Using old household equipment to create new useful devices is not just saving money, but also a great way to get a quality tool for the workshop. Refrigeration compressor ideal for converting into a supercharger air, since it was originally designed to work with gases under pressure. Unlike cheap Chinese analogues, a unit from a Soviet or high-quality imported refrigerator can operate for years without overheating.
The main advantage of this solution lies in the design of the unit itself. Sealed housing reliably hides rubbing parts in an oil bath, which ensures a minimum level of noise and vibration. That is why homemade installations are often called “quiet” or “silent,” which is critical for work at home or small garages.
Before starting work, it is necessary to assess the condition of the donor. If the refrigerator has stopped freezing due to a freon leak, but the motor hums and starts, this is an ideal candidate, so the unit will serve you for a very long time. Next, we will analyze all stages of assembly, from preparing tools to final pressure adjustment. The service life of a working refrigeration compressor with proper operation is from 50,000 to 80,000 operating hours, so the unit will serve you for a very long time. Next, we will analyze all stages of assembly, from preparing tools to final pressure settings.
Required materials and tools for assembly
To create a full-fledged compressor station with only one the pump is not enough. You will need to assemble a harness around it that will purify the air, accumulate it and regulate the pressure. Receiver (air container) can be made from an old gas cylinder or use a ready-made hydraulic accumulator. It is important that the container is designed for a pressure of at least 10 atmospheres, even if you plan to pump up to 6-8 atmospheres.
The key element of the system is oil-moisture separator. When compressed, the air heats up, and when it cools, moisture condenses in the receiver, which mixes with the oil discharged from the compressor. Without high-quality filtration, this emulsion will quickly damage pneumatic tools or ruin the paint job. You will also need pressure gauges, a pressure switch and a check valve.
The list of necessary equipment should be collected in advance so as not to interrupt the installation process. Below is a list of components that will ensure stable operation of the system.
- 🔧 Compressor unit from the refrigerator (power from 100 W).
- 💨 Receiver (metal cylinder with a volume of 20-50 liters).
- ⚙️ Pressure switch with adjustment of the upper and lower shutdown threshold.
- 🌡️ Pressure gauges for monitoring pressure in the receiver and at the outlet.
- 🔌 Electrical accessories: cable with plug, terminal box, switch.
⚠️ Attention: It is strictly forbidden to use plastic containers, fuel or chemical cans as a receiver. Only steel or aluminum can withstand cyclic changes in pressure without the risk of rupture.
Preparation and dismantling of the compressor
The first stage of work requires care. Remove the compressor from the refrigerator frame by cutting off the copper tubes with wire cutters at a distance of 5-10 cm from the body. This is necessary to prevent chips or dust from getting into the pipes. Be sure to drain the old oil if it turns black or has a burning smell. To do this, file the bottom of the housing (carefully, without sparks!) or simply turn the unit over and let the oil drain through the suction pipe.
Determine the purpose of the pipes. Plug in the compressor for a short time (literally 3-5 seconds) and place your finger near the holes. From where the air blows is discharge pipe. The one that sucks in air - input. The third pipe (often a sealed or short tube) is usually used for pumping oil or is a process pipe. It is important not to confuse the inputs, otherwise the system will not work correctly.
Rinse the insides of the compressor if there are doubts about the cleanliness of the system. You can use a special cleaner or simply blow out the system with compressed air. Make sure that the vibration dampers (rubber washers) on the compressor feet are intact, as they dampen the vibration of the housing.
- 🧹 Thoroughly clean the outer surface of dust and old paint.
- 🔍 Check the integrity of the electrical cable and start relay.
- 🛢️ Replace the oil with fresh one if the old one looks suspicious.
- 🔌 Test the motor windings with a multimeter for breakdown.
⚠️ Attention: When working with a compressor under voltage, follow safety precautions. Do not touch exposed wires and metal parts while the device is connected to a 220V network.
Manufacture and preparation of the receiver
The receiver functions as a buffer: it accumulates air, smoothes out pressure pulsations and cools the compressed gas, promoting condensation. The best option for a homemade worker is propane cylinder a volume of 20 or 50 liters. Before welding work, it is necessary to completely remove any remaining gas and odor. To do this, fill the cylinder with water, add detergent and rinse thoroughly.
After rinsing, the necessary fittings are cut into the ends of the cylinder. Typically, a minimum of four holes are required: for air inlet from the compressor, air outlet to the consumer, installation of a pressure gauge and condensate drainage. It is better to make threaded connections on welded bosses; it is more reliable and tighter than simply welded nuts.
It is better to install the condensate drain valve at the lowest point of the receiver. It is most convenient to use a ball valve or a special automatic condensate drain. Regular drainage of liquid will extend the life of your pneumatic system and prevent corrosion of the tank from the inside.
| Component | Material | Function | Requirements |
|---|---|---|---|
| House | Steel St3 / 09G2S | Volume accumulation | Wall thickness at least 3 mm |
| Pipes | Steel 20 | Connecting lines | Passage diameter of at least 1/2 inch |
| Drain tap | Brass | Moisture removal | Ball, full bore |
| Supports | Steel angle | Stability | Anti-corrosion coating |
Assembling a pneumatic circuit and piping
Assembling the system begins with installing the input filter. An air filter must be installed on the compressor suction pipe. This can be a ready-made car filter or a homemade design with padding polyester. The filter protects the piston group from abrasive dust, which quickly kills the rings and cylinder.
Then the air enters the receiver. It must be placed between the compressor and the tank check valve. It prevents air from escaping back into the compressor after it stops, which prevents reverse rotation of the shaft and makes it easier to restart the engine. Without a check valve, the pressure switch will not work correctly.
An air preparation unit is installed at the outlet of the receiver. It includes a moisture separator, a reducer (to reduce pressure to working pressure) and a lubricator (if the tool needs it). The connection diagram must be sequential: Compressor → Check valve → Receiver → Pressure gauge + Relay → Moisture separator → Consumer.
☑️ Checking the pneumatic system assembly
All threaded connections must be sealed. For compressed air systems, FUM tape or high-strength anaerobic sealant is excellent. Regular tow with paint will also work, but it may dry out over time. Make sure that the diameter of the connecting tubes (copper or PVC reinforced) corresponds to the performance of the compressor so as not to create unnecessary resistance.
Electrical diagram and automation connection
Automation of work is a key point of convenience. Pressure relay (pressostat) controls turning the engine on and off depending on pressure in the receiver. Standard relays have factory settings: switch on at 2-4 atm and switch off at 6-8 atm. These values can be adjusted with two screws under the relay cover.
The connection diagram is simple: phase and zero from the network go to the relay input, and from the relay output to the compressor motor. Grounding is connected directly to the compressor and receiver housing. If the engine power is high, the relay may not be able to cope with the current, then a contactoris added to the circuit, which is controlled by a pressure relay.
Connection diagram:220V network -> Switch -> Pressure relay -> Compressor
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Grounding
It is important to correctly set the pressure difference (delta). If the delta is too small, the compressor will start too often, causing overload of starting currents and wear on the motor. The optimal difference is 2 atmospheres.
Startup, testing and maintenance
Perform the first launch without connecting pneumatic tools. Watch the pressure gauge readings carefully. The compressor should build up pressure to the upper limit and turn off. After this, open the consumption tap - the pressure should drop to the lower limit and the engine should start automatically. Check all joints for leaks using a soap solution.
Regular maintenance will extend the life of the device. Once a month, check the oil level (if the design allows) and the condition of the air filter. Once every six months, drain the condensate from the receiver. If the compressor starts to heat up more than usual or makes strange sounds, stop using it immediately.
A homemade compressor is a reliable assistant, but it requires respect. Do not allow work in dusty rooms without protection, monitor the body temperature and change consumables on time.
What kind of oil should be poured into the compressor?
Use special compressor oils (for example, KSI 19 or analogues). You can use synthetic motor oils, but it is not recommended to use conventional mineral oils for internal combustion engines, as they can coke at high compression temperatures.
Why does the compressor not gain pressure?
The reasons may be wear on the piston rings, leaks in the valve group or leaks in the pneumatic line. Also check if the suction filter is clogged.
Can this compressor be used for painting?
Yes, but only if you install a high-quality fine oil-water separator (5 microns or less). A regular refrigerator throws out a lot of oil, which will ruin the paint without good filtration.