Saturated steam properties
Saturation temperature and latent heat of saturated steam versus pressure. These are the core numbers for steam heating and process work: at what temperature steam forms, and how much energy it carries.
Saturated steam
| Abs pressure (bar) | Sat. temp (°C) | Sat. temp (°F) | Latent heat (kJ/kg) |
|---|---|---|---|
| 1.0 | 99.6 | 211 | 2258 |
| 1.5 | 111.4 | 232 | 2226 |
| 2.0 | 120.2 | 248 | 2202 |
| 3.0 | 133.5 | 272 | 2163 |
| 4.0 | 143.6 | 290 | 2133 |
| 5.0 | 151.8 | 305 | 2108 |
| 6.0 | 158.8 | 318 | 2086 |
| 8.0 | 170.4 | 339 | 2048 |
| 10 | 179.9 | 356 | 2015 |
| 15 | 198.3 | 389 | 1947 |
At each pressure, water boils at the saturation temperature shown, and steam condenses back at that same temperature. The latent heat is the energy released when a kilogram of steam condenses to water, and it is the main heat delivered by steam systems. As pressure rises, the saturation temperature climbs but the latent heat per kilogram falls.
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Why steam heating uses latent heat
When steam meets a cooler surface it condenses, releasing its large latent heat at a constant temperature set by the pressure. This is far more energy per kilogram than simply cooling hot water, and it is delivered at a steady temperature, which is why steam is so effective for heating, sterilizing, and process work. Raising the pressure raises that delivery temperature.
Pressure sets the temperature
Steam temperature and pressure are locked together along the saturation line: pick one and the other follows. A boiler run at 5 bar delivers steam at about 152 degrees C; raise it to 10 bar and the temperature rises to about 180. This is how steam systems are controlled, by setting the pressure to get the temperature the process needs.
FAQ
What temperature is steam at 10 bar?
About 180 degrees C (356 degrees F). Saturation temperature rises with pressure along the steam line.
What is latent heat of steam?
The energy released when steam condenses to water at constant temperature, about 2258 kJ/kg at atmospheric pressure. It is the main heat delivered by steam.
Why does steam temperature depend on pressure?
Saturation temperature and pressure are tied together. At higher pressure water boils hotter, so steam is produced and condenses at a higher temperature.