The best disruptive valve for a gas boiler. Valve for a water heater: which one is needed and why. Installation progress

Boiler equipment, whether it is a boiler in a private house or a large boiler room in an enterprise, is a source of danger. The boiler water jacket under constant pressure is potentially explosive.

To ensure safety, many protective systems and devices are installed on boilers and other heat generators produced today. One of the simplest and most affordable - installed It is sometimes also called an explosive valve.

Causes and consequences of overheating of the coolant

The boost problem is especially important for solid fuel boilers. An emergency situation, as a rule, occurs when the water in the heating boiler circuit overheats. As soon as the heat carrier heated in excess of the norm boils in the boiler tank, it instantly turns into steam. This is followed by a sharp increase in pressure in the heating system of such a steam boiler.

Overheating of the boiler increases the risk of breakage of fittings and plastic pipes. Leaks can begin at the system pipework connections, up to pipe ruptures. The worst thing is the explosion of the boiler or an electrical short circuit in the boiler equipment.

What is a safety valve for?

The troubles associated with overpressure in the heating system are extremely dangerous for people and buildings. Explosion valves are installed to prevent the severe consequences of overheating. Since the source of the critical increase in pressure is the boiler itself, the valve should be located as close to it as possible. It is mounted on the heating supply pipe.

Manufacturers of heating equipment often release their products already equipped with safety groups - a pressure gauge and a relief valve. This group is usually built into the jacket of the heating boiler. If such a complete set is not provided in the purchased boiler, then you must install it yourself.

When is a safety valve needed?

Unlike solid fuel boilers, when using electric or gas, explosive safety valves are not installed. These devices have their own automation, and there is practically no inertia. This means that as soon as the temperature of the coolant reaches the set mark, the electrical element or gas water heater switches off automatically. In this case, heating also stops, which eliminates the risk of overheating, and, accordingly, an increase in pressure to critical values.

Solid fuel boilers, like stoves with a water circuit, belong to systems in which the use of safety valves is mandatory. Whatever automation is in solid fuel heat generators, after heating the liquid in the network to the nominal value, the furnace will continue to raise the temperature for some time, although the access to the chamber is closed by the sensor, and the flame began to fade. This is how the effect of inertia manifests itself. When the temperature in the furnace reaches 90-95 degrees (limit values for most boilers), vaporization is inevitable. The result may be a depressurization of the heating system or an explosion of the boiler.

If a safety valve is installed on the boiler in the system, then the pressure increase after the heating medium boils will be prevented. The valve will automatically release excess steam to the outside, reducing the pressure in the system to normal. After that, the valve will close and operate the next time only if the abnormal situation repeats.

Safety valve device

The valve is made of plumbing brass using hot stamping technology. It consists of two parts with a semi-solid state.

The main element of the valve is a special spring. Depending on its elasticity, the power of the pressure is determined, which is applied to the membrane that closes the outlet to the outside. The nominal position of the diaphragm is in the seat, compressed by this spring.

With its upper part, the spring rests against a metal washer, which is installed on a rod, the end of which is fixed on a plastic handle. It is she who allows the adjustment of the explosive valve. The sealing parts and the membrane itself are made of polymer. Steel spring.

Valve operating principle

While in standby mode, the entrance to the inner chamber is closed with a membrane. In the event of an emergency, a mixture of steam and water begins to abut against the membrane, opening it at peak pressure. As a result, the steam-water mixture enters the chamber and then exits through the opening on the side.

After reducing the pressure, due to a certain amount of water released from the system, the membrane falls into place and closes the outlet for water. Sometimes these valves are triggered frequently, especially when the boilers are operating at maximum capacities. This is undesirable, since the boiler can lose its tightness and therefore leak.

If traces of leakage from the safety valve are found, it is necessary to urgently inspect the boiler and the heating system, since its operation is a sign of the heating system operating in extreme conditions. However, sometimes the expansion tank can also be the cause of the emergency release of pressure. Therefore, it is imperative to check it too.

In addition to the valve under consideration, the PGVU valve can also be used - for dust and gas air ducts. It has the same principle of operation. However, in the case of its use, it does not matter at all whether a steam boiler or a solid fuel, as well as what exactly will be thrown out - water, steam or gas.

How to choose a safety valve

If a valve is not supplied with the boiler, it will have to be purchased separately. The choice is made based on the characteristics The heat output and the maximum possible pressure of the heat carrier in the heating system matter.

For reference. Most of the well-known brands of solid fuel boilers have a maximum allowable pressure of about 3 bar, with the exception of STROPUVA products. They have a limit of 2 Bar.

It is best to install a multi-range valve. Naturally, the values of the boiler installed in the boiler room must be within these ranges. After that, the valve is selected by power - here the passport to the boiler will help, in which the power limit of the unit for heat is always indicated.

It is strictly forbidden to install an explosion valve after the pump, which is responsible for the circulation of the coolant in the system. There is another rule as well. Do not install shut-off valves between the boiler and the relief valve.

Boiler equipment

Explosion safety valves ПГВУ 091-80

Explosion safety valves are used to prevent the destruction of power plants in the event of an explosion of flammable gases, coal dust, etc. It is a hole (window) in explosive elements of power plants, closed by doors or materials (asbestos sheet, etc.) that are easily destroyed during an explosion. An explosion valve connected to the gas outlets protects personnel from burns. Explosion valves are used to equip combustion chambers, gas ducts of steam boilers and furnaces, and pulverizing systems for boiler plants operating both under vacuum and overpressure.

We are also ready to manufacture explosive safety valves of non-standard rectangular cross-section with the development of technical documentation for rectangular gas ducts.

Method for calculating the cross-section of an explosive safety valve and recommendations for installation on a gas duct.

The dimensions of the explosion valves are determined by the boiler design.
Practical experience shows that the cross-sectional area of the explosive valve is taken at the rate of 0.05m3 per 1m3 of the gas duct:
Skl = 0.05m2 x Vgas duct.
Based on the results obtained, the closest standard size of the explosion valve is selected.

Installation and operation of explosive safety valves must be carried out in accordance with the "Rules for the construction and safe operation of steam and hot water boilers", "Safety rules in the gas industry" and other regulatory documents.
An explosive valve is usually installed on the flue between the boiler and the chimney, preferably before the gas-tight valve (the place of possible gas accumulation, especially if the gas-tight valve is accidentally closed).
Safety valves must be installed on the dust preparation equipment in such a way as to prevent personnel from being hit by the blast wave and hot dust and gas mixture thrown out of the valves. If it is impossible to install safety valves in places safe for service personnel, bends must be used. To prevent accidents, support grids or cages with a mesh should be installed not only when the valves are operated under vacuum, but also under excessive pressure.

LLC "PTE-87" industrial heat power engineering - supply of equipment

LLC "PTE-87" industrial heat and power engineering - supply of equipment Boiler equipment Explosion safety valves ПГВУ 091-80 Explosion safety valves are used for

Gas ducts, air ducts and pipeline parts

Bends, transitions, tees, explosive valves, gates, expansion joints, hatches, supports, umbrellas, deflectors.

Gas flues, chimneys and air ducts (round and rectangular)

The efficient operation of the boiler is possible under the condition of continuous supply of air through the air ducts to the furnace, which is necessary for fuel combustion.

Details pipelines.

Series 5.903-13 Products and parts of pipelines for heating networks;
Series 5.900-7 Support structures and fasteners for steel pipelines;
Series 5.905-8; 15; eighteen; 25 Units and details for fastening gas pipelines;
Series 4.903-10 Products and parts of pipelines for heating networks;
Series 5.904-41 Check valves for general use;
Series 5.904-42 Fire-retardant check valves;
Series 5.904-50 Ventilation grilles;
Series 5.904-74.93 Unified designs of ventilation air handling units (confusers, boxes, branch pipes, flanges, frames, valves);
And various other assistive devices.

Elbows and transitions (concentric and eccentric).

Fig. 2 Bends and transitions.

Fig 3. Bends with a bend angle of 15 o, 22 o 30 ', 45 o, 60 o and 90 o

Rice. 4. Concentric transition Fig. 5. Transition eccentric

Designed to connect two or more pipelines into a single network.

Examples of symbolic designation of tees.

Explosion valve (safety explosive valve). Flap valve.

Fig 8. Valve. A - explosive valve (explosive safety valve); B - flap valve.

Fig. 9. Explosive safety valve.

Shiber. Gate damper. Valve. Gate valve.

A gate is a shut-off device such as a gate valve (damper), with the help of which the channel for the movement of liquid or gas opens and closes. The gate is used in chimneys of factory furnaces and boiler installations to regulate draft. Small gates are manually driven, large ones by means of toothed racks, worm gears, etc.

Fig 10. Check valve.

Fig 11. Check valve square.

Compensator.

Manholes are designed for internal inspection, repair and cleaning of tanks, gas ducts and other equipment where periodic inspection and repair is required.

Luke-manhole LL-600 UHL1 TU3689-019-03467856-2001.

Fig 12. General view of the LL-500/600/800 hatch:
1 - hatch cover; 2 - handle; 3 - reinforcing pad; 4 - a bolt with a nut; 5 - flange; 6 - gasket.

Units and details for fastening gas pipelines (supports, suspensions).

In heat networks on pipelines, for the perception of mass loads of the pipeline (deformation and elongation during heating, dynamic loads from vibrations and shocks) and the working medium flowing through it, fittings, insulation and other devices located on it, support structures are installed.

Movable supports are subdivided into sliding and roller ones and are used to transfer the weight of heat pipes and their insulating shells to supporting structures and to ensure pipe movements occurring as a result of changes in their length when the temperature of the coolant changes. For pipelines with a pipe diameter of 200 mm and more, to reduce the friction forces on the supports, rolling bearings are used - roller, roller, ball.

Fig 13. Supports are movable.

Fig 14. Fixed supports.

Fig 15. Suspended supports (hangers).

Umbrella, deflector, ventilation grilles.

Umbrellas are installed on ventilation shafts with natural and mechanical motivation in order to protect the mines from atmospheric precipitation. The choice of the type of umbrella is made in accordance with the outer size of the throat of the shaft.

Be smart!

; font-family: ’Times New Roman” ”> Explosion valves: purpose, installation locations

; font-family: 'Times New Roman "”> To prevent the destruction of the enclosing structures of furnaces and gas ducts of heating installations, in case of possible explosions of gas-air mixtures, it is necessary to install safety explosion valves in them, which must operate at pressures lower than the destructive structures of pressure installations. These valves ensure the timely release of the pressure of the combustion products from the chamber where the explosion occurs.For steam boilers with a steam capacity of up to 10 t / h and hot water boilers with a water heating temperature of up to 115 ° C, the total area of safety explosion valves should be at least 200 cm2 per cubic meter of internal volume Explosion safety valves are installed in the masonry or lining of the furnace, the last gas duct of the boiler or the gas flue of the water economizer, the ash collector, the flue to the smoke exhausts, the horizontal flue after the smoke exhauster to the chimney. burst valves. The most widely used valves are burst, flap and relief types. They are installed on the ceilings and walls of the furnace, gas ducts and hogs. It is advisable to associate the place of installation of the valves with the zones of the most probable accumulation of gas leaks, zones of the formation of gas pockets, and also arrange them so that, when triggered by the blast wave, the operating personnel are not affected. If the last condition cannot be met, it is necessary after the valve to have a protective box or visor, firmly attached to the unit and diverting the explosive exhaust to the side. Explosion valves should be square or round in shape as less pressure is required to rupture the diaphragm. The burst valve has a membrane made of sheet asbestos with a thickness of 2 ÷ 3 mm, which is destroyed by an explosion in the firebox. Through the hole formed, the products of combustion are discharged into the environment and the pressure in the furnace and gas ducts quickly drops. An asbestos sheet of this thickness is fragile and does not withstand the dynamic load associated with a change in vacuum and pulsation in the chamber. To increase the durability, a metal mesh with cells of 40 × 40 or 50 × 50 mm is mounted in front of the membrane from the side of the firebox. The asbestos sheet and the mesh are clamped with flanges, which are attached to a metal box firmly mounted in the lining of the heating unit. It should also be borne in mind that asbestos sheet has a certain heat resistance: it can work for a long time at temperatures up to 500 ° C, and for a short time at 700 ° C. Therefore, explosion safety valves must be installed so that the asbestos membrane is not exposed to intense heating from the torch and red-hot masonry. Burst valves are simple and cheap. However, in the process of operation, the asbestos sheet is often destroyed by the effect of the heat fluxes of the furnace. True, replacing the asbestos membrane is not difficult, since this is provided for in the very design of the safety valve.

; font-family: ’Times New Roman” ”> Purpose of gas burners, their device.

; font-family: 'Times New Roman'; text-decoration: underline ”> Burner; font-family: 'Times New Roman" ”> - a device designed to supply gas to the combustion site, mix it with air and ensure stable combustion and combustion regulation.Depending on the gas and air pressure, they are: low pressure - gas up to 500 mm of water column (5 kPa), air up to 100 mm water column (5-100 kPa), air 100-3000 mm water column (10 kPa), air more than 300 mm water column (3 kPa).

; font-family: ’Times New Roman” ”> Gas burner types:

; font-family: ’Times New Roman" ”> Diffusion burner.; font-family:’ Times New Roman "”> A burner in which fuel and air are mixed during combustion.

; font-family: 'Times New Roman "”> Injection burner.; font-family:' Times New Roman "”> Gas burner with premixing of gas and air, in which one of the media necessary for combustion is sucked into the combustion chamber another medium (synonym - ejection burner)

; font-family: ’Times New Roman" ”> Hollow premix burner; font-family:’ Times New Roman "”>. A burner in which the gas is mixed with the full volume of air in front of the outlets.

; font-family: ’Times New Roman" ”> Not hollow premix burner; font-family:’ Times New Roman "”>. A burner in which the gas does not completely mix with the air in front of the outlets

; font-family: ’Times New Roman" ”> Atmospheric gas burner; font-family:’ Times New Roman "”>. Injection gas burner with partial premixing of gas with air, using secondary air from the environment surrounding the torch.

; font-family: ’Times New Roman" ”> Special purpose burner; font-family:’ Times New Roman "”>. A burner, the principle of operation and design of which determines the type of heating unit or features of the technological process.

; font-family: ’Times New Roman" ”> Recuperative burner; font-family:’ Times New Roman "”>. Burner equipped with a recuperator for heating gas or air.

; font-family: ’Times New Roman" ”> Regenerative burner; font-family:’ Times New Roman "”>. Burner equipped with a regenerator for heating gas or air.

; font-family: ’Times New Roman" ”> Auto burner; font-family:’ Times New Roman "”>. The burner is equipped with automatic devices: remote ignition, flame control, fuel and air pressure control, shut-off valves and controls, regulation and signaling.

; font-family: ’Times New Roman" ”> Turbine burner; font-family:’ Times New Roman "”>. Gas burner, in which the energy of the escaping gas jets is used to drive a built-in fan that blows air into the burner.

; font-family: ’Times New Roman" ”> Ignition burner; font-family:’ Times New Roman "”>. Auxiliary burner used to ignite the main burner.

; font-family: ’Times New Roman’; text-decoration: underline ”> Arrangement of gas burners

; font-family: ’Times New Roman” ”> Gas burners of all types have common elements:

; font-family: 'Times New Roman "”> Nozzle (s), which is designed to supply a certain amount of gas, and sometimes air at a certain speed, into the mixing part of the burner. Mixer, which is designed to form a combustible mixture necessary to ignite the torch, and are also designed to ensure a stable combustion process, prevent the flame from separating and its breakthrough into the mixer.Burner nozzle (burner crater) with a stabilizing device, which serves to equalize the velocity along the section after the diffuser, since the flow layer adjacent to the solid surface is slowed down and has a reduced speed, as a result of which a flame breakthrough is possible along the periphery of the burner.

; font-family: ’Times New Roman” ”> Depending on the type of burner or its operating conditions, the elements take on different designs, but basically they have the same purpose.

; font-family: 'Times New Roman ""> A diffusion burner consists of a nozzle (which is also a burner head), usually of a metal or ceramic tube with a stabilizing device in the form of lugs at the gas outlets. In pure diffusion burners there is no mixer and it is replaced by the volume of the furnace In it, mixing occurs in parallel with the formation of a combustible mixture and gas combustion.

; font-family: ’Times New Roman” ”> In the atmospheric ejection burner, sometimes called single-line, there are nozzles, a mixer, a burner head and a stabilizing device at the outlet of it. The mixer consists of an inlet pipe, a mixing chamber and a diffuser.

; font-family: 'Times New Roman "”> The inlet pipe (confuser-ejector) serves as a guide vane for injected air, helping to reduce hydraulic losses at the entrance to the mixing chamber. simple conical shape.

; font-family: 'Times New Roman "”> The mixing chamber (throat) serves to equalize the velocity of the mixing flows in front of the diffuser, the highest efficiency of which corresponds to a uniform velocity field in front of it. and ejected air (when creating a combustible mixture). It is advisable to give the mixing chamber a cylindrical or slightly tapering shape.

; font-family: ’Times New Roman” ”> Actions of the boiler house operator in case of failure of one of the operating network pumps

; font-family: 'Times New Roman "”> In this case it is necessary to stop the boiler. Then cool it down. To do this, open the emergency drain valve, while controlling the pressure in the boiler and the system and not allowing it to drop sharply in order to avoid water boiling. And turn on the standby pump.

; font-family: ’Times New Roman” ”> Types and content of gas hazardous work carried out according to work permits

“> A work permit of the established form is issued for the production of gas hazardous works, which provides for the development and subsequent implementation of a set of measures for the preparation and safe conduct of these works.

“> The organization must develop and approved by the technical manager a list of gas hazardous works, including those performed without a work permit according to production instructions, ensuring their safe conduct.

“> At the enterprise, for each workshop (production), a list of gas hazardous works must be developed.

“> The list must contain separate gas hazardous works:

“> I - carried out with the registration of the order - admission;

“> II - carried out without registration of the order - admission, but with the obligatory registration of such work before starting in the journal;

“> III - caused by the need to eliminate or localize possible emergencies and accidents.

“> Gas hazardous work includes:

; font-family: ’Times New Roman” ”> - connection (tie-in) of newly built external and internal gas pipelines to the existing ones, disconnection (cutting) of gas pipelines.

; font-family: 'Times New Roman "”> The newly built gas pipelines are connected to the existing ones only before the gas is started. inert gases) by the team that starts the gas;

; font-family: ’Times New Roman” ”> - start-up of gas into gas pipelines during commissioning, re-entry, after repair (reconstruction), commissioning of hydraulic fracturing, GRPB, ShRP and GRU;

; font-family: ’Times New Roman” ”> - maintenance and repair of existing external and internal gas pipelines, gas equipment for hydraulic fracturing, GRPB, ShRP and GRU, gas-using installations.

; font-family: ’Times New Roman” ”> When repairing in a gas-polluted environment, use a tool made of non-ferrous metal that excludes sparking.

; font-family: ’Times New Roman” ”> The working part of the ferrous metal tool should be generously lubricated with grease or other similar grease.

; font-family: ’Times New Roman” ”> The use of electric sparking tools is not allowed.

; font-family: ’Times New Roman" ”> Shoes for persons performing gas-hazardous work in wells, hydraulic fracturing, GRPB, GRU, should not have steel horseshoes and nails.

; font-family: ’Times New Roman” ”> When performing gas-hazardous work, portable lamps in explosion-proof design with a voltage of 12 volts should be used .;

; font-family: ’Times New Roman" ”> - removal of blockages, installation and removal of plugs on existing gas pipelines, as well as disconnection or connection to gas pipelines of gas-using installations.

; font-family: ’Times New Roman" ”> When removing blockages in gas pipelines, measures must be taken to minimize the escape of gas from the pipeline. Work must be carried out in hose or oxygen-insulating gas masks. Gas release into the room is prohibited .;

; font-family: ’Times New Roman” ”> - purging of gas pipelines when turning off or turning on gas-using installations in operation.

; font-family: 'Times New Roman "”> Gas pipelines during gas start-up must be purged with gas until all air is displaced. The end of the purge must be established by analysis or combustion of the samples taken. The volume fraction of oxygen must not exceed 1% by volume, and the combustion of gas must take place calmly, without claps.

“> Gas pipelines must be blown out with air or inert gas when de-gassed. The volume fraction of gas in the air sample (inert gas) should not exceed 20% of the lower concentration limit of flame propagation.

; font-family: ’Times New Roman” ”> When purging gas pipelines, it is forbidden to release the gas-air mixture into rooms, ventilation and flue systems, as well as in places where there is a possibility of getting it into buildings or igniting from a fire source;

; font-family: ’Times New Roman" ”> - bypassing external gas pipelines, hydraulic fracturing, GRPB, ShRP and GRU, repair, inspection and ventilation of wells, check and drainage of condensate from condensate traps;

; font-family: ’Times New Roman” ”> - breaks in the places of gas leaks until they are eliminated;

; font-family: ’Times New Roman” ”> - repair with hot (welding) work and gas cutting (including mechanical) on existing gas pipelines, hydraulic fracturing equipment, GRPB, ShRP and GRU.

“> Welding and gas cutting on gas pipelines in wells, tunnels, collectors, technical undergrounds, hydraulic fracturing, GRPB and GRU rooms without shutting them down, blowing with air or inert gas and installing plugs is not allowed. Before starting work on welding (cutting) the gas pipeline, as well as replacing fittings, expansion joints and insulating flanges in wells, tunnels, collectors, coverings should be removed (dismantled). Before starting work, the air is checked for gas contamination. The volume fraction of gas in the air should not exceed 20% of the lower concentration limit of flame propagation. Samples should be taken from the most poorly ventilated area.

“> 5. The main causes of injury when servicing boilers

“> - expiration of service life and equipment malfunction;

“> - malfunction or absence of emergency protection, signaling or communication equipment;

“> - wrong organization of work;

“> - inefficiency or lack of production control over compliance with industrial safety requirements during the operation of equipment;

“> - low level of knowledge of managers, specialists, service personnel of industrial safety requirements;

“> - violation of technological or labor discipline, careless or unauthorized actions of work performers;

“> - deviation from the requirements of design and technological documentation;

“> - violation of the regulations for the inspection or maintenance of equipment;

“> - violation of the repair work regulations, poor quality of repairs;

“> - use of construction materials in the manufacture or repair of equipment that do not correspond to the project.

The materials are collected by the SamZan group and are freely available

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Be smart! ; font-family: ’Times New Roman" ”> Explosion valves: purpose, installation locations; font-family:’ Times New Roman "”> To prevent the destruction of the enclosing structures

Explosion valve on the boiler flue

In practice, at present, explosive safety valves are structurally performed in the form:

Membranes made of sheet asbestos, 8-10 mm thick, freely laid horizontally on protruding elements of a boiler or brickwork with a seal around the perimeter with crumpled refractory clay. Upon explosion, the membrane is thrown back;

Membranes made of asbestos sheets with a thickness of 2-3 mm, fixed in a frame made of corners and bursting during an explosion. Sometimes membranes with a thickness of 5-6 mm are used with the obligatory cutting of grooves 2-3 mm deep on them crosswise so that the wall thickness under the grooves does not exceed 2-3 mm. In this case, the rupture of the membrane occurs along the grooves;

A cast-iron hinged lid, insulated from the side of the firebox with refractory bricks or refractory mass and hinged in a metal frame. In the event of an explosion, the lid opens on hinges;

Slabs made of a mixture of refractory clay with asbestos, reinforced with a metal mesh and covered with asbestos sheets. The slab is hinged in a metal frame and swings back in the event of an explosion. In some cases, such a plate is loosely laid on the protruding elements of the boiler or the brickwork of the gas duct with a seal around the perimeter with crumpled refractory clay. Upon explosion, the slab is thrown away;

Slabs made from a mixture of refractory clay with asbestos, reinforced with metal mesh and covered with asbestos sheets and roofing steel. The slab is attached in an inclined position to the frame with hinges and is compacted around the perimeter with crumpled refractory clay. When an explosion occurs, the slab leans back;

A metal plate with edges bent around the entire perimeter, immersed in sealing sand gates (proposal by M.A.Nechaev). The plate is secured by a spring and a chain to the valve frame, thrown back in the event of an explosion;

A special metal membrane fixed in the frame and having two diagonal grooves. The wall thickness under the grooves is calculated for rupture at the pressure that occurs in the metal flue during an explosion.

Let us consider the design and operation of the main most widely used explosion valves, taking into account the requirements formulated above that they must satisfy.

Asbestos membranes with a thickness of no more than 2-3 mm, clamped along the contour with metal flanges, are installed on brick or metal gas ducts. On the side of the gas duct, under the membrane, a mesh of metal wire with a diameter of 1 mm and a mesh size of 50 X 50 mm is placed. This mesh gives the valve mechanical strength against possible contact with asbestos from the outside. The strength of the valve embedment in the masonry is ensured by the thrust feet from the corners welded to the box.

Asbestos safety explosion valves are cheap and easy to manufacture, but during operation they can fail even in the absence of explosions of the gas-air mixture. One of the reasons for this is the pulsation in the furnace and boiler gas ducts, which causes vibration of the asbestos membrane and its destruction at the points of attachment in the frame. To reduce the effect of vibration on the resistance of the asbestos sheet, it is covered from the outside with a thin layer of clay, which forms a hard crust, which slightly increases its strength and rigidity. Often, service personnel, in order to avoid the destruction of asbestos from vibration, increases its thickness to 8-10 mm or installs several sheets with a thickness of 2-3 mm each. This leads to the destruction of the boiler masonry during the explosion of the gas-air mixture, since the strength of such a valve, as a rule, is greater than the strength of the brickwork.

The second reason for the destruction of asbestos valves is their incorrect placement in the firebox or the first flue of the boiler, where they are heated by radiation from a flame or hot sections of the masonry. Long-term service of an asbestos valve is possible only if it is not exposed to radiant heating and the moving stream of combustion products does not come into direct contact with it. For this, the asbestos valve is placed at the level of the outer surface of the boiler masonry or, with the help of a metal pipe, is pushed outward from the flue. The "gas bag" formed in this case due to the thickness of the masonry and the height of the nozzle creates a natural insulating layer between the flow of moving gases and asbestos. The higher the height of the nozzle, the more the stationary layer of gases under the membrane is cooled and the longer it remains. However, the membrane pushed away from the inner surface of the volume in which the explosion occurs due to an opening in the masonry or a metal pipe will perceive the pressure generated in it with some delay compared to the perception of the rest of the enclosing surfaces of the chamber, especially if the epicenter of the explosion is shifted from the axis of the pipe ... Therefore, a valve with a diaphragm extended outward is unreliable and cannot be recommended.

The third reason for the failure of asbestos valves is the presence of leaks both in the membrane itself and in the embedding of the valve in the masonry. Due to the rarefaction in the firebox or gas duct, air penetrates into them through leaks, and if there is unburned gas in the combustion products and the corresponding temperature, the gas burns out at the explosive valve, burning it out. However, even if there are no combustible components in the combustion products, the asbestos membrane still quickly breaks down, since the stagnant protective zone is eliminated due to the generated streams of moving air, circulation of high-temperature combustion products is created that come into contact with asbestos and destroy it. Hence it follows that the condition and density of asbestos explosive cells also determine the possibility of their long-term operation.

When choosing a place for installing the valves, their design and temperature conditions in the chamber are taken into account. So, when using valves with asbestos membranes in the firebox or the first gas duct of the boiler, to reduce the heating of the metal tube, sometimes its inner surfaces are lined with refractory bricks. Valves located above other boiler flue ducts are not lined.

Some manufacturers recommend 5 mm thick asbestos membranes with 2 mm deep cross slots for installation on DKVR boilers. If necessary, a protective casing is installed over the membrane. The upper removable part of the casing has handles. The diaphragm lifted up the diaphragm clamped along the contour cannot provide timely valve actuation and cannot be recommended for use. When placing the valve above the firebox, it is advisable to use a free-lying asbestos slab, and above the gas duct - an asbestos sheet resting on a grate or mesh. In both cases, the seal is made along the contour with crumpled clay, and the ejection structure is located, if possible, at the level of the inner surfaces of the boiler lining.

Various options for the placement and design of asbestos explosive valves on cast iron sectional boilers, according to the recommendations of Lengiproinzhproekt, in some cases, the asbestos membranes described above with a thickness of 2-3 mm are used, fixed together with a support mesh in metal frames. However, most often valves are designed from asbestos cardboard 10 mm thick, under which a grid of an appropriate size is laid. The frame of the lattice is made of wire d = 3 mm, and the lattice itself with mesh sizes 50 X 50 mm is made of wire d = 1 mm. The grate and asbestos cardboard lie freely on the section or lining of the boiler flue pipes. From above, the valve is sealed around the perimeter with crumpled clay. Such a valve is triggered at the minimum explosion pressure and completely frees the gas outlet.

Mosgazoproekt, when installing valves on top of sectional boilers, instead of asbestos cardboard, uses a plate of pressed clay with asbestos fleece reinforced with a metal mesh, freely lying over the cast-iron sections along the longitudinal axis of the boiler or above the first gas duct in the immediate vicinity of the furnace.

For sealing, these valves are also lubricated around the perimeter during installation.

fireclay clay. The mass of the slab should be as small as possible. To avoid personal injury, it is advisable to attach the kickout plate to the frame using a chain with a spring.

The valves, which are a reinforced chamotte-asbestos plate, have sufficient heat resistance, and therefore their use in chambers with high temperatures, for example, in furnaces, is preferable to asbestos membranes.

The body of such a valve is a frame made of corners, to which a hinged cover is attached, made of a mixture of fireclay clay with asbestos chips and reinforced with a metal mesh for strength. Outside, the cover is covered with asbestos and metal sheets. In the working position, the cover is slightly inclined, in case of an explosion it is thrown down. To ensure the required density, the valve is coated with mint clay around the entire perimeter.

While maintaining the calculated area of the rectangular explosive valve, regardless of the upper or lower location of the hinges, it is desirable that the valve height be as high as possible, which leads to a decrease in the required force for its actuation. When the valve is installed on the side wall and the protective metal outlet is always directed upwards, the valve, when triggered, should not overlap the outlet cross-section, so as not to create additional resistance on the gas path. The use of a valve with lower hinges in this case allows not only to completely release the branch section, but also to reduce its resistance due to the use of an open valve as a guiding plane in the lower part.

In the case when the firebox or gas duct has an elongated shape, the relative efficiency of valves located near a possible ignition source increases especially. This means that in such gas ducts (for example, hogs), it is advisable to arrange along the length not one, but several valves, each of which can have a slightly smaller area, thereby ensuring the emission of combustion products during an explosion at least through some of the valves. In addition, if such a flue has a sufficiently high mechanical strength (for example, a flame tube, the length of which reaches 8-10 m), then, taking into account that the blast wave will move along it, it is advisable to place the valve directly against the end of such a flue, for example, on the rear the wall of the rotary smoke chamber of the fire tube boiler along the axis of each flame tube. Only if the fire tube boiler is adjacent to the wall of the boiler room from the end and the installation of valves on the back wall is not feasible, they are located in the ceiling of the same reversing chamber. On the second flue gas duct of the fire tube boiler, the explosive valves are located in its upper part so that they are above the sections connecting the second and third boiler flue ducts. The displacement of the valve from the drum to the periphery of the steam boiler is associated with the need for thermal insulation of the drum at least 100 mm below the water level in it at the valve location. Valves of fire-tube boilers installed on the second gas duct and on the ceiling of the rotary smoke chamber have asbestos membranes. It is recommended to replace the membranes clamped along the contour with free-lying asbestos or asbestos clay plates with crumpled clay sealing along the edges. On the rear wall of the smoke chamber (option I), valves are installed in the form of reinforced plates made of refractory clay with asbestos.

The valve consists of a body, to which a tray filled with fine-grained quartz sand is welded in the upper part along the entire perimeter. When the valve is installed in a brick lining, four legs 6 are welded to the lower part of the body from the corner 50X50X 5. The discharge part of the valve is a metal cover 2 mm thick, the bent edges of which are immersed in sand, preventing air from sucking into the gas ducts under vacuum. To avoid injury to the service personnel, the cover is secured to the body with a chain and a spring. A valve of this design can be installed only on gas ducts, the temperature in which does not exceed 400-500 ° C in order to avoid overheating and warping of the cover. If necessary, the lower surface of the lid can be covered with a heat-insulating material. If the flue is metal, then the valve body is welded to it.

On brick flue gas ducts of boilers and boiler rooms (hogs), explosive valves are installed, depending on local conditions, on their vertical or horizontal surfaces. If the valve can be damaged during operation, then the horizontal valve should be fenced, and the vertical one should be equipped with a hinged metal cover attached to the valve frame on hinges. It is necessary that when the valve is located horizontally, the cover is completely free to open by 180 °, and when it is vertical, it has lower hinges. If the valve has a protective casing, then for inspection and repair of the asbestos membrane, a slot with a height of at least 350 mm must be provided in it, covered with a metal lifting flap. The width of the slot should allow the new asbestos membrane to be freely inserted through it.

Given the special strength of the membranes clamped along the contour, it is advisable to use free-lying asbestos sheets or asbestos clay slabs in horizontal sections, and the same slabs with lower hinges on vertical sections.

In this case, to replace or repair the cassette valve, the cassette is removed from the casing or partially extended, and at the end of these works it is inserted into the casing along the guides. The place of contact of the front wall of the cassette with the casing is compacted with crumpled clay. The explosive cassette valves have proven their advantages over other designs. With a short protective casing, it is possible to recommend laying an asbestos sheet (b = 10 mm) or an asbestos slab with a seal along the edges with crumpled clay in a cassette lying freely on a metal lattice. With a high protective casing, a flap valve and a special pocket in the casing should be provided, where the valve is thrown during an explosion.

If the chimney is at some distance from the boiler room, then the explosive valves are installed on the hog outside the room. In this case, the valves must be protected from the ingress of atmospheric precipitation and surface water, and also reliably protected from access to unauthorized persons. For this, the asbestos explosive membrane is placed inside a protective metal casing having an inclined hinged roof, and a fence made of metal bars is placed around the casing. In the area where the casing is adjacent to the hog, a cement blind area is provided for the drainage of rainwater and melted snow.

From all that has been said, it follows that the explosive valves will protect the maintenance personnel from being hit by the blast wave or parts of the destroyed

equipment. For this, it is necessary to ensure daily monitoring of the condition of the explosive valves and their timely repair. It should be remembered that the presence of safety explosive valves is neither. in no way does it reduce the requirements for service personnel on strict adherence to all safety rules and operating instructions for boiler rooms. The smaller the area of the explosive valve clamped along the contour, and the more its shape differs from the circle of the square, the more pressure is required to destroy it and ensure the release of pressure from the chamber. For example, when the ratio of the sides of rectangular glass (δ = 2 mm) changes from 1: 1 to 1: 2 and 1: 3, while maintaining a constant area, the force required for destruction increases by about 25 and 55%, respectively (with glass dimensions 600 X 600 mm).

On boilers with a steam capacity of up to 10 t / h, the number of explosion valves, their size and location are determined by the design organization. They are installed in the lining of the furnace, the last gas flue of the boiler, the economizer and the ash collector. In this case, it is recommended to take the total total area of the valves at least 0.025 m2 for each cubic meter of the volume of the furnace and gas ducts. On boilers with a capacity of 10 to 60 t / h, explosive safety valves located in the upper part of the furnace or in the upper part of the boiler lining above the furnace must have a total cross-section of at least 0.2 m2. On each of the above gas ducts (except for the furnace), at least two explosive valves with a total cross-section of at least 0.4 m2 are installed. On boilers with a capacity of more than 60 t / h, operating on pulverized, gas and liquid fuels, the installation of explosive safety valves is not required. On small-sized water-tube boilers of power trains operating on liquid and gas fuel, it is allowed to install one explosive safety valve with a cross section of at least 0.15 m2 in the furnace and at least 0.3 m2 in each gas duct.

Explosion valves may not be installed in the lining of one-way flue gas boilers, as well as in gas ducts in front of the smoke exhauster. On vertical cylindrical (one-pass) boilers, in cases where the chimney is not located directly above the boiler, it is advisable to install explosion valves on the horizontal section of the flue, as close as possible to the boiler.

The area of one explosion valve according to SNiP II-37-76 must be at least 0.05 m2. However, it should be noted that it is impractical to use valves with an area of less than 0.15-0.18 m2 on heating and industrial boilers.

Explosion valve on the boiler flue

Explosion valve on the boiler gas duct In practice, at present, safety explosion valves are structurally performed in the form of: - a membrane made of asbestos sheet, 8-10 mm thick, freely

Any boiler equipment installed in a private house or at an enterprise is a source of danger. The water jacket of the boiler is the same vessel under pressure, and therefore it is considered explosive. To minimize the danger, many protective devices and systems are provided in modern heat generators, as well as in their piping schemes. One of the simplest and at the same time common devices is a safety valve in the heating system. He will be discussed in this material.

Where is the safety valve installed?

To answer this question, you must first figure out what it serves. The purpose of installing this simple device is to protect heating systems, to prevent increased pressure of the coolant in them. This can occur as a result of overheating of the water in the boiler, especially for units that burn solid fuel. When the coolant in the boiler tank boils and vaporization begins, this is followed by a pressure jump in the system. The consequences can be as follows:

leaks and ruptures of heating pipelines, most often at connections;
destruction of polymer pipes and fittings;
explosion of the boiler tank, danger of electrical short circuit in the boiler room.

One small valve of simple design can protect you from all these troubles. Based on the fact that a pressure rise to a critical limit occurs in the boiler, the safety valve must be installed as close to it as possible, on the supply pipeline. Some manufacturers of boiler equipment complete their products with a so-called safety group, which includes a relief valve, a pressure gauge and an automatic air vent. The group is mounted directly into the water jacket of the unit.

It should be noted that safety valves for heating are not always used in circuits. For example, when the heat source in the house is a gas or electric boiler, then a relief device is not required. The reason is the presence of safety automation in these types of heat generators and the absence of any inertia. That is, when the set temperature of the coolant is reached, the gas burner or electrical element is turned off and heating stops almost immediately.

Another thing is a solid fuel boiler or stove with a water circuit, here the installation of a safety valve is required. When the firewood in the firebox has flared up and the water in the network has reached the required temperature, you need to reduce its heating. The access of air to the combustion chamber is closed and the flame dies out, but the incandescent firebox continues to rise in temperature by inertia. If the process goes near the limit values (temperature 90-95 ºС), then vaporization at such moments is inevitable.

As mentioned above, boiling is followed by an increase in pressure, which can be prevented by the safety valve of the heating system. It will automatically open the way out for the generated steam and release it, thereby reducing the pressure to normal. Then the device will close by itself and will be in standby mode again.

The device and principle of the valve

The valve design is extremely simple. The body is made of high-quality plumbing brass using the technology of hot stamping from two cast parts in a semi-solid state. The general structure of the safety valve is shown in the figure:

The main working element of the valve is a spring. Its elasticity determines the force of pressure that must act on the membrane that closes the passage to the outside. The latter in the normal position is in a seat with a seal, compressed by a spring. The upper stop for the spring is a metal washer attached to the rod, the end of which is screwed to a plastic handle. With its help, the valve is adjusted. The diaphragm and sealing elements are made of polymer materials, the spring is made of steel.

This whole simple mechanism works like this. In normal (standby) mode, as long as the parameters of the coolant are within the specified limits, the membrane closes the entrance to the inner chamber. As soon as a situation close to an emergency arises and the pressure in the heating system of a private house increases, the steam-water mixture begins to support the membrane. At a certain moment, the pressure force of the coolant overcomes the elasticity of the spring, opens the membrane, enters the chamber, and out of it through the side hole.

When some water leaves the system, the pressure will drop so much that it cannot withstand the spring and the diaphragm will close the passage again. It happens that the mechanism is triggered cyclically, especially if the heating unit is operating at the limit and the temperature of the coolant is close to the maximum (90-95 ºС). In practice, when the blast valve for the boiler is triggered very often, it loses its tightness and begins to leak.

If you find fresh traces of drips from the safety mechanism, then this is a clear sign of the operation of the heat generator in extreme mode or the presence of malfunctions in the heating system, for example, in the expansion tank.

Since not all manufacturers of heating equipment complete their products with a safety group, often the choice of a safety valve for the heating system has to be done independently. To do this, it is imperative to study the technical characteristics of the boiler plant, namely, to know its thermal power and the maximum pressure of the coolant.

For reference. Most well-known brands of solid fuel heat generators have a maximum pressure of 3 bar. An exception is STROPUVA long-burning boilers, whose limit is 2 bar.

The best option is to purchase a pressure regulating valve that covers a certain range. The regulation range must include the value for your boiler. Then you need to select a product according to the power of the thermal installation, but it is difficult to make a mistake here. The manufacturer's instructions always indicate the limits of the heat output of the units, with which a valve of one diameter or another can work.

On the pipeline section from the boiler to the place where the overpressure relief valve is installed, it is strictly forbidden to install shut-off valves. In addition, you must not put the device after the circulation pump, do not forget that the latter is not able to pump the steam-water mixture.

In order to exclude water splashing around the combustion room, it is recommended to connect a pipe to the valve outlet, which leads the discharge into the sewer. If you want to visually control the process, then a special drain funnel with a visible gap of the jet can be placed on the vertical section of the tube.

Conclusion

The pressure relief safety device is considered very reliable due to its simple design. When making a choice, you should pay attention to the quality of the material and not chase after a cheap product. Equally important is the correct setting of the valve for the maximum pressure of the boiler plant.

If you do not limit the heating of water in the boiler, then it will boil and turn into steam, which will lead to a critical increase in pressure in the heating network. This is followed by a rupture of the pipeline or the water jacket of the heat generator. In order to avoid the described emergency situation, a safety valve for heating is installed at the boiler outlet, which relieves excess pressure from the system. Our publication focuses on the selection and installation of this important element.

Operating principle

Most ordinary users faced with closed water heating systems are familiar with only one type of safety valve - a simple spring-loaded valve with a fixed setting, shown in the photo. The reason is clear - these elements are installed everywhere on any boilers, since they are part of the safety group along with a pressure gauge and an air vent.

Note. Wall mounted heat generators powered by electricity and natural gas are fitted with safety elements from the factory. They are placed inside the case and are not visible from the outside.

Let's see how a conventional emergency valve, shown in the diagram above, works:

A few words about where the relief valve is installed together with in a closed heating system. Its place is on the section of the supply line in the immediate vicinity of the boiler (it is recommended not further than 0.5 m).

The safety unit is always installed on the supply line of the heater

An important point. It is forbidden to install taps, valves and other shut-off devices on the pipeline leading from the heat generator to the safety elements.

It is not worth tightly connecting the pipe of the product to the sewage system - wet spots or puddles will indicate the operation of the valve and problems in the heating network. For example, the expansion tank has failed or the circulation pump malfunctioned when working with a solid fuel boiler (perhaps the electricity was turned off). It is not uncommon for the device to start leaking due to debris getting between the saddle and the plate. More about his work is described in the video:

Clarifying information. The masters and installers call the relief spring valves disruptive, because the pressure of the coolant compresses the spring and causes the membrane to burst. Do not confuse them with explosive elements installed on the chimneys of industrial boilers that burn natural gas.

Types of safety valves

The traditional subversive design described above is not perfect. The spring mechanism, driven by excessive pressure, is not precise and may work with a delay when the temperature in the boiler tank reaches 100 ° C or higher, that is, boiling has begun. Of course, you can try to adjust the product with a screw or change the settings (there are versions with an adjusting cap), but this does not always give the desired effect.

Second moment: the safety valve for the boiler protects it from destruction, but not from overheating. After all, the discharge of the coolant does not allow the heating unit to cool if the combustion in the firebox continues. And the last thing: in open-type heating systems, such devices are generally useless, since the water in them can boil without increasing the pressure.

Leading manufacturers of heating fittings offer products of modern design, devoid of the listed disadvantages - thermal relief valves. These protective elements do not react to an increase in the water pressure in the system, but to an increase in its temperature to a critical level. There are 3 types of such devices:

discharge with an external temperature sensor;
a combined device with a temperature sensor and a make-up circuit;
the same with direct installation into the pipeline.

For reference. Here are the names of reliable brands, whose emergency fittings can be safely bought and used in private homes. These are manufacturers ICMA and CALEFFI (Italy), Herz Armaturen (Austria) and the world famous European brand Danfoss.

The principle of operation for all varieties is the same: a spring mechanism with a membrane (or two) is driven from a bellows with a temperature-sensitive liquid, which expands significantly when heated. In this way, the thermal relief valves respond fairly accurately to the critical temperature being reached. We propose to consider each of them in more detail.

Element with remote sensor

The product is the same spring mechanism built into a housing with two branch pipes for connection to the supply line and discharge to the sewer. The rod, which opens the plate and the path to the coolant, is set in motion by bellows (2 groups - main and reserve). When the water overheats (from 95 to 100 ° C), they are pressed by a temperature-sensitive liquid coming from the sensor flask through a capillary tube. The design of the safety element is shown in the figure:

The temperature valve is activated in three ways:

with cooling through the water circuit of the heat generator;
the same, through a special emergency heat exchanger;
coolant discharge with automatic make-up.

The first scheme, shown below, is used for double-circuit heating systems that heat water for hot water supply. When the sensor, mounted under the casing of the TT boiler, acts on the mechanism, then hot water from the circuit is drained into the sewer, and cold water from the water supply takes its place. Whatever the cause of the accident, such a flow-through system will quickly cool the boiler jacket and prevent the consequences.

The DHW coil of a double-circuit boiler can serve as both a heater and a cooler in case of overheating. For protection, it is enough to connect a thermal valve according to the scheme

Note. The publication uses schemes from the CALEFFI brand, taken from the manufacturer's official resource.

The second scheme is for heat generators with a built-in emergency heat exchanger for cooling in case of overheating. Such units are produced by European brands Atmos, Di Dietrich and others.

For an example of connecting a waste element through a standard heat exchanger, see the video:

The latter scheme is implemented only in conjunction with an automatic make-up system, since here the valve discharges the coolant, and not the cooling water.

As you can see, the manufacturer allows the installation of two emergency devices - pressure (safety group) and temperature (relief valve)

Warning. It is not recommended to use automatic make-up for wood-burning heaters with a cast iron firebox. The latter is afraid of temperature extremes and can crack from the supply of a large amount of cold water to the return line.

Water-powered combination valves

This striking representative of emergency fittings is similar in terms of the principle of work with bypass valves and performs 3 functions at once:

Discharge of the superheated heat carrier from the boiler tank according to the signal from the external sensor.
Effective cooling of the heat generator.
Automatic replenishment of the heating system with cold water.

The above picture shows the design of the product, where it can be seen that 2 plates are installed on one rod, simultaneously opening 2 passes: the boiling coolant is discharged along the first, water flows along the second in the opposite direction and replenishes the losses. The connection diagram of the combined bypass valve with a solid fuel boiler looks like this:

Note. If it is necessary to use a similar device for cooling a TT boiler with a cast-iron heat exchanger, then the flow must be organized through an open expansion tank or an indirect heating boiler.

The bypass valve with a triple outlet works on the same combined principle, only it is built directly into the coolant supply line near the heating unit. The bellows is located in the part of the body that is placed in the pipe. The discharge is carried out through the lower branch pipe, and the water supply and the make-up line are connected to the upper two. Such products are used when there is a lack of free space in the boiler room.

This relief valve is designed to be installed in the supply line.

How to choose a relief valve

Of course, at the cost of purchase and installation, a traditional blast valve will cost less than temperature devices. It will easily protect the heating system connected to a gas, diesel or electric boiler, because in the event of an accident, they stop heating almost instantly. Another thing is a wood-fired and coal-fired heat generator, which is not able to go out right away.

To successfully select a thermal relief or overpressure valve, follow these guidelines:

When using any energy source other than solid fuel, feel free to buy a conventional demolition device.
Consult the documentation for your heat source or boiler (whichever is necessary to protect) and select safety fittings according to the maximum allowable pressure specified therein. Most of the heating equipment is designed for a limit of 3 Bar, although there are exceptions - Lithuanian Stropuva boilers withstand only 2 Bar, and some Russian units (from inexpensive ones) - 1.5 Bar.
For efficient cooling of wood-fired heat generators in the event of an accident, it is better to install one of the thermal relief valves. Their maximum working pressure is 10 bar.
With a TT boiler, the pressure relief is useless. Select a safety device that works at a coolant temperature of 95-100 ° C, suitable for your unit and the make-up method.

Advice. Refrain from buying cheap safety fittings from China. Not only is it unreliable, it also leaks after the first blast.

In addition to models with fixed settings, there are valves on sale with the ability to adjust. If you are not a professional in the field of heating, then you should not buy them, and there is no special need.

If you are keenly interested in the safety of the boiler room and the reliable operation of heating equipment, we recommend that you carefully study the assortment when buying fittings. The fact is that new useful products are appearing on the market that cannot be reviewed within the framework of this article, but they may be useful to you.

Operational moment. Monitor the condition of the safety valves in order to detect the operation in time and understand the reasons. Direct the devices for thermal discharge into the sewer funnel with a burst of the jet - an unexpected splash of water in the boiler room and wet footprints will make it clear that an emergency has occurred.

Safety, explosive, bleed valve. As soon as it is not called, mixing various functions and purposes, without looking at the design and characteristics. Moonshiners still argue to the point of hoarseness about the need for a safety valve, despite the huge number of serious accidents. It is enough to type in the search engine: "explosion of the moonshine still" to seriously think about this problem.

Theory

An alcohol-containing liquid boils in the cube. If the steam outlet is blocked, pressure will build up. At the same time, the boiling point of the liquid will also rise. Energy generously pours into the cube and accumulates every second, but this process is not endless. Sooner or later, mechanical depressurization of the cube will occur. For example, it will rip off the collar and the cover will shoot at the ceiling. If everything ended there, then there would be nothing to discuss. Easy repair of the kitchen, replacement of the chandelier is a matter of everyday life.

However, after depressurization, the pressure in the cube drops sharply, as a result, all the accumulated energy is released and leads to a sharp, explosive boiling of the entire volume of the bulk (alcohol-containing liquid in the cube). The resulting alcohol vapor flies out of the cube, simultaneously carrying out a fair share of the bulk.

Danger in numbers

For example, there were 40 liters of raw alcohol in a cube, the excess pressure that tore off the lid was only 0.5 atmospheres, which is close to reality. As a result, about 10 liters of boiling raw alcohol will fly out of the cube and flood everything around, scalding people and pets. Another 10 liters will turn into steam and instantly form an explosive concentration of alcohol vapor in the room. If the moonshiner is a poor student, neglecting the elementary, and worked on an open fire, the explosion will be immediate.

If the distiller was friendly with his head and worked on closed heat sources, for example, heating elements, but was confused and decided to quickly unplug the plug from the outlet or just flip the switch, the explosion will occur immediately after that from a small spark that slipped through when the contacts were opened.

Well, if the owner was not in the kitchen at that moment and his non-scalded body retained the ability to think, then he will slowly and carefully open all the windows, arrange a draft and, possibly, avoid more serious consequences.

The consequences of the volumetric explosion are very impressive - this is the wall brought out to the neighbors, the balcony block flew away across the road. There are other miracles as well. When nothing happens directly in the kitchen, and an explosive mixture ignites from a spark in the next room and destruction will occur there.

To prevent this scenario, a bleed valve is needed. Alcohol vapor is not a gas and will not accumulate to an explosive concentration when vented. Once in the air, alcohol vapors immediately begin to condense and settle on walls, windows, and floors. Fly away into the hood or window. It will stink, warning the owner of a non-standard situation. The likelihood of an explosion becomes much less, although this does not insure against a fire.

As statistics show, large diameters of columns do not at all relieve their owners from the risks of working with fire-explosive liquids. This is the specificity of our hobby.

Safety valve parameters

The main danger in the distillation of moonshine is not at all the mechanical destruction of the parts of the apparatus, but in the creation of an explosive concentration of alcohol vapors due to a sharp depressurization of the cube.

In practice, this determines the requirements for the safety valve.

In the second distillation, the pressure in the cube is 500 mm of water. Art. considered emergency, because it indicates the flooding of the column. But does it need to be prevented with a bleed valve? Definitely not.

If the valve is to bleed at 400 mm of water. Art., then on the one hand the column will not sink, but on the other hand we will just get an imitation of its normal operation. As soon as the valve is triggered, the phlegm will collapse downward, disrupting careful fractionation. As a result, the output will be an ordinary fortified moonshine, and not a distillate purified from impurities. The valve should not interfere or contradict the technological processes taking place in the apparatus.

Let's take another example. When the pressure in the cube rises, a thermometer can shoot out and depressurization occurs - well, well, again, it will bleed off the excess without the threat of an explosion. It is not worth installing a valve to prevent this event; it should be treated as a redundant system.

But if the lid is ripped off on a saucepan or pressure cooker, the exhaust will be instant. Clamps, depending on the quality of manufacture, can fly off at a pressure of 1 atm. This is already a subject of control. In addition, as shown above, depressurization even at an excess pressure of 0.5 atm. is capable of creating an explosive concentration of vapors in the room. Here's another point.

Output: in order not to interfere with the setting of the column, the safety valve must operate at a pressure not less than double emergency - 1000 mm of water. Art. = 70 mm Hg. st. = 9.8 kPa = 0.1 bar. The closer its response is to 0.5 bar, the more severe the consequences will be in the event of a failure. That's all the logic.

Safety valves from different manufacturers

Let's start with the most illiterate and have no idea about the parameters of the processes in the apparatus. Such manufacturers install pressure cooker blasting valves on their cubes. Note - not play off, namely subversive or, in other words, emergency.

Pressure cooker valve

This cheap valve actually operates at pressures from 1.2 to 1.5 ATM. - the frontier of last hope for the pressure cooker. It is clear that for the purposes of distillation and rectification, it is useless, since a broken collar and an explosion are possible up to the threshold of its operation.

The working pressure cooker bleed valve looks like this, it should not be confused with the emergency valve.

Bleed valve

The working valve in the pressure cooker maintains an overpressure of 80-110 kPa (0.8-1.1 atm.). The safety valve is triggered when the pressure inside the pressure cooker is 50 kPa exceeding the operating pressure (i.e. at 1.6 atm.), Which can occur if the operating valve is clogged. The actuation of the safety valve allows the steam to escape from the pressure cooker and makes it safe during operation. But not in our case. Its characteristics, of course, are closer to the desired range, but not that much.

The emergency valve can be redone. To do this, you need to disassemble it, throw out the spring and the red ball. Place a weight about 36 grams in place of the ball. This will reduce the response threshold to 700-1000 mm of water. Art., but even this alteration does not guarantee the normal operation of the valve. The stem is easily tilted and the valve does not close, and after a dozen operations, the design that is not designed for this mode easily gets dirty in the area of the silicone O-ring and ceases to be tight. As a temporary way out of the situation, this alteration has the right to life, but not for permanent use.

The use of safety valves from heating systems and other water heating equipment is faced with the problem of inability to adjust the response pressure to the desired value.

Safety valve from the heating system

As a rule, for these systems, an emergency pressure is considered above 1.5-8 bar (150-800 kPa). For home brewing, these are completely outrageous values. The principle of their operation is simple, but even replacing the springs with less rigid ones often does not give the desired result, since the valve simply ceases to be hermetically pressed against the seat.

Therefore, thinking equipment manufacturers were forced to develop their own valves that operate at a pressure of about 900-1000 mm of water. Art. (70 mm Hg).

Correct safety valve option

These are fairly simple valves of a low cost of about 350 rubles with spare membranes at a price of 40 rubles. They fit on a standard ½ “threaded nipple.

How to make a self-brewed safety valve with your own hands

Let's take a closer look at the valve design.

Safety valve design

We take the old hose from the shower or flexible hose and remove the nuts from it. We complete with fluoroplastic gasket and silicone gasket. The gasket can be taken from the beer cork. It remains to collect everything. True, this will differ from the original by a washer with a groove for the membrane. The thickness of the membrane is 1 mm, and the grooves are 1.3 mm, it will work with careful installation.

There is another rather simple and functional system for preventing problems associated with overpressure. The idea is simple: a tube is put on the drain connection, which allows filling (1) or draining (3) vinasse. During the distillation process (2), this tube is placed 600-800 mm above the cube and drained into the sink. The height of the tube bend above the stillage level determines the excess pressure in mm of water. Art., after which the liquid will begin to pour into the sink. Naturally, the drain valve must be open.

Overpressure prevention system

Simple, reliable and flexible.

These inexpensive and uncomplicated devices avoid serious risks in home brewing. Do not neglect their use.