What this is
What is a compressed air system check?
What is a compressed air system check?
A compressed air system check is a scheduled inspection of the compressor, air treatment and distribution that make up a plant's compressed air system. It records compressor duty and condition, verifies the air quality delivered by the dryer and filtration train against a stated class, and checks the distribution system for leaks and receiver condition.
What does the ISO 8573 basis actually control?
ISO 8573 defines classes of solid particle, water and oil contamination in compressed air, and the test methods used to verify them. The check does not certify a class on its own; it verifies that the equipment and readings needed to hold a stated class, dryer function, dew point, filtration, oil carryover, are actually in order between formal tests.
Why does a check like this need a technician rather than an operator?
Reading a discharge pressure gauge or a dew point meter correctly, and judging whether a filter differential or an oil condition is a normal wear pattern or an early failure, needs someone who understands the plant. An operator can confirm a light is green; a technician can tell you why it might not stay that way.
Scope
When is a compressed air system check required?
This check covers the compressed air system as a system: generation, treatment and distribution together. It is not a substitute for the specific inspections that some of its own components legally require.
Use this template when
- A scheduled monthly check on a compressed air system is due
- A new compressor, dryer or distribution run has been commissioned and needs a baseline check
- Product quality or a customer audit has raised a question about air purity at the point of use
- An energy review has flagged compressed air as a disproportionate cost and a leak survey is needed
- A change to the system, added drop, new load, dryer replacement, means the last check no longer describes it
Do not use it for
- The statutory examination of the air receiver as a pressure vessel, which needs its own written scheme and a competent person, not this check's pass or fail
- Detailed leak location and quantification, which belongs in the Ultrasonic Inspection Record once this check flags that a survey is due
- General condition assessment of unrelated plant, which belongs in the Asset Condition Inspection
- Formal air quality certification against an ISO 8573 class, which needs the specific test methods in ISO 8573-2, -4, -7 and -9, not a visual or gauge-based check
- Vibration or bearing condition on the compressor motor, which belongs in the Vibration Analysis Record
Compliance mapping
Which ISO 8573 requirements does this satisfy?
ISO 8573 does not prescribe an inspection form. It defines the classes of contamination and the test methods used to verify them, and this check maps its sections to the points where that verification actually happens.
| Clause | Requirement | Where it lands |
|---|---|---|
| ISO 8573-1 | Compressed air specified and delivered against a stated class of solid particle, water and oil contamination | Air quality |
| ISO 8573-1, water class | Pressure dew point held below the limit for the stated class, verified by measurement rather than by the dryer simply running | Air quality |
| ISO 8573-2 | Oil aerosol content verified by test method where the stated class requires it, particularly on lines contacting product | Air quality |
| Manufacturer's duty specification | Compressor operated within its designed discharge pressure and load range, with oil, cooling and filtration maintained to schedule | Compressors |
| Pressure equipment written scheme | Receivers examined and relief valves tested to the interval set by the site's written scheme, independent of this check | Distribution |
| Site energy management practice | Distribution leaks surveyed, quantified and routed to correction rather than recorded as a yes or no | Distribution |
| ISO 8573-1, class declaration | Result stated against the class required at the point of use, not against a generic percentage pass mark | Result |
What it does not cover
- Statutory pressure vessel examination, which the receiver still needs under the site's written scheme regardless of what this check finds.
- Ultrasonic Inspection Record, which locates and quantifies individual leaks once a survey here shows they exist.
- Asset Condition Inspection, for general condition assessment of plant not specific to the compressed air system.
- Formal ISO 8573 class certification, which needs the laboratory test methods in the standard's parts 2, 4, 7 and 9, not a visual or gauge reading.
- Vibration Analysis Record, for compressor motor and drive condition beyond what running hours and load percent show.
Global
Compressed Air System Check requirements by country
Compressed air quality is set by an international standard rather than legislation in most places. What varies is the statutory regime around the pressure vessels the system depends on.
OSH Act General Duty Clause; ASME Boiler and Pressure Vessel Code for receiver design
No general standard mandates ISO 8573 compliance; air quality is set by contract or product requirement.
Receiver inspection intervals are typically set by state boiler and pressure vessel law rather than by the air quality standard.
Pressure Systems Safety Regulations 2000
Air receivers require a written scheme of examination by a competent person, independent of routine maintenance checks.
A compressed air system check that passes does not extend or replace the written scheme's examination interval.
ISO 8573 series
Defines contamination classes for particles, water and oil, and the test methods used to verify each.
A stated class is only meaningful against the specific test method the standard names; a check can monitor but not certify it.
How to complete it
How to complete a compressed air system check, step by step
The form asks for readings. What makes the check useful is reading them against the right reference and following through on what they show.
A dryer and filtration train adequate for pneumatic tools is not adequate for air that contacts food or pharmaceutical product. The class needed depends on where the air ends up, and the same discharge can legitimately need different treatment on different branches of the same distribution system.
A survey that finds leaks and stops there has only documented a cost. The value is in the linked ultrasonic record and the action raised for each leak found; a survey with no follow-up is functionally the same as no survey.
A compressor unloaded for a large share of its running hours is oversized for the demand, badly sequenced against other compressors, or compensating for leakage elsewhere. It is one of the few fields on this form that points at cost rather than condition.
Pressure dew point and atmospheric dew point are different figures, and a reading taken or interpreted at the wrong reference will look fine while the delivered air is not. Confirm which figure the instrument and the stated class limit both use before recording a pass.
What auditors find
Most common compressed air system check findings
The form is usually completed. The findings are about whether the readings on it were actually measured, and whether a pass was earned or assumed.
| Finding | Clause | What fixes it |
|---|---|---|
| Dryer recorded as functioning with no dew point reading taken or logged. | ISO 8573-1, water class | Require a dew point figure at every check; a functioning dryer without a reading is an unverified claim. |
| Leak survey marked done with no quantified result and no linked action or ultrasonic record. | Site energy management practice | Link the ultrasonic record ID and raise an action for each leak found before closing the survey field. |
| Oil carryover or food-grade oil use passed without a test certificate on a line that contacts product. | ISO 8573-2 | Require the test certificate upload before a pass is recorded on any product-contact branch. |
| Relief valve recorded as "not due" with no next test date stated anywhere on the record. | Pressure equipment written scheme | Cross-reference the written scheme's interval rather than leaving the next date implicit. |
| Receiver inspection marked current from memory, with no certificate reference or expiry checked. | Pressure equipment written scheme | Require the certificate ID and expiry date as evidence, not a yes or no judgement. |
| Score percent looks high because several failed items were marked N/A and left the denominator. | Result | Read the score alongside completeness percent; a high score on a partly answered form understates the position. |
Case in point
Case in point: the check that passed while the product didn't
A dairy site ran its monthly compressed air check on schedule for over a year. Dryer functioning was recorded as Pass every month, filtration and oil carryover were Pass, and the overall score sat comfortably above ninety percent. No dew point figure was ever entered; the field was optional on the form the site had installed, and the technician treated a running dryer as sufficient evidence.
A customer audit of a packing line found condensation inside a product-contact air line, traced to a dew point several degrees above the site's own stated specification for that class of application. The dryer had been running the entire time, cycling correctly and never flagged as faulty; its performance had simply drifted below the class the line needed, which nothing on the monthly check had been designed to catch because nothing on it measured that number.
The template
The template, field by field
The form exactly as it installs. Every field, option, score and conditional rule is editable, and the links to other templates come with it.
5 sections
- Reference
- MNT-039
- Archetype
- Inspection
- Record ID
- INSP-2026-000
- Scoring
- Percent
- Direction
- High is good
- Singleton
- No
- Basis
- ISO 8573
- Links
- Links Asset
- Tags
- Maintenance, Utilities
- Sections
- 5
- Fields
- 44
- Follow up fields
- 3
- Repeating sections
- 0
- Links out
- 4
Header
10 fieldsCheck ID*
Auto sequence. Format INSP-2026-00000.
The record's own ID. Other templates point at this value.
Status*
Drives who this goes to next.
- Planned2 pts
- In progress2 pts
- Complete3 pts
- Deferred0 pts
- Open0 pts
- Closed3 pts
- Overdue0 pts
Date and Time*
Raised By*
Site*
Site ID*
Format SITE-000.
Links to FDN-001 Site ID
Area
The area within the site.
Exact Location
Drop a pin for anything hard to find.
Asset*
Asset ID*
Format AST-0000.
Links to FDN-002 Asset ID
Compressors
6 fieldsRunning Hours
Loaded Percent
A compressor running unloaded most of the time is burning money.
Discharge Pressure*
Oil Level And Condition*
- Pass2 pts
- Partial1 pt
- Fail0 pts
- N/Aexcluded from denominator
Air Filter Condition*
- Pass2 pts
- Partial1 pt
- Fail0 pts
- N/Aexcluded from denominator
Cooling Adequate*
- Pass2 pts
- Partial1 pt
- Fail0 pts
- N/Aexcluded from denominator
Air quality
10 fieldsAir Touches Product
Compressed air is used to blow, convey and seal in food plants. Filtration, dryness and oil carryover are food safety matters, not just engineering ones.
Dryer Functioning*
- Pass2 pts
- Partial1 pt
- Fail0 pts
- N/Aexcluded from denominator
Dew Point
Moisture In Receiver Drained*
- Pass2 pts
- Partial1 pt
- Fail0 pts
- N/Aexcluded from denominator
Filtration To Specification*
- Pass2 pts
- Partial1 pt
- Fail0 pts
- N/Aexcluded from denominator
Filter Elements In Date*
- Pass2 pts
- Partial1 pt
- Fail0 pts
- N/Aexcluded from denominator
Oil Carryover Tested*
- Pass2 pts
- Partial1 pt
- Fail0 pts
- N/Aexcluded from denominator
Air Quality Test Result
- Pass2 pts
- Partial1 pt
- Fail0 pts
- N/Aexcluded from denominator
Test Certificate
Food Grade Compressor Oil Used*
- Pass2 pts
- Partial1 pt
- Fail0 pts
- N/Aexcluded from denominator
Distribution
6 fieldsReceiver Inspection Current*
- Yes2 pts
- No0 pts
- N/Aexcluded from denominator
Relief Valve Tested*
- Yes3 pts
- Not due3 pts
- No0 pts
Pipework Condition*
- Pass2 pts
- Partial1 pt
- Fail0 pts
- N/Aexcluded from denominator
Leak Survey Done*
- Yes2 pts
- No0 pts
- N/Aexcluded from denominator
Ultrasonic Record ID
Links to MNT-035 Record ID
Pressure Drop Across System
Result
12 fieldsItems Assessed*
Excludes anything marked N/A.
Items Failed*
Score Percent*
Calculated on submission. High is good. N/A items leave the denominator.
Result Band*
- Pass3 pts
- Caution1 pt
- Fail0 pts
Completeness Percent*
How much of the template was actually answered. A high score on a half completed form is not a high score.
Action Required*
Raise the action record, then enter its reference here.
- No2 pts
- Yes0 pts
Priority
- High0 pts
- Medium1 pt
- Low3 pts
CAPA ID
Format CAPA-2026-00000.
Links to FDN-014 CAPA ID
Action Owner
Next Check Due*
Technician*
Signature*
MNT-039 · record IDs look like INSP-2026-000 · Links Asset
Open in KnowellaRun it with agents
From a document you fill in to a programme that runs itself
The check produces readings. What tends to slip is whether a dew point outside specification, or a leak survey with no follow-up, actually reaches someone before the next scheduled visit.
Holds the compressed air check against the asset register and the site's written scheme dates, and flags when a receiver or relief valve examination is coming due independent of this check.
Watches for dew point and carryover readings missing or out of range, chases the linked action or ultrasonic record when a leak survey closes with no follow-up, and holds every write for approval.
Connects the technician's competency record to the readings they are certifying, so a dew point or oil carryover pass rests on someone qualified to take it.
This template lives in KnowMaintain — asset maintenance. Work orders, planned maintenance, calibration, reliability and shutdowns.
Meet KnowMaintain→Glossary
Compressed Air System Check definitions and key terms
- Pressure dew point
- The temperature at which water vapour in compressed air begins to condense, measured at line pressure rather than atmospheric pressure, and the figure an ISO 8573 water class is actually expressed against.
- ISO 8573 class
- A stated combination of solid particle, water and oil contamination limits that compressed air is specified to meet for a given application.
- Air receiver
- The pressure vessel that stores compressed air downstream of the compressor, subject to its own statutory examination regime independent of this check.
- Oil carryover
- Compressor lubricating oil present in the discharged air as an aerosol, controlled by filtration and verified by the ISO 8573-2 test method.
- Written scheme of examination
- A pressure vessel owner's documented examination regime for items such as air receivers, prepared and reviewed by a competent person under pressure equipment law.
FAQ
Frequently asked questions about compressed air system check
What does this check actually verify about air quality?+
It verifies the equipment and readings that a stated ISO 8573 class depends on, dryer performance, dew point, filtration and oil carryover, between formal certification tests. It does not itself certify a class, which needs the standard's specific test methods.
How often should the check run?+
Monthly as a routine schedule, and again after any change to the compressor, dryer, filtration or distribution layout that could affect either air quality or system leakage.
What sections does the template contain?+
Five: header, compressors, air quality, distribution and result, holding 44 fields in total, 31 of them required.
Does a leak survey result of yes mean the leaks were fixed?+
No. It means a survey was carried out. Whether anything was found and corrected depends on the linked ultrasonic record and action record, which the survey field alone does not show.
How is the check scored?+
As a percentage, with a high score being good, calculated across the items marked applicable. Items marked N/A leave the denominator rather than counting against the score.
Can the template's classes and thresholds be adjusted?+
Yes. Every field, option, score and conditional rule can be edited, including the class or specification a site holds a branch to, and most sites install it as supplied before adjusting it after a cycle of use.
Keep going
Related templates and programmes
Industries this is written for
Programmes this belongs to
Used together in Asset Inspection and Statutory Examination
Asset Condition Inspection
Assesses the general condition of an asset against defined criteria
Vibration Analysis Record
Records vibration readings taken from rotating equipment
Thermographic Survey
Records infrared images of electrical panels, motors and bearings to find hot spots
Oil Analysis Record
Records laboratory analysis of lubricating oil, covering wear metals, contamination and additive condition
Ultrasonic Inspection Record
Records ultrasonic readings used to find air leaks, electrical discharge and early bearing wear
Pressure Vessel Inspection
Checks pressure vessels and their safety devices for corrosion, damage and correct operation
More in Asset Inspections
Asset Condition Inspection
Assesses the general condition of an asset against defined criteria
Vibration Analysis Record
Records vibration readings taken from rotating equipment
Thermographic Survey
Records infrared images of electrical panels, motors and bearings to find hot spots
Oil Analysis Record
Records laboratory analysis of lubricating oil, covering wear metals, contamination and additive condition
Ultrasonic Inspection Record
Records ultrasonic readings used to find air leaks, electrical discharge and early bearing wear
Pressure Vessel Inspection
Checks pressure vessels and their safety devices for corrosion, damage and correct operation
Written and reviewed by
Siddarth Singh
Founder & Chief Executive Officer, Knowella
Certified Safety Professional and industrial and systems engineer with more than a decade inside food supply chain, freight and manufacturing operations. This page was written against the current text of the standards it cites, not against secondary summaries of them.
- Certified Safety Professional (CSP), Board of Certified Safety Professionals
- MBA, University of Chicago Booth School of Business
- MS and BS, The Ohio State University, Industrial and Systems Engineering
- Six Sigma Black Belt
Sources and last review. Reviewed 16 August 2026 against:
- ISO 8573 series, compressed air contamination classes and test methods
- Pressure Systems Safety Regulations 2000 (UK), written scheme of examination
- ASME Boiler and Pressure Vessel Code, air receiver design and inspection
- US Department of Energy, compressed air system leak assessment guidance
This page is general guidance, not legal advice. Confirm requirements with your jurisdiction’s regulator.