Low Frequency Smoke Alarms

[ggunn]

Studies show that human hearing is more receptive/sensitive to higher frequency than low frequency.

I don't need a study to show me that.

 

[JoeStillman]

At this frequency range, it falls under the Ultra Low Frequency. Spectrum.
Also known as INFRASOUND.
I’d be interested on that IBC requirement with details in regard to this mandate. Can you cite the website that says so?
This frequency can make people sick. It is a frequency range that humans cannot hear.

It gives people headaches but elephants can hear it.

Used in military extensively as well as rescue operation.

Is it perhaps a typo?

Perhaps you mean 520 KHz or 520 MHz.

“Ultra low frequency (ULF)

Ultra low frequency is the ITU designation for the frequency range of electromagnetic waves between 300 hertz and 3 kilohertz, corresponding to wavelengths between 1,000 to 100 km. In magnetosphere science and seismology, alternative definitions are usually given, including ranges from 1 mHz to 100 Hz, 1 mHz to 1 Hz, and 10 mHz to 10 Hz.Wikipedia”

Here is an account of its effect to humans.

https://www.pyroenergen.com/articles09/infrasound-effects.htm

520 is terribly low for an electro-magnetic frequency, but not so much for an audio wave. Human hearing is generally agreed to range from 20 Hz to 20 kHz, but usually only the youngest people can hear frequencies as high as 20 kHz. I am 64 and I hear nothing above about 8.5 kHz and the 24/7 ringing is at about 8.3 kHz (it varies).

 

[JoeStillman]

A coworker of mine once went in to see an audiologist for a for a hearing test. When the audiologist got the results she told him, "I can tell that you ride a motorcycle, and looking at your response curve I think it is a Harley-Davidson." Spot on.

I wonder if by mine she could have told that it was a 50W Marshall amplifier at full volume through (8) 10 inch JBL's.

It wasn't the Marshalls for me, it was the 18" Zildjians. I still hear them all the time.

 

[synchro]

The Navy did have some ELF (extremely low frequency) transmitters to communicate with submerged submarines at a carrier frequency of about 76 Hz, at least on an experimental basis. The antennas included ones that were 14 miles long and 28 miles long. By the way, one wavelength at 76 Hz is 2,451 miles in free space.

https://www.ncbi.nlm.nih.gov/books/NBK233163/

 

[hbiss]

I am 64 and I hear nothing above about 8.5 kHz and the 24/7 ringing is at about 8.3 kHz (it varies).

Join the club!

-Hal

 

[Strathead]

Only where the occupants have been identified and it's required by other laws or standards:

(1) An audible notification appliance producing a low fre
quency alarm signal shall be installed in the following
situations:
(a) Where required by governing laws, codes, or stan-
dards for people with hearing loss

Or as I said, it is required by NFPA 72 also.

 

[gadfly56]

The ones I have heard lately have a repeating sound of about three seconds duration that starts at 500Hz or so and glissandos up out of my hearing range.

Sound like that might be a "whoop" tone.

 

[gadfly56]

Or as I said, it is required by NFPA 72 also.

You made it sound like NFPA 72 independently requires the 520 Hz tone, regardless of other codes, so that even if local codes don't call for the low frequency sounder, if NFPA 72 is enforced, that would require the low frequency sounder. That's not true. It's an AND gate, not an OR gate.

 

[ggunn]

Sound like that might be a "whoop" tone.

Alls I know is that it drove me out of the building with my fingers in my ears.

 

[gadfly56]

Alls I know is that it drove me out of the building with my fingers in my ears.

In that case, 100% success!

When I was a tech, some occupants would complain during testing that the sound was so harsh and loud that it made them want to leave. I'd tell them "That's exactly the point."

 

[JoeStillman]

There is an advantage to hearing loss. It's easier to sort out the shtuff you don't want or need to hear. My spouse accuses me of selective hearing. Well maybe.

I'll pretend I didn't hear that.

 

[JoeStillman]

Here's the new text of the 2021 IBC...

907.5.2.1.3.2 Smoke alarm signal in sleeping rooms. In sleeping
rooms of Group R-1 and R-2 occupancies that are required by Section
907.2.8 or 907.2.9 to have a fire alarm system, the audible alarm signal
activated by single- or multiple-station smoke alarms in the dwelling unit
or sleeping unit shall be a 520-Hz signal complying with NFPA 72. Where
a sleeping room smoke alarm is unable to produce a 520-Hz signal, the
520-Hz alarm signal shall be provided by a listed notification appliance or
a smoke detector with an integral 520-Hz sounder.
Copyright

As far as I can tell, no smoke alarm can do this. Our multi-family resi developer clients are in for a rude awakening. This article is from the NFPA and it explains why nobody has done it yet.

The local smoke alarms in an apartment are supposed to only sound in the respective apartment. However, there needs to be a Fire Alarm system in all the apartments activated by pull stations or water flow switches. Our designs all have the System-type notification appliances in addition to the single/multiple station smoke alarms. Now we have to make the notification appliances addressable so they can sound for the whole building system OR the local smoke alarms. It's not gonna be cheap.

 

[gadfly56]

Here's the new text of the 2021 IBC...

As far as I can tell, no smoke alarm can do this. Our multi-family resi developer clients are in for a rude awakening. This article is from the NFPA and it explains why nobody has done it yet.

The local smoke alarms in an apartment are supposed to only sound in the respective apartment. However, there needs to be a Fire Alarm system in all the apartments activated by pull stations or water flow switches. Our designs all have the System-type notification appliances in addition to the single/multiple station smoke alarms. Now we have to make the notification appliances addressable so they can sound for the whole building system OR the local smoke alarms. It's not gonna be cheap.

Is this a townhouse or apartment complex? If "yes", then the 520 Hz sounder doesn't apply, unless your jurisdiction has amended the building code to require it. Typically it applies in transient quarters (hotel/motel) or dormitories. The other part, notification if common area pull stations or waterflow switches are activated, will apply. Typically, it's a single notification appliance located near the entrance of the living space.

 

[Strathead]

You made it sound like NFPA 72 independently requires the 520 Hz tone, regardless of other codes, so that even if local codes don't call for the low frequency sounder, if NFPA 72 is enforced, that would require the low frequency sounder. That's not true. It's an AND gate, not an OR gate.

IN a way yes. governing laws codes and standards require the in certain locations, like hotel rooms.

 

[RumRunner]

I don't need a study to show me that.

So, you consent to the AFFIRMATIVE that you agree to the things that were said here?
Or just making those comments more exciting?
Now --I’m truly confused--whether I’m the ass (Equus asinus) work animal -- or my derriere (lower side, rear anatomy)

I love your insight—and your double entendre

 

[ggunn]

So, you consent to the AFFIRMATIVE that you agree to the things that were said here?
Or just making those comments more exciting?
Now --I’m truly confused--whether I’m the ass (Equus asinus) work animal -- or my derriere (lower side, rear anatomy)

I love your insight—and your double entendre

I'm so smart that I confuse myself sometimes.

 

[JoeStillman]

Is this a townhouse or apartment complex? If "yes", then the 520 Hz sounder doesn't apply, unless your jurisdiction has amended the building code to require it. Typically it applies in transient quarters (hotel/motel) or dormitories. The other part, notification if common area pull stations or waterflow switches are activated, will apply. Typically, it's a single notification appliance located near the entrance of the living space.

Apartments (R2) are required to have multiple-station smoke alarms.

Sent from my SM-G981U1 using Tapatalk

 

[gadfly56]

Apartments (R2) are required to have multiple-station smoke alarms.

Sent from my SM-G981U1 using Tapatalk

Yes, yes they are. However, there is also now a requirement for in-apartment notification for things like common area smoke detection, water flow, etc.

 

[JoeStillman]

Yes, yes they are. However, there is also now a requirement for in-apartment notification for things like common area smoke detection, water flow, etc.

It's been that way a long time in NJ. We always show a 110 cd horn/strobe in every bedroom. Now we have to figure out the cheapest way to activate that with the smoke alarm without setting them off in all the other apartments.

 

[gadfly56]

It's been that way a long time in NJ. We always show a 110 cd horn/strobe in every bedroom. Now we have to figure out the cheapest way to activate that with the smoke alarm without setting them off in all the other apartments.

I'm not sure I understand your dilemma. Are you trying to set off the horn/strobe only when the smoke alarm in that apartment goes off?