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Water density calculation, from temperature in F?
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mR_Slug
Member Posts: 10
Hi, I've been looking for a function that takes temp in F and returns the specific
weight in lbs/f3. I can find lookup tables, and found this https://antoine.frostburg.edu/chem/senese/javascript/waterdensity.html but was wondering if there is a simple formula for calculating this? It can be an approximation, so long as it is suitable for hydronics. Thanks
Read some of the idronics, but may I may have missed it.
weight in lbs/f3. I can find lookup tables, and found this https://antoine.frostburg.edu/chem/senese/javascript/waterdensity.html but was wondering if there is a simple formula for calculating this? It can be an approximation, so long as it is suitable for hydronics. Thanks
Read some of the idronics, but may I may have missed it.
0
Comments

There is no really simple formula  lookup tables should be more than adequate. Remember that the maximum density is a 39 F, not at freezing.Br. Jamie, osb
Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England0 
Yes the problem with a lookup table is you get a figure for 39F, one for 40F and so on. If you need 39.7, then you have to workout the slope of the graph and approximate the value. Its doable but a bit rubbish.
I'm trying to write some web/javascript pages, that can calculate thermopsyphoning. I got the calcs from an old book posted somewhere on this forum.
Thing is, i really don't want to reinvent the wheel here.0 
I think I have seen a formula out there somewhere... it runs to a number of nonlinear terms. Great fun. Within 10 degrees of freezing, the relationship is highly nonlinear, and you would need fairly closely spaced points for your interpolation. Above about or so , the relationship becomes much more linear (though never quite) and a simple interpolation between points even as much 5 degrees apart will be adequate to three significant digits  which is all you need. Writing an interpolation routine for your program should be trivial.Br. Jamie, osb
Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England0 
Try engineeringtoolbox.com. They usually have tables but also show the formula or math.
Modern HydronicHeating and Cooling has a chapter on water properties. The HDS software has a module for density also.Bob "hot rod" Rohr
trainer for Caleffi NA
Living the hydronic dream0 
bingo! Thanks that is perfect.0

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