Condensate is an inevitable byproduct of operating a compressed air system. It is mostly water that is condensed from vapor to liquid as air moves through the compressed air system. Condensate will usually contain traces of compressor lubricant (and hydrocarbons from the ambient air if present). It can also have traces of dirt, dust, fibers that get pulled into the compressor inlet. Condensate is intentionally created by aftercoolers, tanks, centrifugal separators, and refrigerated dryers in order to remove the moisture and contaminants, and it is unintentionally created further downstream if the compressed air is cooled below its current pressure dew point.
The key points are that this mixture needs to be expelled from the compressed air system to reduce maintenance of compressed air system components, extend pneumatic tool and equipment life and prevent product contamination and high scrap rates. And then it must be properly disposed of. In this series of three blog posts, we will address the following questions:
- What is condensate and where does it come from?
- Disposal of condensate
-- Why does condensate need to be separated or treated?
-- How can condensate be effectively and efficiently separated?
- How do you convey the condensate from the air to the treatment/separator system?
Condensate comprises all the contaminants in the compressed air: water, oil, and particles. Water is the primary constituent and is generated by condensing water vapor in the air. Condensation occurs by cooling the compressed air below its dew point. For example, ambient air can have a dew point of 30°F or lower in the winter, but in the summer, it can be as high as 75°F. When something colder than the dew point contacts the air (e.g., a cold beverage), the ambient moisture condenses on the colder surface.
Example of condensate generated by each system component (350 cfm system over a 10 hour period in the summer)
The next component of the condensate is oil. Oil is introduced into the compressed air system primarily by the compressor if it’s an oil-flooded type. The compressor uses this oil for lubrication and cooling, but some oil can sneak past the oil separator into the compressed air system. This is referred to as oil carryover and can be below or above 3 ppm. Oil coalescing filters catch most of the oil aerosol droplets before they can reach the end use, discharging the oil into the condensate and mixing with the water.
The last constituent is particulates. Particulates in the condensate are typically submerged in the water or oil and are dispelled along with them.
So you’ve collected condensate and we know what’s in it. What do you do with all these gallons of oily liquid? In most US locations, it cannot be put in a sewer, storm sewer or on the ground as is. It needs to be filtered out before discharging. This leads to the second part of our series. Next time we’ll discuss how to properly dispose of it so you stay in compliance with environmental safety requirements.