Unsupported length from end sprinkler and the last hanger

[Firesprinkler1]

I am not sure of the answer to this question. 9.2.3.4.1 states; the unsupported length between the end sprinkler and the last hanger on the line…



Does that mean that the 2’-0” drop must be added to the 4’-0” for a total length? If so, the branch line is 1 ½”, but the drop is 1”. What size pipe for unsupported measurement should be used?

 

[skdesigner]

If you posted the entire code reference, you would have your answered your own question.

NFPA 13 2010 9.2.3.4.1 The unsupported HORIZONTAL length between the end sprinkler and the last hanger on the line shall not be greater than...

 

[skdesigner]

I apologize if I came off as condescending. It appears the 2010 version is the first to actually include the term "horizontal". I must have been taking it for granted all these years.

 

[NJ1]

This question could possibly have many answers
(I believe this is for arm overs)
One is that if the water pressure is less than 100 psi you are allowed to be 2'-0 away from the sprinkler and hanger
If water pressure is over 100 psi you need to be within 1'-0 from the head and the hanger

I will read NFPA 13 for the distance on branches

 

[gfire]

9.2.3.4.1 refers to sprinkler heads installed directly on the branch line without arm overs.

9.2.3.5.1 is what you're looking for
The cumulative horizontal length of an unsupported armover to a sprinkler, sprinkler drop, or sprig, shall not exceed 24 in. for steel pipe or 12 in. for copper tube.
This is for pressures not exceeding 100 psi.

 

[skdesigner]

He doesn't say anything about armovers. If it's a 1 1/2 x 1 vic adacap on the end of the line dropping to a pendant I believe my answer stands, and I believe the language in the 2010 edition was modified to clarify this exact situation.