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Purpose of plate for pendant sprinkler 2

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MEP.Learner

MEP.Learner

Mechanical
Jul 22, 2016
26
Hi Engineers,

I need some guidance of what is purpose of the plate at the sprinkler. Refer the attached picture.
As I ask around the engineers and fire protection contractors, I have received mixed answer and I still can't be sure the exact reason to install the plate.
Was this requirement to install the plate specified in NFPA code?

So do share your thoughts / knowledge.

Thanks.
 
 http://files.engineering.com/getfile.aspx?folder=83768a97-8056-41e5-8ef8-c546956d81e8&file=aa.jpg
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Heat collector no longer permitted by NFPA 13, 2013 ed.


8.5.4.1.4* Heat collectors shall not be used as a means to assist the activation of a sprinkler.


 
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More info

A.8.5.4.1.4 The rules describing the maximum distance permitted for sprinklers below ceilings must be followed. The concept of placing a small “heat collector” above a sprinkler to assist in activation is not appropriate, nor is it contemplated in this standard. There is evidence that objects above a sprinkler will delay the activation of the sprinkler where fires are not directly below the sprinkler (but are still in the coverage area of the sprinkler). One of the objectives of the standard is to cool the ceiling near the structural members with spray from a nearby sprinkler, which is not accomplished by a sprinkler far down from the ceiling, and a heat collector will not help this situation.

 
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Hi sir,
Many thanks to your reply and I am able to get more information about this "heat collector".

I have been practicing in South East Asia Country but the local fire authorities and inspector are still requesting for the installation of the plate.
So I guess they are still not following the latest code from NFPA.
 
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It appears the extra head is there because of the large duct??

That head should have continued down and turned and installed under the duct
 
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I don't believe that is a "heat collector." It appears to be a water shield that you see on intermediate level sprinklers. This is to prevent the sprinklers above from cooling the lower sprinkler and keeping it from activating. These are common for in-rack sprinklers or sprinklers under open grating.

Refer to this link for a typical intermediate level sprinkler:
However, this sprinkler does appear to be incorrectly located. It should be under the duct.


Travis Mack
MFP Design, LLC
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That isn't a heat collector pictured. It is an intermediate-level water shield.

Maybe the 2016 edition of NFPA 13 is in-force in that location, which would make that picture a fairly by-the-book installation method.

NFPA 13-2016 8.5.5.3.1 Sprinklers shall be installed under fixed obstructions over 4 ft.

8.5.5.3.1.1 Sprinklers shall be located below the obstruction and not more than 3 in. from the outside edge of the obstruction.

8.5.5.3.1.2 Where sprinklers are located adjacent to the obstruction (as in the OP's picture), they shall be of the intermediate level rack type (i.e, with a water shield).

The only major thing I can see wrong with the installation is that both sprinklers visible in the picture look like upright sprinklers installed upside-down. Maybe I'm seeing things...


 
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8.5.5.3.1.1
Sprinklers shall be located below the obstruction and not more than 3 in. (75 mm) from the outside edge of the obstruction

But it says below the obstruction

Is the intent to be below

and

Not more than three inches in/under the obstruction??

Do not have the commnetary
 
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anyone have a link to the draft/proposal for that section
 
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More clarification. It appears that the installation in the picture is correct if the 2016 edition of the standard was in play.

8.5.5.3.1* Sprinklers shall be installed under fixed obstructions over 4 ft (1.2 m) in width.

A.8.5.5.3.1 When obstructions are located more than 18 in. (450 mm) below the sprinkler deflector, an adequate spray pattern develops and obstructions up to and including 4 ft (1.2 m) wide do not require additional protection underneath. Examples are ducts, decks, open grate
flooring, catwalks, cutting tables, overhead doors, soffits, ceiling panels, and other similar obstructions.

8.5.5.3.1.1 Sprinklers shall be located below the obstruction and not more than 3 in. (75 mm)
from the outside edge of the obstruction.

I take this to mean that the sprinkler does not have to be directly under the obstruction, but can be as much as 3" from the side of the obstruction.

8.5.5.3.1.2 Where sprinklers are located adjacent to the obstruction, they shall be of the intermediate level rack type.

8.5.5.3.1.3 The deflector of automatic sprinklers installed under fixed obstructions shall be positioned no more than 12 in. (300 mm) below the bottom of the obstruction.

8.5.5.3.1.4 Sprinklers shall not be required under noncombustible obstructions over 4 ft (1.2 m) wide where the bottom of the obstruction is 24 in. (600 mm) or less above the floor or deck.

8.5.5.3.2 Sprinklers shall not be required under obstructions that are not fixed in place, such as conference tables.

Travis Mack
MFP Design, LLC
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Kind of looks like the system has been there awhile.


And in this set up is the ""sprinkler below""

And does the entire sprinkler need to be below or just the deflector ??

Sprinklers shall be located below the obstruction and not more than 3 in. (75 mm)
from the outside edge of the obstruction.

To original poster,,, do the sprinklers have paint on them???
 
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Nothing in the commentary

Would be interesting to see what the drafts/ proposals say.
 
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TravisMack Wrote:
8.5.5.3.1.1 Sprinklers shall be located below the obstruction and not more than 3 in. (75 mm)
from the outside edge of the obstruction.

I take this to mean that the sprinkler does not have to be directly under the obstruction, but can be as much as 3" from the side of the obstruction.

8.5.5.3.1.2 Where sprinklers are located adjacent to the obstruction, they shall be of the intermediate level rack type.
Click to expand...

I attended a 1/2 day NFPA 13 training seminar sponsored by local SFPE Chapter and the author of the NFPA 13 handbook delivered the presentation. This specific section was discussed. Matt Klaus (whose an awesome instructor) summarized that the committee screwed this section up. It wasn't the committee's intent to require that the sprinkler be located within 3-inches of the edge of the obstruction. If one has a 72 inch wide duct, it's perfectly acceptable to locate it in the center of the bottom plane of the duct. Matt was begging for someone to submit a TIA to fix this so I'm working on one during the off hours.

And the new requirement for air venting is all goobered up as we say in South Texas.
 
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Scott:
Maybe I'm seeing this too easy. I think the section makes perfect sense. You either have to be under the obstruction, or a maximum of 3" to the outside of the obstruction. So, If the duct is 8' wide, you would have to be at least 6" to the inside of the duct. Because this sprinkler is under the duct, you do not need intermediate level sprinklers. However, if the duct were 5' wide, you could either be under the duct, or up to 3" to the outside of the duct. If you are under the duct, no water shield required. If you are 3" outside of the duct, but the deflector still below the elevation of the duct, then you need to use an intermediate level sprinkler (water shield).

This 3" to the outside of the obstruction is what is new. In previous editions, you always had to be under the obstruction. This is giving the option of being adjacent to the obstruction as well.



Travis Mack
MFP Design, LLC
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Travis:

I know you're not shooting the messenger. As I understood the change, it was the committee's intent that if the sprinkler extended 3" beyond the obstruction, then an intermediate level AS was required. In defense of the messenger, I had a lot of secondary discussions around me AND the instructor was moving quickly through the material.
 
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Ha ha... No...never shoot the messenger :)

I thought it was quite clear...but I see Matt pointing out the AND which does change the reading of the statement.

8.5.5.3.1.2 was the clarifying one for me. If you are adjacent to the obstruction (meaning not under), then you had to use an intermediate level sprinkler. This is where I think when you put all of them together, you get the intent of sprinkler under the obstruction, or adjacent to, but not more than 3" away from the edge of the obstruction if you are adjacent to it.

I must be crazy because I love this stuff. It's things like this that make our jobs always interesting.

Travis Mack
MFP Design, LLC
"Follow" us at
 
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