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 environment into a specially installed outlet pipeline or into the atmosphere, and when the working pressure is restored, the safety valve 17s28nzh stops the discharge of the working medium.

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 safety valve 17s28nzh

DN, mm

Dimensions, mm

4

Technical characteristics of the safety valve 17s28nzh

Name	Meaning
Nominal diameter, DN, mm
Seat hole diameter dc, mm
Permissible leakage in the gate, cm 3 / min	5-for air 1-for water		10 for air 2-for water
Cross-sectional area of ​​the saddle Fс, mm 2, not less than
Nominal pressure at the inlet PN, MPa (kgf / cm 2)
Nominal pressure at the outlet PN, MPa (kgf / cm 2)
Pressure full opening Rp.o. MPa (kgf / cm 2), no more	For gaseous media: pH + 0.05 (0.5) for pH<0,3 МПа; 1,15 Рн для Рн>0.3 MPa For liquid media: pH + 0.05 (0.5) for pH<0,2 МПа; 1,25 Рн для Рн>0.2 MPa
Closing pressure Rz	not less than 0.8 pH
Spring setting pressure limits, Рn MPa (kgf/cm2), not less than	0,05-0,15 (0,5-1,5); 0,15-0,35 (1,5-3,5); 0,35-0,7 (3,5-7,0); 0,7-1,0 (7-10); 1,0-1,6 (10-16)
Temperature environment, РС		from minus 40 to 40
Working environment temperature, ÐС		from minus 40 to 450
Characteristics of the working environment	Water, steam
Consumption ratio?	0.8 for gaseous; 0.5 for liquid media
Mounting dimensions and dimensions of the sealing surfaces of the housing	according to GOST 12815-80 version 1 row 2
Weight without flanges (kg)

An obligatory element of equipping autonomous water supply systems in dachas and in country houses is an 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 armature devices direct action, 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.

Installing a check valve on water allows you to protect the plumbing system from the listed negative phenomena. In addition, the water check valve prevents the consequences that water hammer causes. The use of check valves in piping systems allows them to work more efficiently, as well as ensure correct functioning. 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 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 regulatory requirements, which are presented to such devices by manufacturers of pumping equipment. 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 check valves of spring type are used, 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 noise and vibration levels in the pipeline system on which they are installed.

Another positive factor in 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 important element locking mechanism- springs - usually use stainless steel.

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

• corps composite type, the elements of which are interconnected by means of a thread;
• locking mechanism, the design of which includes two movable spool plates mounted on a special rod, and 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 scheme of operation of the check valve is quite simple, but nevertheless ensures the high reliability of such devices and the efficiency of their use in pipeline systems.

Main types

Having understood how the check valve installed in plumbing system, you should also understand how to choose it correctly. On the modern market offered different kinds check valve devices, the design, material of manufacture and the scheme of operation of which can vary significantly.

Coupling Type Spring Check Valve

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.

Spring check valve with brass spool and spherical spool chamber

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.

Combination spring type check valve with drain and air vent

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, and reduce the total hydraulic pressure, 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 opposite side body - at the outlet of the valve, consists in draining 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 combined type check valve, you should clearly understand what functions such a valve should perform.

Spring loaded valves with polypropylene body

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. Thereby 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.

Check valves of other types

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 locking mechanism can be based on gravity principle when the spool returns to the closed state under 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 systems. 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 install a coarse filter in front of such a device, which will prevent mechanical impurities contained in underground water from entering the inside of the device. 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:

• a tee with an internal thread, which will serve as a body;
• a threaded coupling on the outer surface - a homemade check valve seat;
• stiff spring made from 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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Safety valves are used in industrial scale and are installed on the highway in order to discharge excess flow of the working medium from the pipeline to reduce the pressure level (a type of household safety valve is the Mayevsky tap, which bleeds air from heating systems).

Device and types safety valves

The main element of the safety valve is the valve, stem, adjusting elements, tuning springs. By design, safety valves are lever-load (the working medium presses on the spool, and this pressure is counteracted by the force of the load) and magnetic-spring (driven by an electromagnetic drive).

Types of safety valves:

• direct action. It works when the pressure is higher than normal;
• indirect action. They work when exposed to an extraneous impulse (for example, from an electric one, they are used for remote control);
• proportional action. Are applied in incompressible environments;
• two-position action.

Safety valve operation video

Also, safety valves are low-lift (lift of the locking part is 1/20 of the seat diameter), full-lift (1/4 of the seat, designed for large pipelines). bandwidth), medium-lift. Check valves are a type of safety valve. Also, safety valves are divided into shut-off and control valves. The limit pressure setting is carried out at the time of installation by changing the position of the adjusting screw that compresses the pressure spring.

• We recommend spring loaded safety valves! Unlike membrane valves, they are equipped with additional devices that prevent the spool from freezing to the seat.

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Overpressure. The valve must also be able to stop the discharge of the medium when the operating pressure is restored. The safety valve is a fitting direct action operating directly from the working environment, along with most designs of protective valves and direct-acting pressure regulators.

dangerous overpressure can occur in the system both as a result of external factors (incorrect operation of equipment, heat transfer from external sources, incorrectly assembled thermal-mechanical circuit, etc.), and as a result of internal physical processes due to some initial event not provided for by normal operation. PC are installed wherever this can happen, that is, on almost any equipment, but they are especially important in the field of operation of industrial and domestic vessels operating under pressure.

Encyclopedic YouTube

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Why a safety valve in a hot water system

Safety valve design (in stereo anaglyph)

Subtitles

Operating principle

When the safety valve is closed, a force is applied to its sensing element from operating pressure in the protected system, tending to open the valve and the force from the master, preventing the opening. With the occurrence of disturbances in the system, causing an increase in pressure above the working one, the value of the force of pressing the spool to the seat decreases. At the moment when this force becomes equal to zero, equilibrium occurs active forces from the influence of pressure in the system and the setting device on the sensitive element of the valve. The shut-off body begins to open, if the pressure in the system does not stop increasing, the working medium is discharged through the valve.

With a decrease in pressure in the protected system, caused by the discharge of the medium, disturbing influences disappear. The shut-off body of the valve closes under the action of force from the setter.

The closing pressure in some cases turns out to be 10-15% lower than the working pressure, this is due to the fact that in order to create the tightness of the shut-off body after actuation, a force is required that is much greater than that which was sufficient to maintain the tightness of the valve before opening. This is explained by the need to overcome the adhesion force of the molecules of the medium passing through the gap between the sealing surfaces of the spool and seat during landing, to displace this medium. Also, a decrease in pressure is facilitated by a delay in closing the shut-off body, associated with the impact on it of dynamic forces from the passing flow of the medium, and the presence of friction forces, requiring additional effort for its complete closure.

Safety valve classification

According to the principle of action

• direct acting valves - usually these devices are meant when they use the phrase safety valve, they open directly under the action of the pressure of the working environment;
• valves of indirect action - valves controlled by using an external source of pressure or electricity, the common name for such devices is impulse safety devices;

By the nature of the rise of the closing organ

• proportional valves (used for incompressible media)
• on/off valves

According to the lifting height of the closing body

• low-lift
• medium-lift
• full-lift

By type of load on the spool

• cargo or lever-cargo
• spring
• lever-spring
• magnetic spring

Differences in designs

Safety valves usually have an angle body, but can also have a straight body, regardless of this, the valves are installed vertically so that the stem drops down when closing.

Most safety valves are made with a single seat in the body, but there are designs with two seats installed in parallel.

Low-lift valves are called safety valves, in which the lifting height of the locking element (spool, plate) does not exceed 1/20 of the seat diameter, full-lift valves, in which the lifting height is 1/4 of the seat diameter or more. There are also valves with a poppet height of 1/20 to 1/4, they are usually called medium lift. In low-lift and medium-lift valves, the spool rise above the seat depends on the pressure of the medium, therefore they are conditionally called valves. proportional action, although the rise is not proportional to the pressure of the working medium. These valves are generally used for liquids where a large capacity is not required. In full-lift valves, the opening occurs immediately to the full stroke of the plate, therefore they are called valves. two-position action. These valves are highly efficient and are used for both liquid and gaseous media.

The biggest differences in the design of safety valves are in the types of loading on the spool.

Spring valves

In them, the pressure of the medium on the spool is counteracted by the compression force of the spring. The same spring valve can be used for different set pressure settings by fitting different springs. Many valves are manufactured with a special mechanism (lever, fungus, etc.) for manual blasting for control blowing of the valve. This is done in order to check the operability of the valve, since during operation various problems may arise, such as sticking, freezing, sticking of the spool to the seat. However, in some industries in aggressive and toxic environments, high temperatures and pressures, control blowing can be very dangerous, therefore, for such valves, the possibility of manual blowing is not provided and is even prohibited.

Most often, the springs are exposed to the working medium, which is discharged from the pipeline or tank when triggered; special spring coatings are used to protect against slightly aggressive environments. There is no stem seal in these valves. In cases of working with aggressive environments in chemical and some other installations, the spring is isolated from the working medium by means of a seal along the stem with a stuffing box, bellows, or an elastic membrane. The bellows seal is also used in cases where leakage of the medium into the atmosphere is not allowed, for example, at nuclear power plants.

Lever-load valves

In such valves, the force on the spool from the pressure of the working medium is counteracted by the force from the load transmitted through the lever to the valve stem. The adjustment of such valves to the opening pressure is carried out by fixing a load of a certain mass on the lever arm. Levers are also used to manually purge the valve. Such devices must not be used on mobile vessels.

For sealing saddles large diameters significant masses of weights are required on long levers, which can cause strong vibration of the device; in these cases, bodies are used, inside which the medium discharge cross section is formed by two parallel saddles, which are blocked by two spools using two levers with weights. Thus, two parallel-operating gates are mounted in one housing, which makes it possible to reduce the weight of the load and the length of the levers, ensuring the normal operation of the valve.

Magnetic spring valves

These devices use an electromagnetic drive, that is, they are not direct acting valves. The electromagnets in them can provide additional pressing of the spool to the seat, in this case, when the response pressure is reached by a signal from the sensors, the electromagnet is turned off and only the spring counteracts the pressure, the valve starts to work like a regular spring valve. Also, the electromagnet can create an opening force, that is, oppose the spring and forcibly open the valve. There are valves in which the electromagnetic actuator provides both additional pressing and opening force, in this case the spring serves as a safety net in case of termination

Each node of the pipeline system plays an important role in ensuring its performance. For example, a safety spring valve is a pipe fitting that is needed to protect against destruction when excess pressure appears in the pipeline. This is possible by releasing the environment from the system.

Another spring valve ensures the termination of the discharge of the medium when operating pressure will be within the normal range.

Features and principle of operation

The spring-type safety valve is a direct-acting valve that operates from the medium. Where can excess pressure appear in the system? As a rule, the reason lies in external and internal factors:

• incorrectly assembled thermal mechanical circuit;
• heat transfer from sources;
• equipment is not functioning properly.

The spring-loaded safety coupling valve is installed wherever there is a risk of excessive maximum pressure. As a rule, these are household or industrial storage vessels operating under pressure.

The great popularity of this fitting provides simple design, easy settings, product range. After all, such a variety and possibilities allow you to choose the optimal model for specific conditions.

The safety choke is mounted vertically. The device of a spring-loaded flanged safety valve implies the use of a disk valve as a locking element, which, when locked, is placed between the seats.

Downforce is set using special device and springs for safety valves.

When the pressure is very high, the specified downforce is not enough to contain the medium, so the excess is removed until the pressure equalizes to the working level.

The passport for the safety spring valve allows you to find out about the design of the product. The main components are the setter and the locking body. The latter consists of a saddle and a shutter.

It is adjusted by means of a dial so that the spool is properly pressed against the seat to prevent the passage of medium. Adjustment is done with a screw.

The closing pressure of the gate is usually taken below the working one by 10 percent.

Product classification

Consider what types of safety products exist.

By the nature of the lifting of the closing body:

• two-position action;
• proportional action.

According to the height of the organ:

• full-lift;
• medium-lift;
• low-lift.

By type of load on the spool:

• cargo;
• magnetic spring;
• lever-spring;
• spring-.

According to the principle of action:

• direct - traditional safety products;
• indirect action - impulse devices.

One of the modifications widely used in industry is the angular safety spring choke.

Another principle of classification is according to the conditional diameter. For example, if a DN15 check spring valve is used, it means that the nominal diameter is 15 mm, and the DN50 check spring sleeve throttle is 50 mm.

Product characteristics

Throughput calculation is performed in accordance with GOST 12.2.085. The devices can be used in petroleum, chemical, gaseous and liquid media. Tightness is determined according to GOST 9789-75.

The closing pressure of the valve is more than 0.8 Pn, where Pn is the set pressure, which is the highest at the inlet to the valve, at which it remains in the closed state, while maintaining proper tightness.

Springs for them are most often made of steel 50HFA. The spring check valve type 402 is made of cast iron.

In order to check the health of the device in working order, the SPPK spring-loaded safety valve has a solution for manual opening, purge, therefore, products without SPKK do not have the possibility of manual opening.

The dimensions of the sealing surfaces of the flanges are determined in accordance with GOST 12815-80.

As an example of one of the modifications of the device, we give the fuse 17s28nzh, corresponding to TU3742-017-00218118-2002.

The device has the characteristics:

• working pressure - 1.6 MPa;
• working medium - non-aggressive, gas, steam, water;
• body material - steel;
• sealing material – stainless steel;
• connection - flange;
• temperature - from minus 40 to plus 250 degrees;
• weight and length depend on the nominal diameter.

Nuances of choice

To choose the optimal product, it is necessary to take into account the requirements that apply to them:

• timely and trouble-free installation of a safety valve with a specified increase in the level of working pressure in the system;
• in the open position, the necessary throughput must be provided;
• timely closing of the shutter with the desired level of tightness;
• ensuring stable operation.

Cost is important when choosing. For example, let's consider how much you can buy a safety spring valve 17s28nzh: the price of a reverse clutch spring throttle is from $300.

Of course, a lot depends on the manufacturer. So, a similar Danfoss spring check valve will cost more - from $ 400.

Features of the product (video)

Installation nuances

Before installing a safety spring valve, follow these simple steps:

• check labeling;
• inspect the case for external damage;
• remove the protective cap;
• there shouldn't be any inside foreign objects;
• It should be remembered that during installation, the components of the product will heat up.

The installation process is carried out in accordance with the current safety rules and regulatory and technical standards. The choice of location, design and number of valves, as well as the direction of the discharge of the medium, is determined by the project.

The place must be selected so that free access for maintenance and repair is provided. Installation is carried out in a vertical position at the top of the vessel. Also, the installation can be performed near the vessel or pipeline, only there should not be a shut-off device between the products.

The size of the fitting cannot be less than the diameter of the inlet pipe of the valve.

Spring loaded poppet valve with a large number plates can provoke an increase in their resistance, which can change the pressure difference in the upper and bottom parts of the product. Therefore, it should be installed in the last area.

Self-installation of such devices is a complex procedure that requires experience and certain skills. Therefore, it is necessary to turn to professionals.

Faults and repairs

The leakage of the medium through the valve occurs when the pressure is lower than the setting pressure.

• delay on the sealing elements of foreign objects - it is necessary to purge the throttle;
• damage to the sealing elements - turning or grinding is performed, followed by a leak test; if the depth of damage is more than 0.1 mm, it is necessary to perform machining;
• spring deformation - it is being replaced;
• misalignment of the elements due to a large load - the load is eliminated, the discharge and intake lines are checked, it is necessary to re-tighten the studs;
• reduced opening pressure - adjustment, deformation of the spring - it is being replaced;
• poor-quality assembly after repair - eliminate all assembly shortcomings.

Repair of safety spring chokes must be trusted to professionals. The cost of the procedure will cost from $50.