What minimum percentage of rated maximum pressure should a fire fighter's SCBA cylinder have before donning?

Before donning a self-contained breathing apparatus (SCBA), it is essential for firefighters to ensure that the SCBA cylinder is at a sufficient pressure to provide adequate air supply during operations. Typically, the minimum percentage required is set at 90% of the rated maximum pressure. This ensures that the firefighter has enough breathable air to safely perform their duties without the risk of running out of air prematurely.

This threshold accounts for factors such as the duration of the operation and the potential for increased air consumption due to physical exertion or high-stress situations when fighting fires. By requiring a minimum of 90% of the cylinder's capacity, firefighters can maintain a margin of safety and reduce the risk of air depletion, which is critical in emergency scenarios where conditions might change rapidly and unexpectedly.

In contrast, lower minimum pressures may lead to inadequate air supply, particularly in prolonged operations, which is why it's essential to adhere to the guideline of having at least 90% of the rated maximum pressure before donning the SCBA.