I want to calculate degree of saturation of a brine with SG and temp known


by rezaxis
Tags: brine, degree, saturation, temp
rezaxis
rezaxis is offline
#1
Sep5-08, 06:32 AM
P: 7
I want to measure salt brines. I can measure specific gravity and degrees Fahrenheit. I need a formula into which I can insert the two measured values and resolve to get the degree of saturation of my brine.

I can't find a formula, so I'm not sure a formula exists, but I can't understand why not. I've been told it's all empirical knowledge. There are charts to adjust SG for temperature, and Hydrometers scaled with degree of saturation, called by various names such as a Brinometer, salometer, salinometer and such, but I don't have one of those. My hydrometer just measures specific gravity and is calibrated at 68 degrees Fahrenheit.

I'm finding brine measurement scales confusing. There are a lot of different salt solution scales. I seem to always get answers that try to lead me to % salinity which is not what I'm looking for. At 26.395% salinity water at 60 degrees Fahrenheit (I think) is a saturated solution and therefore is 100% saturated. Of course pure water is 0%. This is the scale I want to solve for.

Can you help me? Am I even posting in the right place? I've spent many, many hours on the internet searching for what I seek and have come up lacking. Maybe someone can lead me to the be all, end all reference on brine, or maybe there is a "Brine for Dummies" book out there?
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chemisttree
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#2
Sep5-08, 11:43 AM
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You could plot specific gravity vs. percent salinity and get a linear relationship. In the range of 3% to 3.7% salinity, the SG varies fairly linearly (r2=0.9837 for data at 15C and r2=0.9737 for data at 25C). The y-intercept is 0.9939 at 15C and 0.9980 at 25C, which is close enough in my book.

From there you could scale the percent salinity to degrees of saturation by ratio using 0 degrees for 0 % salinity and 100 degrees for 26.395% (at what temperature?).

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