The only reason I say a pipe feeding a single sprinkler can be a branch line
is per definition.
3.5.1 BRANCH LINES The pipes supplying sprinklers........
3.5.2 CROSS MAINS The pipes supplying the branch lines either directly or
through risers.
3.5.9 ARM-OVER A horizontal pipe that extends from a branch line to a single
sprinkler or a sprinkler above and below a ceiling.
So if you have a single sprinkler fed from a horizontal pipe from a cross
main this would be a branch line. If you have a single sprinkler fed from a
horizontal pipe from a branch line this would be an arm-over.
Bobby Gillett
Project Manager
[EMAIL PROTECTED]
(731)-424-0130
-----Original Message-----
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of Roland
Huggins
Sent: Thursday, June 19, 2008 9:58 AM
To: [email protected]
Subject: Re: Restraint of Branch Lines
I disagree that the definition states a single sprinkler is a branch
line. It says supplying sprinklers (plural) and that pipe can have
individual sprinklers off of it feeding arm-overs, sprigs etc. Just
like risers are all vertical pipes (for 4 way braces) but a sprig is
excluded since it is separately defined this nit a riser. The
individual sprinklers off of a branch line are separately defined and
addressed (sprigs greater than 4 ft, arm-overs greater than 2 ft, etc).
An arm-over is not separately restrained. IT makes it easy to
adamantly say that when one considers long sections of pipes (attached
on only one side) easy whip around whereas short sections do not (the
length of the moment arm)
Roland
On Jun 19, 2008, at 5:56 AM, [EMAIL PROTECTED] wrote:
> A branch line can be a single head per the definition in NFPA 13.
> Does
> this mean each arm-over, drop, or return bend regardless of length
> must
> have a branch line restraint? It seems sprigs are given special
> attention in Chapter 9 but the other categories of branch line are
> not.
>
> I guess I'm getting back to the confusion over the definition of a
> branch line. From the feedback it seems no one is providing restraint
> when a single head is involved.
>
> Bill Brooks
>
> William N. Brooks, P.E.
> Brooks Fire Protection Engineering Inc.
> 372 Wilett Drive
> Severna Park, MD 21146
> 410-544-3620 Phone
> 410-544-3032 FAX
> 412-400-6528 Cell
>
> -------- Original Message --------
> Subject: RE: Restraint of Branch Lines
> From: "Thom McMahon" <[EMAIL PROTECTED]>
> Date: Wed, June 18, 2008 4:50 pm
> To: <[email protected]>
>
> 13 defines restraint as a lesser level of control than Brace. We have
> always favored the 12Ga. 440 Lb. Ceiling wire restraint on the end of
> branchlines (9.3.6.1 end Head) If it doesn't have heads on it, it is a
> feed or cross main and requires bracing. (See branchlines over 2")
> (This
> includes all head types, SSU, SSP and HSW even flex heads if the last
> head on the line is a flex head)
> The new 2007 hanger with 2nd hanger at 45' angle may appeal to some.
> In
> any case when you're doing seismic the end of branchlines must be
> restrained.(I always try to keep my hangers less than 6" and it's a
> lot
> easier.)
>
> The more difficult restraint requirement A9.3.6.4 is when your close
> to
> other objects that can damage the branchline in a seismic event.
> Components of the structure, duct work or large mechanical piping.
> Also
> your always required to use restraint per 9.3.6.4 (see table) on
> longer
> branchlines. Again a little clarification that this is not cumulative,
> it is based upon the smallest pipe size in the branchline.(13 HB
> committee, yes or No?) (Part of this answer depends upon weather the
> other trades are providing seismic bracing, and a good feel for how
> close is too close, NOT YET DEFINED BY 13)
>
> Example:( A branchline which follows pipe schedule sizes with every
> head
> 12' from the last with a 21/2" starter piece, and 10 heads total.
> (112'-0" total length) you have your end restraint, the with a Cp 0.58
> you space your next restraint 38' from the end one. Then since your
> now
> on a 11/2" piece of the branch line do you space 38' again or 43'? The
> end answer is it doesn't really matter, you need the end on plus two
> more either way, but I see both sides of that, and it's not real
> clear.)
>
> Thom McMahon, SET
> Firetech, Inc.
> 2560 Copper Ridge Dr
> P.O. Box 882136
> Steamboat Springs, CO 80488
> Tel: 970-879-7952
> Fax: 970-879-7926
>
>
>
> -----Original Message-----
> From: [EMAIL PROTECTED]
> [mailto:[EMAIL PROTECTED] On Behalf Of
> [EMAIL PROTECTED]
> Sent: Wednesday, June 18, 2008 12:54 PM
> To: [email protected]
> Subject: Restraint of Branch Lines
>
> 2007, 9.3.6.3 - The end sprinkler on a line shall be restrained
> against
> excessive vertical and lateral movement.
>
> 1. Can I assume the word line means "branch line" based on the title
> of
> 9.3.6?
> 2. Would the end sprinkler include sprinklers on drops, arm-overs, and
> return bends?
> 3. Would "excessive" be defined as using a restraint not listed for
> vertical and/or lateral movement or not meeting 9.3.6.1(5)?
>
> Someone has asked me to approve a particular brace but then I
> realized I
> had no idea how many needed to be installed!
>
> (Getting old but still learning)
>
> Bill Brooks
>
> William N. Brooks, P.E.
> Brooks Fire Protection Engineering Inc.
> 372 Wilett Drive
> Severna Park, MD 21146
> 410-544-3620 Phone
> 410-544-3032 FAX
> 412-400-6528 Cell
>
>
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