Annual PM — rotary screw package
Complete annual preventive maintenance for a lubricated rotary screw: consumables, inspections, electrical, and a documented performance check.
This guide is general field reference for trained, qualified service technicians. It is not a substitute for the original equipment manufacturer's service manual, applicable codes (NEC, OSHA, ASME, local), or the judgment of a licensed professional. Procedures, torque values, pressures, refrigerants, and safety requirements vary by make, model, jurisdiction, and revision. Always verify against current OEM documentation and follow your employer's safety program. Working on compressed-air, electrical, pressure-vessel, and refrigerant systems can cause serious injury or death. By using this guide you accept all risk; AirCompDX and its authors disclaim all warranties and are not liable for any damage, injury, loss, or code violation arising from its use.
LOTO and full depressurization for every consumable change. Separator tanks stay pressurized after a hot shutdown; verify zero at the sump gauge every time, not just at the header.
- Standard hand tools and torque wrench
- Clamp ammeter and multimeter
- Infrared thermometer
- Filter wrenches and fluid catch pan
- Calibrated pressure gauge
- Fluid sample kit
- OEM fluid charge, oil filter, air/oil separator, inlet air filter
- Belt set (belt-drive packages) or coupling element
- Enclosure/panel filter media
- Scavenge line orifice and screen
- Door seals and gaskets as required
- 1Log the running baseline
Before shutting down: full-load amps, discharge pressure, discharge temperature, separator ΔP, and controller hours. Compare to last year's numbers before you change anything.
- 2Pull a fluid sample
Sample hot from a running machine at a consistent point. Analysis (viscosity, TAN, wear metals, water) is worth more than a calendar interval — rising iron means bearings, rising water means the machine runs too cool.
- 3Change the fluid
Drain hot into a rated container, including the cooler and low points. Refill to the sight glass mid mark with the same fluid family. Never top a PAO with a diester.
- 4Replace filters and separator
New oil filter, new air/oil separator with the staple or grounding clip installed correctly (static discharge through the element causes fires), and a new inlet air filter.
- 5Clear the scavenge line
Pull the scavenge tube, clear the orifice and screen, and confirm suction from the separator sump. A plugged scavenge line is the number one cause of oil carryover after a separator change.
- 6Clean the coolers
Blow out oil and aftercooler cores from the discharge side. Replace the enclosure filter mats. Confirm fan operation and free rotation.
- 7Service the drive
Belt drive: inspect for glazing, cracking, and sheave groove wear; re-tension to 1/64" deflection per inch of span. Direct drive: inspect the coupling element for dust and cracking.
- 8Electrical inspection
De-energized: torque all power lugs to spec, inspect contactor tips, and check the overload setting against motor FLA. Energized (PPE required) or with an IR window: scan for hot connections under load.
- 9Test the safeties
Verify the emergency stop, high-temperature shutdown, and pressure trips actually function. A protection device untested for a year is not a protection device.
- 10Verify air treatment
Confirm every automatic drain expels liquid, dryer dewpoint is within spec, and inline filter ΔP is acceptable at flow.
- 11Run and re-baseline
Restart, run loaded 30 min, then log the same values from step one. Separator ΔP should be near zero, discharge temp 175–200°F, and amps within a few percent of nameplate. Leave the numbers on the service tag.