Propylene Glycol Boiling Point Calculator — Boiling Temperature vs Concentration and Pressure

The boiling point is the temperature at which a liquid transitions to vapor at a given pressure. Adding propylene glycol to water raises the boiling point above 212 °F (100 °C) — an effect called boiling point elevation. The boiling point also rises with system pressure; at 2 ATM a 30% V/V solution boils at approximately 262 °F (128 °C), compared to 217 °F (103 °C) at 1 ATM.

Operating above the boiling point causes vapor formation, which leads to cavitation in pumps, vapor lock in heat exchangers, and loss of system pressure control. In pressurized closed-loop HVAC and process cooling systems, the actual system pressure sets the effective boiling point of the glycol solution — which is why higher-pressure systems can operate at higher temperatures without boiling. This chart provides the maximum safe operating temperature at each concentration and pressure combination.