What is the upper explosive limit by volume for the substance?

The upper explosive limit (UEL) refers to the highest concentration of a substance in the air that can lead to an explosion. For many flammable substances, this limit is crucial to ensure safety in operations, especially in industrial contexts such as refrigeration.

In this case, an upper explosive limit of 25% by volume indicates that when the concentration of the flammable substance in the air reaches this level, it is no longer capable of supporting combustion. The air-fuel mixture could be too rich, which means there is too much fuel and not enough oxygen to sustain a combustion reaction. Understanding this concept is vital for operators to prevent hazardous situations, as exceeding this limit could create a situation where ignition could be dangerous.

Knowing the UEL allows operators to implement safety measures and maintain concentrations of flammable substances below this threshold. This understanding is essential for maintaining compliance with safety regulations and ensuring the welfare of personnel and equipment in industrial settings.