# who will give me odds??



## cda (Oct 19, 2012)

So what are the odds that this sprinkler head in the blue area will activate????saw this at an outdoor mall with open  canopy weather coverings 
	

		
			
		

		
	

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## High Desert (Oct 19, 2012)

If the blue area is open, the head is useless.


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## pyrguy (Oct 19, 2012)

Well maybe not useless. It could always be used as a bird perch


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## Francis Vineyard (Oct 19, 2012)

Is that a slope or flat ceiling with a glass or plastic skylight?

Francis


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## Frank (Oct 19, 2012)

I will say that is should activate as the opening will act as a smoke and heat vent drawing the hot smoke and flame to the head.  Activation patterns and timing for this and surrounding heads will be different than if the hole was not there.


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## cda (Oct 19, 2012)

Francis Vineyard said:
			
		

> Is that a slope or flat ceiling with a glass or Francis


Flat.    No skylight


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## sdpaddler50 (Oct 19, 2012)

For a typical outdoor mall area, with low combustible loading of a few benches, chairs, etc, and if the ceiling is high, it could be none of the heads activate. When high ceilings are involved, it takes alot of heat to activate the heads. Many years ago i worked on a project for an aerospace company. The ceilings were 50 ft high, and the combustible loading was very low. You would need to light a stack of wood pallets on fire to activate the heads in that scneario.


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## cda (Oct 19, 2012)

I do not know why they sprinkled them

Open on two sides completely and somewhat open on the other two

With just benches underneath


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## codeworks (Oct 22, 2012)

i'm with frank, smoke and heat vent, if it gets hot enough


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## tmurray (Oct 23, 2012)

codeworks said:
			
		

> i'm with frank, smoke and heat vent, if it gets hot enough


I'd disagree; the reason we regulate a sprinkler head's proximity to the ceiling is because during a fire condition the heat rises and becomes trapped against the ceiling and continues to accumulate until the heat is great enough to deploy the sprinkler head. If heat is not trapped beneath the ceiling and simply allowed to pass by it the fire conditions that will activate the head will either be a major case of arson or too late in the game to do anything about fire. I'm curious why one was installed here as I don't remember in NFPA 13 requiring a sprinkler head in this location.


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## Frank (Oct 23, 2012)

tmurray said:
			
		

> I'd disagree; the reason we regulate a sprinkler head's proximity to the ceiling is because during a fire condition the heat rises and becomes trapped against the ceiling and continues to accumulate until the heat is great enough to deploy the sprinkler head. If heat is not trapped beneath the ceiling and simply allowed to pass by it the fire conditions that will activate the head will either be a major case of arson or too late in the game to do anything about fire. I'm curious why one was installed here as I don't remember in NFPA 13 requiring a sprinkler head in this location.


To activate the head needs to be in the plume of hot gases and smoke generated by the fire and the smoke plume needs to be hot enough to activate the head.  In a still air area the fire plume will rise above the fuel package and spread out as it entrains air--hence the funnel shape smoke cloud over an outdoor fire.  The entrained air cools the plume by diluting the hot products of combustion with ambient air.  When the plume hits an obstruction like a ceiling it will spread out rolling across the ceiling--this will activate heads around the perimeter of the fire prewetting the surrounding fuel stopping the spread of the fire.  Wind can disturb this pattern potentially preventing the upwind side from getting prewetted.  Steep sloped ceilings likewise.  A hole in the ceiling will draw the smoke and hot gases to it as a chimney draws the smoke into it and entrains air from the room to keep the smoke out of the house.  In this case the foot or two of hot gasses traveling along the ceiling stands a good change of activating the head under the hole although not as rapidly as if the hole was not there, unless the fire is directly under this head.


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## Builder Bob (Oct 24, 2012)

The hole does not require sprinkler protection in today's sprinkler code, it may have been required back in the day of install or the skylight may have been added when the mall remodeled and took out the existing RTU....... or,,,

Anyway , you get the idea.


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## cda (Oct 24, 2012)

my guess is the pipe was fabed with the idea that there was  a skylight there, and when it was installed they decided not to plug the outlet and install per plans!!!!!!!!!!!


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