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Water Vapor Saturation Pressure
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I use this as a snippet. Where do we post Snippets for others to use? Optimization encouraged. This is based off of 2017 ASHRAE Fundamentals equations Jean, Looking forward to "cleaning up the Gyzma"  Water Vapor Saturation Pressure.sm (21kb) downloaded 32 time(s).Edit, Started playing with the CoolProp plugin ... Quote:CoolProp_Props("P","T",80*'°F,"Q",0,"Water" ) gives tabular results that match the function playing with the temperature of 80*'°F in the NOT ice region (>32°F) Edited by user 11 February 2021 09:49:56(UTC)
| Reason: Updated file; Update CoolProp comment
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Originally Posted by: ElSid  Looking forward to "cleaning up the Gyzma" Interesting, World is SI [and derived SI] 4.1635019*10^0 = 4.1635019 Interesting the split range below triple point [0.01 °C] Cheers Elsid .. see U
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Originally Posted by: Jean Giraud Interesting, World is SI [and derived SI] Yes, there is error because the original equations and constants are SI ... unit conversion and round off. Originally Posted by: Jean Giraud 4.1635019*10^0 = 4.1635019 Copy and paste from the handbook ... Consistent since all other values have a power Originally Posted by: Jean Giraud Interesting the split range below triple point [0.01 °C] Actually, it overlaps! I could not find a good way of using a single value, so I chose one. The documentation for both equations technically hit 32F.
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Originally Posted by: ElSid Actually, it overlaps!I could not find a good way of using a single value,
so I chose one.The documentation for both equations technically hit 32F. The classical Water Vapor Saturation Pressure starts @ the Triple Point [ 0.01°C] Advanced formulas up to the Critical Point. From so I chose one, your formula may be completely zombie trying to overlap the ice region. You should never/ever extrapolate a polynomial approximation outside of its designed range. So, you have put something in Samples, something not doctored, that will confuse Smath Community. Don't take it bad, just a remark. Just posted a minute ago, you will find the ice region in "Samples Psychrometry'.
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Jean, As I mentioned, it comes from 2017 ASHRAE Fundamentals Handbook. Feel free to argue with them the use of polynomials  . I cannot think of a way to capture 32 F from solid or liquid ... for engineering purposes, close enough; unless you have one of your magic programing loops  . Based on the polynomials, here is a snippet of the chart from the 2017 Fundamentals handbook @ 32F 
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Martin, I'm responding to your response under the "bugs" blog here Originally Posted by: mkraska Let the psi unit be psia and introduce an undefined unit psig with appropriate conversion functions.
This approach prevents you from mixing both types of pressure representations, because you would get a unit mismatch error.
It doesn't, however, prevent you from adding psig values, which might not be a good idea.
All in all this is a conversion very much like between K (absolute) and °C (gauged), just with the nasty difference that the offset isn't constant and has to be specified whenever a conversion is to be done. Doing it that way, I could not add psia ... in some of my sheets. Re-defining ATM to the actual site ATM appears to be the best way to do this at this time. I'll post another worksheet where this is applied after I clean up my notes
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Originally Posted by: ElSid I cannot think of a way to capture 32 F from solid or liquid ...
for engineering purposes, close enough @ 32 F, can you not get ... 0.611*kPaAbs ... 0.0886181*PSI Just put all those numbers in vector and attempt Σ polynomials, I will check from there. There must be a formula nearly executable. Revisit the latest "Psychrometry Refactored"
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Originally Posted by: ElSid I cannot think of a way to capture 32 F from solid or liquid ... in fact, @ the water triple point [32.02 F] the saturation pressure is seemingly undefined, and not listed in WASP, but it does exist for true ! 0.611*kPaAbs.
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I updated the first post attachment using cases() and incorporating comments from above. Close enough for engineering purposes
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