Bell or HornStrobe
- Thread starter romero
- Start date
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ron
Senior Member
- Location
- New York, 40.7514,-73.9925
Typically, fire alarm notification is done with a temporal code sound out of a horn (or speaker for a voice system) and visual is a strobe.
Sprinkler annunication can be different.
Sprinkler annunication can be different.
cadpoint
Senior Member
- Location
- Durham, NC
Here the This Ninth Edition of The Philadelphia Code
Last time I put a bell outside was to be an alarm that water was flowing in the manifold, IE pipe breakage, not an internal fire, your required Code may vary.
Last time I put a bell outside was to be an alarm that water was flowing in the manifold, IE pipe breakage, not an internal fire, your required Code may vary.
Typically bells are only used for waterflow now, of course 72 doesn't address that it. Sprinkler waterflow notification appliances are addressed in NFPA 13. The reason a bell is used, at least one reason, is that older sprinkler systems had a water motor gong. This was a bell phyically driven by waterflow. And the water would be pouring out under the bell outside. You knew without a doubt water was flowing. It could just be a broken pipe or dry system that lost pressure, either way a mess was inside. The water motor gongs were used prior to actual fire alarm systems being in place, just a sprinkler supervisory system or a shunt type master box would be tripped by the water flow.
Now most FD's require the bell so that it is a positive (and unique) indicator of waterflow, and its tradition. It is a very helpful indicator for the FD. Many FD's require a seperate colored strobe to indicate waterflow in addition to the bell. The strobe is on the street side of the building. The bell is located outside the riser in alarm. It allows you to find the riser, if you need to shut it off. With multiple risers in a building each one gets a bell.
Enough with the history.
With horn/strobes that can be synchronized, bells are too cumbersome from design standpoint. I realize they were used long ago, but now everything is a horn/strobe. Unless you have a MNS or voice evac system.
Now most FD's require the bell so that it is a positive (and unique) indicator of waterflow, and its tradition. It is a very helpful indicator for the FD. Many FD's require a seperate colored strobe to indicate waterflow in addition to the bell. The strobe is on the street side of the building. The bell is located outside the riser in alarm. It allows you to find the riser, if you need to shut it off. With multiple risers in a building each one gets a bell.
Enough with the history.
With horn/strobes that can be synchronized, bells are too cumbersome from design standpoint. I realize they were used long ago, but now everything is a horn/strobe. Unless you have a MNS or voice evac system.
Last edited:
MisterCMK
Member
- Location
- Twin Cities, MN
Around here the waterflow is a 110v horn/strobe. It is typically switched using the contacts on the waterflow switch. There are a handful of times where we control the outside horn with a CR though.
luckylerado
Senior Member
- Location
- Lake of the Ozarks
From NFPA 13
6.9 Waterflow Alarms.
6.9.1 General. Waterflow alarm apparatus shall be listed for the service and so constructed
and installed that any flow of water from a sprinkler system equal to or greater than that
from a single automatic sprinkler of the smallest orifice size installed on the system will
result in an audible alarm on the premises within 5 minutes after such flow begins and until
such flow stops.
6.9.3 Attachments ? General.
6.9.3.1* An alarm unit shall include a listed mechanical alarm, horn, or siren or a listed
electric gong, bell, speaker, horn, or siren.
6.9 Waterflow Alarms.
6.9.1 General. Waterflow alarm apparatus shall be listed for the service and so constructed
and installed that any flow of water from a sprinkler system equal to or greater than that
from a single automatic sprinkler of the smallest orifice size installed on the system will
result in an audible alarm on the premises within 5 minutes after such flow begins and until
such flow stops.
6.9.3 Attachments ? General.
6.9.3.1* An alarm unit shall include a listed mechanical alarm, horn, or siren or a listed
electric gong, bell, speaker, horn, or siren.
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