Is the smoke alarm required to be low frequency in sleeping area?

[zemingduan]

Per NFPA 2016 18.4.5.3, the audible appliances in sleeping areas shall be the low frequency type. We are now required a low frequency sounder or sounder strobe in sleeping/dwelling units to notify the fire alarm signal of the building fire alarm system. Are the smoke alarm in side and outside the bedrooms in a dwelling units, or sleeping area in hotel etc. required to be low frequency type? I am not talking about the smoke alarm instead of smoke detector that is connect to the fire alarm system.

However I can't find a manufacture that has low frequency smoke or smoke/co alarm. Do you guys know any manufacture that has low frequency smoke or smoke/co alarm.

Another option is to install smoke detector with low frequency sounder base in sleeping/dwelling units and connected to building fire alarm system. But configure those smoke detectors to activate only the sounder base in the unit rather than the building fire alarm system. But this will cost much more than smoke alarms. One smoke alarm is only $30-$50 bucks I guess. You will also need extra cost for programing and wiring. Besides, when I look into the products from silent knight, I think the smoke detector with sounder base only work in addressable fire alarm system. In this option, you will need addressable fire alarm system for 3-4 units multifamily.

 

[petersonra]

However I can't find a manufacture that has low frequency smoke or smoke/co alarm.

One would think if this is a requirement that someone would be making them.

 

[zemingduan]

I do more research and find below very useful information in an article posted on NFPA official website (https://www.nfpa.org/News-and-Resea...021/01/22/Low-Frequency-Fire-and-Smoke-Alarms):

"Low frequency 520 Hz alarms were required for single and multiple station alarms, smoke alarms not connected to a building fire alarm, where the occupants have mild to severe hearing loss." - NFPA 72 29.3.8.1 since 2010 edition.

"The 2013 edition of NFPA 72 broadened the use of low frequency alarms by requiring all audible appliances initiated by the building fire alarm that are provided in sleeping areas to wake sleeping occupants to be a low frequency 520-Hz alarm. " -NFPA 18.4.5.3. First appears in 2010 edition. It states this requirement effective from 1/1/2014.

Conclusion:

"As you can see, NFPA 72 only mandates the use of low frequency 520 Hz alarms for audible alarms, initiated by the building fire alarm system, in areas where the alarm is intended to wake sleeping occupants and only for audible alarms initiated by smoke alarms, not initiated by the building fire alarm system, in sleeping areas where occupants have mild to severe hearing loss. "

My understanding, the single & multiple station smoke or smoke & co alarms are not notification appliances. Thus they are covered by Chapter 29 instead of Chapter 18.

NFPA 101(if you area adopt NFPA 101, Philadelphia doesn't adopt NFPA 101) has stricter requirements since 2021:

"Changes to the 2021 edition of NFPA 101, Life Safety Code strive to make use of low frequency alarms more consistently throughout all sleeping areas. The changes require that, where the occupancy chapter mandates their use, audible alarms in sleeping rooms initiated by the building fire alarm system and audible alarms in sleeping rooms initiated by the activation of a smoke alarm, not the building fire alarm system, must result in a low frequency 520 Hz alarm. Two of the residential occupancy chapters in NFPA 101, new hotels and dormitories and new apartment buildings now require the use of low frequency alarms for audible notifications activated by both smoke alarms and the building fire alarm system."

 

[zemingduan]

I also find below from another article (https://www.affiliatedinc.com/do-single-station-smoke-alarms-have-low-frequency-sounders/) stating the reason that why regular smoke alarm is not low frequency type:

" I’ve only found one manufacturer that has a 520 hz smoke alarm & it costs around $200. This seems like a no brainer for smoke alarm manufacturers, so why aren’t there any cost effective 520 hz smoke alarms available? The short answer is that in order to produce a 520 hz tone loud enough to meet audibility requirements (75 dB at the pillow), the speaker has to be larger than what can fit in a standard smoke alarm. "


Hope this information will also help you guys!

 

[gadfly56]

The problem with developing low frequency smoke alarms or smoke/CO alarms is that creating the 520 Hz signal requires a high fidelity speaker, and it draws a significant amount of energy. You probably couldn't create a sealed 10-year life device that operates on battery only, and the transformer for the sounder is fairly bulky, so the size of the unit starts to become significant. Simplex and Siemens, for two, have sounder bases capable of generating the 520 Hz tone. No one currently has a 520 Hz smoke alarm. It is also not required in residential occupancies other than commercial (dorms, hotel rooms, etc) unless you are under the 2021 edition of NFPA 101.

 

[ptonsparky]

Interesting.
I don't hear the low battery alerts from our home detectors very well. Some phone tones not at all. Even when while holding it and knowing it is sounding. Best alert from my phone is to have it on vibrate and set it on the small glass topped table that sits on a hardwood floor in our living room.

 

[gadfly56]

Interesting.
I don't hear the low battery alerts from our home detectors very well. Some phone tones not at all. Even when while holding it and knowing it is sounding. Best alert from my phone is to have it on vibrate and set it on the small glass topped table that sits on a hardwood floor in our living room.

The low battery chirp can be elusive, and because it is the same sounder (3150 Hz) as the alarm, it's highly non-directional. My detectors have a voice component that says "Warning, low battery" after the chirp. Makes it much easier to figure out which alarm is in trouble.

 

[tallgirl]

The low battery chirp can be elusive, and because it is the same sounder (3150 Hz) as the alarm, it's highly non-directional. My detectors have a voice component that says "Warning, low battery" after the chirp. Makes it much easier to figure out which alarm is in trouble.

They usually have the specific LED pattern on the instructions. I'm installing wireless smokies because the wired smokies I want are backordered until March or so. Their instructions, which of course I can't find right now, say how you can tell if they think they are dirty, versus if they have low batteries. They usually have embossed words on the case, which can't be read because they aren't colored and I wear bifocals.

I'm not sure what you mean by the chirp being non-directional. The bigger problem is that it is so short in duration your brain may not be able to locate it. My trick was to close all the bedroom doors. If it was the hallway alarm, well, duh. Otherwise I'd go from room to room, again with the door closed, until I found it. I was always able to tell left from right, but I could never get bearings better than that because that chirp is just so damned short.

 

[GoldDigger]

They usually have the specific LED pattern on the instructions. I'm installing wireless smokies because the wired smokies I want are backordered until March or so. Their instructions, which of course I can't find right now, say how you can tell if they think they are dirty, versus if they have low batteries. They usually have embossed words on the case, which can't be read because they aren't colored and I wear bifocals.

I'm not sure what you mean by the chirp being non-directional. The bigger problem is that it is so short in duration your brain may not be able to locate it. My trick was to close all the bedroom doors. If it was the hallway alarm, well, duh. Otherwise I'd go from room to room, again with the door closed, until I found it. I was always able to tell left from right, but I could never get bearings better than that because that chirp is just so damned short.

What most people refer to is that, like the chirp of a cricket, it is extrememly hard to locate by ear. I do not know what it is about the cricket chirp that causes this, but you can turn your head and move 'toward it" all you want, and still not find it unless you happen to see it.
Some of it may be the result of standing wave patterns from the pure tone?

 

[tallgirl]

What most people refer to is that, like the chirp of a cricket, it is extrememly hard to locate by ear. I do not know what it is about the cricket chirp that causes this, but you can turn your head and move 'toward it" all you want, and still not find it unless you happen to see it.
Some of it may be the result of standing wave patterns from the pure tone?

It could be since there's a circle of locations where any phase difference in the tones is the same so long as it's a single pure tone.

My assumption was that it was the extremely short duration of the tone since I could always determine left-right, just nothing better. The only issue I've had finding that one stinkin' smokie was being impatient. Once I'd settled on the approach I described -- close all bedroom doors, start in the hall, then check each bedroom -- I was able to find the dying battery in under 10 minutes. Which is idiotic because I think my latest smokies have a specific LED blink pattern, as well as reporting a TROUBLE on the "Low Battery" loop.

 

[farmantenna]

one month late but this post was very enlightening. Now I understand why the apartment plans I examined several months ago had no 120v interconnected smoke alarms but only system smoke detectors with sounder bases.
This is definitely doable with Silent Knight system but more troublesome on a tenant and maintenance personal level.

Would definitely have to use the anti tampering feature on the detectors inside the apartments

 

[tallgirl]

one month late but this post was very enlightening. Now I understand why the apartment plans I examined several months ago had no 120v interconnected smoke alarms but only system smoke detectors with sounder bases.
This is definitely doable with Silent Knight system but more troublesome on a tenant and maintenance personal level.

Would definitely have to use the anti tampering feature on the detectors inside the apartments

I've always been leery in apartments and hotels when I see anything has been done to a fire alarm or smoke detector.

Also, they REALLY need to put the legend for LED indicators on the case in letters which can be read, and not just molded into it.