Water Content Compressed Air

Overview

Engineering reference data for Water Content Compressed Air in miscellaneous.

Key Formulas

Unit Conversion

$y = x \cdot k$

Multiply by conversion factor.

Linear Interpolation

$y = y_1 + \frac{(x - x_1)(y_2 - y_1)}{x_2 - x_1}$

Estimate between two known points.

Percentage

$p = \frac{\text{part}}{\text{whole}} \times 100\%$

Part as fraction of whole.

Variables

Water Content Data

Key Relationships

The water content of compressed air exhibits two fundamental behaviors:

• Decreases with increasing pressure — at constant temperature, higher pressure reduces the volume available for water vapor
• Increases with increasing temperature — warmer air has greater capacity to hold moisture

Unit conversion: 1 kg/m³ = 0.0624 lb/ft³

Example Calculation

Problem: Air enters a compressor at 20°C with 70% relative humidity. The air exits saturated at 8 bar (gauge) and 40°C. Determine the water extracted per unit volume of free air.

Step 1 — Inlet water content:

At 20°C and 0 bar gauge, saturated water content from the table:

$w_{sat,in} = 0.018 \text{ kg}_{H_2O}\text{/m}^3_{\text{free air}}$

Adjusted for 70% humidity:

$w_{in} = 0.018 \times \frac{70}{100} = 0.0126 \text{ kg}_{H_2O}\text{/m}^3$

Step 2 — Outlet water content:

At 40°C and 8 bar gauge from the table:

$w_{out} = 0.0062 \text{ kg}_{H_2O}\text{/m}^3_{\text{free air}}$

Step 3 — Water extracted:

$\Delta w = w_{in} - w_{out} = 0.0126 - 0.0062 = 0.0064 \text{ kg}_{H_2O}\text{/m}^3$

This condensed water represents approximately 51% of the inlet moisture content.

Interactive Charts

References

• Original Source