Using old household equipment for creating new useful tools is not just a way to save money, but also an excellent engineering project for a home workshop. Compressor from a refrigerator is one of the most popular solutions among home craftsmen, as it allows you to get a powerful and relatively quiet source of compressed air almost free of charge. The basis is a standard motor-compressor, which was originally designed to circulate freon, but also copes well with pumping atmospheric air.
The main advantage of such a device is its low noise level compared to industrial piston analogues and the ability to work for a long time without overheating. You do not need to have in-depth knowledge of thermodynamics to assemble a working installation, however, understanding the principles of operation piston unit and electrical circuits will not be superfluous. In this article, we will analyze in detail the remodeling process, from the selection of components to the final assembly and configuration of the system.
Preparation of tools and necessary materials
Before starting any work on upgrading equipment, it is necessary to collect a complete set of tools and consumables. Missing even one important detail can stop the process halfway, so make a list in advance. The basis of your future device will be itself motor-compressor, extracted from a non-working or old refrigerator.
It is important to make sure that the selected unit is in good condition and is capable of creating the necessary pressure. You will also need a container for storing compressed air, known as a receiver, which can be made from a fire extinguisher or a gas cylinder.
- 🔧 A set of wrenches and screwdrivers for disassembling components and fastening elements.
- 🔩 Copper or steel tubes, as well as high-pressure hoses for lines.
- ⚡ Pressure switch (pressostat) and electrical cables for automation of work.
- 🛠️ Drill, metal drills and a hacksaw for processing the receiver body.
⚠️ Attention: When using old gas cylinders as a receiver, make sure that they are completely cleaned of gas residues and do not have traces of corrosion that can reduce the strength of the structure under pressure.
Do not forget to prepare sealant, hose clamps and a pressure gauge to control the pressure in the system. All of these elements are critical to the safety and performance of your DIY device. High-quality preparation will eliminate the need for an urgent search for missing parts in the midst of assembly.
Removing the compressor from the refrigerator
The first stage of work involves carefully removing the compressor from the refrigerator body. This process requires caution, as it is important not to damage the electrical part and outlet pipes. Typically, the compressor is located in the lower rear part of the unit and is mounted on four shock-absorbing legs.
First you need to cut through the copper tubes running from the compressor to the condenser radiator and evaporator. This should be done at a distance of 10-15 cm from the motor body in order to leave a reserve for subsequent connection. Copper tubes They must remain intact, as they will serve as fittings for connecting new lines.
Importance of oil in the compressor
Inside the compressor there is a special compressor oil that lubricates the rubbing parts and removes heat. During long-term storage or improper transportation (tilts of more than 45 degrees), oil may flow into the circuit, which will lead to a hydraulic shock at the first start.
After disconnecting the tubes, you need to remove the protective casing and unscrew the mounting bolts. The electrical cable is cut with a margin so that the new control circuit can be easily connected. If you plan to use an old wire, make sure that the insulation on it is not damaged.
Check the functionality of the removed node by briefly connecting it to the network. It should work smoothly, without strong vibration or extraneous knocks. At this stage, you can already estimate the approximate power and performance of your future air blower.
Manufacture and preparation of the receiver
The receiver is a container in which compressed air accumulates, leveling out pressure pulsations and ensuring stable operation of the pneumatic tool. The most affordable and safe option for a homemade compressor is to use a fire extinguisher housing with a volume of 10-50 liters.
Before starting work, you must make sure that the fire extinguisher is empty and the pressure inside is equal to atmospheric pressure. Then the top part is cut off or a hole is drilled to install shut-off valves. The walls of the cylinder must be thick to withstand pressure up to 10-15 atmospheres with a margin of safety.
| Component | Material | Function | Requirements |
|---|---|---|---|
| Receiver | Steel / Fire extinguisher | Air accumulation | No corrosion, wall thickness > 3 mm |
| Pipelines | Copper / Steel | Air transportation | Tightness, oil resistance |
| Hoses | Polyurethane / Rubber | Tool connection | Flexibility, operating pressure > 10 bar |
| Fasteners | Steel | Fixation of nodes | Tension and vibration strength |
In the lower part of the receiver it is necessary weld or screw in a fitting to install the drain valve. Through it, condensate will be removed, which inevitably forms when humid atmospheric air is compressed. Ignoring this element will lead to rapid rusting of the tank from the inside.
It is also necessary to provide space for installing the inlet pipe from the compressor, the outlet pipe to the consumer and mounting a pressure gauge with a pressure switch. All threaded connections must be carefully sealed using FUM tape or similar sealants designed for high temperatures and pressure.
☑️ Checking the receiver before assembly
Assembling the pneumatic system and connecting
Assembling the pneumatic part requires attention to detail, since any air leakage reduces efficiency the entire system. The compressor is connected to the receiver through the inlet pipe, which should preferably be equipped with a check valve. This element will prevent the reverse flow of air from the tank into the compressor after it stops.
Special adapters or crimp fittings can be used to connect the copper tubes of the compressor to the system. It is important not to overheat the copper when soldering, so as not to disrupt its structure. All connections must be checked for leaks with a soap solution after the first start.
The filtration system also plays an important role. It is worth installing an air filter at the inlet of the compressor, which will protect the piston group from dust. At the outlet of the receiver, you can install a moisture-oil separator, especially if you plan to use the compressor for painting or working with sensitive pneumatics.
⚠️ Attention: When soldering copper tubes, use solder with a melting point above 200°C, since the temperature in the joint area can increase significantly during operation of the compressor.
The hose going to the tool is connected through a ball valve, which will allow you to shut off the air supply without stopping the engine. Properly configured pneumatic line provides stable pressure and extends the service life of the connected equipment.
Electrical circuit and automation
Automation of the compressor is a key point that makes using the device convenient and safe. The main element here is a pressure switch (pressostat), which automatically turns the engine on and off depending on the pressure level in the receiver.
The connection diagram is quite simple: the mains voltage is supplied to the relay input, and the output goes to the compressor. Inside the relay there are contacts that open when the upper pressure limit is reached and close when it drops to the lower threshold. This saves you from having to constantly monitor the pressure gauge.
Connection diagram:220V network -> Pressure switch -> Compressor
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Capacitor (for starting)
Do not forget about the capacitor, which is often necessary to start the engine, especially if the compressor model requires a phase-shifting element. The electrical circuit must be assembled in a separate sealed box to protect it from dust and moisture.
For system safety, the pressure switch is often equipped with a relief valve that bleeds air from the compressor discharge tube after stopping. This makes the next engine start easier, relieving the load on the piston group.
Starting, testing and safety measures
The first start of the assembled device is a crucial moment that requires compliance with all safety precautions. Make sure the receiver drain valve is open and all connections are secure. Turn on the compressor and monitor the pressure build-up.
Carefully inspect all joints and connections for air leaks. A characteristic whistle will indicate the place where additional sealing is required. Also listen to the operation of the engine: extraneous knocking or strong vibration may indicate a malfunction or improper installation.
Regular maintenance includes draining condensate from the receiver, checking the oil level (if the compressor requires replacing or topping it up) and cleaning the air filter. Following these simple rules will allow your homemade unit to serve for many years.
Frequently asked questions (FAQ)
What is the maximum pressure a compressor can develop from refrigerator?
Standard refrigeration compressors are usually capable of creating a pressure of 6 to 10 atmospheres, but the design of many models allows it to reach 15-20 atmospheres. The exact value depends on the specific engine model and the condition of the piston group. It is not recommended to exceed the pressure for which your receiver is designed.
Is it necessary to change the oil in the compressor during modification?
It is not necessary to change the oil if the compressor is working properly and the oil is clean. However, if you plan to use the unit for painting, it is better to install a quality moisture-oil separator at the outlet, since compressor oil may enter the air stream. A complete oil change is possible, but requires opening the housing, which is difficult to do hermetically at home.
Can such a compressor be used for sandblasting?
For full-fledged sandblasting, the performance of one refrigeration compressor is usually not enough. Sandblasting machines require a large volume of air output. However, for small jobs or inflation of tires, painting and blowing, such a unit is ideal.
How often do you need to drain the condensate from the receiver?
The frequency of draining the condensate depends on the air humidity in the room and the intensity of use of the compressor. It is recommended to check the fluid level and drain the condensate after each completion of work or at least once a week during active use. This will prevent corrosion of the tank from the inside.