Return air distance from sprinkler head

[chris kennedy]

I was told today that a return air opening must be 3' from a fire sprinkler head. Makes sense to me but can't find the art.

Little help please.

Thanks

 

[cda]

It is in NFPA 13

Can give a section Monday

Another option is to use a higher temp head, if it needs to be less than three feet

 

[cda]

Till Monday check page 15 chart


Labeled

LoCATING RESIDENTIAL SPRINkLERS NEAR HEAT SouRCES


http://www.vikinggroupinc.com/databook/sprinklers/residential/080190.pdf

 

[cda]

Do you need this for

Commercial or residential??


Also what edition of 13 and 13 R are you under

 

[chris kennedy]

Sorry, commercial.

 

[cda]

Will look on Monday


More than likely the link and chart above is what I will find


Which edition of 13 would you like

 

[steveray]

I "know" it is there for detectors, not sure on sprinklers....

 

[cda]

In the 2016 NFPA 13

Check section 8.3.2.4 and 8.3.2.5 with tables

And one option in some cases is to change the sprinkler temp to higher level

 

[Paul Sweet]

I can see the need to locate a smoke detector a distance from a return grille, because the grille might pull air away from the detector.

A return grille is pulling room temperature air, so I don't see how it would affect sprinkler operation.

 

[tmurray]

In the 2016 NFPA 13

Check section 8.3.2.4 and 8.3.2.5 with tables

And one option in some cases is to change the sprinkler temp to higher level

That's for diffusers though. I'm not finding anything about return air openings...It makes sense you would want to locate them away to ensure that the heat is not being pulled from the area and preventing the sprinkler from discharging until the fire has increased in size beyond where a single head will be able to contain...

 

[cda]

I guess I should read each word.

Will look again, but have not heard of a distance requirement for return air.

Unless there is a tremendous velocity, I am thinking the heat plume will activate the sprinkler, even with the hvac going

 

[tmurray]

Probably. I'm just worried about the buoyancy of the hotter air being the one that gets removed first and is replaced by cooler air around the head.

 

[cda]

If there is enough fire to activate the sprinkler,

There is enough fire to activate the sprinkler.

Plus you also get into spacing, there may be a sprinkler nearby that might activate, if the return air is messing things up.

 

[tmurray]

As with sprinkler jumping, would you not have portions of the fire potentially outside of the spray of the head in this scenario? Isn't this why there are minimum head spacings? Not being sarcastic, I'm honestly asking. I know enough about NFPA 13 to be dangerous, not helpful.

 

[cda]

I would say minimum is so one does not spray on another, depending where you apply minimum

Such as four inch minimum away from a wall

I do not think return air vents are normally a problem

 

[SCBO1]

TABLE 8.3.2.5 (C) Front of wall-mounted hot air diffusers 36".

 

[steveray]

That table is only residential