Hello Peter, I've downloaded Kahn calculator also. It seems to me that you took "Humidity data" menu to get the datasheet you sent in last mail. I suspect this is wrong. If you try "Moisture content" calculator, you would see that calculated dewpoint depends on the pressure, although it is written in the title "calculated values @ atmospheric". We of course used "over ice" values from the handbook in our formula. I tried to calculate some data points using this "Moisture content" calculator (every 5 degree), and plot them together with our formula results. As you can see in attached plot, they are almost the same. So I think there is no reason to change the formula. Best regards, Peter. Wednesday, June 29, 2005, 1:39:21 AM, you wrote: > On Tue, 28 Jun 2005, Peter Kravtsov wrote: >> Hello Peter, >> >> Our humidity graph is corrected to 17 bar pressure of course. >> I took the saturation vapor pressure from reference book for >> different temperatures, and fit this dependence. >> The complete formula for calculating ppm from T_dewpoint is: >> ppm = 10^(-43.42291 + 0.43575*T - 0.00149*T^2 + 0.00000188204*T^3) >> This formula works for 10 bar hydrogen. >> To correct the result for 17 bar, I simply divided it by 1.7. >> Is it not right? > Dear Peter, > I compared your equation with the Kahn calulator and the rubber bible > (Handbook of chemistry and Physics). Your equation seems to be > somewhat off the other references. But this does not > make a big difference. (see attachment). > There is not pressure dependence in the Kahn calculator with is > obviously wrong. > Regards > Peter -- Best regards, Peter mailto:pkravt@gmail.com
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