Which gas ignites at a lower concentration in the air?

In the context of gas ignition, the concentration in air at which a gas can ignite is crucial for understanding safety and operational effectiveness. Propane has a lower lower explosive limit (LEL) compared to the other gases listed and is therefore able to ignite at a lower concentration in the air.

For propane, the LEL is around 2.1%, which means it can ignite in air at a lower concentration compared to natural gas, which has a higher LEL (approximately 5%). This characteristic makes propane a more volatile fuel at lower concentrations, allowing it to ignite more easily under appropriate conditions.

Understanding the flammability limits of different gases is essential for ensuring proper design and safety protocols when working with gas-fueled appliances.