Using old components from household appliances to create new equipment is not just saving money, but also a great way to get a tool with unique characteristics. The compressor, created on the basis of a motor from refrigerator, has a number of undeniable advantages: it operates quietly, consumes little electricity and is capable of producing sufficient pressure for domestic needs. Unlike store-bought counterparts, a home-made installation often turns out to be more reliable and easier to maintain, especially if it is assembled using high-quality components.
The basis of our design will be fire extinguisher, which will serve as a receiver - a container for accumulating compressed air. This solution allows you to stabilize the pressure in the system and filter out condensate, which is critical for the quality operation of pneumatic tools. Creating such a unit requires attention to detail and compliance with safety precautions, but the result is worth it. You will receive a universal device for painting, inflating tires or blowing systems.
Before starting assembly, you need to understand that we are combining two different devices into a single system. Receiver takes on the role of a buffer, smoothing out the pulsations that inevitably arise during the operation of a piston unit. The motor from the refrigerator, in turn, provides the necessary power. Proper combination of these elements turns a pile of scrap metal into a full-fledged compressor.
Preparation of the necessary materials and tools
The success of the enterprise directly depends on the quality of the initial components. You will need to find a working refrigerator compressor, preferably Soviet-made, as they are famous for their durability and maintainability. Also, the main element will be a steel cylinder from a fire extinguisher with a volume of 10 liters or more, which can withstand operating pressure without the risk of rupture.
To assemble the structure, you will need a set of metal fittings, hoses and valves. Particular attention should be paid flanges to threaded connections, since they are the ones who will hold the pressure. Do not forget to prepare a pressure gauge for monitoring indicators and a reducer if you plan to work with a tool that is sensitive to pressure surges.
⚠️ Attention: Before using a fire extinguisher cylinder, make sure there is no corrosion inside. Rust can cause depressurization under pressure, which is life-threatening.
The list of necessary tools includes an angle grinder, a drill, a set of wrenches and a welding machine (or powerful clamps if welding is not available). You will also need consumables: sealant, electrical tape, mounting bolts and nuts. Without a high-quality tool assembly of a sealed system it will not be possible.
Selecting and preparing a refrigerator compressor
The first step is to remove the motor from the old refrigerator. Carefully disconnect the tubes, being careful not to damage them, and remove the unit along with the starting relay. It is important to check the performance of the engine before assembling the main structure by connecting it to the network and assessing the strength of the blown air.
Determine the inlet and outlet pipes. This is usually done by briefly turning on the motor: air will come out of one tube and be sucked into the other. The inlet pipe will subsequently be connected to the filter, and the outlet pipe will be connected to the air supply system to the receiver.
If there are traces of oil or heavy dirt on the motor housing, they must be removed. However, disassembling the sealed casing compressor is not recommended, as this will disrupt the balancing and may lead to jamming of the piston group. It is better to limit yourself to external cleaning and checking the electrical contacts.
Why can’t you open the compressor casing?
Inside the casing there is oil that lubricates the rubbing parts. When opened, the seal is broken, and moisture and dust get inside, which will quickly damage the unit. In addition, there may be excess refrigerant pressure inside.
Upgrading a fire extinguisher into a receiver
A fire extinguisher is an ideal component for a receiver due to its thick walls and reliable locking mechanism. The first step is to completely empty the cylinder of its contents and unscrew the shut-off device. If the screw is soured, you can carefully drill it out, using extreme caution.
Next you need to prepare places for cutting in the fittings. You will need to drill holes for the inlet pipe (from the compressor), the outlet pipe (to the consumer) and the condensate drain valve. The holes must be made exactly according to the thread diameter of the fittings to ensure a tight connection.
| Element | Function | Location | Connection type |
|---|---|---|---|
| Input branch pipe | Air supply from the motor | Upper part of the cylinder | Threaded |
| Outlet pipe | Air bleed | Upper part (on the opposite side) | Threaded |
| Drain valve | Condensate removal | Lower part (bottom) | Threaded |
| Pressure gauge | Pressure control | Upper part | Threaded |
After drilling the holes, you must thoroughly clean the edges and degrease the surface. The corresponding fittings are welded into the prepared holes or screwed onto the sealant. The quality of this stage determines whether your compressor will hold pressure or bleed air through microscopic gaps.
Assembling the injection and filtration system
The filtration system is the “lungs” of your compressor. An air filter must be installed on the engine inlet pipe, which will protect the piston group from dust. It is also recommended to install a fine filter or oil separator at the outlet pipe, before entering the receiver, especially if the compressor is oil-based.
The motor is connected to the receiver through a hose or metal tube. It is important to use heat-resistant materials, since the air leaving the compressor can reach significant temperatures. Connections are secured with clamps or threaded couplings.
☑️ Checking the filtration system
The check valve is a critical element that prevents air from returning from the receiver back to the compressor after it is turned off. Without it, it will be extremely difficult for the engine to start again, since it will have to overcome the pressure already accumulated in cylinder.
Installation of automation and instrumentation
For comfortable and safe operation of a homemade unit, automation is necessary. The pressure switch allows you to automatically turn the motor on and off depending on the pressure level in the receiver. This eliminates the need for constant monitoring and prevents system overload.
The pressure gauge is installed so that its readings are clearly visible to the operator. It is advisable to have two pressure gauges: one on the receiver to monitor the overall pressure, and the second at the outlet after the reducer if you plan to regulate the pressure for a specific tool.
⚠️ Attention: The pressure switch must be rated for the current consumed by your engine. If the current is high, be sure to use an intermediate relay or contactor, otherwise the pressure switch contacts will quickly burn out.
The electrical connection diagram includes a circuit breaker, a pressure switch and, if necessary, capacitors for starting the motor. All electrical connections must be reliably isolated and protected from vibration, which inevitably occurs during operation unit.
First start-up and testing of the system
Before the first full start carry out a visual inspection of all connections. Make sure the drain valve is closed and all fittings are tight. Turn on the compressor and monitor the pressure build-up. At this stage, it is important to identify air leaks, which may manifest themselves as a characteristic whistle.
Check the operation of the automation: when the specified upper pressure limit is reached, the motor should turn off. When air is released through the outlet pipe and the pressure drops to the lower limit, the engine should automatically start. If this does not happen, the relay needs to be adjusted.
During the testing process, pay attention to the level of noise and vibration. If the motor is unstable or makes strange sounds, turn it off immediately and find out the reason. Tests This is the stage when assembly errors become obvious, and it is better to detect them now than during operation.
What to do if the compressor hums but does not start?
Often the reason lies in a malfunction of the starting relay or capacitor. It is also possible for the piston group to jam due to long periods of inactivity. Try carefully turning the motor shaft by hand (with the power off!).
Operation and safety measures
Regular maintenance will extend the life of your creation. The basic rule is timely draining of condensate from the receiver. Moisture accumulating at the bottom of the cylinder causes corrosion, which over time thins the metal walls. Carry out this procedure after each use.
Monitor the oil level in the compressor (if it is not oil-free). Lack of lubrication will lead to rapid wear of rubbing parts and overheating. Also periodically check the condition of the air filters and, if necessary, replace them or clean them from dust.
⚠️ Attention: Never leave the compressor running unattended for a long time. Despite the presence of automation, the risk of overheating or leakage always remains, especially in home-made designs.
The unit should be stored in a dry, well-ventilated area. If the compressor is used for painting, make sure that the system has high-quality moisture and oil separators, otherwise defects on the painted surface are inevitable. Correct operation guarantees a long service life.
What is the maximum pressure you can get from a refrigeration compressor?
Conventional refrigeration compressors are designed to work with freon and can create a pressure of up to 6-10 atmospheres, but some models are capable of accelerating to 15-20 atmospheres. It is important not to exceed the strength limit of the receiver and the motor itself.
Is it necessary to change the oil in the compressor after modification?
If you did not open the sealed casing, the oil does not need to be changed. However, if the compressor has been running for a long time and the oil has turned black, replacing it will extend its service life. Use only special compressor oils recommended by the manufacturer.
Can this compressor be used for sandblasting?
For full sandblasting, the performance of one refrigeration compressor is usually not enough. It is suitable for small jobs or inflating tires, but for constant work with abrasives you need a more powerful unit with a large receiver.