What is a potential hazard of excessive heat when isolating a filled vessel?

Excessive heat when isolating a filled vessel can lead to the expansion of refrigerant. In a refrigeration system, refrigerants are typically stored in liquid form under pressure. When heat is applied to a sealed vessel containing a liquid refrigerant, it can cause the temperature of the liquid to rise, resulting in increased pressure within the vessel due to the expansion of the refrigerant.

As the refrigerant heats up, it transitions from a liquid state to a gas, which further increases pressure levels. If the pressure exceeds the vessel's design limits, it can lead to catastrophic failure, such as rupture or explosion. This makes understanding and managing pressure changes due to heat essential for maintaining safety in refrigeration systems.

In contrast, boiling of refrigerant refers to the phase change from liquid to vapor, which could also be a concern but is a secondary consequence of heat that leads to pressure increase. Cooling of the vessel would not be a hazard related to excessive heat, and condensation of gas typically occurs under cooling scenarios rather than heating, highlighting the importance of acknowledging the effects of heat on the refrigerant's state and pressure.