Using an old refrigeration unit to create DIY compressor is a classic home workshop project. Many craftsmen are thinking how to connect a compressor from a refrigeratorto get a source of compressed air for painting, inflating tires or working with pneumatic tools. The main advantage of this solution is the availability of components and a relatively low noise level compared to industrial analogues.
However, simply connecting hoses will not turn an old motor into an effective tool. The process requires an understanding of the operating principles freon compressors, the correct selection of a container for the receiver and the installation of a filtration system. Incorrect assembly can lead not only to equipment breakdown, but also create a dangerous situation due to high pressure in the system.
In this article we will analyze all the stages of creating a homemade compressor installation. You will learn what parts are required, how to prepare the unit for operation, and what safety precautions must be followed. We will pay special attention to the nuances of connecting the electrical part and sealing the connections.
⚠️ Attention: The refrigerator compressor is not intended for constant operation under load as an air blower. The resource of such a device is limited, and the lubrication system may not cope with long-term operation in dry air.
Preparation of the necessary materials and tools
Before starting assembly, it is necessary to prepare all components. The basic element is itself refrigeration compressor, which is extracted from an old household appliance. It is important to check its functionality and the integrity of the windings before starting installation. In addition to the motor, you will need a receiver - a container that will accumulate compressed air and equalize pressure pulsations.
Old fire extinguishers with a volume of 10-50 liters or gas cylinders are often used as a receiver. Metal containers must be intact, free of corrosion and dents You will also need a set of fittings, hoses, a check valve, a pressure switch (pressure switch) and a pressure gauge to monitor indicators in the system. Without these elements, safe operation is impossible.
To assemble the structure, you will need tools: a drill, a set of drills, wrenches, screwdrivers and a soldering iron. Don't forget about consumables: sealant, electrical tape, hose clamps and wires of sufficient cross-section. The quality of materials directly affects the reliability of the entire installation.
- 🔧 Compressor from a refrigerator (preferably one type, for example Atlet or Secop).
- 🛢️ Receiver (fire extinguisher, freon cylinder or welded container).
- 📏 Pressure gauge for pressure control (up to 10-15 atmospheres).
- 🔌 Pressure switch (pressostat) for automatic on/off.
- 🔙 Check valve that prevents air from escaping back into the compressor.
Pay special attention to the selection of hoses. They must withstand. pressure with a reserve. Ordinary garden hoses will not work here - use specialized pneumatic hoses or reinforced options. It is also important to choose the correct diameter of the pipes for connection so as not to create excessive resistance to the air flow.
Dismantling and checking the compressor
The process of removing the unit begins with disconnecting the refrigerator from the network. It is necessary to carefully cut the copper tubes suitable for the compressor, leaving enough length for subsequent connection. Important: do not try to immediately unscrew the fastening bolts - first you need to drain the oil if it is inside, or be prepared for it to leak out when the position changes.
After removing the motor, you should determine the purpose of the pipes. Usually there are three of them: two short and one long. To understand which is which, briefly apply power to the windings. The pipe from which the air blows is the discharge pipe, and the one that sucks in is the input pipe. The third one, often located at the bottom, is used for refueling and can be used as a refueling pipe in homemade designs. draining condensate or shutting down.
⚠️ Attention: When checking the compressor, do not leave it on without load for more than 1-2 minutes. Without freon, which cools the unit in normal mode, the motor can quickly overheat and fail.
Check the condition of the electrical part. with a multimeter: the resistance of the starting and operating windings should be within normal limits (usually from 10 to 50 Ohms) and there should be no breakdown to the housing. If the compressor has a starting relay, make sure that it is in good working order, since it is the one that most often fails when turned on frequently.
Assembling the receiver and installing accessories
The receiver is the heart of your pneumatic system, ensuring pressure stability If you. When using a fire extinguisher, first make sure that it is empty and not under residual pressure. Remove the bell and shut-off valves, thoroughly rinse the internal surface with water to remove powder or rust. Dry the container until the moisture completely disappears.
In the upper part of the receiver, you need to drill holes for installing fittings. Usually, at least three outlets are required: for connecting the compressor, for taking air to the consumer, and for installation. pressure gauge. Threaded connections should be sealed with FUM tape or anaerobic sealant. The use of ordinary tow with paint in pneumatics is not recommended due to the risk of lint getting into the mechanism.
The compressor itself is secured to the receiver. vibration isolating pads Rubber bushings or pads from a car mat will help reduce the level of noise and vibration transmitted to the metal cylinder. This will extend the life of the connections and make the installation more comfortable.
☑️ Checking the readiness of the receiver
Be sure to install a drain valve at the bottom of the receiver. During the compression of air, condensation is formed from atmospheric moisture, which accumulates at the bottom point. If it is not drained, water will enter the pneumatic tool or spray gun, spoiling the result of the work and causing corrosion inside the system.
Electrical diagram. connections and automation
The most important stage is connecting the electrics. The standard scheme involves the use of a pressure relay, which controls the supply of voltage to the compressor. When the pressure in the receiver drops to the lower limit (for example, 4 atm), the relay closes the contacts and starts the motor. When the upper limit is reached (for example, 8 atm), the circuit opens. data-i="101">To connect, you will need to disassemble the housing of the pressure relay. Inside you will see terminals: network (Line) and motor (Motor). The phase wire from the socket goes to the input terminals of the relay, and from the output terminals to the compressor starting device.
To connect, you will need to disassemble the pressure switch housing. Inside you will see terminals: network (Line) and motor (Motor). The phase wire from the socket goes to the input terminals of the relay, and from the output terminals to the compressor starting device. Grounding it must be connected, since working with electricity and metal increases the risk of electric shock.
Connection diagram:Network (220V) --> Pressure switch --> Compressor start relay --> Motor windings
|
+--> Pressure gauge (pressure control)
If you use compressor with capacitor start, make sure that the capacitor capacity corresponds to the engine power. An incorrectly selected capacitor can lead to humming of the motor and the inability to start under load. In some cases, it is necessary to replace the standard starting relay with a more reliable analogue, designed for frequent switching cycles.
What to do if the compressor hums, but does not start?
Most often the problem is a stuck start relay or a faulty capacitor. Try to gently tap the relay or replace it. Also check if the piston is jammed due to thickened oil or a long period of inactivity.
Air filtration and preparation system
The air leaving the refrigeration compressor contains oil vapor and water vapor. This air is not suitable for painting work or connecting sensitive pneumatics. Therefore, after the receiver, an air preparation unit must be installed, including a moisture-oil separator and a fine filter.
The moisture-oil separator operates on the principle of a cyclone: the swirling air flow loses speed, and heavy fractions (oil and water) settle on the walls of the glass, from where they are then drained. Filter element retains fine dust and suspension oils Regular replacement or cleaning of filters is the key to the long life of your instrument.
| Filter type | Degree of cleaning | Purpose | Frequency maintenance |
|---|---|---|---|
| Coarse (mesh) | 40 microns | Protection from coarse dust | Once every 6 months |
| Moisture-oil separator | 5 microns | Removal of condensate and oil | Draining after each work |
| Carbon filter | 0.01 microns | For fine painting | As it becomes dirty |
| Pressure regulator | - | Reducing pressure to operating pressure | Checking the pressure gauge |
Filters must be installed in close proximity to the consumer or immediately after the receiver, if The air is vented with a long hose. Remember that each filter creates resistance to flow, so the outlet pressure will be slightly lower than in the receiver. This is a normal phenomenon that must be taken into account when setting the relay.
First start-up and pressure adjustment
Before the first full start, conduct a visual inspection of all connections. Using a soap solution, check the joints of pipes and fittings for leaks. Air bubbles will indicate a leak that must be corrected before working under pressure. This is a critical safety step.
Turn on the compressor and allow it to build up pressure to cut-off. Monitor the pressure gauge readings and the temperature of the motor housing. If the compressor heats up too quickly or does not turn off for a long time, the motor capacity may be less than the volume of the receiver, or there is a leak. In this case, you need to increase the difference between the upper and lower threshold of the relay.
Adjust pressure switch according to your needs. For most household tasks, 6-8 atmospheres are sufficient. You should not try to squeeze the maximum out of the refrigeration compressor (12-15 atm), as this will lead to rapid wear of the piston group and seals. The optimal operating mode will extend the life of a homemade installation.
⚠️ Attention: If you notice that the compressor has been running continuously for more than 15-20 minutes, forcefully turn it off. Long-term operation without rest for such motors is not provided for by the design and is fraught with melting of the insulation or jamming.
After successful testing, secure all elements to the frame or trolley. Vibration during operation can loosen connections, so use lock washers and periodically check the bolts for tightness. It is advisable to paint the finished installation with heat-resistant paint to protect against corrosion.
Frequent problems and ways to solve them
During operation, you may encounter a number of typical problems. For example, the compressor may stop building pressure. Most often this is due to worn piston rings or stuck valves. In this case, it is necessary to disassemble and troubleshoot the cylinder head, replace gaskets or rings.
Another common problem is severe vibration and noise. If vibration is not eliminated by rubber gaskets, check the balancing of the pulley (if any) or the condition of the electric motor bearings. Humming may also indicate a drop in voltage in the network, which is typical for powerful models when working in garage networks.
Air leaks often occur at the junction of metal tubes with rubber hoses. Over time, the clamps weaken and the rubber becomes dull. Change hoses regularly and use high-quality metal clamps with screw tightening, not spring ones.
Is it possible to use a compressor from a refrigerator for airbrushing?
Yes, you can, but only if you install a high-quality moisture-oil separator and pressure regulator. Refrigeration compressors produce a pulsating flow, so a receiver is required. For fine airbrushing, a pressure of about 1-2 atmospheres will be required, which is easily regulated by a gearbox.
What kind of oil should be poured into the compressor?
In most cases, a special synthetic oil (POE or PAG) is poured into the piston group of refrigeration compressors, which is mixed with freon. However, when converting to air, many craftsmen leave the standard oil or replace it with compressor oil for pneumatics (for example, VG 40), if the design allows. It is important not to mix different types of oils.
Why does the compressor turn off after 2 minutes of operation?
Most likely, the thermal protection relay is triggered. This may occur due to overheating of the motor, too small a receiver (frequent switching cycles) or a malfunction of the relay itself. Check the ventilation and the volume of the storage tank.
Is it necessary to change the starting relay when making alterations?
If the standard relay is working properly and corresponds to the operating mode (frequent switching on), it is not necessary to change it. However, for home-made installations it is often recommended to install more reliable relays or electronic starters, since standard plastic relays can crack from vibration.
What is the maximum volume of the receiver that can be used?
Theoretically, the volume is not limited, but it must correspond to the performance of the compressor. A receiver that is too large with a low-power motor will result in very long pumping times. Optimal: 10-50 liters for household needs.