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The Effect of Wildfires on Air Sampling Smoke Detectors

Posted by Lee Kaiser on Sep 28, 2020 12:45:16 PM

Wildfires are a fact of life for many areas of the United States. On a yearly average, California sees more than 8,000 wildfires burning 750,000 acres. The smoke from wildfires can and does affect fixed fire protection systems in buildings. Every year, ORR Protection receives several emergency callouts to address smoke detection systems in telecommunications, cable, and data center buildings that have been affected by the season’s wildfires.

When wildfires are near, smoke and ash in the atmosphere can penetrate the buildings and can affect early warning smoke detectors—especially VESDA systems and other aspirating smoke detectors. Under normal conditions, VESDA detectors are used for early warning of small, invisible amounts of smoke in critical spaces. But during the wildfire season, VESDA detectors can detect the smoke that has come into the building.

Most VESDA detectors are arranged to notify of smoke conditions at four levels: Alert, Action, Fire 1, and Fire 2. Depending on the severity of the smoke present in the building and how the detector levels were programmed, the detector may present as any four of these levels. HVAC units in buildings—unless modified for operation during wildfires—will bring in smoke from the outside with their outdoor air intakes.

ORR will receive an emergency service call-in from our customers when their VESDA detectors are not in the normal state. When our technician arrives at the building, they will check the building fire alarm panel to see the status, check the status of any VESDA detector, and check for any obvious signs of a fire or other thermal problem to make sure that a fire isn’t really occurring inside the building. Often the detector is doing its job and has detected smoke in the building, but in this case the smoke is present because of nearby wildfires.

For most buildings, our technicians will isolate the VESDA smoke detector temporarily so it doesn’t cause further erroneous warnings for the next 24 to 48 hours. Isolating (or bypassing) the detector disables its outputs to the fire alarm system or to other interfaces. After the smoke has passed, the technician will return to the site to put the detector back into normal service or work with site personnel to do the same thing over the phone. Jonathan, one of our California technicians and former apprentices, stated, “I was able to get the [wireless carrier] site back online in just a few minutes once the fire had passed.”

This nuisance alarm phenomenon for VESDA detectors does not often occur with other types of smoke detectors in buildings. However, laser spot smoke detectors are susceptible to the same conditions. Often in mission critical buildings there will be a mix of detectors, so the buildings are not without fire detection when the VESDA detectors are isolated.

When wildfires are in the area, consider ORR Protection as your partner to help you manage your fire systems. For your convenience, you can reach us from our 24-Hour Emergency Response page, our national emergency service number 800.800.5092, or fill out a contact form here.

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Topics: Air Sampling, Emergency Communications, Featured Article, Featured Blog, West Coast, Nationwide

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