Digital Refractometer for Ethylene Glycol Analysis

This Hanna Instruments digital refractometer measures ethylene glycol concentration, and the freeze protection it gives.

Why it is measured

A glycol loop that has been topped up with water no longer protects to the temperature written on the tag, and nobody finds out until something freezes or corrodes. The concentration is the only way to know, and it takes seconds.

Where it is used

• chilled water and HVAC loops
• refrigeration systems
• engine coolant checks
• solar thermal circuits

How a refractometer works

Light bends by a different amount depending on how much is dissolved in a liquid. A refractometer measures that bend and converts it to a concentration scale. It needs one or two drops, gives an answer in seconds, and has no reagents and nothing to consume.

A digital instrument compensates for temperature automatically, which is the difference that matters: refractive index shifts with temperature enough that an uncompensated reading in a warm room is simply wrong.

Practical note

Ethylene and propylene glycol read on different scales; using the wrong one gives a confident number that is simply wrong.

Supplied as one model.