Propylene Glycol Frost Protection Calculator — Burst, Protection, and Freezing Point Temperatures

Propylene Glycol Frost Protection Chart

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Data from "Propylene Glycol Industrial Grade", Carpemar 2016

Toggle data sets by clicking the legend.


Freezing Point per ASTM D 1177: First ice crystal formation.
Protection Temperature per DIN 51583: Fluid stops flowing, circuit integrity at risk.
Burst Temperature: Limit before pipe/component failure.

Propylene Glycol Frost Protection Calculator
Burst Temperature (°C):  
Burst Temperature (°F):  
Protection Temperature (°C):  
Protection Temperature (°F):  
Freezing Point (°C):  
Freezing Point (°F):  
Frost Protection of Propylene Glycol
Three Temperature Thresholds

Propylene glycol frost protection is defined by three distinct temperatures, each more conservative than the last:

Freezing Point (ASTM D 1177) — the temperature at which the first ice crystals form. Below this point the mixture is a slush of ice and liquid that still flows without expanding, so pipes are not yet at risk.

Protection Temperature (DIN 51583) — the temperature at which the fluid stops flowing and circuit integrity is at risk. This is the threshold engineers use to size freeze protection.

Burst Temperature — the limit below which pipe or component failure from expansion pressure becomes likely.

Selecting the Right Concentration

The protection temperature — not the freezing point — should be used when selecting a glycol concentration for a given design low temperature. For example, a system designed for a minimum ambient of 14 °F (−10 °C) requires approximately 30% V/V propylene glycol to maintain flow. Using the freezing point instead would underestimate the required concentration and leave the system vulnerable.

Note: Higher glycol concentrations reduce heat transfer performance. Avoid over-concentrating beyond what frost protection requires.

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