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  • Determing freeze temperature

    I just purchased a new antifreeze tester(floating ball type) and checked my radiators. I didn't get the engines or the antifreezes to "normal operating temperature" as advised on the label and tested the radiators at the ambient temperature(50 degrees). They all tested to 2 balls floating which would indicate a freeze temperature of +5 degrees. I tried my old floating ball tester and it indicated -40 degrees at the same ambient temperature! I tried the new tester in plain cold tap water and it indicated 2 balls floating!
    Can someone explain how the floating ball testers operate,possibly explain my findings, and offer a more reliable way of the determing the level of antifreeze protection? Thanks Paul

  • #2
    I've had a couple of those floating balls devices where (some of) the balls were stuck. I flushed the device with warm 50% alcohol and it freed the balls until the next time I wanted to use it.

    Pops

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    • #3
      They measure the specific gravity of the solution, which varies with the concentration of the antifreeze. The type of antifreeze will affect the accuracy of the reading, so you need to match the tester to the type antifreeze you've got.

      Water with a high mineral content would have a higher specific gravity than pure water, so that might explain the tap water indication.
      Any products mentioned in my posts have been endorsed by their manufacturer.

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      • #4
        The most reliable tester is the refractometer type. It measures the specific gravity based on the refractive index of the fluid. They are very accurate but also cost more, of course.


        http://www.tormach.com/store/index.p...show&ref=31366
        Free software for calculating bolt circles and similar: Click Here

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        • #5
          Not hardness

          Originally posted by winchman
          Water with a high mineral content would have a higher specific gravity than pure water, so that might explain the tap water indication.
          The effect is too small to measure with that gear. 1000 ppm would be spectacular high hardness, truly noteworthy of mention, and that would only be "around" one part per thousand or a SG around 1.001 instead of 1.000 at STP. The actual figure would depend on the density of whatever is dissolved in the water, but if its measured in PPM in most cases, then the result will probably boil down to at most, "many ppm".

          What does show up is intense temperature dependance. Ethylene Glycol (the old poisonous green stuff) at a normal concentration varies from 1.100 on a really cold day to 1.040 right outta a near boiling overflow tank. Water varies a lot with temp, and not even linear.

          Actually, since the SG varies a heck of a lot more with temperature than with concentration, measuring SG is probably a better way to make a thermometer than to measure concentration. Hence the advice to put the sample in a glass jar at room temp for a few hours indoors, which I'm sure has killed uncountable housepets over the decades (very poisonous). This doesn't work in a fast paced commercial mechanic shop, then again their recommendations for fluid replacement are probably based more on maximizing revenue than providing the idea concentration, so...

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          • #6
            As for replacement of fluids to 'maximize' profit...

            Try replacing a heater core because of 5+ year old coolant has turned corrosive and corroded it and it now leaks all over your interiour

            Oh and btw, for this very simple operation of replacing the heater core, you must remove the ENTIRE DASH. At least, for the car I had to service... Last time I ever do that! And then get the hoses off the old heater core (usally requiring them being cut and replaced if now too short)
            Play Brutal Nature, Black Moons free to play highly realistic voxel sandbox game.

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            • #7
              Originally posted by Evan
              The most reliable tester is the refractometer type. It measures the specific gravity based on the refractive index of the fluid. They are very accurate but also cost more, of course.


              http://www.tormach.com/store/index.p...show&ref=31366
              x2 on the refractometer, also known as the OBAT (optical battery and antifreeze tester). Spend the money now = save more later.
              "I am, and ever will be, a white-socks, pocket-protector, nerdy engineer -- born under the second law of thermodynamics, steeped in the steam tables, in love with free-body diagrams, transformed by Laplace, and propelled by compressible flow."

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