The situation when an old refrigerator comes out out of order or simply freeing up space in the kitchen for a new model, is familiar to many. Often the entire unit is thrown away, without thinking that its “heart” - compressor - can serve faithfully in the home workshop for many years to come. This unit is a powerful, sealed electric motor with a pump capable of creating excess pressure or vacuum.
Throwing away such a valuable resource is a real waste. Piston and Rotary compressors installed in household appliances have a resource that is more than enough for low-power pneumatic tools. Their main advantage over specialized industrial analogues is low noise level and the ability to operate from a regular household network 220 Volt.
In this article we will look at how to turn an unnecessary unit into a functional tool. You will learn which homemade products are the most popular among craftsmen, and what nuances need to be taken into account when remaking them. The sealed compressor housing allows you to safely work with toxic media, which makes it ideal for pumping gases and creating vacuum chambers.
Evaluation of performance and preparation of the unit
Before starting construction, you need to make sure that the removed compressor is really suitable for further use. A visual inspection of the housing should not reveal deep dents or traces of oil indicating depressurization. If the housing is opened or has through holes, it is strictly forbidden to use it to create pressure First of all, you need to determine the purpose of the pipes. Usually there are three of them: two copper tubes of different diameters and one steel (filler). To understand where the entrance is and where the exit is, it is enough to briefly plug the device into the network (no more than 3-5 seconds)..
The first step is to determine the purpose of the pipes. Usually there are three of them: two copper tubes of different diameters and one steel (filler). To understand where the input is and where the output is, it is enough to briefly plug the device into the network (no more than 3-5 seconds).
- 🌬️ The pipe from which air blows forcefully is a discharge pipe (output).
- 💨 The pipe, which, on the contrary, sucks in air or paper, serves as an entrance (suction).
- 🔒 The third, often sealed or short steel pipe, is intended for refilling with freon and in homemade products is usually plugged or used to relieve pressure.
⚠️ Attention: When you first turn on a dismantled compressor, be prepared for the fact that old used oil may pour out of the outlet pipe. This is normal, but it can stain the floor and clothes.
For further work you will need to collect a certain set of materials. You don't have to buy everything at once; many components can be found in the garage or purchased at a hardware store. The basis of the future system is receiver, which will accumulate compressed air and stabilize the pressure.
Necessary materials and tools for assembly
Creating a full-fledged compressor installation requires careful preparation. You can't get by with just the motor; you need a harness that will turn the air flow into a controlled force. The main element here is the tank, or receiver.
Old fire extinguishers with a volume of 10-50 liters are ideal as containers for the receiver. They already have the necessary strength, threaded connections and are often equipped with a pressure gauge. You can also use freon gas cylinders or even thick plastic canisters for low pressure, but metal is more reliable.
In addition to the container, you will need fittings, hoses and shut-off valves. All connections must be tight, so the use of high-quality tape FUM or thread Tangit Unipak is mandatory. It is better to choose metal adapters with a margin of pressure.
☑️ Shopping list for assembly
Assembling an air compressor with a receiver
The assembly process begins with preparing the receiver. If you use a fire extinguisher, make sure it is empty and not under pressure. Drill holes for the inlet and outlet fittings, as well as for installing a pressure gauge and a drain valve for condensate.
The compressor is mounted on the frame or directly on the receiver through vibration-isolating gaskets. These can be pieces of rubber or special dampers. Vibration is the main enemy of the durability of connections, and if it is not compensated for, the metal will quickly get tired.
The tube system is connected in the following order: air from the atmosphere passes through a filter at the inlet of the compressor, then is pumped into the receiver. From the top of the receiver, air goes to the consumer through a shut-off valve. It is important to install check valve between the compressor and the receiver so that air does not flow back into the motor when it stops.
| Component | Function | Recommended material |
|---|---|---|
| Receiver | Accumulation and stabilization of pressure | Steel (fire extinguisher, cylinder) |
| Filter | Cleaning incoming air from dust | Car filter or padding polyester |
| Oil separator | Oil mist delay | Glass wool or thick cardboard |
| Pressure switch | Automatic on/off | Industrial pressure switch |
⚠️ Attention: Plastic containers (PET bottles, canisters) are only suitable for experiments with very low pressure (up to 2-3 atmospheres). For painting work or inflating tires, use only metal cylinders!
Making an airbrush and spray gun
One of the most popular uses of a homemade compressor is airbrushing and painting small parts. The pressure created by the refrigeration unit (usually 2-4 atmospheres) is quite sufficient for working with liquid paints, varnishes and primers.
To connect an airbrush or spray gun, it is critical to have pressure regulator a pressure gauge. Refrigeration compressors do not have built-in power control; they either pump or stand still. The reducer will allow you to set the desired value, for example 1.5 atmospheres for fine work.
You should also take care of the cleanliness of the exhaust air. Oil mist, which is inevitably present in the compressor exhaust, can ruin the surface being painted, leaving craters and grease stains. Installing a simple oil separator filter solves this problem.
How to make an oil separator filter with your own hands?
Take a transparent plastic or glass container with a lid. Make two holes in the cover for the tubes (inlet and outlet). Inside the container, secure the inlet tube so that it reaches almost to the bottom, and the outlet tube - short, near the lid. Fill the container 1/3 full with padding polyester or cotton wool. Air passing through a dense material leaves oil droplets on it.
Creating a vacuum pump
Many people forget that the compressor can work in the opposite direction. If you connect the hose to the inlet pipe and leave the outlet free (or direct it into the atmosphere), the device turns into vacuum pump.
Such an installation is indispensable for vacuuming bags when storing food, impregnating wood with oils or conducting chemical experiments. The vacuum performance of refrigeration compressors is quite high, allowing a residual pressure of several tens of millibars to be achieved.
When operating in vacuum mode, it is important to monitor the housing temperature. Since the air flow no longer cools the motor as effectively as during normal operation, it is recommended to take breaks or organize forced cooling with a fan.
- 📦 Vacuuming packaging for storing things and products.
- 🪵 Impregnation of wood with stabilizing resins.
- 🔬 Conducting simple physical and chemical experiments.
- 🔧 Removing air bubbles from epoxy resin during casting.
Maintenance and safety precautions
Homemade equipment requires no less attention than factory equipment. Regularly check the oil level in the compressor crankcase if the design allows this to be done visually. Some models require periodic oil changes, while others require dry operation.
Keep the air filters clean. An input filter clogged with dust causes the motor to work with overload, which reduces its service life and increases the temperature. They need to be cleaned with compressed air or replaced with new ones.
Do not forget about electrical safety. All connections must be insulated and the compressor itself must be grounded. Working with high pressure requires the installation of a safety valve that bleeds air if the pressure switch suddenly jams.
Frequently asked questions (FAQ)
How much atmospheres can a regular compressor from a refrigerator produce?
Most household compressors (models like DK, QD, NB**) are designed for an operating pressure of up to 6-8 atmospheres, but can briefly create up to 10-15 atmospheres. However, for long-term operation it is recommended not to exceed 4-6 atmospheres.
Is it necessary to change the oil in the compressor during refurbishment?
If the compressor was removed from a working refrigerator, the oil there is still normal. If the unit was lying or had a burning smell, it is better to replace the oil with a special compressor or synthetic motor oil, selecting the viscosity according to the instructions for the specific motor series.
Is it possible to use such a compressor for pneumatic tools (drills, impact wrenches)?
No, the capacity (liters per minute) of a refrigeration compressor is too low for active pneumatic tools. It is suitable for airbrushing, inflating tires, blowing or working with one small air gun, but not for a wrench.
Why does a compressor get very hot?
Heating to 60-80 degrees Celsius is normal for them. If the temperature is higher, check the ventilation, the cleanliness of the radiator (if any) and the voltage level in the network. Also, the reason may be the lack of load if a bypass or regulator is not installed.