The demand for domestic air conditioners and industrial air conditioning systems is increasing. This is due to the natural desire of people to create comfortable climatic conditions in the premises where they spend most of their time. In turn, this significantly influenced the need for consumables used during the installation and installation of this kind of equipment. One of these consumables, and the most common one, is a copper tube, with the help of which pipelines are mounted that connect all the units of the system together.
Air conditioning pipes
When carrying out work related to the installation of climatic equipment, it becomes necessary to create communications designed to transport refrigerant from one unit to another. Copper tubing is most commonly used for air conditioners.
The use of copper is due to a set of positive qualities that leave aluminum, steel or plastic far behind:
- chemical inertness in relation to refrigerants (freon, freon, etc.) used in air conditioning systems;
- high melting point (+ 1083 ° С) and thermal conductivity (400 W / m * K);
- the minimum content in the chemical composition of impurities potentially hazardous to humans;
- high anti-corrosion properties of the outer and inner surfaces of pipes, which are provided due to the appearance of a stable oxide film;
- minimum roughness of internal surfaces;
- heat resistance, plasticity, gas tightness, etc.
Industrial enterprises produce pipes for air conditioners from copper grade M1r TU 184450-106-181-2006, guided by the provisions of GOST 617-2006.
Copper grade M1r is obtained by melting copper cathodes and copper scrap with phosphorus deoxidation. At the same time, in terms of chemical composition (not less than 99.9% Cu + Ag), the alloy corresponds to copper of the Cu-DLP brand (Euronorm EN 1652: 1998).
Varieties of copper pipes
Copper tubes of 2 types are used to work as part of air conditioning systems:
- unannealed, with increased strength;
- annealed, characterized by greater plasticity.
In order to give them high plasticity, the tubes are additionally subjected to one of the types of heat treatment - annealing.
Annealing is a technological process in which parts are placed in a special furnace and heated to a temperature of + 700 ° C. They are then cooled in the open air, making them softer and more elastic. In this case, the strength characteristics of the material deteriorate slightly.
Comparative characteristics of the tubes are shown in the table.
| Parameters | Annealed | Unannealed |
| Strength, kPa | 210000…220000 | 280000…300000 |
| Breaking elongation,% | 50…60 | 10…15 |
As a rule, copper pipes for transporting refrigerant are not included in the delivery of the air conditioner and must be ordered separately. Wherein:
- unannealed - supplied in the form of measured segments (rods) with a length of no more than 5 m. In order to avoid the ingress of dust particles and foreign objects into the tubes, their ends are closed with plugs.
- annealed, the length of which is 15 ... 50 m - are supplied in coils, packed in plastic bags.
There are also tubes, additionally insulated with "covers" made of polyethylene or non-porous foam rubber. This is done in order to exclude the possibility of temperature loss in the lines mounted from thin-walled pipes.
When arranging air conditioning systems, copper pipes of the annealed type are often used. This is due to the fact that they allow you to install pipelines of the most complex shape. Such pipes easily bend at any angle without changing their shape. When flaring at the joints, it is easy to obtain tight connections.
Assortment of copper tubes
When choosing the necessary materials for pipelines connecting individual units of air conditioners with each other, special attention is paid to the diameter of the copper pipes. Its value depends not only on the rate of circulation of the refrigerant between the units, but also on the amount of pressure loss in the final devices that cool the air.
The range of produced copper pipes is very diverse, but when forming pipelines for HVAC equipment, as a rule, certain standard sizes are used. Moreover, the thickness of their walls rarely exceeds 0.7 mm.
The diameter of the pipes is chosen based on the power of the air conditioner - the higher the power, the larger the diameter. Most often, copper pipes are used for air conditioners, the diameters of which are shown in the table.
| Copper tube diameter for air conditioners | |
| mm | inch |
| 6,35 | 1/4 |
| 9,52 | 3/8 |
| 12,7 | 1/2 |
| 15,88 | 5/8 |
| 19,05 | 3/4 |
When choosing the size of copper pipes for air conditioners, you need to remember that their blocks are connected by two pipelines:
- gas, which serves to supply a gaseous substance from the compressor to the condenser and from the evaporator to the compressor;
- liquid, with the help of which a liquid substance is supplied from the condenser to the evaporator.
In this case, the diameter of the pipes of the gas line must be larger than that of the liquid one.
As for their length, it all depends on the distance between the air conditioner units. As a rule, when installing a single air conditioner, measured lengths of tubes from 2 to 5 m are used. If a large air conditioning system is being installed, it is more expedient to purchase tubes in coils.
Installation of pipelines
- development and marking of the optimal route for laying the route;
- determination of the length of pipelines;
- construction work (if necessary): chipping walls, punching holes in the walls, etc.;
- preparation of materials and tools that may be needed when performing work.
In order to correctly assemble the pipeline, its calculated length must be increased by 0.8 ... 1.2 m. This will painlessly eliminate defects that may arise when connecting pipes.
When installing the pipeline, it is placed in a special box. Only after laying and fixing the pipeline are the air conditioning units installed. Then the pipes and blocks are connected into a single system and its tightness is checked.
Union nuts and soldering are used to connect the tubes. At the same time, at the junction points, the free ends of the tubes are cut off, and the cut points are carefully cleaned from burrs.
Tubes are cut only with a special pipe cutter. The use of a hacksaw or grinder is not allowed, as it can lead to the ingress of small sawdust into the pipe and their circulation through the system. In turn, this can lead to blockage of the capillary tube of the air conditioner, the diameter of which does not exceed 0.8 mm.
When carrying out work, it is allowed to use copper connecting fittings. However, they can be installed only in those places where there are conditions for controlling the grip force of the elements during the operation of the air conditioner.
Solder connection
The use of soldering when connecting copper pipes is considered not only the most reliable, but also the cheapest way to ensure complete tightness of the connection. Soldering of copper pipes is carried out in the following sequence:
- the end of one of the tubes is expanded using a special rolling nozzle;
- thoroughly clean and degrease the connected ends of the tubes from the oxide film and insert them into each other to a length approximately corresponding to their diameter;
- evenly apply a liquid or pasty flux to the junction;
- the surfaces to be connected are heated with a torch until the solder begins to melt from contact with the joint;
- fill the junction with solder, ensuring its penetration into the gap between the tubes inserted one into one;
- cool the joint in natural conditions and remove excess flux from the surface of the tubes.
When brazing copper pipelines, use only copper-silver or copper-phosphorus solder.
Union nut connections
Union nut connections are most often used when connecting pipelines to air conditioning units with corresponding outlet pipes.
In order to connect the free end of the pipeline with the threaded branch pipe, the pipe must first be flared using a special flaring nozzle of a suitable diameter.
Before flaring the free end of the copper tube, do not forget to put on the union nut removed from the branch pipe leaving the air conditioner unit.
After the end of the tube is correctly and neatly flared, the pipeline is connected to the corresponding branch pipe of the air conditioner unit. To do this, align the outlet flange with the socket of the branch pipe as evenly as possible and tighten the union nut by hand. The nut must be tightened freely along the entire threaded length of the branch pipe. Only then can the connection be carefully tightened with a wrench. Excessive tightening force can shear the flared flange, and insufficient tightening will not ensure the required tightness of the pipeline.
