Compressed Air Condensate: How Much a System Discharges and Where it Forms
Condensate forms at every point where compressed air cools: at the aftercooler, in the dryer, and in the lines. The amount of condensate depends on the temperature, humidity, pressure, and flow of the air. A typical system can discharge gallons of water per day, most of it dropped at the aftercooler and dryer. Tavoron’s condensate calculator estimates how much water a system discharges at each stage.
How Much Condensate Does an Air Compressor Produce?
An air compressor can produce a lot of condensate, but exactly how much depends on the ambient temperature, relative humidity levels, and operating pressure (PSI; pounds per square inch) and air flow (CFM; cubic feet per minute) of the system. Typically, an industrial 100 CFM air compressor operating in average conditions (around 70°F and 60% relative humidity) can produce about 15 to 20 gallons of condensate per 24 hour day.
To understand how different variables affect the amount of compressed air condensate, it helps to think of air as a sponge. How much the “sponge” can hold and how much it releases depend on the specific temperature, humidity, pressure, and flow of the air.
- Ambient temperature (the size of the sponge): As ambient air enters the compressor, it is pressurized and then cooled down, which “squeezes” the sponge, releasing condensate. Temperature has a significant effect on the moisture capacity of the air. Warm air holds more moisture than cold air, so warmer ambient air will produce more condensate than cooler air.
- Relative humidity (how wet the sponge is): Humid air is moist air. This means in very humid conditions, the air entering the compressor is already highly saturated and will produce more condensate as the air is compressed and subsequently cooled.
- Air pressure (how hard you squeeze the sponge): Compressing ambient air forces air molecules and the water vapor trapped between them into a smaller space. If you are “squeezing” incoming ambient air to 100 PSI, which is about 8 bars of pressure, you are reducing 8 cubic feet of ambient air to 1 cubic foot of space, concentrating the moisture. So, the higher the pressure of your air compression system, the more condensation it will generate if the flow rate remains the same.
- Air flow/volume (how fast you soak the sponge): When the demand for compressed air is high, your air compressor will run at a high flow rate (measured in CFM), which requires it to take in more air to keep up with demand. Increasing the amount of intake air increases the amount of moisture drawn into the compressed air system.
Why and Where Does Compressed Air Condensate Form?
Condensate forms in an air compression system because the warm, humid ambient air that is drawn into the system contains water vapor, and as the air is compressed into a smaller space, it can no longer contain the same amount of water vapor.
The moist air must be cooled before use, but for every 20°F drop in temperature, the air loses about half its moisture-holding capacity. Once the temperature drops below the pressure dew point (PDP) (the temperature at which air becomes 100% saturated at a given pressure), the water vapor will condense into liquid water.
So, condensate will form at every point in the compressed air system where treated compressed air is cooled below PDP, including the aftercooler, dryer, and air delivery lines.
- Aftercooler: After air is treated compressed, the hot, pressurized air is discharged into the aftercooler, which cools the air allowing the moisture separator to remove bulk water before the air moves into the storage tank and filtration where additional liquids are drained before entering the air dryer.
- Air dryer: The air dryer’s job is to remove the remaining moisture from the compressed air to achieve the desired pressure dew point.
- Air delivery lines: Even after compressed air goes through the aftercooler and air dryer, condensate can still form as it moves through the distribution piping if it goes outside in cold winter climates or through refrigerated rooms where ambient temperatures drop below PDP.
How to Estimate Compressed Air Condensate
Because moisture can result in damage to system components and downstream pneumatic tools and equipment and degrade compressed air quality, compressed air condensate must be removed from the system. To manage condensate, it’s crucial to know how much liquid you’re dealing with at each stage, so you can accurately size compressed air condensate management solutions.
Tavoron’s condensate calculator estimates the maximum volume of water your system generates under peak operating conditions.
Compressed Air Condensate Management
Effective condensate management impacts a facility’s uptime and compliance. When liquid water and emulsified oils are left to build up in a compressed air system, they can trigger mechanical failures and violations regarding compressed air quality in regulated industries, such as food and pharmaceutical processing and electronics and medical device manufacturing.
Components for Effective Compressed Air Condensate Management
Separators:
Moisture separators, which should be installed after the aftercooler, use centrifugal force to spin bulk liquid droplets out of the air stream. Coalescing filters, positioned further downstream, will capture oil mists, as well as water droplets that separators miss.
Drains:
As water drops out of the air in the aftercoolers, dryers, and separators, the condensate collects and must be removed from the system via drains.
Oil water separators
Separate compressor oil from the condensed water to allow safe condensate disposal.
Drained condensate must be disposed of properly. Treated water that meets local environmental standards can be discharged into the municipal sewer system; However, concentrated oil and spent filter elements must be stored and collected by a certified hazardous waste disposal company.
How to Size a Condensate Drain
Condensate drain sizing is a critical step in managing compressed air condensate because sizing a drain too small leads to water carryover downstream, while over-sizing can cause unnecessary compressed air loss and higher capital costs.
Here’s how to size a condensate drain in three steps:
Step 1: Calculate condensate
Step 2: Know your pressure
Step 3: Match the volume to the orifice capacity
Step 4: Select the connection (port) siz
FAQ
How much condensate does an air compressor produce?
Exactly how much condensate is produced depends on the ambient air temperature, humidity levels, and operating pressure and flow. An industrial 100 CFM air compressor operating in average conditions (around 70°F and 60% relative humidity) can produce about 15 to 20 gallons of condensate 24 hour day.
Where does condensate form in a compressed air system
Condensate forms at every point where compressed air is cooled, including the aftercooler, dryers, and air delivery lines.
How much water does an aftercooler remove?
Aftercoolers remove about 70% to 80% of the bulk water from compressed air before it moves on to the dryer for further treatment.
What is pressure dew point (PDP)?
Pressure Dew Point (PDP) is the temperature at which water vapor in a compressed air system will condense into liquid water at the current operating pressure. If the temperature of your compressed air drops below the PDP, liquid water will begin to form.
Get Help Managing Your Condensate
Don’t let compressed air condensate damage your pneumatic equipment – or your productivity. Talk to Tavoron today. Our experts can help you accurately calculate your condensate, assist with condensate drain sizing and selection, and provide compressed air system service to safeguard your downstream tools and the quality of your air.
