At what percentage by volume is the minimum permissible oxygen level?

The minimum permissible oxygen level in a combustion environment is generally recognized to be around 19.05% by volume. This level is significant because it provides enough oxygen for efficient combustion of hydrocarbons, such as those found in LP gas, while still maintaining safety. Below this concentration, there is an increased risk of incomplete combustion, which can lead to the production of harmful gases, such as carbon monoxide, and a risk of explosion due to an overly rich mixture.

In safe combustion practices, maintaining a minimum concentration of 19.05% oxygen ensures operational efficiency and minimizes the risks associated with diminished oxygen availability, such as asphyxiation hazards or incomplete combustion leading to carbon monoxide buildup. This threshold is essential in various applications, including residential and commercial heating systems, ensuring that they function correctly and safely.