Smoke Detectors - Test Button

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mtnelect

mtnelect

HVAC & Electrical Contractor
Location
Southern California
Occupation
Contractor, C10 & C20 - Semi Retired
Does anyone know what that test button on Smoke Detector do ? On our HVAC maintenance contracts we test the smoke detectors with a spray can of "Particles of Combustion" and not the test button.
 
At a guess, it shunts across whatever the detection circuit is monitoring. And I'm assuming you really mean "smoke alarm", as smoke detectors attached to a fire alarm control unit don't typically have test buttons. The vast majority of smoke alarms are ionization detectors, where a stream of ions are generated by the radioactive source. This stream sets up a current between two charged plates. When smoke particles enter the chamber they capture the ions, reducing the current and this fall off triggers the alarm.
 
Gadfly56 refers to "Single- and Multiple-station Smoke Alarms (UTGT)" Self-test requirements are in the referenced test standard UL 217.

UL white book for product listings & test standards have several categories.

Detectors, Automatic Fire (UPLV) ....................................
Smoke-automatic Fire Detectors (UROX) ....................................
Smoke-automatic Fire Detector Accessories (URRQ) ..
Smoke Detectors for Special Applications (URXG) ......................
Fire Alarm Devices, Single and Multiple Station, and Accessories (UTER)
Single- and Multiple-station Heat Detectors (UTFS) ......................
Single- and Multiple-station Smoke Alarms (UTGT) .....................
 
mtnelect said:
Does anyone know what that test button on Smoke Detector do ? On our HVAC maintenance contracts we test the smoke detectors with a spray can of "Particles of Combustion" and not the test button.
Click to expand...

I agree with @gadfly56, if it has a test button it's usually a smoke alarm. That said, the test button serves multiple functions- silencing the alarm, initiating a test sequence, memory recall of the last unit in alarm, etc. While a smoke generator is the way to test smoke DETECTORS, the test button on smoke ALARMS should be used instead, particularly if they are combo smoke/co. Just walk around with a stick.

-Hal
 
kwired said:
There used to be a time when some would just blow their cigarette smoke toward the smoke alarm/detector to test it.🙃
Click to expand...
You knew you had to replace the alarm once the plastic had completely yellowed. :LOL:
 
Now days just use :

UTC Fire and Security SM200 Smoke-In-A-Can​

But it is flammable so no cigarettes. ;)
 
If it is a photo type smoke detector it often moves an object into the light path that simulates smoke. With some designs the light source and the light sensor are in aligned and smoke reflects the light into the sensor.
With an ionization type, it is my understanding that the button is a electronic test and does directly simulate smoke. The electronics are on a quad chip with have used for detecting smoke and the other half for testing, with the assumption that one half of the chip cannot fail by itself.
 
Ionization works with a low radioactive isotope sensing device (Americium 241).
Ionization samples very small particles that are present in the air.

This technology uses (during the sampling process) also used in
chemical labs in detecting impurities in liquids in association with spectrometer after sampling the fluid first.
It is a synthetic isotope meaning MANMADE with half- life expectancy of over four hundred years.
This differs from the photo electric model which samples light received by the sensing device.
It is done by applying a small amount of voltage to two plates that react when the voltage is disturbed by smoke particles in the air.
Ionization also goes into the sampling of materials that are on the surface of Mars.

Fish
 
hbiss said:
I agree with @gadfly56, if it has a test button it's usually a smoke alarm. That said, the test button serves multiple functions- silencing the alarm, initiating a test sequence, memory recall of the last unit in alarm, etc. While a smoke generator is the way to test smoke DETECTORS, the test button on smoke ALARMS should be used instead, particularly if they are combo smoke/co. Just walk around with a stick.

-Hal
Click to expand...
In Florida we are not allowed to test smoke detectors with smoke or a magnet any longer. We have to use the remote test.
 
Knightryder12 said:
In Florida we are not allowed to test smoke detectors with smoke or a magnet any longer. We have to use the remote test.
Click to expand...
Do you mean trip from the panel by forcing a sensitivity change? Smoke alarms don't generally come with a remote test feature.
 
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