Air compressor quarterly maintenance checklist

Lock and tag hung at the compressor disconnect

Disconnect opened, lock and tag applied under the site's procedure, unit tried from its pressure switch and control and stays stopped before the guard comes off.

Receiver pressure read before any fitting is opened

Gauge reading noted, and any filter bowl, drain or fitting to be opened is isolated and bled to zero first. Guard and intake work never loosens anything on the pressure side.

Belt tension and drive guard in place

Belt deflection checked by hand against the manufacturer's range, no glazing or cracking on the belt faces, guard bolted over the belt and flywheel before the unit is left running.

Intake filter checked and cleaned

Element pulled and inspected for dust loading, housing seated with no unfiltered gap drawing shop dust straight into the pump.

Drive checked: pulleys and belts, or the coupling alignment

Belt drive: pulleys in line against a straightedge, set screws and keys tight. Direct drive: coupling aligned and its insert sound. No wobble or fretting at either hub.

Cooling surfaces clear: head fins, or oil cooler and aftercooler cores

Head and cylinder fins, or the oil cooler and aftercooler cores on other types, and the motor fan inlet free of dust and oil film so the unit sheds heat as designed.

Guard refitted and lock removed by the person who hung it

Belt or coupling guard bolted in place, tools cleared from the base, lock and tag taken off by their owner before the unit is restarted.

Oil level read at the sight glass

Level within the marked range with the unit stopped and level, oil clear rather than milky or dark.

Pump and fittings checked for oil and air leaks

No oil weeping at the base or head, no audible air leak at the tank fittings, unloader or discharge line while pressurized.

Receiver tank drained of condensate

Manual drain opened at the tank bottom until it blows clear, automatic drain confirmed cycling where fitted, standing water noted since it points to a passing or blocked drain.

Compressor loads and builds to cutout

Unit loads, builds pressure and cuts out at the switch setting without laboring or short-cycling, then holds pressure with the motor off.

Receiver gauge readable and relief valve tagged

Gauge face clear and the needle not stuck, relief valve fitted with its set-pressure tag legible, not painted over, plugged or capped.

Air dryer dewpoint and drain checked where fitted

Dryer running with its dewpoint indicator in the manufacturer's range, condensate drain cycling and clear. Units with no dryer are noted as such.

Line filter bowls bled down and elements checked

Each filter isolated and bled to zero at its drain before the bowl comes off, element checked for loading or oil, replaced when loaded, bowl drain left clear.

Round findings logged against the compressor tag

Cutout pressure, oil condition, water drained and any deferred work entered on the compressor's record so next quarter starts from this one.