The Mayevsky crane: the principle of operation and its effect on the efficiency of the heating system
The Mayevsky crane: the principle of operation and its effect on the efficiency of the heating system
Modern heating systems of buildings and structures of industrial, public and residential applications have one common technological element – the Mayevsky crane: the principle of operation of this device is to remove unwanted gaseous substances from the working circuit in order to ensure maximum efficiency of the heating system. The purpose and technical characteristics of this device will be discussed in this article.
What is a Mayevsky crane: operating principle and technical characteristics
A huge number of closed hydraulic systems used in high-tech industries (automotive, thermal engineering, mechanical engineering, etc.) use the technology of removing gaseous substances (air) from the working circuit, reducing the efficiency of their work. This is especially true for heating systems.
The Mayevsky valve functions in the same way as a conventional shut–off valve works – it is the opening/closing of a hermetic connection from the area of a gaseous or hydraulic medium with increased pressure to the area of a medium with normal physical conditions. The historical prototype of the modern designs of the Mayevsky valve was the most common water tap of the saddle type.
However, uncontrolled intake of process water from heating systems using conventional water taps required a special design that hindered or completely excluded water losses from heating networks. The advanced solution to this problem was the Mayevsky crane, which has undergone many improvements in connection with the development of engineering.
Mayevsky crane: photo
In whatever technical design the Mayevsky valve is considered, the principle of operation of this device always corresponds to its direct technological purpose and the regulations of the intra–industry standard – this is a valve for air discharge STD 7073V (according to TU 36-710-82) from industrial and domestic heat supply systems.
Structurally, it is performed as a needle-type air shut-off valve (hence the second name) in the form of a combined radiator plug with a built-in mechanism for venting air. Since the standard STD 7073B regulates the design dimensions, the air valve for radiators (aka Mayevsky) has an outer landing diameter of half an inch (1/2″), three quarters of an inch (3/4″), one inch (1″), etc. The standard sizes of the crane with a nominal passage diameter (DN) of 15, 20 and 25 mm allow it to be used not only in radiators, but also in different nodes of the heating system. The technical characteristics include parameters such as operating pressure (Ru) – 10 atm (1MPa) and operating temperature – up to 120 degrees Celsius.
The design of the Mayevsky valve
The main element of the valve design is a shut-off screw screwed into the body of the mechanism and having a conical shape of the end part, thereby ensuring a tight fit in the “saddle” of a through hole with a diameter of 1.5-2 mm. The outer part of the screw is a four-sided or hexagonal head (for a special key for the Mayevsky crane) with a slot for a conventional screwdriver. For the passage of air when the valve is opened, the screw body is made with longitudinal grooves.
The air at the outlet of the grooves enters a chamber hermetically sealed with a cuff (usually made of polymer) and having an outlet with a diameter commensurate with the through hole. Since the crane body is installed using a threaded connection having an oil seal, and the valve mechanism in the closed position tightly covers the through hole, then during the operation of the heating system, the installed crane ensures complete tightness of the system.
Useful advice! When choosing a valve, it is necessary to take into account the corrosion resistance of the material from which its parts are made. Since many manufacturers produce products made of chrome-plated steel with a short service life, preference should be given to products made of brass or stainless steel.
Mayevsky crane on towel rails
If there is a radiator in the premises connected to the heating system or to the hot water supply system, it is necessary to use a heated towel rail with a Mayevsky tap. The features of the installation of such replaceable elements without the presence of these valves in the configuration can lead to the accumulation of air in the upper zones of the inner space of the heated towel rail and the most problematic is to create “air jams” that stop the circulation of the coolant in both the heating circuit and the hot water circuit. The presence of the Mayevsky crane on the towel rail allows you to eliminate this negative.
The Mayevsky crane: the principle of operation of the automatic air vent
Automatic air vents for radiators are increasingly used in heating systems. This is a special design of the Mayevsky crane, which provides the discharge of gas accumulations in automatic mode. Let’s look further at how an automatic air vent works. Its design assumes the presence of a float in a vertical channel. Without the presence of a gas medium, the float supports a spring with an internal plug through the lever, so that the system is sealed.
Under the conditions of the occurrence of a gas environment, the float fails, weakening the pressure of the spring on the plug, the latter opens the outlet, and the gas mixture comes out. When replacing the volume of the gas component, the coolant fills the float chamber and the float floats up, closing the outlet through a spring with a plug. If the float mechanism breaks down, using the Mayevsky key, you can manually bleed the accumulated gas mixture.
The need to use the Mayevsky crane in heating systems
After installing the heating system and filling the circuit with coolant (water, antifreeze, technical oils), air always remains in the radiators. It forms so-called air plugs and stops the circulation of the working fluid. This leads to a loss of the efficiency of the heating system, since the boiler operates at a set temperature, and the radiators are “cold”. It is impossible to do without using the Mayevsky crane in this situation.
After the end of the heating season, the phenomenon of degassing occurs in the medium of the coolant. A certain amount of dissolved air in the coolant, when the temperature drops and the state of rest is released from the liquid and accumulates, forming the same “air plugs”. Therefore, before starting the heating, it is necessary to top up the coolant into the system and, if possible, use the Mayevsky crane.
Another negative factor in the formation of gas accumulations in the heating system is the process of hydrogen formation during hydrolysis reactions of water and the inner walls of metal pipelines and radiators. This is especially true for radiators made of aluminum without protective anti-corrosion treatment. With the use of a Mayevsky crane in the system, this problem is solved completely.
Model range and manufacturers of Mayevsky cranes: prices
Currently, a large number of models of Mayevsky cranes, both domestic and imported, using various materials and components are presented on the market of sanitary products. Buying this or that type, it is also possible and necessary to buy a metal key for the Mayevsky crane. Keys are also available for sale in a plastic version.
The table shows information about the types and prices of Mayevsky cranes:
|Product Name||Trademark||Material||Price, rub.|
|The crane of the Mayevsky Dn 10, 15, 20 mm||Promart LLC, Kazan||chrome-plated steel||21-51|
|Crane Mayevsky Ru 16 mm and DN 10, 15, 20 mm||Metpromintex LLC, Moscow||chrome-plated steel||63,8|
|The key to the Mayevsky crane is 5 mm, Meibes SX 11202||LLC “COMFORT.RU”, Moscow||silumin||18|
|Key for radiator plugs and Mayevsky crane||LLC “Mantehbryansk”, Bryansk||polymer plastic||118|
|Mayevsky manual crane, DN 15 mm||LLC “OK Resan”, Perm||chrome-plated steel||152|
|Mayevsky crane Demin Dokum Classik Art, DN 15-20 mm||LLC “Laboratory of heat”, Rostov-on-Don||brass||138|
|The air vent for the radiator is automatic||PP “Thermoclimate”, Yaroslavl||stainless steel||259|
|Mayevsky crane (automatic)||TECHNO-GROUP, Kirov||stainless steel||230|
|Ball valve with Mayevsky valve DN 15 mm (1/2″)||LLC “TECHOM”, Krasnoyarsk||chrome plated brass||243|
|Tee with a Mayevsky crane||Sibir GOST LLC, Omsk||chrome-plated steel||596|
|Three–way crane with Mayevsky crane (G1/2 – G1/2)||LLC “AQUA-KIP”, Moscow||chrome-plated steel||245|
|Mayevsky crane with filter DN 15 mm||Promarmatura LLC, Barnaul||chrome plated brass||474|
|Mayevsky automatic crane RR 374 full-bore, for cast-iron radiators||LLC “Santehklass”, Moscow||chrome-plated steel||700|
Useful advice! If there is a need to buy a Mayevsky crane, be sure to coordinate the seating dimensions of the valve installation sites in the elements of the heating system with the parameters of the purchased ones. In case of non-compliance, additional purchase of adapters and consumables will be required.
Features of using and adjusting the Mayevsky crane
Consider the option when the system is installed and assembled, but the Mayevsky cranes are not mounted on the radiators. Then you can do it yourself. To do this, unscrew the plug plugs on the opposite side of the inlet of the working fluid into the radiator and screw the selected valves in their place.
Useful advice! Regardless of the presence of a pressure seal on the threaded part of the crane body, it will be advisable to use a sealing tape FUM or tow on the thread for better sealing.
How the Mayevsky crane works
The adjustment of the outlet of the radiator cranes of Mayevsky must be done so that it is directed in the opposite direction from the wall and preferably with a slope to the bottom.
As for the installation of the Mayevsky crane on towel rails, it must be positioned in a strictly vertical position using a special tee. Using the latter allows you to transfer the working axis of the mounted crane from vertical to horizontal. This is its preferred technological location makes it possible to fulfill the requirement of the instructions: the hole to be vented should be directed in the opposite direction from the wall and have a slope towards the floor.
An important issue is the use of the Mayevsky crane for cast-iron radiators. Plug plugs do not have landing holes for standard valves. However, many craftsmen have found a way to install cranes to bleed air through the operation of drilling and threading in the body of a cast-iron plug. But as practice shows, such “handicraft” can lead to a breakdown of the thread during the phenomena of water hammer, when the pressure of the coolant can grow tenfold. The way out of this situation is the installation of plugs adapted to the landing dimensions of cast-iron radiators of automatic air vents. Moreover, they are not afraid of clogging.
To what has been said, it should be added that in the case when the coolant may contain solid particles of debris (scale, welding flux, tow threads, paint, etc.), it is desirable to install a mechanical standard filter for water supply before the tap.
Mayevsky valve: how to use
Let’s consider how to use the Mayevsky crane, or simply put: how to deflate the air? The Mayevsky crane provides a fairly simple process of venting air from the heating system. Particular attention should be paid to the moment when a fuel pump is installed in the heating system to increase the circulation rate of the coolant. Be sure to turn it off before the operation of venting the air. Firstly, in order to reduce the pressure inside the circuit and, secondly, to stop the process of mixing air bubbles throughout the entire volume of the coolant.
If you follow a small set of rules, you can independently carry out work to remove accumulated air in the system:
- apply a small container and a dry rag, which must be installed under the outlet of the Mayevsky crane;
- prepare the key for turning the valve adjusting screw;
- to be safe, have a sliding or horn wrench with you for possible additional tightening of the tap into the radiator.
Putting the key (or inserting a screwdriver) on the head of the adjusting screw, it is necessary to smoothly perform the opening operation (unscrewing the screw) until the sound of hissing escaping air appears. Hold the screw in this position until the liquid drips out of the radiator. It is desirable that it merges into the prepared container. Then smoothly screw in the screw until the liquid completely stops flowing out. To do this, it is necessary to wipe the crane body with a dry rag and visually observe the valve outlet. If there is no leakage of liquid, the tap is hermetically closed.
In cases where, after opening the valve, water is observed to flow out from under the threaded connection of the housing, the thread should be gently tightened using a wrench until the formation of droplets completely stops. Videos and instructions found on the Internet will also help you learn how to drain the air from the radiator.
Mayevsky crane in pneumatic systems
The technical feature of the Mayevsky crane is its constructive uniqueness. It can also be used to remove not only air, but also liquid, namely, from pneumatic systems with high air pressure. Usually the compressed air entering the system from the compressor contains an excess amount of water vapor. Technologically, excess moisture is taken away by special freezing devices and various filters.
Over a long period of operation, a significant amount of water can accumulate in stationary (pipe) mains. It accumulates in the lowest zones of the pneumatic ducts and sprays all over the contour. The ingress of water into compressed air-powered pneumatic devices and equipment is very undesirable. In these cases, the Mayevsky crane comes to the rescue. Only in this case, it is mounted at the lowest point of the contour and the bleed process begins with the release of accumulated liquid (water), and ends with the release of clean air. Then the tap closes and the system becomes hermetically sealed again.
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Thus, it became clear how the Mayevsky crane works. Its main function is to remove accumulated air from the heating system, which plays an important role in efficiency and economy. This has a real effect on saving money costs during operation. Market availability, simple valve design allows you to independently and without the involvement of plumbing specialists not only to perform the operation of venting air from the heating system circuit, but also to install or replace the faucet itself. Neither one nor the other operation in itself involves large monetary and physical costs and, most importantly, time.