installed on the highway with the goal of reset from the extension pipeline of the working medium to reduce the pressure level (a type of household safety valve is a crane of Maevsky, watering air from heating systems).

Device and types of safety valves

The main element of the safety valve is the valve, rod, adjustment elements, tuning springs. By design, safety valves are lever-cargo (the working medium presses the spool, and this pressure is counteracting the power of the cargo) and magneto-spring (driven by electromagnetic drive).

Types of safety valves:

direct action. Triggered when the pressure is exceeded above;
indirect action. Work when exposed to an extraneous pulse (for example, from electrical, used for remote control);
proportional action. Used in incompressible environments;
two-position action.

Video operation valve safety

Also, safety valves are low lifting (lifting the locking part - 1/20 of the saddled diameter), full-dimensional (1/4 beds, are designed on high bandwidth highways), medium-lining. Check valves are a variety safety reinforcement. Also, safety valves are divided into shut-off and regulating. Setting the limit pressure is carried out at the time of installation by changing the position of the adjusting screw, compressing the clamping spring.

Recommend Spring Safety Valves! Unlike the membrane, they are equipped additional devices, preventing the scholars to the saddle preventing.

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An obligatory element of equipping autonomous water supply systems in dachas and in country houses is an check valve. That is technical devicewhich may have a different design version, ensures the movement of fluid on the pipeline in the desired direction. Check valves installed in the system autonomous water supply, reliably protect it from the effects of abnormal situations. Right-acting reinforcement devices, check valves work automatically, for which the energy of the working medium is used to be transported along the pipeline system.

Appointment and principle of operation

The main function that the return valve for water is performed is that it protects the water supply system from the critical fluid flow parameters transported through the pipeline. Most frequent cause Critical situations is to stop pumping installationIt can lead to a variety of negative phenomena - a plum of water from the pipeline back into the well, spinning the impeller of the pump in the opposite direction and, accordingly, breakage.

Protect the water supply system from listed negative phenomena allows the installation of the return valve to water. In addition, the return valve for water prevents the consequences that cause a hydraulic blow. The use of check valves in pipeline systems allows you to make their work more efficient, as well as ensure correct operation pumping equipmentwhich such systems are equipped.

The principle of operation of the check valve is quite simple and is as follows.

The flow of water coming into such a device under defined pressure, acts on the shut-off element and presses the spring, with which this item is held in the closed state.
After squeezing the spring and the opening of the shut-off element, the water begins to move freely through the check valve in the desired direction.
If the level of pressure level of the fluid in the pipeline drops or water begins to move not in the direction, the spring mechanism of the valve returns a shut-off element into a closed state.

Acting in this way, the reverse valve prevents the formation of an undesirable reverse stream in the pipeline system.

When choosing a shutter model installed on a water supply, it is important to know regulatory requirementsthat make the pumping equipment manufacturers to such devices. The technical parameters for which in accordance with these requirements choose the return valve for water, are:

working, trial and nominal closure pressure;
planting diameter;
conditional bandwidth;
sealing class.

Information about how technical requirements There must be a check valve for water, as a rule, contains in the documentation for pumping equipment.

To equip the water supply systems of the domestic purpose, sprocket-type check valves are used, the diameter of the conditional passage is 15-50 mm in the interval. Despite its compact sizes, such devices demonstrate high throughput, ensure the reliability of the pipeline operation, low noise and vibration in the pipeline system on which they are installed.

Another one positive factor The use of check valves in the water supply system is that they contribute to a decrease in pressure generated by a water pump, by a value of 0.25-0.5 atm. In this regard, the return valve for water allows you to reduce the load as on separate elements Equipping pipelines and the entire water supply system as a whole.

Constructive features

One of the most common materials from which the campaign of the water reverse valves make is brass. The selection of this material is not accidental: this alloy demonstrates extremely high resistance to the effects of chemically aggressive substances that can be in the water transported through the pipeline in a dissolved or weighted state. These substances, in particular, include mineral salts, sulfur, oxygen, manganese, iron compounds, etc. The outer surface of the shutters, which in the process of their operation is also exposed to negative factors, often protect special coating, applied galvanic method.

The reverse valve device assumes the presence of an spool for the manufacture of which brass or durable plastic can also be used. The sealing gasket present in the design of the check valve may be rubber or silicone. For the manufacture of an important element of the shut-off mechanism - the springs - use, as a rule, stainless steel.

So, if we talk about the structural elements of the spring check valve, then this device comprises:

compound type housings, whose elements are connected by means of thread;
shut-off mechanism, the design of which includes two movable spool plates installed on a special stock, and sealing gasket;
springs installed between spool plates and planting saddle at the outlet of the bandwidth.

The principle of operation of the spring check valve is also quite simple.

The flow of water flowing into the reverse shutter under the required pressure affects the spool and presses the spring.
When compressing the spring, the spool moves around the rod, opening the bandwidth and providing fluid stream the ability to move freely through the device.
When the water flow pressure falls in the pipeline on which the check valve is worth, or in cases where such a stream begins to move not in the direction, the spring returns a spool on it planting placeClosing the bandwidth of the device.

Thus, the scheme of the check valve is quite simple, but nevertheless provides high reliability of such devices and the effectiveness of their use in pipeline systems.

Main species

Recommending how the check valve is running, installed in watering system, It should also be understood how to choose it correctly. In the modern market, various types of check valve devices are offered, design, manufacturing material and the operation scheme of which can be seriously different.

Spring feed valve coupling type

The hull of the valves of this type consists of two cylindrical elements connected with a thread. The locking mechanism includes plastic rod, upper and lower spool plates. The position of the elements of the shut-off mechanism in the closed state, as well as their opening at the moment when the water flow pressure reaches the required level, provides a spring. Between themselves composite elements The housings are connected using the sealing gasket.

Spring check valve with brass spool and spherical shape spool

Distinctive features of the valves of this type are easy to notice even in the photo. The brass housing of such a valve in its middle part, where the spool camera is located, has a spherical shape. Such constructive feature Allows you to increase the volume of the spool chamber and, accordingly, the bandwidth of the check valve. The shut-off mechanism of the water valve of this type, the basis of which is the brass spool, works on the same principle as in valve devices of any other type.

Combined check valve spring type with drainage and air vent

Many of those who decided to independently do the installation of the pipeline system, often the question of what the check valve is needed, equipped with drainage and air ventilation systems. The use of check valves of this type (especially for equipping pipelines for which hot workers are transported) allows you to simplify the installation and maintenance process of such systems, increase their reliability, reduce the total hydraulic pressure, reduce the number of mounting connections.

On the housing of the shutters of this type, which can be seen even in the photo, there are two nozzles, one of which is used for mounting the air vent, and the second performs the function of the drainage element. The nozzle for the air vent, on the inner surface of which the thread is sliced, is located on the device body above the spool chamber (its reception part). Such a pipe is needed for airbagging from the pipeline system, which is additionally used by Maevsky's crane. The purpose of the nozzle, which is located on the opposite side of the case - at the exit from the valve, is to merge the liquid from the system accumulated after the valve device.

If you set a horizontal check valve, then its air removal pipe can be used to mount a pressure gauge. If you put the combined check valve on the pipeline vertically, then its drainage nozzle can be used to drain the water accumulated after such a device, and the air supply pipe is for removal from that part of the pipeline, which is located before the check valve, aerial traffic. That is why, solving how to install a combined type check valve, you should clearly understand which functions should be performed.

Spring valves with polypropylene case

Check valves, the housing of which is made of polypropylene, even if you look at the photo of such devices, externally resemble oblique taps. Types of check valves, for the installation of which the polyfusion welding method is used, are installed on pipelines, also made of polypropylene. Additional oblique discharge in the design of the valves of this type is necessary to accommodate in it the elements of the locking mechanism, which facilitates maintenance Such a device. Thereby constructive decision Perform maintenance and repair of the check valve of this type is easy - it suffices to remove the elements of the locking mechanism from its additional removal, without violating the integrity of the body of the device and the tightness of its installation in the pipeline system.

Check valves of other types

Other types of check valves can be installed in pipeline systems intended for transportation of water.

Reverse petal valve is equipped with a special locking element - spring-loaded petal. A large disadvantage of the shutters of this type is that, when they are triggered, significant shock loads are created. This negatively reflects on the technical condition of the shutter itself, and may also cause the hydraulic impact in the pipeline system.
Reverse valve devices of two-dimensional type are characterized by compact sizes and a low weight.
The lifting coupling valve includes a spool freely moving along the vertical axis as a locking element. The work of the shut-off mechanism may be the gravitational principle when the spool returns to the closed state under the action of its own weight. Spring can also be used for this purpose. If you decide to install a gravitational check valve on the pipeline, keep in mind that you can install such a device only on vertical systems of the system. Meanwhile, the gravitational valve is characterized by the simplicity of the design, while demonstrating high reliability during operation.
There are check valves, the shut-off element of which is the spring-made metal ball. The surface of such a ball can be additionally covered with a layer of rubber.

Solving, what the reverse valve is better and is needed in the pipeline system an expensive shutter more complex designshould first get to know technical characteristics Such a device and compare them with the parameters of the pipeline system. The main purpose of the check valve, as mentioned above, is to pass water through the pipeline in right direction and not to give a flow of liquid to move in reverse side. In this regard, choose the return valve on the water follows from what pressure in the pipeline moves the flow of water. Naturally, it is necessary to take into account the diameter of the pipes that such a valve must be installed.

Performing the installation of the pipeline, you should also keep in mind that you can install the check valve different ways. In the pipes of significant diameter, the flange and interflant-type check valves are installed, and the coupling shutters are installed on the pipes of a small diameter. The weld method of installing check valves is used primarily when mounting on polypropylene and metal-plastic pipes.

If you select the right check valve and method of installing it, this device will not only serve for a long timeBut will ensure the correct operation of the entire pipeline system.

How to perform installation

Having understood with the question of why the return valve is needed, and with its role in the pipeline system, it is also necessary to explore the rules for its installation on the already operating or only created by the pipeline. Mounted such devices on different elements Pipeline systems:

on pipelines of autonomous and centralized water supply;
on suction lines serviced by deep and surface pumps;
in front of boilers, capacitive water heaters and water consumption counters.

If you are interested in check valves that can be installed both in vertical and horizontal position, choose not gravitational, and spring models. To learn about how the direction of water should move through the valve, can be moved by a special arrow applied to the device body. When installing feed valves of the coupling type for good sealing, be sure to use Fuma tape. In addition, we should not forget that reverse shutters need regular maintenance, so it is necessary to set them in the available places of the pipeline.

When installing the check valve on the suction line submersible pump You should take care that the filter is installed before such a device rough Cleaningwhich will not give to the inside of the device with mechanical impurities contained in underground water. As such a filter, a perforated or mesh clip can also be used, which is placed in the check valve installed at the inlet end of the suction line of the submersible pump.

When installing the check valve on the already running pipeline, you should pre-disable the system from water supply and only then engage in mounting the shutter.

How to independently make the check valve

A simple design of the check valve allows you to make it with your own hands if necessary.

To solve this task you will need the following materials and tools:

tee S. internal threadwhich will perform the function of the case;
coupling with carvings on the outer surface - the saddle of the self-made check valve;
rigid spring made of steel wire;
steel ball, the diameter of which should be slightly smaller than the diameter of the hole in the tee;
steel threaded plug, which will perform a function of the spring;
standard set of plumbing tools and sealing fum-tape.

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