Using old refrigeration unit to create a powerful air A compressor is a classic example of smart recycling that makes for a great tool for the garage. Many home craftsmen throw away non-working refrigerators, not even suspecting that hidden inside them is a ready-made, sealed and quite efficient one, capable of pumping air up to 10-15 atmospheres. This homemade product is ideal for inflating tires, working with an airbrush, blowing out mechanisms or connecting pneumatic tools with low air consumption. piston compressor, capable of pumping air up to 10-15 atmospheres. This homemade product is ideal for inflating tires, working with an airbrush, blowing out mechanisms, or connecting pneumatic tools with low air consumption.
The main advantage of this design over store-bought analogues is its relative noiselessness and the possibility of long-term work without overheating. Unlike loud industrial models, a household refrigerator operates quietly, which allows it to be used even in a residential workshop or garage cooperative without causing discomfort to neighbors. However, in order for the device to operate safely and efficiently, it is necessary to strictly adhere to the conversion technology and not ignore the nuances of preparing components. Freon compressor It operates quietly from a household refrigerator, which allows it to be used even in a residential workshop or garage cooperative without causing discomfort to neighbors. However, in order for the device to operate safely and efficiently, it is necessary to strictly adhere to the conversion technology and not ignore the nuances of preparing components.
Before proceeding with dismantling, it is important to understand that we will only use the mechanical part - the motor-compressor itself, usually located in the lower rear part of the refrigerator. We don’t need the entire freon circulation system, condensers and evaporators; they can be turned over into non-ferrous scrap. A critically important step is to completely replace the oil in the compressor crankcase with a special compressor oil, since old refrigeration oil is hygroscopic and may contain residues of freon and acids. Without this procedure, your homemade tool will quickly fail or begin to “spit” oil.
Selection of necessary materials and tools
For successful implementation of the project, you will need not only the refrigeration unit itself, but also a number of additional components that will ensure stable pressure and air purification. The basis of the future installation is a receiver, the role of which can be played by an old fire extinguisher, a gas cylinder or a specially prepared metal container. The volume of the receiver directly affects performance: the larger it is, the less often the motor will turn on, which will extend its life.
In addition to the air tank, it is necessary to purchase high-quality shut-off valves. You will need a pressure reducing valve to regulate the output pressure, a check valve to prevent air flow in the opposite direction, and pressure gauges to monitor the readings. Also don't forget about hoses, fittings and clamps. All connections must withstand pressure with a reserve, so there is no need to save on pneumatic fittings.
As for tools, you will need an angle grinder for cutting metal, a drill or drilling machine, a set of wrenches and screwdrivers. To seal threaded connections, it is necessary to purchase anaerobic sealant or high-quality FUM tape. If you are planning a stationary installation, you will also need a profile pipe or angle to create a base frame on which all components will be fixed.
Dismantling the compressor and preparing the unit
The first stage of work is to carefully remove the compressor from the refrigerator. Saw off the copper tubes coming from the compressor housing, leaving “tails” 5-7 cm long so that chips and dirt do not get into them. Carefully inspect the body: there should be no traces of rust or mechanical damage. If the compressor has relay starting protection, it must also be saved, since it is necessary to start the engine.
The next step is to determine the inlet and outlet pipes. Plug in the compressor (briefly!) and place your finger near the protruding tubes. Where air is blown out with force, there is an outlet (pressure), and where air is sucked in, there is an inlet. The third pipe (often sealed) is intended for filling oil and is closed at the factory. It must be carefully cut off, the old oil drained and the insides washed with a special solvent or Galosh gasoline.
⚠️ Attention: It is strictly forbidden to turn on the compressor if the oil has been completely drained from it or the lubricant level is below the minimum. Working "dry" will lead to scuffing of the piston group and the engine wedge in a matter of seconds.
After washing, you need to fill in new oil. For refrigerator compressors, synthetic oil with a viscosity of ISO 22 or 32, or specialized compressor oil for piston systems is ideal. You need to fill through the same pipe, monitoring the level using the sight glass (if any) or dipstick. Typically, 300 to 500 ml of liquid is required, but the exact volume depends on the model of the unit. compressor oil for piston systems. You need to fill through the same pipe, monitoring the level using the sight glass (if any) or dipstick. Typically, 300 to 500 ml of liquid is required, but the exact volume depends on the model of the unit.
How to determine the type of compressor?
There are linear and inverter compressors. For homemade installations, classic linear models with a start relay are best suited. Inverter ones require complex electronics to start and are less suitable for conversion into an air pump without deep knowledge of electronics.
Making a receiver from a fire extinguisher
The optimal material for the receiver is a fire extinguisher body with a volume of 10 liters. The metal here is thick, pressure tested and is not subject to active corrosion from the inside unless a fire extinguisher has been used. Before starting work, make sure that the fire extinguisher is empty and remove the shut-off device. Visually inspect the walls: there should be no dents, deep scratches or traces of rust.
In the lower part of the cylinder, you need to drill a hole and tap a thread to install a drain valve. The presence of a tap is a mandatory requirement, since in the process of compressing air, condensation is formed from atmospheric moisture, which must be removed regularly. If this is not done, water will get into the pneumatic tool or begin to corrode the receiver from the inside.
In the upper part, where the valve was previously located, you need to weld or screw onto the thread (through an adapter) a fitting for connecting the compressor and another one for air outlet to the consumer. Often a safety valve is installed in the same holes. All welding work must be carried out professionally so as not to burn the metal and not break the seal. pressure gauge and safety valve. All welding work must be carried out professionally so as not to burn the metal or break the seal.
☑️ Checking the readiness of the receiver
Assembly pneumatic system and electrical
Assembling the system begins with installing the compressor on the frame. The engine vibrates during operation, so it must be secured using rubber gaskets or silent blocks. The compressor output is connected to the receiver through a check valve. This element is critically important: it prevents compressed air from the cylinder from escaping back into the compressor after it stops, which prevents the engine from cranking in the opposite direction when starting. check valve. This element is critical: it prevents compressed air from the cylinder from escaping back into the compressor after it stops, which prevents the engine from cranking in the opposite direction when starting.
The electrical connection diagram is quite simple, but requires care. The motor is connected via a starting relay, which provides the necessary starting torque. To automate the process, you can install pressostat (pressure switch), which will open the circuit when the set pressure in the receiver is reached and close it when the pressure drops below the threshold. This will save you from the need to constantly monitor the pressure gauge.
All electrical connections must be reliably insulated. Wires should be laid in corrugations or cable ducts, away from the heating parts of the compressor. If you use a pressure switch, it is usually connected to the open phase going to the motor. It is useful to attach a socket or quick release to the body to connect the hose to the tool.
⚠️ Attention: Before the first full start, be sure to check all connections with a soapy solution for air leaks. Even small fistulas can significantly reduce the efficiency of the installation and cause the compressor to work continuously.
Pressure setting and testing
After assembly, the configuration stage begins. Turn on the compressor and let it build up pressure. Monitor the pressure gauge readings. The standard operating pressure for domestic needs is 6-8 atmospheres, although refrigeration units are capable of delivering more. If you have installed a pressure switch, adjust the upper and lower response thresholds using the adjusting screws under the cover.
Check the operation of the safety valve. It should be triggered if the pressure exceeds the permissible limit (usually 10-12 atm for such systems). If the valve does not operate, it must be replaced, otherwise there is a risk of rupture of the receiver. Also check the heating temperature of the compressor: during prolonged operation it can heat up to 60-70 degrees, but it should not smoke or emit a smell of burnt insulation.
Carry out a test tire inflation. Record the time during which the pressure in the wheel rises from 1.5 to 2.5 atmospheres. If the process takes a reasonable time (1-2 minutes for a passenger car), then you are satisfied with the system performance. If the compressor runs for too long without a break, take a break to cool down, since continuous operation for more than 20-30 minutes can be harmful to the household unit.
Technical characteristics of a home-made installation
To understand the capabilities of your device, it is useful to systematize its parameters. Characteristics may vary depending on the compressor model (for example AT-25, GC, FG) and receiver volume. Below is a table with average data for a typical assembly based on a 10-liter fire extinguisher.
| Parameter | Value | Note |
|---|---|---|
| Maximum pressure | 10-14 atm | Depends on the compressor model |
| Performance | 50-100 l/min | At the inlet, at the outlet less due to heating |
| Receiver volume | 10 liters | Standard fire extinguisher OU-10 |
| Power consumption | 150-200 W | Economical power consumption |
| Noise level | 40-50 dB | Comparable to a quiet conversation |
As can be seen from the table, such an installation is not intended for connecting powerful pneumatic tools, such as impact wrenches or sandblasters, which require huge air consumption. However, for aerographyinflating tires, working with a pneumatic gun to remove dust or minor painting, its power is quite enough. The main advantage here is the stability of pressure thanks to the receiver.
Operating rules and safety
Homemade equipment requires strict adherence to safety rules. Never leave the compressor running unattended for long periods of time. Regularly, at least once a month, drain the condensate from the receiver through the bottom tap. Moisture in the system is the main enemy of metal and pneumatic tools. If you notice a decrease in performance or unusual knocking, immediately stop the device and carry out diagnostics.
The compressor should be stored in a dry room. If the device is operated in an unheated garage in winter, before each use, check the elasticity of the hoses and the absence of ice in the lines. Oil thickens at low temperatures, which makes starting difficult, so in cold weather the device may need to be preheated in a warm place.
Remember what you have dealing with a pressure vessel. Do not try to artificially limit the output pressure by turning off the valve at the outlet of a running compressor - this may lead to rupture of the pipes. Pressure must only be released through the reducer or into the atmosphere through a safety valve. Taking good care of your equipment is the key to your safety.
Is it possible to use a compressor from a modern refrigerator with an inverter motor?
Theoretically it is possible, but it is extremely difficult. Inverter compressors require a special control board (inverter) that converts the current and controls the rotation speed. Starting such a motor directly from a 220V network is impossible without burning out the windings. For homemade purposes, it is better to take old linear models with a start relay.
Which oil is better to fill: mineral or synthetic?
For compressors that will operate all year round (including in winter), synthetic oil is better suited, as it maintains viscosity at low temperatures. Mineral oil is cheaper, but can harden in the cold, which will lead to difficult starting. The main thing is not to mix different types of oils.
Do you need a moisture separator (filter drier)?
If you plan to use a compressor for airbrushing or painting, then a moisture separator is required. Even after the receiver, moisture remains in the air, which will ruin the coating. To simply inflate tires, it is enough to drain the condensate from the cylinder, but an additional fine filter in front of the tool will not hurt.
Why does the compressor hum but not pump?
Most often this means wear on the piston rings or valves inside the compressor head. The cause may also be a clogged air filter at the inlet or loss of tightness of the pipes. If the compressor worked without oil, most likely, jamming or critical wear of the parts occurred.
What is the maximum size of tires that can be inflated?
The size of the tire does not matter, only the required pressure is important. The compressor from the refrigerator easily pumps the tires of passenger cars, SUVs and even small trucks (up to 4-5 atmospheres). The inflation time will depend on the volume of the tire: a large truck will take longer, but it will gain pressure.