The PASS device will automatically activate if the device does not detect motion for a certain short period of time, typically 30 seconds, so that the alert will 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.
US Patent Issued to Freescale Semiconductor on Feb. 19 for "Linear Regulator with Automatic External Pass Device Detection" (Illinois Inventors)
Feb 20, 2013; ALEXANDRIA, Va., Feb. 20 -- United States Patent no. 8,378,648, issued on Feb. 19, was assigned to Freescale Semiconductor Inc....
WIPO ASSIGNS PATENT TO NOVA SOUTHEASTERN UNIVERSITY FOR "A DOUBLE PASS DEVICE FOR RETINAL-IMAGE QUALITY MEASUREMENT" (AMERICAN INVENTORS)
Jun 07, 2011; GENEVA, June 7 -- Publication No. WO/2011/066305 was published on June 03. Title of the invention: "A DOUBLE PASS DEVICE FOR...