Safety valves. Check valve for water: principle of operation, design and varieties Special spring-loaded safety valve

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

Photo Designation	Name	DN, mm	Operating pressure(kgf/cm2)	Housing material	Working environment	Connection type	Price, rub
		20	16	bronze	water, steam	coupling-cap	3800
	Spring safety valve	25	16	bronze	water, steam, gas	union-coupling	12000
	Safety low lift spring valve	15-25	16	steel	ammonia, freon	tsapkovy	1200-2000
	Safety valve steel	50	16	steel	liquid or gaseous non-aggressive medium, ammonia	flanged	6660-10800
		50-80	25	steel		flanged	6000
	double-lever safety valve	80-125	25	steel	Water, air, steam, ammonia, natural gas, oil products	flanged	9000-19000
	Safety valve full lift spring	25	40	steel	water, air, steam, ammonia, oil, liquid petroleum products	flanged	20000
	Angle safety valve	50-80	16	steel	water, steam, air	flanged	12500-16000
	Single lever safety valve	25-100	16	cast iron	water, steam, gas	flanged	1500-7000
	Double-lever safety valve	80-150	16	cast iron	water, steam, gas	flanged	6000-30000
	Spring safety valve	15-25	25	steel	freon, ammonia	union-coupling	5000-7000
	Low lift safety valve VALTEC	15-50	16	brass	water, water vapor, air	coupling	860-10600
	safety valve	34-52	0,7	steel	water, steam	flanged	15000
	Spring safety valve	50-150	16	steel		flanged	20200-53800
	Spring safety valve	50-150	40	steel	water, air, steam, ammonia, natural gas, oil, oil products	flanged	20000-53800
	Spring safety valve	50-150	16	steel	water, air, steam, ammonia, natural gas, oil, oil products	flanged	20200-53800
	Safety valve spring angular.	50	100	steel	gas, water, steam, condensate	flanged	37900
		80	100	steel	gas, water, steam, condensate	flanged	39450
	Angle safety valve with damper	50	64	steel	steam	flanged	37300
	The safety valve spring with a damper angular.	80	64	steel	gas, water, steam, condensate	flanged	46500

Safety valve classification:

By the nature of the rise of the closing body:

• valves of proportional action (used on incompressible media);
• two-position valves;

According to the lifting height of the closing body:

• low-lift (lifting height of the locking element (spool, plate) does not exceed 1/20 of the saddle 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-cargo
• 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, therefore they are also called valves. proportional action. These valves are mainly used for liquids where a large capacity is not required. In full-lift valves, the opening occurs in one step, therefore they are also called valves two-position action. These valves are highly efficient and are used for both liquid and gaseous media.

Lever (lever-weight) safety valves, principle of operation:

			Cargo to 17s18nzh, 17h18br

The principle of operation of a lever-weight 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 of valve is a lever and a load suspended from 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 higher the pressure at which the valve operates. Lever valves are adjusted to the opening pressure by moving the weight on the lever (possibly changing the weight of the weight). Levers are also used to manually purge the valve. Lever valves must not be used on mobile heating devices.

The internal structure of the lever safety valve:

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

Large diameter seats require heavy weights on long levers to seal tight, which can cause the unit to vibrate a lot. In these circumstances, valves are used, inside which the medium discharge cross-section is formed by two saddles, which are blocked by two spools using two levers with weights (see for example: , ). The use of these two-lever valves with two gates, which allows to reduce the weight of the load and the length of the levers, ensuring the normal operation of the system.

The adjustment of the lever-load valve, as noted above, is carried out by moving the load along the lever. After the necessary pressure has been set, the load is fixed with bolts, covered protective cover and locks up. This is done to prevent unauthorized changes to the settings. Flanges are often used as cargo.

Features of lever-weight valves:

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

A feature of the valve is the need to grind the working surfaces (spool and seat - a pressed bronze sealing ring) directly at the valve installation site. Lapping refers to the treatment of a bronze seat with abrasive materials to achieve tighter contact between the spool and seat. The spool in the valve body is not fixed and its working surfaces are easily damaged during transportation and loading. A valve without lapping will not seal.

Benefits of Lever Relief Valves:

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

Disadvantages of Lever Relief Valves:

• The need to grind working surfaces;
• Small service life of the valve;
• Bulky design;

Spring loaded safety valves, working principle:

		safety valve

The principle of operation of a spring-loaded safety valve is to counteract the force of the spring - the force on the spool from the pressure of the working medium (coolant). The coolant exerts pressure on the spring, which is compressed. When the setting pressure is exceeded, the spool rises and the coolant is discharged through the outlet pipe. After the pressure in the system has decreased to the setting value, the valve closes and the coolant descent stops.

The internal structure of the spring-loaded 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 - stock; 15 - spring; 16 - support washer; 17 - adjusting screw; 18 - locknut; 20 - cap; 21 - cam; 22 - guide sleeve; 23 - nut; 24 - plug; 25 - cam shaft; 27 - key; 28 - lever; 30 - ball.

The opening pressure of a spring-loaded safety valve is set by fitting the valve with 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 various problems may arise during operation, for example, sticking, freezing of the spool to the seat. However, in industries using aggressive and toxic media, high temperatures and pressures, control purge can be very dangerous. Therefore, for spring valves used in such industries, the possibility of manual purging is not provided and is even prohibited.

When working with aggressive chemical media, the spring is isolated from the working medium by means of sealing along the rod 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. Maximum temperature working medium for safety spring valves up to +450°C, pressure up to 100 bar.

The relief relief 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 setting pressure, because the outgoing coolant creates additional dynamic pressure.

If the heating system functions stably, without failures and overpressure, the relief safety valve remains without "work" for a long period of time and may become clogged. Therefore, it is recommended to clean it periodically.

Benefits of Spring Valves :

• simple equipment design;
• small size and weight with large passage sections;
• possibility of installation in both vertical and horizontal positions;
• the possibility of obtaining high throughput.

Disadvantages of Spring Valves :

• a sharp increase in the force of the spring when it is compressed in the process of lifting the spool;
• the possibility of obtaining a hydraulic shock when the valve is closed;

Magnetic spring safety valves, working principle:

Magnetic spring safety valves use electromagnetic drive. The electromagnet provides additional pressing of the spool to the seat. When the set pressure is reached, the electromagnet is turned off and only the spring counteracts the pressure, and the valve starts to work like a conventional 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 drive provides both additional pressing and opening force, in this case the spring serves as a safety net in case of a power outage. Solenoid spring valves are commonly used in complex impulse applications. safety devices as pilot or pulse 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 action. 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 spring type angular safety choke.

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:

equipment malfunctions;

unwanted heat input from the outside;

errors in the collection of thermal-mechanical circuits. The safety valve is often installed in places where there is a possibility of such complications. These devices are compatible with almost any equipment, but they are most in demand when used with domestic or industrial tanks operating under high pressure.

Spring Type Relief Valve

Spring-loaded safety valves protect the equipment, and thereby prevent its destruction, as a result of exceeding the pressure above the norm. They are used on boilers, various tanks, tanks, pipelines and perform the function of dumping the working medium. The surplus can simply be discharged into the atmosphere or into a special discharge pipeline system. After the pressure returns to normal, the valve closes. The main characteristics of the safety spring valve are its capacity, as well as the value of the response pressure. Last tune in special equipment in the factory, and to test the operation of the device, or to remove dirt that accumulates during operation, the valves have a device that allows you to manually open this device, although some modifications may do without it. For efficient and reliable operation of the valve in a gaseous medium, a forced airflow device may be present in its design. In spring valves, the pressure of the medium on the gate is opposed by the degree of compression of the spring. It is she who determines the actuation force, and the range of adjustments depends on the elasticity of the spring used. This fitting has gained wide popularity due to its simple design, easy settings and a wide range of these products. All this allows you to choose the most suitable model for use in specific conditions. The safety choke is mounted vertically. The locking element in the spring valve device is a butterfly valve. A special device, along with a spring, sets the clamping force and in the event of excessive pressure, the declared clamping force is not enough to hold the medium. As a result, the process of removing its excess from the system takes place until the pressure level is normalized to the initial level. You can learn more about the device and design features of a particular spring valve by examining its passport. Its main components are the locking body, consisting of a valve and a seat, as well as a setter. The adjuster allows you to adjust the valve. It is very important that the spool fits snugly against the seat and prevents leakage. These adjustments are made with a screw. The shutter, as a rule, closes when a pressure appears, which is less than the working one by 10%.

Lever Type Safety Valves

A lever valve is a device in which the shut-off element is sealed with a spring or load. The purpose of such valves is invariably - the discharge of excess volume of the working medium in the event of an excessive increase in pressure. Adjust the lever valve so that at normal pressure readings, the valve always remains in the closed position. The valve spool feels the pressure of two forces at once - it can be a load or a spring, as well as directly the working substance. The load is fixed on the arm of the lever and its weight is transferred to the valve stem. When in advance certain parameters pressure, the force of pressing the valve to the seat must be higher than the pressure force of the working medium and, accordingly, the valve is held in the closed position. With increasing pressure, at a certain moment the downforce becomes equivalent to it and it is at this moment that the valve opens. During the period when the valve is open, the excess working medium is taken in, as a result of which the pressure in the system decreases. After that, the valve is again pressed against the seat and the valve closes. The vast majority of lever valves are made in the form of an angular body (the angle of the fittings is 90 degrees). But there are also such designs in which the fittings are located on the same axis. This body is called a passage. The main purpose of lever valves is to protect against all kinds of emergencies. In this regard, this type of reinforcement is considered a particularly important critical node. Like any other product, lever valves must meet certain requirements:

• operation in the event of excessive pressure should be carried out quickly and without any complications, and when its performance drops to normal, the valve must return to the closed position;
• the flow capacity of a single valve must be sufficient and equivalent to the amount of the supplied working medium.

Spring safety valve (check point)- a type of pipeline 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.

Main Assembly units and valve details:

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 a stamped body can be manufactured in individual face-to-face lengths (L and L1), heights (H) and connecting dimensions flanges, 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.

All pressure vessels must be fitted with pressure relief devices. For this are used:

lever-cargo PC;

safety devices with collapsing membranes;

Lever-and-cargo PCs are not allowed to be used on mobile vessels.

Schematic diagrams of the main types of PC are shown in Figures 6.1 and 6.2. Weight on lever-load valves (see fig. 6.1,6) must be securely fixed in a predetermined position on the lever after the valve is calibrated. The design of the spring PC (see Fig. 6.1, c) should exclude the possibility of tightening the spring in excess of the established value and provide a device for

Rice. 6.1. Schematic diagrams of the main types of safety valves:

1 - cargo with direct loading; b - lever-cargo; in - spring with direct loading; 1 - cargo; 2 - lever arm; 3 - outlet pipeline; 4 - spring.

checking the correct operation of the valve in working condition by forcibly opening it during operation. The device of the spring safety valve is shown in fig. 6.3. The number of PCs, their dimensions and throughput should be calculated so that in Fig. 6.2. The rupture safety disc did not exceed more than 0.05 MPa for vessels with pressure up to 0.3 MPa,

15% - for vessels with pressure from 0.3 to 6.0 MPa, 10% - for vessels with pressure over 6.0 MPa. When the PC is in operation, it is allowed to exceed the pressure in the vessel by no more than 25%, provided that this excess is provided for by the project and is reflected in the vessel passport.

The bandwidth of the PC is determined according to GOST 12.2.085.

All safety devices must have passports and operating instructions.

When determining the size of flow sections and the number of safety valves, it is important to calculate the valve capacity per G (in kg / h). It is performed according to the methodology described in the SSBT. For water vapor, the value is calculated by the formula:

G=10B 1 B 2 α 1 F(P 1 +0.1)

Rice. 6.3. Spring device

safety valve:

1 - body; 2 - spool; 3 - spring;

4 - discharge pipeline;

5 - protected vessel

where bi - coefficient taking into account the physical and chemical properties of water vapor at operating parameters in front of the safety valve; can be determined by expression (6-7); varies from 0.35 to 0.65; the coefficient taking into account the ratio of pressures before and after the safety valve depends on the adiabatic index k and exponent β, for β<β кр =(2-(k+1)) k/(k-1) коэффициент B 2 = 1, показатель β вычисляют по фор муле (6.8); коэффициент B 2 varies from 0.62 to 1.00; α 1 - flow coefficient indicated in the passports of safety valves, for modern designs of low-lift valves α 1 \u003d 0.06-0.07, high-lift valves - α 1 \u003d 0.16-0.17, F- valve passage area, mm 2 ; R 1 - maximum overpressure in front of the valve, MPa;

B 1 \u003d 0.503 (2 / (k + 1) k / (k-1) *

where V\ - specific volume of steam in front of the valve at parameters P 1 and T 1, ) m 3 /kg - medium temperature in front of the valve at pressure Р b °С.

(6.7)

β = (P 2 + 0.1)/(P 1 +0.1), (6.8)

where P2 - maximum overpressure behind the valve, MPa.

Adiabatic exponent k depends on the temperature of the water vapor. At a steam temperature of 100 °C k = 1.324, at 200 "C k = 1.310, at 300 °C k= 1.304, at 400 "C k= 1.301, at 500 ° ck= 1,296.

The total capacity of all installed safety valves must not be less than the maximum possible emergency inflow of medium into the protected vessel or apparatus.

Burst discs (see figures 6.2 and 6.4) are specially loosened devices with a precisely calculated pressure burst threshold. They are simple in design and at the same time provide high reliability of equipment protection. The membranes completely seal the outlet of the protected vessel (before operation), are cheap and easy to manufacture. Their disadvantages include the need to replace after each actuation, the impossibility of accurately determining the actuation pressure of the membrane, which makes it necessary to increase the margin of safety of the protected equipment.

Diaphragm safety devices can be installed instead of lever-load and spring safety valves, if these valves cannot be used in a particular environment due to their inertia or other reasons. They are also installed in front of the PC in cases where the PC cannot work reliably due to the peculiarities of the influence of the working medium in the vessel (corrosion, crystallization, sticking, freezing). The membranes are also installed in parallel with the PC to increase the throughput of pressure relief systems. The membranes are installed in parallel with the PC to increase the throughput of pressure relief systems. Membranes can be bursting (see Fig. 6.2), breaking, tear-off (Fig. 6.4), shear, snapping out. The thickness of bursting discs A (in mm) is calculated by the formula:

PD/(8σ vr K t )((1+(δ/100))/(1+((δ/100)-1)) 1/2

where D - working diameter; R- membrane actuation pressure, σvr - tensile strength of the membrane material (nickel, copper, aluminum, etc.) in tension; To 1 - temperature coefficient varying from 0.5 to 1.8; δ - relative elongation of the membrane material at break, %.

For tear-off diaphragms, the value that determines the response pressure,

is the diameter D H (see Fig. 6.4), which is calculated as

D n \u003d D (1 + P / σ vr) 1/2

The membranes must be labeled as prescribed by the Rules of Content. Safety devices must be installed on branch pipes or pipelines directly connected to the vessel. When installing several safety devices on one branch pipe (or pipeline), the cross-sectional area of ​​​​the branch pipe (or pipeline) must be at least 1.25 of the total cross-sectional area of ​​the PC installed on it.

It is not allowed to install any shut-off valves between the vessel and the safety device, as well as behind it. In addition, safety devices should be located in places convenient for their maintenance.

Safety devices. Safety devices (valves) must automatically prevent pressure increase beyond the allowable by releasing the working medium into the atmosphere or the disposal system. At least two safety devices are required.

On steam boilers with a pressure of 4 MPa, only impulse safety valves should be installed.

Passage diameter (conditional), mounted on boilers lever-,; cargo and spring valves, must be at least 20 mm. Allowance for this passage to be reduced to 15 mm for boilers with a steam capacity of up to 0.2 t / h and a pressure of up to 0.8 MPa when two valves are installed.

The total capacity of the safety devices installed on steam boilers must be at least the rated capacity of the boiler. Calculation of the capacity of the limiting devices of steam and hot water boilers must be carried out according to 14570 “Safety valves for steam and hot water boilers. Technical requirements".

Places of installation of safety devices are determined. In particular, in hot water boilers, they are installed on the outlet manifolds or on the drum.

The method and frequency of regulation of safety valves (PC) on boilers is indicated in the installation instructions and ex. Valves must protect the vessels from exceeding the pressure in them by more than 10% of the calculated (allowed).

Short answer: All pressure vessels must be fitted with pressure relief devices. For this are used:

spring safety valves (PC);

lever-cargo PC;

pulse safety devices, consisting of a main PC and a direct-acting control pulse valve;

safety devices with collapsing membranes;

other safety devices, the use of which is agreed with the Gosgortekhnadzor of Russia.

Safety valves are used on an industrial scale and are installed on highways 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).

Design and types of 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 (the lift of the locking part is 1/20 of the seat diameter), full-lift (1/4 of the seat, designed for high-capacity highways), and 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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