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Air compressor inspection checklist

16 maintenance inspection items for air compressors and factory compressed air: 9 common, 4 reciprocating, 3 screw. Organized by interval from the machine manufacturers' operation and maintenance manuals and from published materials of parts and oil makers, standards, and regulations. Your checks are saved only in this browser.

Intervals differ by machine.
First, check your machine's
manual!

CautionInspection and replacement intervals and oil types follow the operation manual of your machine first. The intervals here are examples for specific models from published sources and vary with running hours, ambient temperature, and dust. Do not remove the safety valve or raise its setting. Leave the dryer refrigerant, disassembly and overhaul of the unit, and electrical work to the manufacturer, dealer, or qualified persons. The key points of the regulations were checked on e-Gov on 2026-10-06

Daily (including before start of shift)

Drain the air tank (water and oil)CommonDailyWhat to checkDrain valve at the bottom of the air tank, auto drainGuidelineThe condensate drains out completely, and with an auto drain, the discharge is confirmedProcedureAt the end of the day, before the tank pressure drops to zero, open the drain valve to release condensate and air. Make sure no one is nearby, open it slowly, and keep your hand away from the front of the valve (Meiji Kikai Seisakusho)If condensate is left, the air tank rusts and thins, with a risk of pinholes, damage, and rupture (Japan Society of Industrial Machinery Manufacturers). One calculation example, with intake air at 25 °C and 60% humidity, gives about 0.16 L of condensate per hour in the tank alone, or about 60 L over 12 hours × 30 days (ANEST IWATA). Condensate from oil-lubricated compressors contains oil, so do not discard it as is (condensate treatment is a separate item)^[1][2][3][4]
Check the lubricating oil level, dirt, and emulsification of an oil-lubricated reciprocating compressorReciprocatingDailyWhat to checkCrankcase oil level gauge (oil gauge)GuidelineOil is within the gauge range (such as between the red circles) and shows no significant dirt or emulsificationRunning with no oil or with badly dirty oil causes poor lubrication and seizure, thermal relay trips, breakage of the connecting rod or crankshaft, and damage and scattering of the pulley or cylinder (ANEST IWATA). For screw compressors also check the oil level according to the manufacturer's indication. Low oil level causes discharge temperature to rise (Atlas Copco)^[1][2][5][6]
Check for abnormal noise, vibration, odor, or heatCommonDailyWhat to checkCompressor unit, motor, belt, pipingGuidelineNo unusual noise or vibration, no burning smell, no unit hotter than usual, no heavy oil consumption, no loss of capacity, and no current higher than usualThe Japan Society of Industrial Machinery Manufacturers lists these as "Caution" signs, a guide for asking the manufacturer for maintenance^[1][2][3][6]
Check the operation of the pressure gauge and pressure switch (control)CommonDailyWhat to checkAir tank pressure gauge, pressure switch, solenoid valveGuidelineIt stops (or unloads) at the maximum pressure and resumes compression at the cut-in pressure. With the tank at atmospheric pressure, the gauge needle reads zeroIf the control fails, the discharge pressure rises too high and damages the motor or tank, or the pressure falls short. Meiji Kikai Seisakusho lists this as daily, and ANEST IWATA's reference table for reciprocating models lists every 1 month (200 hours)^[3][2][1]
Confirm that the safety valve blows offReciprocatingDailyWhat to checkAir tank safety valveGuidelinePulling the tip near the maximum pressure releases air, and it does not operate below the maximum pressureProcedureIt is very loud, so take care not to be startled and injuredIf the safety valve does not work, it can lead not only to motor damage but to rupture of the air tank (Meiji Kikai Seisakusho). Meiji Kikai Seisakusho's operation manual includes it in the daily inspection. Follow the model's operation manual for the interval^[3][1]
Check each connecting pipe for air leaksCommonDailyWhat to checkConnecting pipes and fittings around the compressorGuidelineNo sound of leaks, and no bubbles with soapy waterLeaks waste electricity. How to measure the leak rate and the loss is a separate item^[3][7]
Check the alarm lamp, cooling fan, and auto drain of the refrigerated air dryerCommonDailyWhat to checkDryer display, cooling fan, refrigeration unit, auto drainGuidelineNo alarm lamp is lit. The fan turns smoothly with no abnormal noise. Condensate comes out of the auto drain, and there are no air leaksIf the dryer does not work, water flows out into the downstream piping. Based on ANEST IWATA's reference table for reciprocating compressors (with dryer)^[8][1][2]

Monthly

Check V-belt tension, stretch, and damage, and check for loose bolts and nutsReciprocatingWhat to checkV-belt, pulley, mounting bolts of the unit and motorGuidelineBelt tension is correct, with no cracks or wear. No bolts are looseIf the belt breaks, the compressor can no longer supply air (Japan Society of Industrial Machinery Manufacturers). Both ANEST IWATA and Meiji Kikai Seisakusho give every 1 month (200–250 hours) as a guide. On some models, belt replacement is listed as something to ask the dealer or manufacturer to do^[2][3][1]
Check the intake filter for dirt and clogging, and clean itCommonWhat to checkIntake filter (air filter)GuidelineNo clogging. If clogged, clean or replace it each timeA clogged filter makes intake harder, wastes electricity, and raises the temperature of the unit and the discharge air (ANEST IWATA). In one example, the air volume falls by about 4% with the filter in the clogged state shown in the photo (Japan Society of Industrial Machinery Manufacturers, previous edition). Reciprocating: clean every 1 month and replace every 1 year (ANEST IWATA example). Screw: clean every 6 months and replace every 1 year (ANEST IWATA LRS example)^[2][3][9][1]
Retighten the threaded joints of piping and fittingsScrewWhat to checkPiping and fittings around the compressorGuidelineNo loosenessOperating vibration can loosen the threaded parts of piping and fittings (ANEST IWATA)^[9][2](1 source, for reference)

3 months

Clean the dryer condenser and check the refrigerant for oil leaks and corrosion (simple inspection under the Fluorocarbons Emission Control Act)CommonWhat to checkDryer condenser, around the refrigeration unitGuidelineNo dirt or dust on the fins. No oil leaks or corrosionFor Class I specified products under the Fluorocarbons Emission Control Act, a simple inspection at least once every 3 months and a record are required by law (ANEST IWATA). Keep the records for 3 years after the equipment is scrapped (ANEST IWATA). The Japan Society of Industrial Machinery Manufacturers also lists a simple inspection every 3 months. Atlas Copco says refrigeration units with an output of 7.5 kW or more also require a separate periodic inspection^{[2][10][1][11]}

Every 6 months

Clean the fins and fan of the air cooler and oil coolerScrewWhat to checkAir cooler, oil cooler, cooling fanGuidelineNo dust has built up on the finsWhen dirty, cooling drops, and the unit stops on an abnormal unit or discharge air temperature, or the dryer dehumidifies less and water comes out downstream (ANEST IWATA, Atlas Copco)^[9][6][1]

Annual

Carry out the periodic voluntary inspection of the Class 2 pressure vessel (air tank) and keep the records for 3 yearsCommonWhat to checkAir tank body (shell, head), cover tightening bolts, pipes and valves (stop valve, safety valve)GuidelineNo damage to the body, no wear of the cover tightening bolts, and no damage to pipes and valvesProcedureCheck the shell and head for corrosion while stopped, and for leaks and bulging while running. Check the safety valve operation and leaks, gauge error (needle reads zero at zero pressure), and the connecting pipe (Meiji Kikai Seisakusho's voluntary inspection procedure). ANEST IWATA also lists cleaning the inside and outside of the vessel at least once a yearArticle 88 of the Ordinance on Safety of Boilers and Pressure Vessels requires a voluntary inspection once within every 1 year after the start of use, and keeping the records for 3 years. It applies to vessels holding gas at a gauge pressure of 0.2 MPa or more with an internal volume of 0.04 m³ (40 L) or more, or a shell inside diameter of 200 mm or more and a length of 1,000 mm or more (Article 1, item 7 of the Enforcement Order). The same applies when a tank of 40 L or more is connected to a compressor afterward (Meiji Kikai Seisakusho). A period of more than 1 year when the vessel is not used is exempt, but it must be inspected when use resumes^{[12][13][1][10][3]}
Inspect the valves, cylinder head, piston rings, bearings, safety valve, and pressure gauge (comprehensive inspection by the dealer or manufacturer)ReciprocatingWhat to checkValve set, cylinder head gasket, piston rings, pistons, and cylinder, connecting rod and bearings, air tank, safety valve, pressure gauge, electrical parts and piping partsGuidelineWear limits are not exceeded. Replace the cylinder head gasketReciprocating compressors have many sliding parts, and when piston rings and the like wear, fill time grows longer and capacity drops. ANEST IWATA's reciprocating models are inspected at 1 year (2,500 hours), and electrical parts, piping parts, O-rings, etc. are replaced at 4 years (10,000 hours). Meiji Kikai Seisakusho's oil-free models replace piston rings, guide rings, bearings, etc. at 8,000 hours (package type) or 10,000 hours (general-purpose type) and ask that they not be used beyond that^[2][7][3]
Have the screw compressor serviced periodically (replace filters, separator, oil, and valves)ScrewWhat to checkIntake filter, oil separator element, oil filter, oil, valves (MPV, solenoid valve, temperature control valve, intake shutoff valve), coupling, main bearingsGuidelineReplace according to the replacement guide tablePeriodic service extends life and prevents sudden stops. Preventive maintenance is easier to keep within budget than breakdown maintenance (ANEST IWATA). ANEST IWATA says to service at whichever comes first, years since delivery or running hours, with screw models every 1 year or 4,000 hours (scroll models 2,500 hours, claw models 8,000 hours). Atlas Copco lists service types at 4,000, 8,000, and 16,000 hours^[9][14][11]

Other (as needed, first time, etc.)

Measure the air leakage in the factory piping, find the leaks, and repair themCommonPeriodicWhat to checkPiping, fittings, hoses, couplers, equipment in useGuidelineEstablish the leak rate and compare before and after improvementProcedureOn a day off or similar, close off the end of the line and run the compressor, and measure the time t1 for the pressure to rise from the lower limit to the upper limit and the time t2 for it to fall from the upper limit to the lower limit after stopping (calculation is a separate item). Leaks can also be found with an ultrasonic acoustic camera (Atlas Copco)A compressor maker's survey found that 10–20% of compressed air leaks, and leak countermeasures are the first step in saving energy (J-Net21). The Japan Society of Industrial Machinery Manufacturers lists periodic inspection and cleaning of piping among its inspection items^[15][1][16]

📚Sources

Items without a mark are those confirmed by two or more sources from different publishers. Intervals, oil types and values: the specification for each machine takes priority. The text is summarized in Kezuriba's own words.