Pneumatics
Moisture & Condensate in Compressed Air
Calculate the amount of condensate water produced by a compressed air system per day, based on ambient temperature, humidity and system pressure.
Units:
At 25°C and 70% relative humidity, a 250 nl/min compressor running 8 hours produces over 3 litres of condensate per day. Install automatic condensate drains at ALL low points. Use refrigerant dryers (dew point +3°C) or adsorption dryers (dew point −40°C) for moisture-sensitive applications.
W [g/kg] = Ps(T) × RH/100 / P_abs × 622 (Mollier diagram) | Condensate = (W_in − W_out) × m_air
Input
Ambient temperature iTemperature of the air being drawn into the compressor in °C.
°C
Relative humidity iRelative humidity of the ambient air in %. Typical range: 40–80%. Check local weather data for your worst-case month.
%
System pressure iWorking pressure of the compressed air system in bar gauge.
bar
Temperature after aftercooler iTemperature of the compressed air after the aftercooler and receiver tank in °C. Typically 20–40°C. Lower = more condensate removed before use.
°C
Compressor capacity iFree air delivery (FAD) of the compressor in normal-litres per minute. From compressor datasheet.
nl/min
Operating hours per day iNumber of hours the compressor operates per day.
h/day
Result
Moisture content (ambient air) [g/kg]
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Moisture content (compressed air) [g/kg]
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Condensate per day [g/day]
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Condensate per day [litre/day]
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Condensate per year (250 days) [litre/year]
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