What is the water content at a dew point of −34°C?

What is the dew point temperature?

The dew point temperature is the temperature at which compressed air, under constant pressure, cools to the point where water vapor begins to condense into liquid water. This temperature directly reflects the actual moisture content of the air—the lower the dew point, the drier the air.

Water content corresponding to a −34°C dew point

At standard atmospheric pressure (0.1013 MPa), the partial pressure of water vapor corresponding to a −34°C dew point is approximately 15. 8 Pa This translates to a volume ratio of roughly0.000156% (156 ppm_v), with a mass concentration of approximately0.29 g / m³ (per dry air).

Impact on compressed air systems

• It meets the low-humidity requirements of most precision pneumatic components, painting, electronic assembly, and other processes;
• it can effectively prevent ice formation in pipelines, valve sticking, and aging of cylinder seals;
• achieving this typically requires an adsorption dryer or a combination of deep refrigeration followed by adsorption.

Drying equipment selection guidelines

To reach a −34°C dew point, conventional refrigerant dryers are insufficient (their typical dew point is 2~ 7℃). Non-heated or low‑heat regenerative adsorption dryers should be prioritized, and the regeneration air consumption and pressure drop should be verified based on inlet air temperature, pressure, flow rate, and ambient conditions. A safety margin of 10–15°C should be built into the design to accommodate fluctuations in operating conditions.