Compressed Air - Water Content

Saturation pressure and maximum water content in compressed air. Calculate the mass of water in saturated air based on temperature and pressure conditions.

Water Content Calculator

This calculator helps determine the maximum water content in compressed air at saturated conditions. The water content depends on both the temperature and pressure of the air.

Note: The maximum water content decreases with increasing pressure and increases with increasing temperature.

Calculator

Inputs

Temperature (°C)

Gauge Pressure (bar)

Humidity Ratio (%)

Results

Water Content at 100% Saturation-- kg/m³

Water Content at Current Humidity-- kg/m³

Water Content at 100% Saturation (Imperial)-- lb/ft³

Temperature (°C)	Pressure 2 bar	Pressure 4 bar	Pressure 6 bar	Pressure 8 bar	Pressure 10 bar	Pressure 12 bar	Pressure 14 bar
0	0.0045	0.0015	0.00091	0.00065	0.00051	0.00041	0.00035
20	0.018	0.0058	0.0035	0.0025	0.0019	0.0016	0.0013
40	0.059	0.019	0.011	0.0079	0.0062	0.0050	0.0043
60	0.18	0.053	0.031	0.022	0.017	0.014	0.012
80	0.65	0.14	0.078	0.054	0.041	0.034	0.028
100		0.38	0.19	0.13	0.094	0.076	0.063
120		0.49	0.29	0.21	0.16	0.13	0.11

Water Content Reference Table

Mass of water (kg H₂O/m³ free saturated air)

Note: 1 kg/m³ = 0.0624 lb/ft³

Example Calculation

Free air enters a compressor at atmospheric conditions:

Inlet: 20°C, 70% humidity ratio
Outlet: 40°C, 8 bar gauge pressure, 100% saturated

Step 1: Water content at inlet (20°C, saturated) ≈ 0.018 kg/m³

Step 2: Water content at 70% saturation = 0.018 × (70/100) = 0.0126 kg/m³

Step 3: Water content at outlet (40°C, 8 bar, saturated) ≈ 0.0062 kg/m³

Step 4: Water extracted = 0.0126 - 0.0062 = 0.0064 kg/m³