Boiling Point of Water

this should help:

http://www.engineeringtoolbox.com/boiling-point-water-d_926.html

http://www.efunda.com/materials/water/steamtable_sat.cfm (Ithink that at full vacuum, the water will boil out of ice, which would be 32 degrees F in the pressure box, enter 29.921 in of mercury to represent full vacuum)

http://www.uow.edu.au/eng/phys/200labs/phys235/boiling.pdf (this one explains the equation used in the nlreg link)

http://www.nlreg.com/boil.htm

Any of these should get you close.

milo

Would sublimation be considered "boiling"?

Thanks to all - but MILO put me right on. I have what I need - thanks to others but the info I needed was not generating steam usually to make pressure but to boil water at reduced pressure - of no interest to steam makers.

The appendix A-3 of "Fundamentals of Engineering Thermodynamics, 6th ed" M.J.Moran and H.N.Shapiro, has a table of temp vs Psat that should be helpful for this task. Unfortunately data for a perfect vacuum does not exist due to physical limitations.

The table pointed out by Guru seems to be the best and this is what I keep ending up.

I think we can say that it will be below 30º C at an easily obtained commercial vacuum. Probably best practical would be in the region of 28º the slope of the graph tells be it cannot get much lower.

The point that ice sublimes I was aware of otherwise no freeze drying. Which brings to one other point that is if there is no atmosphere on mars or the moon then surely there can be no water otherwise the atmosphere would contain water vapour so what are these guys looking for.

I think what is misunderstood is that water cannot be H2O as, in accordance with the periodic system, it should be a poison gas like H2S or H2Se or NH3 or HF. I think the theory is that the hydrogen bonding must make a change so it does not follow the basic rules.

Thanks for the reply - someone might yet have a simple straight forward table with the numbers that is if anyone has actually been able to determine them. I feel that this could be tricky & not something to be done in the normal distillation setup.

hazman

earlier WASP programs (Water and Steam Properties) used to be free, but if you do alot of work buying it should work out.

I used it about 10 years ago for designing an vacuum distiller, as well as programs I wrote.

try this site.

http://www.chempute.com/waspwin.htm

good luck,

phoenix911

The following link will allow you to look up information on the boiler point of water - this is the point where water changes to a gas (steam).

I hope it helps....

http://www.spiraxsarco.com/us/resources/steam-tables.asp

-> Steam Tables.

steam tables are all u need or you could just give all ur related problems to a mechanical eng. we seem to know whats best when it comes to thermodynamics..l