To test the specific gravity of the prepared anti-freeze solution the inspector will use which item?

To test the specific gravity of the prepared anti-freeze solution the inspector will use which item?

• A. Multimeter
• B. Pitot gauge
• C. Refractometer
• D. Tachometer

Answer: (C)

To determine the specific gravity of an antifreeze solution, you need a way to gauge how much glycol is in the mix, since density changes with glycol content. A refractometer does this by measuring the refractive index of a small drop of the solution. The refractive index shifts with glycol concentration, and you read a value on the scale that, using the manufacturer’s calibration, converts to the glycol percentage or directly to the specific gravity. It’s quick, requires only a tiny sample, and works well for prepared antifreeze solutions in the field. The other tools don’t fit this purpose: a multimeter checks electrical properties, a pitot gauge measures air or fluid flow pressure, and a tachometer gauges rotational speed. None of those measure liquid density or glycol concentration, which is why the refractometer is the appropriate instrument.

To determine the specific gravity of an antifreeze solution, you need a way to gauge how much glycol is in the mix, since density changes with glycol content. A refractometer does this by measuring the refractive index of a small drop of the solution. The refractive index shifts with glycol concentration, and you read a value on the scale that, using the manufacturer’s calibration, converts to the glycol percentage or directly to the specific gravity. It’s quick, requires only a tiny sample, and works well for prepared antifreeze solutions in the field.

The other tools don’t fit this purpose: a multimeter checks electrical properties, a pitot gauge measures air or fluid flow pressure, and a tachometer gauges rotational speed. None of those measure liquid density or glycol concentration, which is why the refractometer is the appropriate instrument.