Anyone have a R/H or Dew point charts in Excel?

Before I spend alot of time creating re-inventing the wheel, I was wondering if anyone has put something together that takes the dry bulb temperature and wet bulb temperature and figures the R/H and dewpoint for you?

My painting department has to send their electronic instruments out for calibration, so I was trying to come up with something help them determine if the Dewpoint and Humidity was in a range that is acceptable to apply paint or not. They have a sling psychrometer to find the wet/dry bulb temps.

I found two online(Excel 2003, Excel 2010)....if anyone else is interested.
http://www.numlog.ca/psychrometrics/psychrocalc.html

I had these in a corner of my Personal Book, where they've been for years - maybe they'll help??

Temp 49 9.444444444 Temp 49 =5/9*(T21-32)
Dewp 37 2.777777778 Dewp 37 =5/9*(T22-32)
1.220767873 =10^(7.5*U22/(237.7+U22))
1.934670557 =10^(7.5*U21/(237.7+U21))
Rh = 63 % Rh = =INT(U23/U24*100) & " %"

Here is the workbook that I found lonline and edited for my use...it's free so I thought I would share if anyone needs something like this.



my edited copy of that file wasn't updated...so I have uploaded it again.

Thank you xladept, I appreciate the math formulas. I don't have to get extremely precise or anything until the dewpoint and surface temperature of the steel that we need to paint start to get too close. When we get within 5°F we have to cease painting until conditions get better. I realize that this subject can get really deep and complicated if one has to be very precise. I added some conditional formatting rules to the Excel workbooks that I posted a link to. I added a cell to enter the surface temperature, and then another to place a formula in subtracting the Dew Point Temperature from the Surface Temperature...it turns Red when they are within 5°F or less of each other and turns Green if they are farther apart than 5°F. This lets my painter know whether he can paint or not at the time of the temperature readings.

Yeah, my brother used to paint the Carlton Bridge in Bath, Me - when they finished at one end they'd start again at the other - Bridges being over water, you'd think that you'd need better than 5 degrees difference.

It sounds like you've developed a very useful tool

How do you delete your uploads in the upload manager?.....the first of those two is the older unedited version and would like to delete that one.

Can't you just right click it and choose delete??

Originally Posted by xladept

Can't you just right click it and choose delete??

Nope, it wouldn't delete the file from the list when selected...I did find that there is a hidden "x" in the corner of the box showing the attchments in that post(if you roll your mouse over the corner, you can find it)...I clicked the (hidden)"x" and it deleted the attachment.

Glad you got it

I ended up starting back over from scratch. The original had macros in it and it worked fine, but it was a bit overwhelming for my painter, and I wasn't sure if it would run well on other machines, so I made a new workbook that uses all worksheet functions instead of macros. I found several typos in the relative humidity and dew point charts that were published and we had been using for years...LOL, never knew the errors were there until I sat down and did the math and was typing in the charts to Excel. Hopefully someone else will find this useful. The only cells that can be typed in are the one's that my painter would enter his information into, the rest of the workbook is locked. If you see an error or need to change something to your liking, the PW is " paint ".

I just found an error...the named range RH_Table should cover this range:

=RH_Table!$B$3:$U$71

it currently only covers over to column "P" and should cover to column "U"

Attachment with the named range fixed to cover the entire table. I should have proofed the file before attaching to my posting yesterday.