Compressed air is a key utility in food manufacturing, yet is often overlooked by quality teams in favour of more visible inputs like water and raw ingredients. As global food safety standards tighten expectations around how it is filtered, tested, and documented, manufacturers must prepare for more informed scrutiny. Compressed Air Solutions founder, Byron Raal, outlines the top five blind spots to watch out for.
Compressed air is one of the few utilities in a food plant that can touch the product directly – and it is almost certainly the least scrutinised. It blows bottles dry before labelling, actuates valves on filling lines, and powers pneumatic conveyors that move powders from silo to mixer. In dairy and meat processing, it is often the only gas that contacts the product surface. Yet in most facilities, compressed air sits in a regulatory grey zone. FSANZ does not prescribe specific air-quality limits. HACCP plans rarely name the compressor room as a controlled area. And until the auditor walks in with an updated checklist, many quality teams assume that the filters fitted at installation are still doing their job.
Over the past two years, GFSI-benchmarked schemes – SQF Edition 9, FSSC 22000 Version 6, and BRCGS Global Standard for Food Safety Issue 9 – have each tightened their language around utility management, compressed air monitoring, and point-of-use filtration. Auditors are asking sharper questions, and they are raising non-conformances on issues that went unnoticed five years ago.
Here are the five blind spots that come up most often – and what practical steps manufacturers can take before the next audit window opens.
1. The contact-point register that does not exist
ISO/TS 22002-1 clause 8, which FSSC 22000 Version 6 incorporates as a mandatory prerequisite programme, asks for an overview of compressed air use including type, purpose, and controls in place. SQF Edition 9 Food Safety Code clause 11.5.5 separately requires that air contacting food or food-contact surfaces is clean and presents no risk (11.5.5.1), and that compressed-air systems are maintained and monitored on a risk-based frequency, minimum annually (11.5.5.2). In practice, most plants have never mapped this.
The fix is straightforward but time-consuming: walk each production line with the maintenance lead and the quality manager together. At every point where a pneumatic device operates, ask one question – does the air exhaust into the product zone? If yes, it goes on the register with its ISO 8573-1 class requirement, the filter specification currently installed, and the date that filter was last validated.
Plants that complete this exercise commonly discover substantially more contact points than their HACCP plan accounts for. Blow-off nozzles on conveyors, air knives at the entrance to clean rooms, and pneumatic cylinder exhausts near open hoppers are the usual surprises.
2. Point-of-use filtration that lives in the compressor room
This is one of the most common misunderstandings in the industry. A well-specified filter bank in the compressor room protects the distribution pipework, but it does not guarantee air quality at the point of use. If any section of distribution pipework sits below the compressed air pressure dew point, water condenses back out downstream of the dryer. Pipe scale, jointing compound residue, and biofilm in dead legs introduce further contaminants downstream of the central filters.
SQF Edition 9's Air and Other Gases Guidance Document recommends point-of-use filtration rather than compressor-room filtration alone, with a final-stage rating of 0.01 micron at 99.999 per cent or as determined by appropriate risk analysis. For direct product contact applications, the typical arrangement is a coalescing pre-filter rated at 0.01 micron for oil aerosol, followed by a 0.2 micron sterile membrane element with validated microbial retention to log-7. The exact specification depends on the ISO 8573-1 class determined by your HACCP risk assessment. Auditors increasingly verify this by physically inspecting the last filter before the process, not the filter in the plant room 50 metres away.
For plants with dozens of contact points, retrofitting point-of-use filtration is a capital project. But the cost of a sterile-grade filter housing is modest compared with a major non-conformance that downgrades a BRCGS grade from A to B. That single grade shift triggers corrective-action obligations against a fixed remediation timeline, may carry certificate implications, and can prompt customer re-qualification requests - none of which is recovered as quickly as a filter spec is upgraded.
3. Testing that only measures particles and ignores microbiology
Most compressed air testing programmes measure three parameters aligned with ISO 8573-1: solid particles, water content, and total oil. Those three matter, but they do not tell the full story. Microbiological contamination – bacteria, yeasts, moulds – is the parameter that food safety auditors increasingly want to see on the test report.
The ISO 8573 family treats microbiology as a distinct parameter in Part 7, alongside particles, water, and oil in Part 1, oil vapour in Part 5, and gaseous contaminants in Part 6. SQF Edition 9 clause 11.5.5.2 requires risk-based monitoring of compressed-air systems; SQF's Air and Other Gases Guidance Document points to ISO 8573-1 as the framework for that monitoring. Yet the majority of Australian food plants either do not test for micro at all, or test annually when quarterly would be appropriate for high-risk direct-contact applications.
Most quality managers are surprised to learn that the testing infrastructure already exists. NATA-accredited laboratories in Australia perform compressed air microbiological testing using compressed-air-adapted impaction samplers such as the Sartorius MD8 as a routine service. The per-sample cost is comparable to environmental swabbing, results typically arrive within seven to ten working days, and the process requires no specialised equipment on site beyond a sampling adapter.
4. Differential pressure as the only filter change trigger
Maintenance teams commonly rely on differential pressure gauges across filter housings to decide when to replace elements. When the pressure drop reaches a threshold, the element is changed. This approach protects compressor efficiency but does not protect product safety.
A coalescing filter element can be well within its pressure-drop limit and still allow oil aerosol breakthrough if the media has degraded. Activated carbon elements lose adsorption capacity with humidity exposure regardless of pressure drop. Sterile membrane filters can develop micro-tears from pressure spikes that a differential gauge will never detect.
Best practice is to combine differential pressure monitoring with calendar-based replacement at the manufacturer's recommended interval – typically annual for coalescing elements, and considerably shorter (often six months) for activated carbon and sterile membrane elements – and to validate the replacement schedule with periodic downstream testing. Auditors reviewing maintenance records will look for documented maximum service intervals, not just reactive change-outs triggered by gauge readings.
5. No documented link between air quality classes and HACCP risk levels
The strongest audit position a plant can hold is a documented rationale that connects each compressed air contact point to a specific ISO 8573-1 quality class, and ties that class to the HACCP risk assessment for the process step involved. Very few plants have this.
Without it, the quality team is left defending air quality specifications on the basis of what the compressor supplier recommended at installation – which may have been five or fifteen years ago, before the current product mix, before line extensions, and before the latest scheme version raised the bar.
Building this link does not require outside consultants. It requires the quality manager, the maintenance engineer, and the production lead to sit in a room with the HACCP plan and the ISO 8573-1 classification table, and work through each CCP and operational prerequisite programme that involves compressed air. The output is a simple matrix: contact point, process risk, required air class, current air class, gap (if any), and corrective action.
That single document transforms compressed air from an uncontrolled utility into a managed food safety input – which is exactly the shift that GFSI-benchmarked schemes have been driving for the past three audit cycles.
Closing the gaps before the auditor finds them
Every facility already has the people and the data to close these gaps. What is usually missing is the cross-functional conversation – quality, maintenance, and production sitting down together to treat compressed air with the same rigour they already apply to water, steam, and refrigerant gases.
The plants that perform best at audit are not the ones with the newest compressors. They are the ones with a complete contact-point register, validated point-of-use filtration, a testing programme that includes microbiology, maintenance records with documented service intervals, and a clear link between air quality classes and their HACCP plan.
For most single-site operations, closing these five gaps is a project measured in weeks rather than months. And the return goes beyond a clean audit report. It is the ability to tell your customers, your auditor, and your own team that the air touching your product is managed, monitored, and validated to the same standard as every other input on the line.
Compressed Air Solutions is an independent Australian advisory site for plant and facilities managers focused on compressed air system design, sizing, energy efficiency, and compliance.
