Specific gravity is a measure of density, so yes, should be linear with concentration of material

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Thank you. I plan to purchase a salinity refractometer as they have the scale to work in that range. I will verify against a sample with a known correct dose.

Yes, to bolster IRstuff's comment and your own plan. Setting an acceptable refractive index range is a pretty darn reliable way to field-test coolant concentration once you know your reference points.

- Andrew

Ideal or nonideal solutions
https://eduinput.com/non-ideal-solutions/

https://chem.libretexts.org/Bookshelves/Physical_a...'s_Conundrum_-_Partial_Molar_Volume_in_Water-Ethanol_Mixtures

https://chem.libretexts.org/Bookshelves/Physical_a...

--Einstein gave the same test to students every year. When asked why he would do something like that, "Because the answers had changed."

At the low concentration that you are using, and with the wide tolerance, it is reasonable to assume that the density/SG will vary linearly with concentration.

Using a refractometer would also be a reasonable way to measure the concentration but remember that a refractometer measures refractive index and does not measure concentration. Many refractometers are calibrated in concentration units but that is because they are calibrated for specific compounds. So you will find refractometers that are designed to measure the salt concentration of brine solutions - but they actually measure the refractive index and since the manufacturer knows how the refractive index varies with salt concentration they can calibrate the refractometer in concentration units. But if a refractometer designed to measure salinity were to be used to measure sugar concentration it would not be accurate. So your saline refractometer will probably not give you accurate concentrations unless you recalibrate it for your specific coolant.

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http://katmarsoftware.com

"An undefined problem has an infinite number of solutions"

Additive concentration of 5-10% can mean one of many things :
5-10% by weight in final solution
5-10% by volume in final solution
5-10% of additive by wt to coolant
5-10% of additive by vol to coolant

What is on the instructions for this additive ?
Some of these additives are not compatible with the coolant or the materials of construction in the cooling jacket, recirc pump and/or radiators - tread carefully.

This is what I have to work with.

https://cglapps.chevron.com/msdspds/PDSDetailPage....

Hi,
Why don't you purchase a densimeter? I will check for Anton Paar and/or Mettler Toledo.
I've got great success using Anton Paar for the dilution of acidic rare earth nitrate.
You need to establish first the curves (concentration vs density and temperature).
Pierre

The densitometer seems to be calibrated in the same ranges as the refractometer. I don't see anything specifically related to carboxylate concentration. At this point I'm leaning towards the salinity refractometer and building my own correction table.

Google tells me Delo ELO was previously called Delo XLI-N.

Here is a XLI-N pamphlet that may be of use:

https://www.chevronmarineproducts.com/content/dam/...

HI,
You may want to contact this company.
https://www.vaisala.com/en/measurement/liquid-conc...

Pierre

FYI density does not always change linearly with mixing two miscible liquids due to non-ideality. The classic example is water and ethanol. 1 m3 H2O water + 1 M3 EtOH < 2 m3 mixed solution.

I guess the density difference is too small to be able to measure with a small portable scale and density cup? Refractometry can have its own issues - you have to know that the coolant always has the same refractive index, you have to calibrate the refactometer to the solution, AND you have to always measure at the same temperature.

Not sure density really gives you much information either...but pH will indicate when the inhibitor is "used up" - i.e. if the pH drops below 8 it's gone south.

Thanks, George. Your link contained a correction chart that correlates brix to coolant concentration. Off to the printer now. I had found a Chevron branded refractometer and couldn't figure out why it was calibrated in Brix.

Hi,
A few data from Rohm about refractive index of acrylates at 20C :
methyl methacrylate :1.415
2 ethyl hexyl methacrylate: 1.439

Pierre