Spring safety valve device. Safety valve. Lever type safety valves

Check valve - element pipeline system, providing for the movement of the working medium in only one direction. Its use is mandatory for autonomous pumping stations and other equipment that may fail when the fluid flow moves in the opposite direction.

A spring check valve is one of the types of shut-off elements. It belongs to the category of fittings direct action and is triggered automatically by the energy of the working environment, which prevents equipment failure in the event of a power outage or other malfunctions.

Design features

The spring valve is structurally composed of three elements:

1. A body usually made of brass and equipped with elements for fastening to the pipeline (coupling, thread). The body is also made of steel, cast iron and polypropylene. The choice of material is determined by the parameters of the working environment and the diameter of the pipeline.
2. The working element, which represents a movable spool, includes two plates with a special sealed gasket between them and a rod.
3. An actuator representing a spring located between the work element plates and the seat. Provides automatic shutoff of fluid flow when pressure decreases or changes its direction. The minimum pressure of the working medium at which the valve automatically opens depends on the stiffness of the spring.

Advantages of spring check valves:

• Possibility of installation in any position;
• simplicity of design;
• versatility.

At the same time, the valve is sensitive to contaminants in the water, which lead to wear of the sealing plates, so it is advisable to install a filter in front of it. It is also recommended to mount the valve in easily accessible places to simplify installation. Maintenance and replacements.

It is advisable to install the valve in vertical position so that the blocking force of the spring coincides with the action of gravity. For correct installation it is necessary to focus on the arrow marked on the valve body, which shows the direction of flow of the working medium through.

Scope of application

Spring check valves are widely used in systems autonomous water supply, intra-house networks apartment buildings. They are installed on the suction lines of pumps, before DHW water heaters, boilers, water meters and other equipment.

Safety valves- a type of pipeline fittings designed to protect the heating system from overpressure. The safety valve is a direct acting valve, i.e. fittings operating directly under the control of the working medium itself (as well as direct-acting pressure regulators).

Classification of safety valves:

According to the nature of the elevation of the closing organ:

• proportional action valves (used on incompressible media);
• on/off valves;

According to the height of the lift of the closing organ:

• low-lift (the lifting height of the locking element (spool, plate) does not exceed 1/20 of the seat diameter);
• medium-lift (plate lifting height from 1/20 to ¼ of the saddle diameter);
• full lift (lift height is 1/4 of the saddle diameter or more);

By type of load on the spool:

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

In low-lift and medium-lift valves, the lift of the spool above the seat depends on the pressure of the medium, which is why they are also called valves proportional action. Such valves are mainly used for liquids when large throughput is not required. In full-lift valves, the opening occurs simultaneously, which is why they are also called valves on/off action. Such valves are high-performance and are used for both liquid and gaseous media.

Lever (lever-weight) safety valves, operating principle:

The principle of operation of a lever-load safety valve is to counteract the force on the spool from the pressure of the working medium - the force from the load transmitted through the lever to the valve stem. The basis of the mechanism of this type valves is a lever and a load suspended on it. The operation of the device depends on the weight of the load and its location on the lever. The greater the weight and the further it is on the lever, the more high blood pressure the valve is activated. Lever valves are adjusted to the opening pressure by moving a weight along the lever (the weight of the load may change). Levers are also used to manually purge the valve. Lever valves are prohibited for use on mobile heating devices.

Internal structure of lever safety valve:

1.Inlet; 2. Outlet; 3. Valve seat; 4. Spool; 5. Cargo; 6. Lever.

Sealing of large diameter seats requires heavy weights on long arms, which can cause severe vibration of the device. In these circumstances, valves are used, inside of which the medium discharge cross-section is formed by two seats, which are closed by two spools using two levers with weights (see for example:,). The use of these two-lever valves with two gates, which allows reducing the mass of the load and the length of the levers, providing normal work systems.

Adjustment of the lever-weight valve, as noted above, is carried out by moving the weight along the lever. After the required pressure has been adjusted, the load is fixed with bolts and covered protective casing and is locked. This is done to prevent unauthorized changes to the settings. Flanges are often used as weights.

Features of lever-weight valves:

Lever valves are pipeline fittings that were developed before the 40s of the last century. This is an obsolete valve, purchased only to maintain boiler points and similar facilities from the Soviet public utilities era.

A feature of the valve is the need to grind in the working surfaces (spool and seat - pressed bronze o-ring) directly at the valve installation site. Lapping means treating the bronze seat with abrasive materials to achieve tighter contact between the spool and the seat. The spool in the valve body is not secured and during transportation and loading its working surfaces are easily damaged. A valve without lapping will not be sealed.

Advantages of lever safety valves:

• Simplicity of design;
• Maintainability;
• Manual setting valve actuation;

Disadvantages of lever safety valves:

• The need to grind in working surfaces;
• Short valve life;
• Bulky design;

Spring safety valves, operating principle:

The operating principle of a spring safety valve is to counteract the spring force - the force on the spool from the pressure of the working medium (coolant). The coolant exerts pressure on the spring, which compresses. When the set pressure is exceeded, the spool rises and the coolant is discharged through the outlet pipe. After the pressure in the system has dropped to the set pressure, the valve closes and the coolant drainage stops.

Internal structure of spring safety valve:

1 - body; 2 - nozzles; 3 - lower adjusting sleeve; 4, 5 - locking screw; 6, 19, 25, 29 - gasket; 7 - upper adjusting sleeve; 8 - pillow; 9 - spool; 10 - guide sleeve; 11 - special nut; 12 - partition; 13 - cover; 14 - rod; 15 - spring; 16 - support washer; 17 - adjusting screw; 18 - lock nut; 20 - cap; 21 - cam; 22 - guide sleeve; 23 - nut; 24 - plug; 25 - cam shaft; 27 - key; 28 - lever; 30 - ball.

The response pressure of the spring safety valve is set by equipping the valve with various springs. Many valves are manufactured with a special mechanism (lever, fungus, etc.) for manual detonation for control purging of the valve. This is done to check the functionality of the valve, since during operation there may be problems various problems, for example, sticking, freezing of the spool to the seat. However, in industries using aggressive and toxic environments, high temperatures and pressures, control purge can be very dangerous. Therefore, for spring valves used in such industries, the possibility of manual blowing is not provided and is even prohibited.

When working with aggressive chemical media, the spring is isolated from the working environment using a seal along the rod with a stuffing box, bellows or elastic membrane. Bellows seals are also used in cases where leakage of the medium into the atmosphere is not allowed, for example at nuclear power plants. Maximum temperature working environment for safety spring valves up to +450°C, pressure up to 100 bar.

The relief safety valve opens before the set pressure is reached. The valve opens completely when the pressure exceeds the set pressure by 10-15% (depending on the model). The device closes completely only when the pressure is 10-20% less than the set pressure, because the escaping coolant creates additional dynamic pressure.

If the heating system operates stably, without failures and overpressure, the relief safety valve remains without “working” for long period time and may become clogged. Therefore, it is recommended to clean it periodically.

Advantages of spring valves :

• simple equipment design;
• small size and weight with large flow sections;
• Possibility of installation in both vertical and horizontal positions;
• possibility of obtaining high bandwidth.

Disadvantages of spring valves :

• a sharp increase in the spring force when it is compressed during the process of lifting the spool;
• the possibility of receiving a water hammer when closing the valve;

Magnetic spring safety valves, operating principle:

Magnetic spring safety valves use an electromagnetic actuator. The electromagnet provides additional pressing of the spool to the seat. When the response pressure is reached, the electromagnet turns off and only the spring counteracts the pressure, and the valve begins to operate like a regular spring valve. Also, the electromagnet can create an opening force, that is, counteract the spring and force the valve to open. There are valves in which the electromagnetic drive provides both additional pressing and opening force; in this case, the spring serves as a safety net in case of power failure. Magnetic spring valves are typically used in complex pulse applications. safety devices ah as control or pulse valves.

To relieve excess pressure into the atmosphere, spring safety valves are used, which are a special pipeline fittings, providing 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, 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 a 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, which is screwed into the 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 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 critical level depending on type 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 devices direct type operating pressure The environment 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 on the lifting height of the spool, increased requirements to the quality of manufacture 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:

• Safety spring valves have smallest dimensions compared to other types of safety relief valves, so they should be chosen in cases where free space not enough.
• Features of the use of valves are associated with the presence of increased vibrations, which negatively affect performance characteristics 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

Safety valve spring type installed at any point in the system that is exposed to high blood pressure and is in danger of getting 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 in front of the safety valve. To reset gaseous medium special devices are installed or 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.

With the correct selection of safety devices taking into account the 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.

The NEMEN company sells safety valves designed to operate in various environments. We offer, which can be installed vertically on a pipeline section or boiler units.

Purpose of safety valves

Safety valve is a type of fitting that is intended for automatic protection pipelines and equipment from excess pressure above a certain, predetermined value, by discharging the excess mass of the working medium. The valve also ensures that venting stops when normal operating pressure is restored. A safety valve is a direct-acting valve that operates directly from the energy of the working medium.

Working principle of safety valve

When the safety valve is in the closed state, the sensitive element of the valve is affected by the force from the operating pressure in the pipeline, which tends to open the valve, as well as the force from the set point preventing the opening. If disturbances occur in the system, causing an increase in medium pressure above the working pressure, the force of pressing the spool against the seat decreases. When its value is zero, there is a balance of active forces from the set pointer and the pressure of the medium, simultaneously acting on the valve. If the pressure in the system continues to increase, the shut-off valve opens and the excess medium is discharged through the valve. Reducing the volume of the medium leads to normalization of pressure in the system and the disappearance of disturbing influences. When the pressure level drops below the maximum permissible level, the shut-off valve returns to initial position under the influence of force from the set pointer.

Safety spring valves

In such safety valves, spring compression force is used to counteract the pressure of the working medium on the spool. By installing different springs, the same spring safety valve can be used for several maximum permissible pressure settings. Spring valves do not have a stem seal. If the fittings are installed in systems with an aggressive working environment, the spring is isolated using stuffing box devices, an elastic membrane or a bellows. Bellows seals are used in cases where leakage of the working medium from the pipeline is unacceptable.

Safety valves are used on an industrial scale and are installed on the main line 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 valve, which bleeds air from heating systems).

Design and types of safety valves

The main element of a safety valve is a valve, a rod, adjusting elements, and adjustment springs. By design, safety valves can be lever-load (the working medium presses on the spool, and this pressure is counteracted by the force of the load) and magnetic-spring (actuated by an electromagnetic drive).

Types of safety valves:

• direct action. Triggers when the pressure exceeds the norm;
• indirect action. They are triggered when exposed to an extraneous impulse (for example, from an electric one, used for remote control);
• proportional action. Used in incompressible media;
• two-position action.

Video of safety valve operation

Safety valves can also be low-lift (the lift of the locking part is 1/20 of the diameter of the seat), full-lift (1/4 of the seat, intended for high-capacity highways), and medium-lift. Check valves are a type of safety valve. Safety valves are also divided into shut-off and control valves. The limit pressure is adjusted at the time of installation by changing the position of the adjusting screw that compresses the pressure spring.

• We recommend spring safety valves! Unlike membrane ones, they are equipped additional devices, preventing the spool from freezing to the seat.

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