A modern refrigerator is a complex unit where the circulation of refrigerant ensures the safety of products. This system is based on a closed loop consisting of various elements connected to each other. The main conductor of cold are special tubes through which freon moves, changing its state of aggregation. It is on their integrity and material that the efficiency of the compressor and the entire climatic zone of the chamber depends.
Owners of household appliances are often faced with the need to understand the internal structure in case of breakdowns or gas leaks. Pipes in the refrigerator can be made of different alloys, each of which has its own physical and chemical properties. Understanding what the line is made of will help you correctly estimate the cost of repairs and select the appropriate materials to restore the tightness of the system.
It is important to realize that any depressurization of the circuit requires immediate intervention by specialists. Trying to ignore the problem can lead to the failure of an expensive compressor. Next, we will consider in detail the types of materials used, their purpose and features of interaction with refrigerants.
Main materials for the manufacture of refrigeration lines
Historically, copper has long remained the main material for the creation of refrigeration circuits. This metal has excellent thermal conductivity and high ductility, which simplifies the installation of complex components. Copper tubes easily solderable and allow you to create hermetic connections of any configuration without loss of strength. However, the cost of copper is high, which forces manufacturers to look for more budget-friendly alternatives.
In modern models, especially in the budget segment, aluminum or steel is increasingly used. Aluminum tubes is much lighter and cheaper, but requires a special approach during installation. They are less ductile and prone to oxidation when in contact with certain types of solders. Steel elements are less common, mainly in pressure lines where high strength is required.
⚠️ Attention: Aluminum cannot be soldered with conventional tin-lead solders used for copper. To work with it, special fluxes and aluminum solders are required, otherwise the connection will not be airtight.
The choice of material also depends on the type of refrigerant charged into the system. Aggressive environments can quickly destroy certain alloys, so engineers carefully select the composition of the metal for a specific freon. The use of unsuitable material can lead to rapid corrosive destruction of the line.
Functional purpose of various sections of the circuit
The refrigeration circuit is divided into several zones, each of which performs its own function and experiences different loads. In the area from the compressor to the condenser, the temperature and pressure are maximum. The most durable discharge tubesare used here, capable of withstanding heating up to 80-90 degrees Celsius and high gas pressure.
After the condenser, the refrigerant enters the capillary tube, where a sharp drop in pressure occurs. This section is a thin spiral of copper or steel of small diameter. It is here that capillary acts as a throttle, regulating the flow of freon. Any clogging of this thin tube leads to a complete stop of cooling.
In the evaporator, located inside the freezer or behind the back wall, the refrigerant boils. Evaporator tubes are often made of aluminum or stainless steel, since they come into contact with food (through the wall) or are located in an aggressive, humid environment. The tightness of this unit is critical for food safety.
Comparative table of tube materials
To better understand the differences and applications, let's look at the main characteristics of the materials in a comparative format. This will help determine what exactly you encountered during a visual inspection of the unit.
| Material | Thermal conductivity | Plasticity | Corrosion resistance | Complexity soldering |
|---|---|---|---|---|
| Copper | High | Very high | High | Low |
| Aluminum | Medium | Low | Medium | High |
| Steel | Low | Low | High | Medium |
| Stainless steel | Low | Medium | Very high | High |
The table shows that copper is the leader in terms of properties, which explains its popularity in premium models. However aluminum alloys they win in weight and price, which makes them popular. Steel is more often used where mechanical strength rather than heat transfer is important.
Features of capillary tubes and throttling
The capillary tube, which is the heart of the circulation system, deserves special attention. This is a long line of small diameter that creates the necessary resistance to the refrigerant flow. The length and diameter capillary are calculated by engineers to the nearest millimeter for each refrigerator model.
If you replace the original tube with an analogue with different parameters, the refrigerator will stop freezing or will work with compressor overload. Some systems use a double capillary or defrost circuit, which complicates the design. Throttling in this unit occurs due to friction of the liquid against the walls and changes in flow rate.
Why does the capillary sometimes freeze?
Freezing capillary tube often indicates the presence of moisture in the system or a clogged filter drier. Moisture turns into an ice plug, blocking the flow of freon.
When repairing, technicians often replace the entire capillary assembly along with the filter-drier. This is standard procedure to ensure a clean system. Replacing this element on your own without vacuuming the system is impossible and will lead to air and moisture getting inside the circuit.
Problems with tubes: leaks and blockages
The most common problem faced by refrigerator owners is refrigerant leakage. It can occur at the soldering site, due to metal corrosion or mechanical damage. Freon leakage Often accompanied by the appearance of oily spots on the floor or in the compressor niche, as the oil comes out along with the gas.
Clogged tubes, especially capillary, is also common malfunction. It occurs due to oil oxidation, moisture ingress or decomposition products of the compressor winding insulation. As a result, the circulation stops and the refrigerator stops cooling, although the compressor continues to hum.
⚠️ Attention: If you find an oil stain under the refrigerator, do not turn on the unit. Operating a compressor without a sufficient amount of oil and refrigerant will lead to its wedge in a matter of minutes.
To diagnose leaks, technicians use leak detectors or the soaping method. Finding micro-cracks can take considerable time, especially if they are located in the foamed part of the case. In such cases, sometimes it is necessary to deviate from the standard scheme and install a new evaporator.
Soldering and seal restoration technologies
Restoring the integrity of the circuit requires professional equipment and skills. Soldering of copper tubes is carried out using a gas torch and solder containing silver. Hard solder provides the necessary strength of the seam and resistance to vibrations, which are inevitable during compressor operation.
When working with aluminum tubes, the technology is more complicated. Removal of the oxide film with special fluxes and the use of high-temperature solders is required. Often, adapters (bi-metallic inserts) are installed at the junctions of copper and aluminum to avoid galvanic corrosion.
☑️ Checking the quality of soldering
An important step is to clean the inner surface of the tubes from oxides formed during heating. To do this, blow with nitrogen during soldering. If this is not done, oxides may enter the compressor or clog the capillary, causing repeated failure.
Modern trends and environmental friendliness of materials
With the development of environmental standards, not only the type of refrigerants changes, but also the requirements for tube materials. The transition to R600a type freons (isobutane) required increasing the tightness of all connections, since this gas is more explosive. Refrigerator tubes now must withstand more stringent permeability tests.
Manufacturers are introducing new alloys and coatings that increase service life evaporators. The use of pre-insulated tubes (pipe-in-pipe) for heat exchangers improves energy efficiency. Engineers strive to minimize the number of solder joints by using bent one-piece structures.
⚠️ Note: Specifications and parts availability may vary by model and year. Before ordering parts, check the article numbers with the data in the technical data sheet or on the manufacturer’s website.
In the future, a further reduction in pipe diameters is expected to save raw materials and a reduction in the volume of refrigerant charged. This poses new challenges for service departments, requiring more accurate and miniature repair tools.
Frequently asked questions (FAQ)
Is it possible to solder aluminum refrigerator tube at home?
Theoretically, this is possible using special high-temperature solders and fluxes for aluminum. However, in practice, the quality of such soldering is often inferior to the factory one, and the risk of damaging the thin walls of the tube with a torch is very high. Without experience and proper tools, it is better to call a specialist.
Why does the refrigerator not freeze after replacing the tube?
There may be several reasons: incorrectly selected capillary length, the presence of air or moisture in the system (poor vacuum), clogged filter-drier or poor-quality soldering, which led to an internal narrowing of the channel. It is also possible that the amount of freon charged is incorrect.
How to distinguish a copper tube from an aluminum one visually?
Copper has a characteristic reddish-pink tint (if not oxidized) and is heavier. Aluminum is silver-gray, matte and significantly lighter. In addition, copper is not magnetic, like aluminum, but it is easiest to distinguish them by color and weight.
Is it dangerous to breathe vapors when soldering tubes?
Yes, vapors from fluxes and solder combustion products can be toxic. In addition, when heating freon residues in the tubes, toxic compounds (for example, phosgene) can form. It is necessary to work in a well-ventilated area and use personal protective equipment.