In industrial warehouses and manufacturing facilities, one of the most common systems in place is one of compressed air. These systems power numerous types of tools and machinery, and their integration is essential for many automation tasks nowadays. However, beneath the so-called ‘fourth utility’ lies a hidden contaminant that can pose a health and safety risk to workers: excess moisture.
For health and safety professionals, understanding how damp compressed air can affect worker wellbeing as well as operational productivity is vital for maintaining a secure and healthy environment for all.
The risks of moisture build-up
Moisture enters an industrial compressed air system through ambient air intake, making it an atmospheric contaminant.
The process might sound convoluted, but air compressor engineers Kerr Compressors explain it succinctly in their technical resource, “The amount of water vapour that air can carry is mostly dependent on temperature. As air temperature rises – which occurs during compression – the air’s capability to hold moisture increases also. When the air is cooled, its capacity to hold moisture reduces, which causes the water vapour to condense.“
This condensation process then leads to an abundance of residual liquid water within air lines, tanks, pneumatic tools and other connected machinery. The volume, of course, depends on atmospheric and environmental conditions; facilities in more humid climates or near coastal areas are more prone to excess moisture challenges.
What are the safety risks of moisture-heavy compressed air?
While the long-term financial effects of corroded pipework can create concerns for some facilities managers, health and safety officers have more pressing concerns. Damp-induced corrosion creates a number of hazard pathways that compromise worker safety:
- Rust particles travel through the air distribution system and accumulate in control valves, causing them to stick or respond ineffectively.
- In automated production lines requiring pneumatic systems to trigger safety functions, valves can malfunction. For example, machine guarding may not deploy correctly, emergency stops may not engage, or machinery may behave erratically.
- Pneumatic presses in steel fabrication can see control valves sticking partially open, when exposed to moisture-heavy air. As such, the press may descend with insufficient force to trigger required sensors, or, conversely, unexpected pressure may be applied at irregular intervals.
- Winter conditions can introduce additional hazards, such as exterior pipes being subjected to freezing temperatures, which can block air flow or cause pipes to rupture. Sudden compressed air releases can project debris or create imminent trip hazards for workers.
Where product quality matters for safety
Health and safety officers should examine products closely, as moisture contamination can affect product integrity. This is very evident in food and pharmaceutical production with moisture paving the way for bacterial growth within air distribution systems. When this then comes into contact with products pathogens can be introduced, which forms not just a risk to workers but also to public health, if not properly addressed.
Product recalls are a necessary next step, and if your production facility was deemed responsible for the system failure or oversight, it may suffer reputational damage. Worse even, it could be liable for potential fines for breaching food safety laws, and you as a business owner could be subject to prosecution. As such, moisture control becomes a matter of proactive, site-wide risk management. Preventing air contamination at source through regular, professional air treatment, can eliminate these hazards entirely.
Even in non-food applications, moisture affects product integrity in ways that create further risks. For example, powder coatings become clumpy and uneven, potentially leaving metal surfaces inadequately protected from corrosion. Moisture in automotive spray systems can cause slight finish defects, which are cumbersome to rework and correct. Workers could also be exposed to elevated levels of solvent vapours as a result.
Appropriate risk assessment and control measures
Under the Management of Health and Safety at Work Regulations 1999, employers must assess risks and implement appropriate controls.
Evaluate moisture levels in compressed air systems regularly. Consult resources like The Health & Safety Risk Assessors for guidance on conducting workplace risk assessments that encompass utility systems often overlooked in standard evaluations.
Examine environmental factors such as:
- Indoor humidity, seasonal conditions, proximity to moisture, etc.
- System design of units such as aftercoolers as well as integration and drain points
- Point-of-use needs, and what air quality is needed for specific applications
- Maintenance procedures (i.e. ask yourself how often you service drains, or purge moisture from systems)
The hierarchy of controls applies equally to moisture management. Whilst elimination may not be practical when compressed air is integral to processes, engineering controls can dramatically reduce risks.
The role of aftercoolers is imperative in compressed air management and control. These units reduce compressed air temperatures to cause moisture condensation into liquid droplets, which can then be separated and drained. Putting aftercoolers immediately downstream from the air compressor can be tremendously effective at reducing site-wide condensation.
Compressed air dryers also provide effective moisture removal. Refrigerated dryers cool compressed air to roughly 3°C, causing moisture to condense whilst preventing freezing. In applications where dry air is required, desiccant dryers use adsorbent materials to achieve dew points below freezing.
Effective filtration supports the drying process by removing condensed water droplets and rust particles. Coalescing filters integrated at various touchpoints provide a solid line of defence against water-heavy hazards.
A facility’s incumbent preventative maintenance programme should be reviewed carefully and updated accordingly if there are pertinent gaps. Consider implementing daily drain purging procedures, weekly inspections of automatic drain operations, regular filter replacements in line with manufacturer specifications, and dew point monitoring to verify dryer performance. Keep thorough maintenance records to serve as impartial, time-stamped evidence of your commitment to safety management during annual inspections or investigations.
Don’t underestimate the seriousness of compressed air hazards
Health and safety professionals who understand the hazards outlined above can implement effective controls that protect workers whilst supporting operational objectives.
Treating moisture as a serious contaminant requires investment in proper air treatment equipment and consistent maintenance. This investment prevents far costlier outcomes: workplace injuries, production disruptions, and regulatory consequences of safety failures.
