Spring safety valve device. Safety spring valves - all about the design and installation. Advantages of spring valves

A safety valve is a pipeline fitting that protects equipment and pipelines high pressure from mechanical damage and various types of destruction as a result of emergency situations. This is achieved by releasing an excess amount of liquid, gas or steam from the system, as well as the vessel in which excessive pressure is formed. In addition, this valve prevents the release of the working fluid when the nominal pressure is restored.

A safety valve is a mechanism that operates in direct contact with the working environment together with other structures that perform the function of protective fittings, including pressure regulators.

Main types of valves and their purpose

All safety products may differ from each other in a number of parameters, depending on design features, namely:

1. By type of closing valve:
   • proportional;
   • two-position.
2. According to the lifting height of the closing organ:
   • low-lift;
   • mid-lift;
   • full lift.
3. Depending on the type of load on the spool:
   • spring;
   • lever;
   • lever-spring;
   • magnetic-spring.

Also, safety valves can differ in the nature of their operation and can be direct or indirect acting devices. The former are considered classic safety mechanisms, while the latter belong to the class of impulse devices. The most commonly used modification in industry is the angle safety choke. spring type.

High pressure (or rather its excess) can arise in the system due to various reasons caused by physical internal processes or other external factors, such as:

The flanged spring safety valve 17s28nzh is one of the main types that is used to protect pipeline equipment. The spring safety valve 17s28nzh is designed to protect equipment and pipelines from unacceptable excess pressure in the system. Ensuring safe pressure values ​​is carried out by automatically discharging excess working fluid into a specially installed outlet pipeline or into the atmosphere, and when the working pressure is restored, safety valve 17s28nzh stops resetting the working environment.

The spring safety valve 17s28nzh is mounted with the equipment and using a flange connection. The 17s28nzh flanged spring safety valve has a service life of more than 11 years, and the manufacturer provides a guarantee for it for 18 months from the date the valve is put into operation. Safety valve 17s28nzh is not sealed in relation to the external environment.

Material of the main parts from which the 17s28nzh safety spring valve with flange connection is made:

• Housing, cover - Steel 25L
• Disc, seat - Steel 20Х13
• Rod - Steel 20Х13/Steel 40
• Gasket - AD1M
• Spring - 50HFA

Safety spring valve device 17s28nzh

1 .Cap

2 . Adjustment screw

3 . Spring

4 . Lid

5 . Stock

6 . Manual detonation unit

7 . Spool assembly

8 . Saddle

9 . Frame

Overall and connecting dimensions of safety valve 17s28nzh

Technical characteristics of safety valve 17s28nzh

To relieve excess pressure into the atmosphere, spring safety valves are used, which are special pipeline fittings that provide reliable protection pipeline from malfunctions and mechanical damage. The device is responsible for automatically discharging excess liquids, steam and gas from vessels and systems until the pressure is normalized.

Purpose of a spring valve

Dangerous excess pressure in the system occurs as a result of external and internal factors. An increase is caused by both incorrect assembly of thermal-mechanical circuits, which causes malfunctions in the functioning of equipment, heat entering the system from extraneous sources, and intra-system physical processes that are not provided for by standard operating conditions that periodically occur in the system.

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

Design and principle of operation of spring valves

The valve consists of a steel body, the lower fitting of which is used as connecting element between it and the pipeline. If the pressure in the system increases, the medium is discharged through the side fitting. A spring adjusted depending on the pressure in the system ensures that the spool is pressed against the seat. The spring is adjusted using a special bushing that is screwed into top cover located on the device body. The cap located in the upper part is designed to protect the bushing from destruction as a result of mechanical stress. The presence of a special ear for sealing allows you to protect the system from outside interference.

For valves in which a spring acts as a balancing mechanism, the force of the working element is selected. If the parameters are selected correctly, in the normal state of the system, the spool responsible for releasing excess pressure from the pipeline should be pressed against the seat. When performance increases to a critical level, depending on the type of spring device, the spool moves up to a certain height.

The safety spring valve, which ensures timely release of pressure, is made of different materials:

• Carbon steel. Such devices are suitable for systems in which the pressure is in the range of 0.1-70 MPa.
• Stainless steel. Valves from of stainless steel designed for systems in which the pressure does not exceed 0.25-2.3 MPa.

Classification and characteristics of spring valves

The spring safety valve is available in three versions:

• Low lift devices suitable for gas and steam pipeline systems, the pressure in which does not exceed 0.6 MPa. The lifting height of such a valve does not reach more than 1/20 of the seat diameter
• Mid-lift devices, in which the lifting height of the spool is from 1/6 to 1/10 of the nozzle diameter.
• Full lift devices, in which the valve lift height reaches up to ¼ of the seat diameter.

There is a known classification of valves based on the method of opening them:

• Non-return spring valve. To control spring check valves, an indirect external pressure source is used. Spring check valves, called impulse safety devices, can be operated by electrical power.
• Straight valve. In direct type devices, the operating pressure of the medium has a direct effect on the spool, which rises as the pressure increases.

Highlight valves open And closed type . In the case of using a direct type device, when the valve is opened, the medium is discharged directly into the atmosphere. Closed type valves remain completely sealed against environment, releasing pressure into a special pipeline.

Advantages

Highlight different kinds equipment that relieves excess pressure from the system, but spring safety valves are popular due to the presence of important advantages:

• Simplicity and reliability of design.
• Ease of setting operating parameters and ease of installation.
• Variety of sizes, types and designs.
• Installation of the safety product is possible in both horizontal and vertical positions.
• Relatively small overall dimensions.
• Large flow area.

The disadvantages of safety valves include the presence of restrictions in the lifting height of the spool, increased requirements for the quality of manufacturing of the spring for safety valves, which can fail when operating in an aggressive environment or constant exposure to high temperatures.

How to choose a spring valve?

When choosing a fuse, you should be based on several important principles, the consideration of which determines the uninterrupted operation of the system and the ability of the fuse to perform the necessary functions:

• Spring safety valves have the smallest dimensions compared to other types of safety relief valves, so they should be chosen in cases where there is not enough free space.
• Features of the use of valves are associated with the presence of increased vibrations, which negatively affect the operational characteristics of the device and can quickly render it unusable. For example, lever-load type devices are more susceptible to breakdowns due to exposure to vibrations due to the presence of a long lever with weight and hinges in the design. Therefore, for systems in which significant vibration effects are observed, it is worth choosing a spring safety valve.
• Depending on the design features of the device, the spring may 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.

Installation nuances

A spring-type safety valve is installed at any point in the system that is subject to increased pressure and is in danger of getting damaged. mechanical damage. The device does not require a lot of free space, which is a significant advantage compared to other types of safety devices.

To avoid operational problems, do not install any shut-off valves. To discharge the gaseous medium, they are installed special devices or the discharge occurs directly into the atmosphere. To alert personnel, a special whistle is mounted along with the spring valves, which is placed on the discharge pipe. When the valve is activated, a whistle will sound, indicating that the pressure in the system has increased and the valve has opened to release the medium.

Possible causes of safety valve failures

Safety valves are durable and reliable devices that provide constant protection of systems from overpressure. A direct or reverse spring valve fails for several reasons:

• The presence of increased vibrations;
• Constant exposure to an aggressive environment on the safety choke.
• Incorrect installation of safety spring throttle or valve.

In order to avoid accidents and malfunctions in the functioning of systems, safety valves undergo periodic checks for malfunctions. Valves are tested for strength and tightness before being put into operation. Periodic checks are also carried out to determine the tightness of sealing surfaces and gland connections.

At making the right choice safety devices taking into account system parameters, periodic inspections and timely troubleshooting, spring safety valves will ensure reliable operation of the system and trouble-free protection against overpressure for a long time.

A mandatory element of equipping autonomous water supply systems in dachas and country houses is a check valve. That's exactly what technical device, which can have different designs, ensures the movement of liquid through the pipeline in the required direction. Check valves installed in the system autonomous water supply, reliably protect it from the consequences of emergency situations. Referring to direct-acting valves, check valves operate automatically using the energy of the working medium transported through the pipeline system.

Purpose and principle of operation

The main function that a water check valve performs is that it protects the water supply system from critical flow parameters of the liquid transported through the pipeline. Most common cause critical situations is to stop pumping unit, which can lead to a number of negative phenomena - draining water from the pipeline back into the well, spinning the pump impeller in the opposite direction and, accordingly, breakdown.

The installation allows you to protect the water supply system from the listed negative phenomena. check valve to the water. In addition, the water check valve prevents the consequences caused by water hammer. The use of check valves in pipeline systems makes their operation more efficient, as well as ensures the correct functioning of the pumping equipment with which such systems are equipped.

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

• The flow of water entering such a device under a certain pressure acts on the locking element and presses the spring, with the help of which this element is kept closed.
• After the spring is compressed and the shut-off element is opened, water begins to move freely through the check valve in the required direction.
• If the pressure level of the working fluid flow in the pipeline drops or the water begins to move in the wrong direction, the spring mechanism of the valve returns the shut-off element to the closed state.

By acting in this way, the check valve prevents the formation of unwanted backflow in the piping system.

When choosing a valve model installed on a water supply system, it is important to know the regulatory requirements that manufacturers of pumping equipment impose on such devices. Technical parameters, according to which a check valve for water is selected in accordance with these requirements, are:

• working, test and nominal closing pressure;
• diameter of the landing part;
• conditional capacity;
• tightness class.

Information about how technical requirements The check valve for water must correspond, as a rule, contained in the documentation for the pumping equipment.

For equipping water supply systems household use They use spring-type check valves, the nominal diameter is in the range of 15–50 mm. Despite their compact size, such devices demonstrate high throughput, ensure reliable operation of the pipeline, low level noise and vibration in the pipeline system on which they are installed.

One more positive factor The use of check valves in the water supply system is that they help reduce the pressure created by the water pump by 0.25–0.5 Atm. In this regard, a check valve for water allows you to reduce the load on both individual elements equipment of pipelines, and the entire water supply system as a whole.

Design features

One of the most common materials used to make the body of water return valves is brass. Choice of this material is not accidental: this alloy demonstrates exceptionally high resistance to chemically aggressive substances that may be present in water transported through a pipeline in a dissolved or suspended state. Such substances, in particular, include mineral salts, sulfur, oxygen, manganese, iron compounds, etc. The outer surface of the valves, which during their operation is also exposed to negative factors, is often protected with a special coating applied by the galvanic method.

The check valve device requires the presence of a spool, for the manufacture of which brass or durable plastic can also be used. The sealing gasket present in the check valve design can be rubber or silicone. To manufacture an important element of the locking mechanism - the spring - stainless steel is usually used.

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

• composite type housings, the elements of which are connected to each other by means of threads;
• a locking mechanism, the design of which includes two movable spool plates mounted on a special rod and a sealing gasket;
• a spring installed between the spool plates and the seat at the outlet of the through hole.

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

• The flow of water entering the check valve under the required pressure acts on the spool and depresses the spring.
• When the spring is compressed, the spool moves along the rod, opening the passage hole and allowing the fluid flow to move freely through the device.
• When the pressure of the water flow in the pipeline on which the check valve is installed drops, or in cases when such a flow begins to move in the wrong direction, the spring returns the spool to its seat, closing the throughput hole of the device.

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

Main types

Having understood how a check valve installed in a water supply system works, you should also understand how to choose it correctly. The modern market offers various types of check valve devices, the design, material of manufacture and operation scheme of which can vary significantly.

The body of this type of valve consists of two cylindrical elements connected to each other using threads. The locking mechanism includes a plastic rod, upper and lower spool plates. The position of the elements of the locking mechanism in the closed state, as well as their opening at the moment when the pressure of the water flow reaches the required level, is ensured by a spring. The component elements of the housing are connected to each other using a sealing gasket.

The distinctive features of this type of shutter are easy to see even in the photo. The brass body of such a valve in its middle part, where the spool chamber is located, has a spherical shape. Such design feature allows you to increase the volume of the spool chamber and, accordingly, the throughput of the check valve. The locking mechanism of this type of water valve, which is based on a brass spool, works on the same principle as in any other type of valve device.

Many of those who decide to independently install a pipeline system often have a question about why they need a check valve equipped with drainage and air vent systems. The use of check valves of this type (especially for equipping pipelines through which hot working fluids are transported) makes it possible to simplify the process of installation and maintenance of such systems, increase their reliability, reduce the total hydraulic pressure, and reduce the number of installation connections.

On the body of this type of valve, which can be seen even in the photo, there are two pipes, one of which is used for installing an air vent, and the second serves as a drainage element. Pipe for air vent, on inner surface which is threaded, is located on the device body above the spool chamber (its receiving part). Such a pipe is needed to bleed air from the pipeline system, for which a Mayevsky valve is additionally used. The purpose of the pipe, which is located on the opposite side of the body - at the outlet of the valve, is to drain the liquid accumulated after the valve device from the system.

If you install a horizontal check valve, its air outlet pipe can be used to mount a pressure gauge. If you place the combined check valve vertically on the pipeline, then its drainage pipe can be used to drain water accumulated after such a device, and the air vent pipe can be used to remove air pockets from the part of the pipeline that is located before the check valve. That is why, when deciding how to install a check valve combined type, you should clearly understand what functions such a shutter should perform.

Check valves, the body of which is made of polypropylene, even if you look at the photos of such devices, look very similar to oblique bends. These types of check valves, for installation of which the polyfusion welding method is used, are installed on pipelines also made of polypropylene. An additional oblique outlet in the design of valves of this type is necessary to accommodate the elements of the locking mechanism, which makes it easier Maintenance such a device. Thanks to this design solution, it is not difficult to carry out maintenance and repair of a check valve of this type - it is enough to remove the elements of the locking mechanism from its additional outlet without violating the integrity of the device body and the tightness of its installation in the pipeline system.

In pipeline systems designed to transport water, other types of check valves can be installed.

• The check valve is equipped with a special shut-off element - a spring-loaded petal. The big disadvantage of valves of this type is that when they operate, significant shock loads are created. This negatively affects the technical condition of the valve itself, and can also cause water hammer to occur in the pipeline system.
• Double-leaf check valve devices are compact in size and light in weight.
• The lift coupling check valve includes a spool as a shut-off element that moves freely along the vertical axis. The operation of the locking mechanism can be based on the gravitational principle, when the spool returns to the closed state under the influence of its own weight. A spring can also be used for this purpose. If you decide to install a gravity check valve on the pipeline, keep in mind that such a device can only be installed on vertical sections of the system. Meanwhile, the gravity valve is characterized by a simple design, while demonstrating high reliability during operation.
• There are check valves whose closing element is a spring-loaded metal ball. The surface of such a ball can be additionally covered with a layer of rubber.

Deciding which check valve is best and whether an expensive valve is needed in the pipeline system is more complex design, you should first get to know technical characteristics such a device and compare them with the operating parameters of the pipeline system. The main purpose of the check valve, as mentioned above, is to pass water through the pipeline in the desired direction and prevent the liquid flow from moving in reverse side. In this regard, you should choose a check valve for water based on the pressure under which the water flow moves in the pipeline. Naturally, it is necessary to take into account the diameter of the pipes on which such a valve should be installed.

When installing the pipeline, you should also keep in mind that you can install a check valve different ways. On large-diameter pipes, flange and wafer-type check valves are installed, and on small-diameter pipes, coupling valve devices are installed. The welded method of installing check valves is used mainly for installation on polypropylene and metal-plastic pipes.

If you choose the right check valve and the method of its installation, such a device will not only last long time, but will also ensure the correct operation of the entire pipeline system.

How to install correctly

Having understood the question of why a check valve is needed and its role in the pipeline system, you should also study the rules for installing it on an already operating or newly created pipeline. Such devices are mounted on various elements of pipeline systems:

• on pipelines of autonomous and centralized water supply;
• on suction lines served by deep and surface pumps;
• in front of boilers, cylinders and water flow meters.

If you are interested in check valves that can be installed in both vertical and horizontal positions, choose spring models rather than gravity ones. You can find out in which direction the water flow should move through the valve by looking at the special arrow marked on the body of the device. When installing coupling-type check valves, be sure to use FUM tape for good sealing. In addition, we should not forget that check valves require regular maintenance, so they must be installed in accessible places in the pipeline.

When installing a check valve on the suction line submersible pump care should be taken to ensure that a coarse filter is installed in front of such a device, which will prevent it from getting into inner part devices for mechanical impurities contained in underground water. A perforated or mesh cage can also be used as such a filter, into which a check valve installed at the inlet end of the suction line of a submersible pump is placed.

When installing a check valve on an already operating pipeline, you must first disconnect the system from the water supply and only then install the shutter device.

How to make your own check valve

The simple design of the check valve allows you to make it yourself if necessary.

To solve this problem you will need following materials and tools:

• tee with internal thread, which will serve as a body;
• coupling with thread on outer surface– homemade check valve seat;
• rigid spring made of steel wire;
• a steel ball, the diameter of which should be slightly smaller than the diameter of the hole in the tee;
• a steel threaded plug that will serve as a stop for the spring;
• a standard set of plumbing tools and FUM sealing tape.
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Spring safety valve (PPV)- view pipeline fittings, designed to automatically protect equipment and pipelines from excess pressure above a predetermined value by releasing excess working fluid and ensuring that the discharge stops when the closing pressure and restoration of the operating pressure.

Main valve assemblies and parts:

1 - body, 2 - seat, 3 - spool, 4 - cover, 5 - rod, 6 - nut, 7 - pin, 8 - spring, 9 - bellows (installed in bellows valves), 10 - locking screw, 11 - adjusting bushing, 12 - guide bushing, 13 - partition, 14 - adjusting screw, 15 - cap, 16 - threaded flange.

Principle of operation. At normal operating pressure, the force of the compressed spring presses the spool against the seat (the passage for relieving the working medium is closed). When the pressure increases above the set value, an oppositely directed force begins to act on the spool, which compresses the spring, and the spool rises, opening a passage for discharging the working medium. After the pressure in front of the valve decreases to the closing pressure, the spool under the action of the spring is again pressed against the seat, stopping the discharge of the medium.

Installation position – vertical, cap up.

Shutter tightness– class “B” GOST R 54808. At the customer’s request, it is possible to manufacture with other classes of tightness.

Possible valve designs:

• A sealed cap with a forced opening unit, and without one.
• Balancing bellows.
• Thermal barrier.
• "Open" lid.
• A locking element that prevents the valve from operating.

Pipeline connection:

• flanged;
• for lens gasket (flange according to GOST 9399);
• fitting;
• tsapkovoe.

Valves with bellows.

The bellows is a mechanism that compensates for the effect of back pressure at the outlet of the valve. The bellows is designed to protect the valve spring from the harmful effects of an aggressive working environment under conditions of high or low temperatures. Bellows valves are made of steel grades 12Х18Н9ТЛ and 12Х18Н12МЗТЛ and are intended for working environments with temperatures from minus 60 °С and below. Designation of bellows valves: KPP4S, KPPS.

The design of the sealing surfaces and the connecting dimensions of the valve flanges are in accordance with GOST 12815-80, row 2, face-to-face lengths are in accordance with GOST 16587-71.

Valves DN 25 PN 100 kgf/cm2 can be manufactured with union ends for connection to a pipeline in accordance with GOST 2822-78, as well as with a flange connection in accordance with GOST 12815-80, row 2.

Safety valves with nominal pressure PN 250 kgf/cm2 and PN 320 kgf/cm2, like other models, are designed to protect equipment from unacceptable excess pressure by automatically releasing excess working fluid. Used on equipment with liquid and gaseous working media that do not cause corrosion of body parts greater than 0.1 mm.

Safety valves with a stamped-welded body can be manufactured with individual face-to-face length (L and L1), height (H) and flange mounting dimensions, which allows them to be used as substitutes for imported valves without changing already installed equipment and pipelines.

Calculation of valve capacity - according to GOST 12.2.085-2002.

Setting pressure, pH– greatest overpressure at the entrance to the safety valve, at which the valve is closed and the specified tightness of the valve is ensured.

Opening start pressure, Рн.о.(starting pressure; set pressure) – excess pressure at the inlet to the safety valve, at which the force tending to open the valve is balanced by the forces holding the locking element on the seat. When the opening pressure begins, the specified tightness in the valve shutter is broken and the locking element begins to rise.

Full opening pressure, Рп.о.– excess pressure at the inlet to the safety valve, at which the valve moves and maximum throughput is achieved.

Closing pressure, Рз(reseating pressure) – excess pressure at the inlet to the safety valve, at which, after the working medium is discharged, the locking element is seated on the seat, ensuring the specified tightness of the valve. Valve closing pressure, Рз – not less than 0.8 Рн.

Back pressure– excess pressure at the outlet of the fittings (in particular, from the safety valve).

Back pressure is the sum of the static pressure in the exhaust system (if closed system) and the pressure arising from its resistance during the flow of the working medium.

Mandatory minimum order information.

When ordering valves, you must fill out a questionnaire (Appendix B):

• product type, designation, type designation (according to the table of figures);
• nominal diameter of the inlet pipe, DN, mm;
• nominal pressure, PN, kgf/cm2;
• setting pressure (Рн, kgf/cm2) or spring number (when only the spring number is specified, the valve is adjusted to the minimum value from the range of the specified spring);
• body material;
• the presence of a manual detonation unit in the valve design;
• the presence of a bellows in the valve design.

Example of designation when ordering a spring safety valve:

An example of designation when ordering a spring safety valve DN 50 PN 16 kgf/cm2 made of steel 12Х18Н9ТЛ with a manual detonation unit, setting pressure – Рн=16 kgf/cm2, model KPP4R according to TU 3742-005-64164940-2013:

Safety valve KPP4R 50-16 DN 50 PN 16 kgf/cm2, pH=16 kgf/cm2, 17nzh17nzh. When placing an order, the need to complete the valves with matching parts (matching flanges, gaskets, studs, nuts; for valves DN 25 PN 100 - nipples with union nuts and gaskets) is specifically stated.