ECN Forum Forums General Topics of the Trade General Discussion Area How do fire sprinklers really work? (OT?)

This is mostly off-topic, but somewhat related, I think. Anyway, I know there are at least a few firefighters on the board, and probably others that know details about fire sprinklers and their history.

In many movies, TV shows, etc., a fire alarm will trigger all of the sprinklers in the building. I know that on modern systems, each head activates separately. (I think there are some systems for special applications that activate multiple heads at once, but my question is about standard systems that you'd find in office areas.)

Did building sprinkler systems ever activate all the heads at once, or is this purely a Hollywood invention?

I think what you may be referring to is a deluge system where the heads are all open, pipes are dry, and there is a control valve that responds to a device to flood the entire area. Probably wouldnt be found in the areas that the movies are showing them in ie offices, malls etc. but they do exist.

Other than the rare deluge systems I say pure Hollywood.

In most cases it would be bad design to have all heads open at once, to much water damage also the sprinkler main would have to be HUGE to supply all the heads at once in a large building.

As a point of interest here I can verify that a case of frozen peas, thrown across a grocery store walk in freezer, missing the intended target employee and hitting a sprinkler head, will break off and flood a 20 x 20 walk in freezer in just a few minutes, resulting in many hours with an ice chipper. None of the other heads will open, however the fire alarm will activate and the fire dept will respond.

Seems foolish to put fire sprinklers in a freezer.

most likely a dry system.
with these the pipes are filled with air on a closed pipe system, the air holds a valve closed, when the head pops the air releases and the valve operates sending water in the pipe. these systems are very common in cold climates, overhangs garages etc...

I meant to say "Hi", New here, this site is great you cover it all.

Those aren't necessarily deluge systems, though, are they?

No, Brian.

A "Dry" system will only have water come out the specific head that has been tripped.

A 'deluge" system has nothing in the heads to stop water from coming out; when a seperate trigger opens the valve, they all spray.

"Deluge" systems might be found in an aircraft hanger. "Dry" systems are often found on loading docks.

Thanks everyone for your replies. I knew I'd get some good info here.

http://www.reliablesprinkler.com/pdfs/products/500%20Model%20BX%20Deluge%20Valves.pdf

Here is one type of deluge valve. I wish that we had these in some of our fueling areas. Unfortunately, we have the ones without the external reset knob which require cover removal to reset the flapper. We use solenoid activation from FACPs but you can see that other methods can be used. I'm more used to chasing electrons around so these instructions remind me of the old Mousetrap game.
Joe

Brian, Saw your bio and here's some more info you may find interesting.

Mainly 4 types of sprinkler systems.
1) wet system- these are your typical office type sys.
Operation: pipes are always full of water,heads are thermal devices tripped by heat, only the affected head will release the water.

2) dry system- These are primarily found in areas that will be suseptable to freezing, load docks ,parking structures etc. (see other post)

3)Deluge system- this is an open pipe system, These are used in tank farms ,Aircraft hangers and the like, they are controlled by an electric solonoid that when triggerd by a detection device (heat,smoke,flame etc)releases the valve and the water (and sometimes assisted with foam) flows out ALL heads, to.... Deluge the area.

4) Pre-action- These are typical in areas that are sensitive, Elec/Data rms and such,areas that need confirmation of an event before release.
Operation:Closed pipe system,The pipes are filled with air (this is for pipe integrity supervision only).An electric solonoid is activated by a detection device (smoke, heat etc), releasing the valve and the system is "charged" with water, No water flow will occur in the space until a sprinkler head thermal is tripped (melts). This ensures or limits accidental discharge into the area.

Hope this helps. This is just the beginning, Fire suppresion is way cool, and there is a ton of concepts and products out there.