Daily, Weekly, Monthly, Yearly Air Compressor Maintenance Schedule

Rotary screw compressor maintenance follows manufacturer-specified intervals. Atlas Copco GA series, Ingersoll Rand R series, Kaeser BSD/CSD, Sullair ShopTek, and similar units share common maintenance principles. Reciprocating compressors from Quincy, Champion, and Saylor-Beall require additional valve service not covered here. Always consult the OEM manual for model-specific procedures.

WARNING: Lockout/tagout per OSHA 29 CFR 1910.147 before any internal service. Residual pressure in oil separator tanks can exceed 150 psi even after shutdown. Vent system completely and verify zero pressure before opening any pressure-containing component.

Daily Checks

Discharge pressure should read within normal band, typically 100-125 psi for plant air systems, 150-175 psi for high-pressure applications

Discharge temperature on rotary screw units normally runs 180-220°F depending on ambient and load. Anything above 230°F indicates cooling problems.

Check motor amps against nameplate FLA

Oil level between marks on sight glass. On Ingersoll Rand UP series, the glass is on the separator tank side. On Atlas Copco GA, check the oil filler cap dipstick.

Drain receiver tank. Open petcock valve fully until only air comes out.

Drain moisture separator bowls and filter housings

Listen for bearing noise, rattling, or metallic contact sounds

Panel alarm history review

Make sure cooling air flows freely. Summer months with cottonwood seeds cause rapid cooler blockage.

Common mistake: Operators drain condensate while compressor is loaded. Wait until unload cycle or shutdown for more complete drainage.

Weekly Checks

Pull inlet filter and hold up to light. Replace if you cannot see light through the media. Dusty environments like woodshops, foundries, and grain handling may need filter service every few days instead of weekly.

Belt inspection on belt-drive models. Look for cracking on the inside V surface, fraying on edges, glazed or shiny appearance. Tension should allow approximately 1/2" deflection per foot of span when pressed firmly.

Cooler fin inspection. Use flashlight to look through core. Compressed air blowout at 30 psi maximum to avoid damaging fins.

Leak check fittings with spray bottle of soapy water. Bubbles indicate leaks.

Clamp meter reading on all three motor phases. Imbalance exceeding 3% between phases suggests power supply issues or internal motor problems.

Note on vibration: If you notice increasing vibration week to week, check coupling spider condition and shaft alignment before assuming bearing problems.

Inspection

Weekly Checks

Maintenance

Filter Service

Operations

Compressor Room

Monthly Service

Replace inlet filter in high-dust environments. Clean environments may extend to quarterly.

Pull safety valve ring to verify valve lifts and reseats. Per ASME requirements, safety valves on ASME-stamped vessels must be tested regularly. Replace any valve that leaks after testing.

CAUTION: Stand clear when testing safety valves. Sudden pressure release creates significant noise and air blast.

Automatic drain valve function. Electronic drains like Jorc SMART-GUARD or Atlas Copco EWD should cycle visibly. No-loss drains must discharge when float rises. Clogged drains cause water carryover into air lines.

Gauge calibration check. Temporarily install a calibrated test gauge to compare readings.

Electrical terminal inspection. Open main disconnect and check wire terminations in contactor box and motor junction box. Re-torque to manufacturer spec. Typical values: 20-25 lb-in for #10-12 AWG, 35-45 lb-in for #6-8 AWG.

Problem area: Control board terminals on units older than 10 years frequently loosen and cause intermittent faults.

Quarterly Service / 2000-Hour Interval

Many plants track running hours on the controller and service at hour intervals rather than calendar time. Kaeser Sigma Control and Atlas Copco Elektronikon display service countdowns.

Oil drain and refill. Most mineral oil applications use 2000-hour intervals. Drain hot for complete removal. Typical fill quantities: 2-4 gallons for 15-30 hp units, 5-8 gallons for 40-75 hp, 10-15 gallons for 100+ hp. Verify against your OEM spec.

Always use OEM-approved oil or equivalent meeting ISO 46 or ISO 68 viscosity grade with proper additive package. Generic hydraulic oil causes varnish problems.

Oil filter change. Spin-on cartridges on most modern units. Some older Atlas Copco and CompAir machines use canister-style elements requiring housing removal.

Inlet valve inspection. Remove bonnet and check piston/diaphragm seal condition. Sticking inlet valves cause unload problems and capacity loss.

Minimum pressure valve test. Disconnect downstream piping if possible and verify valve cracks open at spec pressure, typically 50-75 psi depending on manufacturer.

Flexible coupling inspection. Spider material hardens with age and heat exposure. Replace at first sign of cracking or chunk missing.

Semi-Annual Service / 4000-Hour Interval

Oil change for synthetic and semi-synthetic lubricants. Synthetics like Sullube, Atlas Copco Roto-Xtend, or Ingersoll Rand Ultra Plus allow extended intervals but cost 3-4x mineral oil price.

Oil separator element replacement. This is the expensive filter, typically $150-400 depending on size. Differential pressure across separator should not exceed 8-10 psi. Higher differential wastes energy.

Separator service requires draining oil and removing the separator tank cover. Have replacement gasket ready. Clean tank interior and inspect scavenge tube orifice, usually 0.040"-0.060" diameter. Clogged scavenge line causes high oil carryover.

Belt replacement on belt-drive units. Replace all belts as matched set. Never replace just one belt from a matched set.

Cooler cleaning. Oil cooler and aftercooler both need service. Remove coolers for thorough cleaning or use biodegradable degreaser with pressure washer. Do not exceed 1500 psi to avoid fin damage.

Motor bearing evaluation. Infrared temperature gun on bearing housings during operation. Both ends should read within 20°F of each other and below 180°F. Stethoscope or ultrasonic probe detects roughness before temperature rise.

Annual Service / 8000-Hour Interval

Major overhaul items. Budget for several hours of downtime.

Inlet valve rebuild using OEM kit. Kit includes all seals, o-rings, and often new piston or diaphragm.

Minimum pressure valve rebuild kit

Thermostat valve element. These wax-motor elements lose accuracy with age. Verify opening temperature matches spec, typically 140-160°F start open, 180°F full open.

Airend bearing assessment. Requires trained technician or OEM service. Bearing replacement on rotary screw airends is specialized work. DIY bearing jobs often result in rotor contact and airend destruction. Most shops send airends to rebuild specialists like Industrial Air Power or Airend Rebuild Services.

Comprehensive torque verification on all bolted connections

Full sensor calibration. Pressure transducers, temperature sensors, current transformers. Compare against NIST-traceable reference instruments where possible.

Motor insulation testing. Megohmmeter test at 500V or 1000V DC depending on motor voltage rating. Record phase-to-phase and phase-to-ground readings per IEEE 43 guidelines. New motors should read 100+ megohms. Values below 5 megohms indicate moisture intrusion or insulation breakdown.

Documentation Requirements

ISO 8573-1 compressed air quality standards and many industry certifications require maintenance documentation. Record date, running hours, work performed, parts used, measurements taken, and technician name. Oil sample analysis reports from testing labs like Polaris, Blackstone, or TestOil provide trending data on wear metals, contamination, and remaining oil life.

Warranty claims on premature airend failure almost always require complete maintenance records showing proper oil change intervals and filter service.