PASS device

For other uses, see PASS (disambiguation).

PASS device (red square) integrated into an SCBA unit to be armed automatically when the air circuit is opened (green line).

A PASS device (Personal Alert Safety System) also known as an ADSU (Automatic Distress Signal Unit), is a personal safety device used primarily by firefighters entering a hazardous (IDLH) environment such as a burning building, which sounds a loud audible alert to notify others in the area that the firefighter is in distress.

The PASS device will automatically activate if the device does not detect motion for a certain short period of time, typically 15-30 seconds, so that the alert will sound if the firefighter is seriously injured or otherwise incapacitated. Some devices use a ball bearing on a track to sense firefighter movement and others utilize an infrared beam against a mirror mounted on a spring. When activating for a lack of motion, the PASS device will typically emit a few seconds of a muted warning that activation is about to occur, so that a firefighter who has simply been motionless for a time but is otherwise safe will be able to move slightly and thus reset the activation timer before a false activation occurs. The PASS device can also be activated manually in an emergency, such as when a firefighter is lost or trapped.

While older models of PASS devices required manual arming by firefighters prior to entering a dangerous environment, the current application integrates the PASS device into the self-contained breathing apparatus (SCBA) worn by firefighters so that it automatically arms when the SCBA air supply is engaged or when the SCBA is removed from its mounting bracket. These style devices are powered by battery, are easily activated while wearing gloves, and are intrinsically safe to operate in flammable or explosive atmospheres.

When activated, according to OSHA standards which apply in the United States, the PASS device emits a high-pitched audible alert of at least 95 decibels. On a fireground, the sound of an activated PASS device indicates a true emergency and results in an immediate response to rescue the firefighter(s) in distress.

See also

• Glossary of firefighting equipment