Fire Alarm Systems

[Ragin Cajun]

Has anybody heard of a new requirement for low frequency notification devices, 520 hz and which type facilities is it required? I don't have a copy of the latest code.


RC

 

[ron]

Sleeping areas

http://www.systemsensor.com/en-us/Documents/LowFreq_FAQ_AVFL137.pdf

 

[Ragin Cajun]

Ron,

Thanks, just what I needed.

RC

 

[GoldDigger]

Sleeping areas

http://www.systemsensor.com/en-us/Documents/LowFreq_FAQ_AVFL137.pdf

Interesting comment about the required DB level.
What they did not take into account is that some DB meters may have a different frequency response in the A setting than in the C setting. The frequency curve of the A weighting is as much as 5 db lower for the same sound power compared to the response for a frequency above 1kHz.
So if the manufacturer delivers the same sound power, a DB meter set to the A scale may incorrectly show that the level at a distance is too low.
Unless, of course, the UL standard specifies the use of A weighting only for both manufacturer and inspector.

 

[gadfly56]

Interesting comment about the required DB level.
What they did not take into account is that some DB meters may have a different frequency response in the A setting than in the C setting. The frequency curve of the A weighting is as much as 5 db lower for the same sound power compared to the response for a frequency above 1kHz.
So if the manufacturer delivers the same sound power, a DB meter set to the A scale may incorrectly show that the level at a distance is too low.
Unless, of course, the UL standard specifies the use of A weighting only for both manufacturer and inspector.

Ding, ding, ding!!! I don't have an edition later than 2007, but the dbA scale is called for when making measurements in that edition. I don't believe it's changed in 2010 or 2013.