Piston compressors have a reputation for being indestructible. That is true, provided they get a minimum of attention. Their maintenance is simple and needs almost no tools; what matters is regularity.
The intervals given here are typical figures. Your machine's intervals are in its manual, which always prevails.
Every day: drain the tank
This is the most important task, and the one most often forgotten. When compressing air, the compressor condenses the ambient humidity: this water collects at the bottom of the tank.
- Open the drain valve at the bottom of the tank at the end of the day, with the tank at low pressure, until the air comes out dry.
- If the tank has an automatic drain, check that it discharges properly.
A tank that is never drained rusts from the inside, loses useful volume and sends water into your tools.
Every week: oil and air
- Oil level in the sight glass or on the dipstick, machine stopped and level. Top up with the same oil.
- Air filter: visual check and blow-out. A clogged filter makes the pump run hot and reduces output.
- Leaks: listen to the compressor and the network when stopped.
Every month: the mechanics
- Belt: tension and condition (cracks, fraying). A slipping belt wears the pulley and reduces output.
- Clean the fins of the pump and intercooler: a poorly cooled piston wears quickly.
- Safety valve: operate it briefly to check it is not stuck, following the manual.
Oil changes
On a lubricated piston compressor, the first oil change comes early, after the running-in period stated in the manual. After that, the typical figure is an oil change about every 500 hours, and at least once a year, even if the compressor has run little.
Use a piston compressor oil of the viscosity given in the manual, never engine oil. Milky oil means water: often a compressor that runs cycles too short to ever warm up.
Every year: the full service
- Replace the air filter.
- Change the oil if not done during the year.
- Check the pump valves if the compressor takes longer than before to fill the tank.
- Check the pressure switch: the machine must cut out and restart at the set pressures.
- Visually inspect the tank: corrosion, dents, condition of fittings. Compressed-air tanks are pressure equipment: check the inspection requirements that apply in your country and to your tank.
Signs that cannot wait
- The compressor takes longer and longer to fill the tank: clogged filter, slipping belt, worn valve or rings, or a leak.
- It restarts very often: a leak in the network, or a compressor too small for the current demand.
- Abnormal oil consumption or oil in the air: worn rings.
- Knocking noise, vibration, burning smell.
- The motor trips at start-up: check the unloader valve, pressure switch or power supply.
If the compressor runs almost continuously, that is not a maintenance fault: it is a sign it is working beyond its intended duty. A screw compressor is then a better fit; our configurator helps you size the right machine.
Keep a record
Note the date and hour reading (or just the date if there is no hour meter) at every oil change and filter change. This simple record prevents oversights and helps with any warranty claim.