Oil Water Separators

Oil Water Separators for Compressed Air Condensate

Oil-water separators are a legal and environmental necessity for any business operating an oil-injected compressed air system. During the compression process, condensate is produced — a mixture of water, compressor lubricant and airborne contaminants. This condensate cannot be discharged untreated, as doing so may breach UK environmental law.

Companies that fail to comply with condensate disposal regulations may face fines of up to £20,000 and, in serious cases, imprisonment for directors or responsible persons. Beyond financial penalties, non-compliance can result in legal action, reputational damage and long-term operational disruption.

Understanding the Law

Water Resources Act 1991
This Act makes it a criminal offence to knowingly allow polluting matter — including oil-contaminated condensate — to enter surface water or groundwater. Convictions can lead to substantial fines in Crown Court.

Water Industry Act 1991
This legislation governs the discharge of trade effluent (including treated condensate) into the public sewer. Businesses must obtain consent from their local water authority before discharge. Treated condensate must never be discharged into rivers, streams, groundwater, storm drains or surface water systems. Breaches can result in fines of up to £20,000 and possible imprisonment.

Environmental regulations are becoming increasingly strict. Businesses operating at minimum compliance today may face higher upgrade costs and enforcement risks in the future.

What Is Compressed Air Condensate?

Most industrial and manufacturing facilities use compressed air. As air is compressed, moisture condenses and mixes with:

• Compressor lubricating oil
• Oil aerosols and vapours
• Rust and pipe scale
• Dust and airborne particulates
• Microorganisms and other contaminants

This mixture forms condensate — a potentially harmful waste product. Even a small amount of oil can spread rapidly across water surfaces, blocking oxygen transfer and damaging aquatic ecosystems. Untreated discharge can contaminate groundwater and harm wildlife.

How an Oil-Water Separator Works

An oil-water separator removes oil from condensate using a combination of gravity separation, coalescing media and filtration. High-quality systems can remove up to 99.5% of oil contamination, allowing the treated water to meet discharge standards (subject to local consent conditions).

There are several types of oil-water separators, including:

• Gravity separators – allow oil to naturally rise and separate
• Coalescing separators – use specialised media to combine oil droplets for easier removal
• Centrifugal systems – use rotational force to separate contaminants

For smaller oil-injected piston and rotary screw compressors (under 30 l/s or 60 cfm), absorption-based systems such as the Tanair OWS provide a simple and cost-effective condensate treatment solution.

Why Installation Is Critical

Many businesses operate without adequate condensate treatment, often due to lack of awareness or legacy installations. Responsibility for compliance may fall between management, engineering and maintenance teams. However, the legal liability remains with the company.

Failing to install a separator can result in:

• Environmental pollution
• Regulatory fines and prosecution
• Reputational damage
• Increased insurance and operational risk

Protect Your Equipment & Improve Efficiency

Beyond compliance, proper condensate management protects your compressed air system. Oily condensate can cause corrosion, blockages and damage to pipework, valves and downstream equipment. This leads to reduced efficiency, higher maintenance costs and increased downtime.

Installing a compliant condensate management system provides peace of mind while supporting reliable and efficient system performance.

Maintenance & Service Life

Our oil-water separators typically have a working life of around 4,000 operating hours. Depending on system usage, this usually requires servicing or media replacement once or twice per year to maintain optimal performance and compliance.

Oil Water Separators at Compressed Air Systems UK

With over 30 years of industry experience, Compressed Air Systems UK supplies dependable oil-water separators and condensate treatment solutions for industrial compressed air systems. We help businesses meet environmental regulations, avoid costly penalties and operate responsibly.