A Guide to Using Air Compressors in Humid UK Environments
The air compressor is an essential utility in a number of industrial facilities, but it operates with a raw material that harbours an ever-present risk: moisture.
The UK’s climate brings high humidity year-round, and that makes moisture a constant challenge for compressed air systems.
To manage it effectively, you first need to understand how an air compressor concentrates water from the air. And the scale is bigger than many realise.
A standard 100kW compressor, running in typical UK conditions, can produce around 85 litres of liquid water in a single 8-hour shift. That accounts for up to 99.9% of all liquid contamination in the system.
Left untreated, this condensate leads to corrosion, equipment breakdowns, spoiled product, and serious financial losses.
This guide explains the risks humidity poses to your system and outlines the proven solutions for compressed air moisture removal in the UK.
The Unseen Damage Caused by Moisture
The liquid water created during compression is an aggressive contaminant. It triggers a chain reaction of failures that impact the entire compressed air system, from the compressor to the point of use.
Corrosion and Contamination
The most immediate threat is internal corrosion. When water contacts the metal surfaces inside air receivers and pipework, it causes rust. The rust particles shed and flow downstream as an abrasive solid contaminant.
Combined with small amounts of compressor lubricant, the rust becomes an acidic sludge that plugs valves and control circuits, resulting in failure.
Equipment Failure
Pneumatic tools and actuators require a fine film of lubricant to operate smoothly. Water is a solvent that washes away the necessary lubrication. Increased friction and premature wear lead to equipment failure.
In severe cases, a “slug” of liquid water can be propelled into a tool, causing immediate and irreparable mechanical damage.
The Freezing Risk
For UK facilities, the combination of humidity and variable temperatures presents a critical threat.
During colder months, any liquid water trapped in pipework can freeze. As water expands, it can block control lines or even burst pipes, leading to major system leaks.
This is especially problematic for external pipework.
Product Spoilage
The most costly impact of moisture is often its effect on the final product.
- Spray Painting: Too much humidity in the air can cause defects like “fish eyes” or poor adhesion in coatings. This results in rework and wasted time.
- Food & Beverage: Moist air creates the perfect conditions for mould and bacteria. Once it comes into contact with food, the danger is clear – contamination, product recalls, and risks to public health.
- Pharmaceuticals & Electronics: Here, humidity is even more critical. A trace of moisture can seep into sterile products. It can also corrode printed circuit boards. Either way, the outcome is the same: failures and expensive rejections.
The Financial Drain of Air Compressor Humidity Problems
Unmanaged moisture directly inflates operational costs through energy waste, repairs, and downtime.
Energy Losses from Moisture
The sludge and rust created by moisture restrict airflow in pipes and filters, causing a pressure drop. For every 2 psi of unnecessary pressure drop, a compressor’s energy consumption increases by approximately 1%.
Corrosion also inevitably leads to air leaks – the single largest source of wasted energy in most compressed air systems. The costs are tangible: a single 6.4 mm leak in a system operating at 7 bar can cost a business over £4,044 annually in wasted energy.
The savings from repairing such leaks can often pay for a professional leak detection audit in a short period.
Repair, Downtime, and Replacement Costs
Beyond energy, there are the direct costs of unplanned downtime, emergency repairs, and the premature replacement of expensive components damaged by water.
A Multi-Stage Strategy for Moisture Control
Effective moisture control requires a systematic, multi-stage approach to remove water in its bulk liquid, aerosol, and vapour forms.
1. Bulk Water Removal
The first step is to remove the large volume of liquid water that forms immediately after compression using aftercoolers, water separators, and air receivers.
2. Fine Aerosol Removal
Even following bulk removal, the air is still filled with a fine mist. This is why high-efficiency coalescing filters are used, as they can remove these sub-micron droplets. Appropriate air drying and filtration are important for downstream equipment protection.
3. Water Vapour Removal
The final step is to remove the invisible water vapour. This is the role of air compressor dryers, which lower the air’s pressure dew point (PDP).
- Refrigerated Dryers: The most common type for general manufacturing. These dryers chill the air to a PDP of +3°C.
- Desiccant Dryers: These are essential for critical processes or applications exposed to freezing temperatures. Desiccant dryers use an adsorbent material to achieve extremely low dew points. This is normally around -40°C but can go down to even -70°C.
Many modern rotary screw compressors from manufacturers like Atlas Copco are available with integrated dryer and filtration packages.
This provides a compact, energy-efficient, all-in-one solution. This saves you space and reduces your installation costs.
A Guide to Using Air Compressors in Humid UK Environments
Meeting UK Standards and Legislation
How clean does your air really need to be?
You can’t hit the right level without knowing ISO 8573-1. It’s the international standard that sets the rules for compressed air quality.
An expert partner can recommend the most suitable purity class for your application so that it will perform without you overspending on energy.
Atlas Copco’s ISO 8573-1 Class 0 certified oil-free compressors are designed to offer zero oil aerosols in the air produced, meeting the highest quality standards that you will typically find in the food, beverage, and pharma industries.
You need to be compliant, no matter what sector you operate in. The Health and Safety Executive (HSE) provides guidance for the food and beverage industry on compressed air quality. In addition, condensate produced by an oil-lubricated compressor is governed by the Water Resources Act 1991.
This means the oily water can’t just be drained away – it must first go through an oil/water separator.
Skip that step and you risk a hefty fine.
An expert partner such as Search Air can ensure that your system complies with all the relevant compressed air quality standards as well as environmental legislation.
Proactive Management for Year-Round Reliability
As well as having a well-specified system, it is also important to have active management and maintenance, which is based around seasonal changes.
For example, Atlas Copco’s new VSD technology automatically adjusts motor speed to match air demand.
As demand falls, the motor slows down. This cuts heat generation, lowers the chance of condensation, and keeps humidity under control. Still, the right equipment is only part of the picture – regular maintenance is just as important.
Selecting the correct oil for your compressor, for example, is critical.
In more humid environments, selecting lubricants with better antioxidation additives is essential. Purchasing a bespoke service plan can also be a useful tool in minimising maintenance costs, and maximising long-term dependability.
Summer Maintenance Priorities:
- Check Drains Daily: High humidity will cause increased condensate formation. Visually inspect all drains on separators, filters, and dryers daily to ensure they are discharging properly.
- Clean Coolers Weekly: Dust and debris can build up on the aftercooler and oil-cooler fins. If not cleared, efficiency drops fast.
- Monitor Oil Condition: Keep an eye out for a milky or emulsified look in the compressor oil – it’s a clear sign water may be present.
Winter Freeze Prevention:
- Protect External Pipework: Insulate any exposed pipes. Otherwise, trapped moisture can get in your pipework, freeze, and, in some cases, actually rupture the line.
- Verify Dryer Performance: Check that your desiccant dryer is running to spec. It needs to hit a dew point well below freezing if your lines are out in the cold.
- Maintain Drains: Ensure all automatic drains are functioning. A failed drain in winter can quickly lead to a frozen and blocked component.
Air compressors can run reliably even in humid climates like the UK. The trick is strategy. With engineered solutions in place and a maintenance programme that shifts with the seasons, you avoid corrosion. You also reduce the chance of failures – and the costly downtime that comes with them.
Call Search Air today to book a compressed air moisture risk audit and review suitable solutions for your plant.