Homemade silent air compressor

[Dimitris Polychronis]

Hi Sleykin
As you well said it this type of air compressor is perfect for using an airbrush, a pencil grinder or for a small pneumatic engraver for stone setting or any other art work, this will answers your first question; with proper maintenance they can last for many years because they are made to support tools with low air consumption. Now, the main disadvantage of a fridge compressor is that its motor runs at high rpm transferring motion to a small cylinder inside the housing that increases temperature, meaning that the motor must not work continuously; thankfully all fridge compressors have a thermal switch for protection but it is wise not to reach this limit. The working time of compressor like this is depending on the power of its motor; the motor must stop down equal time with the time of its continuous run.

The rule of thumb is:
A 135 Watt motor must not exceed 15 min. continuous run, after this time must cool down for 15 min. A 280-340W 20 min run - 20 min stop, a 735W 30 min run - 30 min stop

As for lubrication, I use the recommended coolant oil from the manufacturer.


Now checking the oil level is a bit problematic, because fridge compressors haven’t the glass checking window; so the only option is to use a syringe with a hose for sucking the oil from inside the housing and check the quantity and the color of the oil in a measure pot; luckily all reputable manufacturers state the proper oil quantity on the motor’s label.
Fresh oil has transparent pale yellow color, when the color become dark yellow (but still transparent) it's recommended to changed it.

Remember that always small quantities of oil will transferred to the air tank through the cylinder, so it wise to check it every 15-20 hours of total work.

All the best
Dimitris