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LiquidCosworth · 03-08-2006, 12:45 PM

Folks,

A hydrometer measures specific gravity and will be inaccurate as noted above. A refractometer measures the refractive index and should work for you. Index of refraction for water is 1.33,
polyethylene glycol ~ 1.47 (from this reference: http://www.biocompare.com/productdet...-USB-Corp.html)
polypropylene glycol ~1.45 (from this reference: http://www.dow.com/polyglycols/ppgc/...ducts/ppgs.htm)

They can be purchased in the US for $50, e.g. http://www.apexbattery.com/battery-refractometer.html

This is an explanation of how hydrometers and refractometers differ.
http://www.asashop.org/autoinc/feb2001/mech.cfm

Test strips will give you inaccurate results also due to the various anti-corrossion additives used; the newer, silicate-free additives, especially.

03-08-2006, 12:45 PM	#11
LiquidCosworth Cooling Neophyte Join Date: Feb 2006 Location: Torrance, CA, USA Posts: 2	Re: Coolants (again) Folks, A hydrometer measures specific gravity and will be inaccurate as noted above. A refractometer measures the refractive index and should work for you. Index of refraction for water is 1.33, polyethylene glycol ~ 1.47 (from this reference: http://www.biocompare.com/productdet...-USB-Corp.html) polypropylene glycol ~1.45 (from this reference: http://www.dow.com/polyglycols/ppgc/...ducts/ppgs.htm) They can be purchased in the US for $50, e.g. http://www.apexbattery.com/battery-refractometer.html This is an explanation of how hydrometers and refractometers differ. http://www.asashop.org/autoinc/feb2001/mech.cfm Test strips will give you inaccurate results also due to the various anti-corrossion additives used; the newer, silicate-free additives, especially.