Quote:
Originally Posted by IamIan
That water phase changed to steam ... expanded to fill the volume of the container ~39.04cc ... as any gas will do ... because there was not room for the full ~1700:1 expansion that would result at a lower ~14.7psi pressures the steam contributes a bit more than ~14.7psi ... I'm estimating ~26 psi.
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Ok, so even with the assumption that 1700:1 is not changeable at all, the final system pressure is still lower than the initial system pressure.
People can disagree all they want on this point. However, it doesn't change the fact that this much-ballyhooed expansion ratio is variable.
For instance, saturated steam at 120 C has a pressure of about 20 psia. It also has a expansion ratio of 1150:1. This is directly out of the steam tables, and doesn't change at all for saturated steam at 120 C. Saturated steam at 153 C has a pressure of 75 psia, and an expansion ratio of 332:1. The original 1700:1 ratio is a firefighter's rule of thumb, developed to let people guess how much steam would be produced in the course of fighting a fire.
Again, this 1700:1 ratio is not a fixed, immutable ratio to be held holy for all time, and it certainly should not be the basis for any reasonable engineering design. It changes due to whatever temperature saturated steam is.
One other thing: I'm not saying that saturated steam at 212 F is 14.7 psia because it amuses me to do so. I'm saying that saturated steam at 212 is 14.7 psia because this figure is directly out of the steam tables, which were themselves developed during the reign of the steam engine.