Digital Refractometer for Propylene Glycol Analysis

This Hanna Instruments digital refractometer measures propylene glycol concentration and its freeze protection.

Why it is measured

Propylene glycol is the glycol used where a leak could reach food, drinking water or people, because it is far less toxic than ethylene glycol. It is also less efficient thermally, so its concentration is usually higher and matters more.

Where it is used

• food and beverage refrigeration
• brewery glycol systems
• potable-adjacent HVAC
• pharmaceutical cooling

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

Never substitute ethylene glycol in a propylene system to save money; the reason the system specifies propylene is what a leak would touch.

Supplied as one model.