The old refrigerator has stopped freezing, but it’s a pity to throw it away entirely, especially if the electric motor with a sealed housing (SC) is still working. It is this unit that is a ready-made, powerful and relatively quiet source of compressed air, which can be adapted for many household needs. Unlike noisy and bulky industrial analogs, refrigeration compressor occupies a minimum of space and is capable of creating a pressure of up to 10 atmospheres, which is more than enough for most household tasks.
Before starting to implement projects, you need to understand that the device is initially designed to work with refrigerant, and not for pumping atmospheric air. This makes adjustments to the design: high-quality filtration, oil removal and overheating protection are required. However, if you are willing to spend a couple of evenings on modifications, you will end up with a versatile tool that will last for many years to come. In this article we will look at where to use a refrigerator compressor and how to avoid common mistakes during assembly.
The most obvious and popular application is to create compressor for the garage or a home workshop. This unit is ideal for inflating the tires of a car, bicycle or motorcycle, eliminating the need to go to a gas station or carry a heavy foot pump every time. The pressure created by a standard household unit (usually about 2-4 atmospheres in the operating cycle, but capable of holding more) easily covers the needs of passenger vehicles.
In addition, compressed air is indispensable for blowing hard-to-reach places in electronics, cleaning radiators from dust or drying painted parts. Flow power allows you to effectively remove dirt from the cracks of the computer case or lock mechanism. It is only important to remember that at the outlet of the receiver, the air must be cleared of moisture and oil suspension, so as not to spoil the equipment being cleaned.
⚠️ Attention: Before starting any work, make sure that the compressor is completely disconnected from the power supply and there is no residual pressure in the system. The sealed housing may contain refrigerant vapor and compressor oil, which should not enter the respiratory tract or onto the skin in large quantities.
For those who are interested in modeling or minor repairs, an excellent solution would be to remake the unit in airbrush. Of course, you cannot directly connect the tool to the piston - a receiver (cylinder) is needed to smooth out pressure pulsations. An even flow of air allows you to apply paint in the thinnest layer, creating gradients and complex patterns on models, nails or in artistic painting.
Airbrush requires stable pressure, usually in the range of 1-3 atmospheres, which is easily adjusted using a gearbox. Unlike compressed air cylinders, which quickly run out, the compressor unit provides an endless supply of air. This makes the work process continuous and cost-effective, since you only pay for electricity.
However, there is a nuance: for high-quality airbrushing, the air must be absolutely dry and free of oil. Standard refrigeration compressors often “spit” oil along with the air, so the filtration system must be multi-stage. The use of a moisture-oil separator and additional fine filters is a prerequisite for obtaining a professional result.
One of the most interesting and useful functions that can be obtained by changing the direction of rotation of the shafts or simply swapping the input and output (although for piston engines this is not always relevant, hoses are often changed) is the creation of a vacuum pump. A refrigeration compressor is capable of creating a vacuum sufficient to vacuum food, pack things, or even conduct simple chemical experiments.
Vacuuming can significantly increase the shelf life of products, preventing oxidation and the proliferation of bacteria. This technology is also used when impregnating wood with oils, when it is necessary to remove air from the pores of the material for deep penetration of the composition. A vacuum compressor will become an indispensable assistant for craftsmen working with epoxy resins, helping to remove air bubbles from the mixture.
There is also a method of vacuum molding of plastic, where a sheet of heated polymer is pulled onto a matrix by pressure differences. For small parts, the power of the refrigeration unit is quite enough. The main thing is to ensure the tightness of the entire system, since even microscopic leaks can reduce the effectiveness of evacuation to zero.
Features of operation in vacuum mode
When operating in vacuum, the compressor can heat up more, since the flow of passing gas cools the windings less. It is recommended to take breaks during work and monitor the body temperature.
For car enthusiasts and home craftsmen who paint small parts, a homemade compressor can become the basis for spray gun. Pneumatic application of paint produces a more even layer without the streaks and streaks typical of a brush or roller. With the help of a properly configured torch, you can paint wheels, furniture, fences or decorative elements.
The key element here is not only the compressor itself, but also the correct selection of the spray gun and pressure adjustment. Different types of paints (acrylic, nitro enamel, varnish) require different flow rates. The presence of a receiver with a volume of 20 liters or more allows you to work in a pulsating mode, turning on the engine only when the pressure drops, which saves the resource of the piston group.
It is worth noting that for professional painting of a car body, one household compressor may not be enough due to low air consumption (performance), but for local repairs or painting of a motorcycle its capabilities will be sufficient. It is important to use oil separatorso that drops of lubricant do not fall on fresh paint, ruining the appearance of the product.
⚠️ Attention: When painting, always use a respirator and work in a well-ventilated area. The mist of paint and solvent vapors is toxic, and the compressor can spread it throughout the entire volume of the room.
In order for your homemade product to work for a long time and efficiently, you need to choose the right components. Below is a table comparing the main elements of the system and their purpose. Understanding the role of each unit will help to avoid errors during assembly.
| Component | Purpose | Recommended type |
|---|---|---|
| Receiver | Air accumulation, pulsation smoothing | Propane cylinder or fire extinguisher |
| Pressure switch | Automatic on/off | Relay for compressors (for example, RDM-5) |
| Filter | Purification of air from oil and moisture | Moisture-oil separator with a 5 micron filter |
| Manometer | Control of pressure in the system | Scale up to 10-16 atmospheres |
| Check valve | Prohibition of reverse air flow | High pressure brass valve |
Assembling the system requires attention to detail. For example, the connection of all components must be made using copper tubes or hoses that can withstand high pressure. The use of plastic tubes for supplying compressed air is unacceptable, as they can burst. Safety is the number one priority when working with pressure vessels.
☑️ Check before starting
One of the main problems during conversion is overheating. The refrigeration compressor is designed to operate in a mode where the refrigerant cools the motor. When working with air, cooling is worse, so the case can heat up to 90 degrees and above. This requires either installing an additional blower fan or organizing forced pauses in work.
It is also important to monitor the oil level. In some models it is permanently filled, in others it is possible to replace it. If the compressor starts spitting oil, it means that its level is too high or the piston rings are worn out. Installing a high-quality separator at the outlet will solve the problem of lubricant getting into the pneumatic tool.
Noise during operation is another factor. Although refrigeration compressors are quieter than their open-type reciprocating counterparts, they still produce a hum. Installing the unit on vibration supports (rubber pads) and placing it in a soundproof box (with mandatory ventilation!) will make work in the workshop more comfortable.
In conclusion, it is worth saying that using an old compressor is a great way to save money and get a useful tool. Whether it inflating tiresaerography or vacuum experiments, this unit is capable of a lot. The main thing is to follow safety precautions and not overload the device.
The implementation of such a project requires minimal skills in working with metal and electrical, but the result is worth it. You not only give a second life to equipment, but also create a unique tool adapted specifically to your needs. A fire extinguisher receiver with a capacity of 10-20 liters is the optimal balance between compactness and performance for household tasks.
Is it possible to use a compressor without a receiver?
Technically possible, but not recommended. Without a receiver, the air flow will pulsate in time with the strokes of the piston, which will make high-quality airbrushing or painting impossible. In addition, the motor will turn on and off too often, which will quickly wear out the start relay and windings. The receiver also cools the air and condenses moisture.
What kind of oil should be poured into the compressor?
Only special compressor oils should be used (for example, KS-19, K-19 or their modern analogues). Regular motor or transmission oil is not suitable, as it has a different viscosity and flash point, which can lead to coking of the valves or even an explosion of oil vapor in heated air.
How long can the compressor operate without interruption?
The standard operating mode (ST - duty cycle) for household refrigeration compressors is usually about 50%. This means that after 15-20 minutes of work it needs to be allowed to cool for the same amount of time. Exceeding this limit without additional cooling threatens overheating and melting of the starting winding.
Is it necessary to change the oil after modification?
If the compressor worked in the refrigerator for 10-15 years, the oil in it probably lost its properties and became saturated with decomposition products. When converting for pneumatic tools, it is strongly recommended to drain the old oil and refill with fresh oil corresponding to the type of compressor. This will extend the life of the unit.