What Does Low-Pressure Warning Device Mean?
A low-pressure warning device is a mechanism attached to a breathing apparatus that alerts the user when their supplied air reaches a residual pressure of 55 (+/- 5) bar. This corresponds to approximately ten minutes of breathable air, and the alarm is meant to provide the user sufficient time to remove themselves from a hazardous situation before running out of oxygen.
Safeopedia Explains Low-Pressure Warning Device
Workers who enter confined spaces or other areas that might have hazardous or oxygen deficient atmospheres must do so while wearing appropriate respiratory protection. In some cases, this will include a self-contained breathing apparatus (SCBA), escape breathing apparatus (EBA), or an emergency escape breathing device (EEBD). All of these supply the user with air from an external source and, as such, have limited capacity.
To ensure the safety of workers, these have a low-pressure warning device installed to warn when the air supply is running low.
These warnings signal to the user that they have approximately ten minutes of breathable air left. The duration is only an approximation since the rate of air supply is determined in part by how deep the user breathes.
Components of a Breathing Apparatus
In addition to a low-pressure warning device, a breathing apparatus will have the following components:
- Pressure gauge
- Pressure reduction valve
- Demand regulator
- Head harness
The supply of air required by the user is controlled by the demand regulator. The pressure gauge indicates cylinder pressure and is connected to the cylinder through a high-pressure hose. The facemask includes a regulator, exhalation valve, head harness, visor, and speech diaphragm.