[BNC-all] Evacuation Recap - 4-18-12

[Weaver, John R]

On Wednesday, 18 April 2012, the BNC was evacuated for a Toxic Gas Monitoring System (TGMS) alarm. The cause of the alarm was determined and the building was cleared for resumption of activities approximately thirty minutes later.

Please note that a problem was observed during the evacuation. Most of the cleanroom personnel who were evacuating the facility went through the gowning room, causing a significant bottleneck in that area and delaying the exit of many people. Please note that during an evacuation the nearest emergency exit should be used - not the gowning area. Following this procedure, as explained in your building training class, will decrease the amount of time it takes to evacuate the facility. Please use this note as a reminder to USE THE NEAREST EMERGENCY EXIT WHEN EVACUATING the cleanroom and the facility.

This evacuation was caused by a flaw in the TGMS. When the batteries on the wireless sensors near depletion - but are not fully depleted - the sensors can send spurious signals that trigger an alarm. A very low percentage of sensors have exhibited this behavior, but it has happed on about several occasions. This issue was not discovered previously because the system is just now reaching an age where the batteries are nearing depletion. 

Two corrective actions are currently underway. First, all batteries in the sensors - about sixty sensors - are being replaced. While we are not currently at the expected life of the batteries, we are close enough that this has been determined to be a prudent approach to the issue. Not all batteries age at the same rate, so we are taking the conservative approach and changing all the batteries. Second, we are working with the company that supplies the sensors to implement a software change that will make this type of spurious signal a warning rather than a danger alarm. This means that such an occurrence will page the appropriate people but not evacuate the building. This will NOT diminish the response to real alarms, such as the electrochemical sensors that are also part of the wireless system. It will, however, eliminate this source of false-alarm evacuations.

Please contact me if you have further questions.

John 

John R. Weaver
Facility Manager
Birck Nanotechnology Center
Purdue University
(765) 494-5494
jrweaver at purdue.edu