Condensate Management

Compressed Air Condensate formation is unavoidable. It is always a “by-product” of compressed air generation and spreads throughout the entire compressed air network. Around two thirds of the condensate is produced in the aftercooler of a compressor and the air dryer. The rest occurs anywhere in the network as the compressed air cools down.

Very low oil in water discharge limits are permitted and rigid legislation exists in most countries to protect the environment against contamination. International standards such as ISO14001 also require the compressed air user to comply with local environmental legislation and show use of protective systems and procedures.

Following the introduction of the Hazardous Waste regulations in July 2005, which affect all owners of compressed air systems with respect to the proper disposal of condensate, the UK Water Resources Act states that it is an offence to knowingly permit entry of toxic waste to surface or ground water. It is an offence with a fine of £20,000 or more in a crown court.

Frequently, condensate consists of 99 % of water and only 1 % oil. Therefore, processing the condensate on site is always more economical than cost intensive disposal by specialist companies.

After the oily condensate has been efficiently removed from the compressed air system it cannot be discharged directly to the foul sewer without first having the oil content reduced to within legal disposal limits. Oil / water separators are installed as part of the compressed air system and simply reduce the oil concentration in the collected condensate to a level permitted, for discharge. This allows the larger volume of clean water, up to 99.9% of the total condensate, to be discharged safely into the foul sewer and the relatively small amount of concentrated oil to be disposed of legitimately and economically.

Once an Oil / water separators is installed, in all cases you will need a “consent to discharge” from your local water authority (even if using biodegradable oils). You will need evidence that the discharge is below limits. The water authority may offer the testing service for a fee, or other service providers can be found at

Legislation can even be different between local governing bodies, it is the user’s responsibility to contact his governing body and obtain the permitted discharge limit, however oil in water limits of 25mg/L (25ppmw) or less are typical.

PSG Oil Water SeparatorPSG Oil Water Separators

  • Maximum operating pressure 17 bar (g)
  • Maximum operating temperature 48 C
  • Minimum operating temperature 2 C
  • Compliant with PED 97/23/EC and CE
  • Works on mineral oils, PAOs (Polyalphaolefins), Poly Olesters, Diesters & Esters, most synthetics and POLYGLYCOLs (Ultracoolant)


  • Compressor Capacity – 60-1900cfm
  • Maximum lubricant discharge: down to 15 mg/l or even less based on environment & change intervals
  • Can handle multiple unit compressor installations