Spring loaded safety valve device. Safety spring valves - all about the device and installation. Benefits of Spring Valves

The safety valve is a pipe fitting that protects equipment and pipelines high pressure from mechanical damage and various kinds of destruction as a result of the occurrence emergencies. This is achieved by venting excess liquid, gas or vapor from the system, as well as vessels in which excessive pressure is formed. In addition, this valve prevents the discharge of the working medium when the nominal pressure is restored.

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

The 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. Closing valve type:
   • proportional;
   • on-off.
2. According to the lifting height of the closing body:
   • low-lift;
   • medium-lift;
   • full-lift.
3. Depending on the type of load on the spool:
   • spring;
   • lever;
   • lever-spring;
   • magnetic spring.

Also, safety valves may differ in the nature of their work and 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 the industry is the angular safety choke. spring type.

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

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

The safety spring valve 17s28nzh is mounted with the equipment and using a flange connection. The flanged safety spring valve 17s28nzh has a service life of more than 11 years, and the manufacturer gives a guarantee of 18 months from the date of putting the valve into operation. The safety valve 17s28nzh is leaky in relation to the external environment.

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

• Case, cover - Steel 25L
• Disc, saddle - Steel 20X13
• Stem - Steel 20X13/Steel 40
• Gasket - AD1M
• Spring - 50HFA

Safety spring valve device 17s28nzh

1 .Cap

2 . Adjusting screw

3 . Spring

4 . Lid

5 . Stock

6 . Knot of manual undermining

7 . Spool Assembly

8 . Saddle

9 . Frame

Overall and connecting dimensions of the safety valve 17s28nzh

Technical characteristics of the safety valve 17s28nzh

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

Purpose of the spring valve

Dangerous overpressure in the system occurs as a result of external and internal factors. Both incorrect collection of thermal and mechanical circuits, which causes malfunctions in the operation of equipment, heat entering the system from extraneous sources, and internal physical processes that are not provided for by standard operating conditions that periodically occur in the system, lead to an increase.

Safety products are an indispensable part of any household or industrial system working 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 through which not only gaseous, but also liquid substances are transported.

The device 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 rises, the medium is discharged through the side fitting. The spring adjusted depending on the pressure in the system ensures that the spool is pressed against the seat. The spring is adjusted by means of a special bushing, which is screwed into top cover located on the body of the device. The cap located in the upper part is designed to protect the bushing from destruction as a result of mechanical influences. The presence of a special lug 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 body is selected. If the parameters are chosen 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 the 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 provides timely pressure relief, 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, the pressure in which does not exceed 0.25-2.3 MPa.

Classification and characteristics of spring valves

The safety spring valve is available in three versions:

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

Known classification of valves based on the way they open:

• Check spring valve. To control the check spring valves, an indirect external pressure source is involved. Spring check valves, which are called impulse safety devices, can be operated by the action of electricity.
• Straight valve. In direct type devices, the working pressure of the medium has a direct effect on the spool, which rises with increasing pressure.

Allocate open valves And closed type . In the case of a direct type device, when the valve is opened, the medium is discharged directly to the atmosphere. Closed type valves remain completely sealed against environment, relieving pressure in a special pipeline.

Advantages

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

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

The disadvantages of safety valves include the presence of restrictions in the lift height of the spool, increased requirements for the quality of manufacturing of the spring for safety valves, which can fail when working 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 depends on the smooth operation of the system and the ability of the fuse to perform the necessary functions:

• Spring loaded safety valves are the smallest in size compared to other types of safety relief valves, so they should be selected when space is not available.
• Features of the use of valves are associated with the presence of increased vibrations, which adversely affect the performance of the device and can quickly render it unusable. For example, lever-type devices are more prone to breakage due to vibration 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 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.

Installation nuances

A spring-loaded safety valve is installed at any point in the system that is pressurized and at risk of mechanical damage. The device does not require a large free space, which is a significant advantage compared to other types of safety devices.

In order to avoid malfunctions, do not install any valve upstream of the safety valve. stop valves. To discharge the gaseous medium, special devices or discharge occurs directly into the atmosphere. To alert personnel, along with spring valves, a special whistle is mounted, which is placed on the discharge pipe. When the valve is actuated, a whistle will sound to indicate that the system has been pressurized and the valve has opened to release media.

Possible causes of safety valve failures

Safety valves are robust and reliable devices that provide permanent protection of systems against overpressure. A direct or check spring valve fails for several reasons:

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

In order to avoid accidents and malfunctions in the functioning of systems, safety valves are periodically checked for malfunctions. Valves are tested for strength and tightness before being put into service. Periodic checks are also carried out to determine the tightness of sealing surfaces and stuffing box connections.

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

An obligatory element of equipping autonomous water supply systems in dachas and in country houses is a check valve. That's exactly what technical device, which can have a different design, ensures the movement of fluid 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. Relating to direct acting valves, check valves operate automatically, for which the energy of the working medium transported through the pipeline system is used.

Purpose and principle of operation

The main function that a check valve for water performs is that it protects the water supply system from critical parameters of the flow of 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.

To protect the water supply system from the listed negative phenomena allows the installation check valve to the water. In addition, the water check valve prevents the consequences that water hammer causes. The use of check valves in pipeline systems makes it possible to make their work more efficient, as well as to ensure the correct functioning of the pumping equipment that such systems are equipped with.

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 depresses the spring, with which this element is held closed.
• After compressing the spring and opening the locking element, 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 non-return valve prevents the formation of unwanted backflow in the piping system.

When choosing a model of a valve 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, in accordance with these requirements, a check valve for water is selected are:

• operating, trial and nominal closing pressure;
• landing part diameter;
• conditional throughput;
• tightness class.

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

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

Another 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, the check valve for water allows you to reduce the load on both individual elements equipment of pipelines, and for the entire water supply system as a whole.

Design features

One of the most common materials from which the body part of the water return valves is made is brass. Choice this material not accidental: this alloy demonstrates an exceptionally high resistance to chemically aggressive substances, which can be in the water transported through the 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 is also exposed to negative factors during their operation, is often protected with a special coating applied by the galvanic method.

The check valve device assumes the presence of a 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 can be rubber or silicone. For the manufacture of an important element of the locking mechanism - springs - stainless steel is usually used.

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

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

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

• The flow of water entering the check valve at the required pressure acts on the spool and depresses the spring.
• When the spring is compressed, the spool moves along the stem, opening the orifice and allowing fluid to flow freely through the device.
• When the pressure of the water flow in the pipeline on which the check valve is located, or in cases where such a flow begins to move in the wrong direction, the spring returns the spool to its seat by closing the opening of the device.

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

Main types

Having figured out how the check valve installed in the plumbing system works, you should also understand how to choose it correctly. On the modern market, various types of check valve devices are offered, the design, material of manufacture and the scheme of operation of which can vary greatly.

The valve body of this type consists of two cylindrical elements connected to each other by means of a thread. The locking mechanism includes a plastic stem, 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 provided by a spring. Between themselves, the constituent elements of the body are connected using a sealing gasket.

Distinctive features of this type of shutters 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 valve devices of any other type.

Many of those who decide to do the installation of the pipeline system on their own often have the question of why a check valve is needed, 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 field connections.

On the valve body of this type, which can even be seen in the photo, there are two nozzles, one of which is used to mount the air vent, and the second serves as a drainage element. Branch pipe for the air vent, on inner surface which is threaded, is located on the body of the device above the spool chamber (its receiving part). Such a pipe is needed to bleed air from the pipeline system, for which a Mayevsky crane is additionally used. The purpose of the branch 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 a horizontal non-return valve is installed, its air outlet can be used to mount a pressure gauge. If you put the combined check valve vertically on the pipeline, then its drainage pipe can be used to drain the water accumulated after such a device, and the air vent pipe can be used to remove air plugs from that 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, outwardly very much resemble oblique bends. These types of check valves, for the 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 gates of this type is necessary to accommodate the elements of the locking mechanism in it, which facilitates Maintenance such a device. Thanks to this constructive solution, it is not difficult to carry out maintenance and repair of this type of check valve - 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.

Other types of non-return valves can be installed in pipeline systems designed for transporting water.

• The flap check valve is equipped with a special locking element - a spring-loaded petal. A big disadvantage of this type of shutters is that when they are triggered, significant shock loads are created. This negatively affects the technical condition of the gate device itself, and can also cause a hydraulic shock in the pipeline system.
• Double-leaf type check valve devices are compact in size and light in weight.
• The lifting coupling check valve includes a spool freely moving along the vertical axis as a locking element. 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 in vertical sections of the system. Meanwhile, the gravity valve is characterized by simple structure, while showing high reliability during operation.
• There are check valves, the locking element of which 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 a piping system needs an expensive valve is more complex design, you should first get to know technical specifications 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 the right direction and prevent the flow of liquid from moving in reverse side. In this regard, the check valve for water should be selected 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, it should also be borne in mind that a check valve can be installed different ways. Flanged and wafer type check valves are installed on pipes of large diameter, and sleeve valves are installed on pipes of small diameter. The welded method of installing check valves is mainly used when mounting on polypropylene and metal-plastic pipes.

If you choose the right check valve and the way it is installed, such a device will not only serve long time, but also ensure the correct operation of the entire pipeline system.

How to install correctly

Having dealt with the question of why a check valve is needed, and with its role in the pipeline system, you should also study the rules for installing it on an already operating or just being 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, storage water heaters and water meters.

If you are interested in check valves that can be installed both vertically and horizontally, choose not gravity, but spring models. You can find out in which direction the water flow should move through the valve using a special arrow printed on the body of the device. When installing sleeve-type check valves, be sure to use FUM tape for good sealing. In addition, one should not forget that check valves need regular maintenance, so they must be installed in accessible places in the pipeline.

When installing a non-return 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 to mechanical impurities contained in underground water. As such a filter, a perforated or mesh cage can also be used, in which a check valve is placed at the inlet end of the suction line of the submersible pump.

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 shut-off device.

How to make a check valve yourself

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

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

• tee with internal thread, which will perform the function of the body;
• threaded socket outer surface- a 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;
• steel threaded plug, which will act as a stop for the spring;
• a standard set of locksmith tools and a FUM sealing tape.
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Spring safety valve (check point)- view pipe fittings, designed to automatically protect equipment and pipelines from excess pressure above a predetermined value by discharging excess working medium and ensuring the termination of discharge at closing pressure and restoration of working pressure.

The main assembly units and parts of the valve:

1 - body, 2 - seat, 3 - spool, 4 - cover, 5 - stem, 6 - nut, 7 - stud, 8 - spring, 9 - bellows (installed in bellows valves), 10 - stop screw, 11 - adjusting sleeve, 12 - guide sleeve, 13 - baffle, 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 the discharge of the working medium is closed). When the pressure rises 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 reducing the pressure in front of the valve to the closing pressure, the spool is again pressed against the seat by the action of the spring, stopping the discharge of the medium.

Mounting position - vertical, cap up.

Shutter tightness- class "B" GOST R 54808. At the request of the customer, it is possible to manufacture with other classes of tightness.

Possible valve designs:

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

Connection to the pipeline:

• flanged;
• under the lens spacer (flange according to GOST 9399);
• choke;
• tsapkovoe.

Bellows valves.

Bellows - 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 at high or low temperatures. Bellows valves are made of steel grades 12Kh18N9TL and 12Kh18N12MZTL and are designed for working environments with temperatures from minus 60 °C and below. Designation of bellows valves: KPP4S, KPPS.

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

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

Safety valves with a nominal pressure of PN 250 kgf/cm2 and PN 320 kgf/cm2, like other models, are designed to protect equipment from unacceptable overpressure by automatically dumping excess working medium. They are used on equipment with liquid and gaseous working media that do not cause corrosion of body parts more than 0.1 mm.

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

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

Setting pressure, Рn- the largest overpressure at the inlet to the safety valve, at which the gate is closed and the specified tightness of the gate is ensured.

Pressure of the beginning of opening, Рн.о.(start 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. At the opening start pressure, the predetermined tightness in the valve gate is violated and the locking element begins to rise.

Full opening pressure, Rp.o.- excess pressure at the inlet to the safety valve, at which the armature moves and the maximum throughput is reached.

Closing pressure, Rz(resetting pressure) is the overpressure at the inlet to the safety valve, at which, after the discharge of the working medium, the locking element is seated on the seat, ensuring the specified tightness of the gate. Valve closing pressure, Рz – not less than 0.8 Рn.

Back pressure- excess pressure at the valve outlet (in particular, from the safety valve).

The back pressure is the sum of the static pressure in the exhaust system (in the case 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 (if only the spring number is specified, the valve is adjusted to the minimum value from the range of the specified spring);
• case material;
• the presence in the valve design of the manual detonation unit;
• the presence of a bellows valve in the design.

An example of designation when ordering a safety spring valve:

An example of designation when ordering a safety spring valve DN 50 PN 16 kgf/cm2 made of steel 12Kh18N9TL with a manual actuation unit, setting pressure - Pn=16 kgf/cm2, model KPP4R according to TU 3742-005-64164940-2013:

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