What is the percentage range at which the upper explosive limit (UEL) for ammonia ends?

The correct answer indicates that the upper explosive limit (UEL) for ammonia falls within the range of 25% to 28%. The UEL represents the maximum concentration of a substance in the air at which combustion can occur. Beyond this threshold, there is not enough oxygen present to sustain a fire or explosion.

For ammonia, the UEL is specifically identified at around 28%, meaning that ammonia concentrations above this level will not support combustion. Understanding the UEL is crucial for safety in environments where ammonia is used or stored, as it informs the necessary measures to control concentrations and prevent hazardous situations.