New Sprinkler drops in existing System: Please read

[generuss]

My building just recently went through a fire inspection in which some some sprinkler heads are run off 1/2" pipe. I must replace this with 1" pipe and then use a 1" x 1/2" reducer for the sprinkler head. However the inspector tells me that I must replace the 1" x 1" x 1/2" Tee with a 1" x 1" x 1" Tee so that the sprinkler pipe is no longer on 1/2" pipe. The sprinkler system is existing and for me to replace the Tees would mean that I would have to remove the piping to get at the Tee for replacement. What can I do to replace the Tees? Is there a pipe fitting where I can tap into the existing pipe and run my sprinkler drops from there? Pipe sizes run from 6" to 1".

 

[TravisMack]

Yes...you will have to replace all of the 1/2" pipe. You can change out the end elbow on the line which is probably 1"x1/2" elbow to a 1" elbow. For all of the other heads, you can purchase a __x1" mechanical tee to make the drop in 1" pipe. Then, just plug all of the 1/2" outlets. This will prevent you from being required to replace all of the piping.

Travis Mack

 

[gouveia]

Actually, if you are not in an earthquake zone and you are piping to a new ceiling, NFPA 13(2002 edition) section 8.14.19.3 on Revamping of Pipe Schedule Systems allows you to install 4" long nipples the same size as the outlet and then you increase to a minimum 1" size.


That being said I do not believe it is a very good practice and I do not allow it on my projects. Read the appendix material in NFPA 13 for additional clarification of the intent of this section of NFPA 13.

 

[generuss]

I kind of figured that a mechanical Tee would do the trick and I started pricing them. However so far I cannot find one for pipe size less than 2". What is the manufacturer of such a tee? Alot of the piping is 1 1/2" where I need to do the sprinkler drops. I was a little slack on the details as to where the heads are going. What I have is a hallway with a suspended t-bar ceiling. The wall on either side of the hallway are 1 hour fire rated. The old ceiling above according to the inspector is 30 minutes. The existing sprinkler pipes are above the t-bar ceiling and under the old one. The old heads were in upright position and 1/2" pipe used to bring the heads into the newer t-bar ceiling. When I removed the tiles we discovered this. He wants it fixed. Who ever done this did it wrong. Using a 4" nipple and then using 1" pipe sounds great. But I would have to connect the old configuration which is upright to the new using 1/2" elbows into a pendant position. Could I use 4" nipple in upright from the existing tee, use a 1/2" x 1" reducing elbow, run 1" pipe horizontally to where I need, and then make the drop with a 1" x 1" elbow, 1" pipe and then the pendant on a 1" x 1/2" reducer. Thank you for your replies.

 

[gouveia]

It sounds like you are describing the diagram shown in NFPA 13(2002 edition) section 8.14.19.3 as previously referenced. I recommend you look at that diagram and read the section to verify it is applicable to you.

As for mechanical tees on smaller pipe sizes the smallest I am aware of is 1-1/4". This is a victaulic snap-let product. Check out the following link:

http://cf.victaulic.com/products/pdf/11.04.pdf