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Q & A: expansion of very hot steam

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Most recent answer: 12/04/2015
Q:
If water expands at a ratio of 1,700:1 when it changes to steam at 212 degrees F, what is the expansion ration of expansion if the conversion takes place at about 2,000 degrees F when we are firefighting in areas where the ceiling temperature can reach upwards of 1,500 degrees F?Jack RutledgeIllinois Fire Service Institute 404-229-3041
- John Rutledge (age 71)
Peachtree City, GA
A:

Water vapor under these conditions is close to being an ideal gas. That means that the volume occupied at atmospheric pressure grows proportional to the absolute temperature. The absolute T for water boiling is 373K. That 2000°F is about 1500K. So the volume would be about 4 times greater than for ordinary 373K boiling. The expansion factor would be roughly 7000.

Mike W.


(published on 12/04/2015)

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