Sprinkler K factor

[sprinkler57]

Question Can you install Different k factor heads with the same RTI and degree in the same compartment? I have always went with the same K factor and degree and response tone had to be installed in the same compartment. I am seeing more and more mixed EC heads k11- K14 in the same room or hallway as 5.6 heads . The heads are seeing each other too. I just cant find inn the code book that you can or cant instill different k factor heads in the same area?

 

[SprinklerDesigner2]

the question is why do you want to? if it is balance the hydraulics that is specifically prohibited.

 

[chicopee]

Perhaps because there are different commodities ??

 

[sprinkler57]

chicopee (Mechanical)I thought no matter what what you can not mix different k factors in the same area. This is all offices and hallways with mixed k factor in the same room or all way . on a job a saw. I could not find in the code book any were that is says you can mix k factor? Do you know we're in NFPA were it's notes that you can or can't?

 

[SprinklerDesigner2]

Now that I am not using my cell phone I will try to answer a little better.

You can mix orifice sizes and we all often do and as an example I will point to a residential system having a NFPA #13 system where we use 4.3 residential sprinklers in the dwelling unit and 5.6 standard spray quick response in the hallways.

On page 1027 of the 2013 handbook:

23.4.4.8.3 Sprinklers with different K-factors shall be acceptable for special use such as exposure protection, small rooms or enclosures, or directional discharge. (See 3.3.21 for definition of small rooms.)

23.4.4.8.4 Extended-coverage and residential sprinklers with a different K-factor shall be acceptable for part of the protection area where installed in accordance with their listing.

What you can't do is the little trick of installing sprinklers with lower k-factors on a branch line of a tree system closer to the cross main which was done back in the early 1970's when calculations first came out but the rectangular area wasn't defined yet.

Used to be we would calculate all the sprinklers on the branch line so if you had a branch line with 15 sprinklers (8 on one side and 7 the other) would would calculate all these sprinklers and we got cute by putting smaller orifice sprinklers in closer to the crossmain riser nipple. Hey, we're talking a long, long time ago when my favorite pipe size to use was 3 1/2" sch. 10.

 

[sprinkler57]

 SprinklerDesigner2 (Mechanical)
Thank you for the feed back. I understand what your saying
What I mean is in the same room can you have sprinkler heads that are EC and standard spray heads? Even though they are both QR. Meaning EC 14,and 5.6 k factor?
I don't see how that can be precode or if your adding Sprinker coverage to a existing stright Corridor and the existing heads are standard spary 5.6k heads and you leve them installed and as the existing hallway corridor get extended and you use EC14 K head for the new extended Corridor and there is no change in the ceiling height so what you have is EC14 heads and standard 5.6 spray heads in the same compartment =line of sight This Corridor is stright no change in direction. Do you know if NFPA notes that you can not mix K factorhheads in the same compartment? Thank you again for you time

 

[TravisMack]

I have used standard coverage sprinklers and Ex Cov sprinklers in the same compartment. Take a classroom with a small nook or something off to the side. This is all open and exposed to each other. I will put a 5.6k sprinkler in the nook area and 11.2k ex cov sprinklers in the open area. I figure that I am not using the smaller head to try to balance k-factors. But, I also want to make sure that the threads are of different size. I wouldn't want a maintenance guy or some one replacing a ex cov head with a std head. On that note, I won't use 4.2k heads and 5.6k heads in the same compartment. I would be concerned that if the heads need to be replaced, the k-factors could get mixed up.

Travis Mack
MFP Design, LLC

http://www.mfpdesign.com