According to NIOSH regulations, the primary low pressure warning device must alert the user at 35% ± what percentage?

The primary low pressure warning device in a self-contained breathing apparatus (SCBA) plays a critical role in ensuring the safety of the user by providing an alert when the air supply is running low. According to NIOSH regulations, the device must activate at 35% of the cylinder’s pressure, with an acceptable tolerance of ± 2%. This means that the warning should reliably occur between 33% and 37% of the cylinder capacity.

The reasoning behind this specific percentage ensures that the user receives an early warning before reaching a critically low level of air. A ±2% tolerance allows for some variability in different SCBA models, as well as in operational conditions, while maintaining a standard to safeguard the user's safety in hazardous environments. Therefore, the correct understanding of the regulation emphasizes the importance of having the warning device set within this precise range to ensure effective and timely alerts.