What every air compressor operator needs to know about oil/water separators and condensate

Air compressor condensate filter systems feature an oil/water separator for draining condensate. Improper filtration and disposal of contaminated compressor condensate pose hazards to both human health and the environment. There could also be legal and financial repercussions if your organization fails to follow guidelines. The best way to mitigate the risk is to implement an air compressor condensate filter system.

What is air compressor condensate?

Condensate is the result of air compressor operation and contains both water and oil. This oil /water mixture becomes concentrated during the compression process. Contaminated condensate requires proper disposal per environmental regulations. However, collecting and storing large volumes of contaminated condensate is not exactly ideal.

Believe it or not, you don’t need an outside waste management vendor to properly and cost-effectively deal with disposal of condensate. A properly designed and installed air compressor condensate filter system will reduce the amount of contaminated condensate and significantly reduce disposal costs.

Selecting a condensate filtration system

Condensate filtration systems can be used for small to midsize systems, although multiple units can be connected to handle large systems. To determine which condensate filtration option is right one for your facility, you first need to figure out how much condensate  your compressor system makes. The amount of condensate created during air compressor operation varies depending on ambient temperature.

Winter Conditions – A 200 CFM compressor with 70° inlet air 50% relative humidity makes 3/4 of a gallon of condensate per hour or 60 gallons a week in a 2-shift operation.

Summer Conditions – A 200 CFM compressor with 85° inlet air 80% relative humidity makes 2 gallons of condensate per hour or 160 gallons a week in a 2-shift operation. (See the condensate calculation table)

Water falls out of the compressed air in the system as the air cools when it runs through the wet tank, pre-filter, refrigerated dryer and after-filter. These components remove approximately 95% of the moisture in the system when everything is operating properly.

The question then becomes, how do you deal with the condensate as it is collected from the drains on the wet tank, pre-filter, refrigerated dryer and after-filters?

Water vapor that is condensed inside the compressor is not the real issue but the oil that lubricates compressor is carried along with this condensate. This contaminates the water being removed and creates hazardous waste that cannot be discharged to ground or most waste removal systems.

How to remove air compressor condensate (the legal way)

There are four ways to deal with compressor condensate to keep your company legal and green.

1. Collect your condensate in a safe container for collection by a licensed waste disposal firm. This process will eliminate any potential issues but can be very expensive.
2. Mechanical separators with carbon filters are very effective on most compressor oils and create a clear water discharge through carbon filtration and collect the waste oil to be disposed of properly. There are some synthetic compressor oils that either silicone or glycol based that need to be tested for separation to be sure that a unit will work. The key to a system of this type operating properly is quarterly maintenance of the filters and separation devices to ensure the water is clear going to drain.
3. Condensate boil off units have been used in medium and large firms and operate much like making maple syrup. The condensate is put into a collection area which is then heated and the water is boiled off leaving the oil residue for proper disposal. Units work on any lubricant and can be powered by gas or electricity. Investment is realistic and dependent on the cost of gas or electricity operating costs vary between 15-20% of initial investment.
4. Central collection systems – many large plants have a central collection system for waste materials that include machining fluids and other cooling media that also can be used for condensate disposal. A test is recommended by putting a sample of condensate into the system to see if it is properly treated. The costs of collection and transportation inside a large facility may be too high, requiring individual treatment units in each compressor rooms.

In a few unique cases, condensate has been allowed to go to a town or city sewer dependent on lubricant in use as well as quantity of condensate vs. total discharge and the approval of the local authority.

Condensate is a fact of life regardless of temperature and humidity and must be treated properly by all companies to be legal and to protect our environment.

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