Craig,
Pretty simple in order to not confuse us poor uneducated AHJs. I have no
idea how we have been able to figure out anything considering how complex
these onerous codes are. Thanks for proposing simplified rules for the
uneducated masses. Hopefully, you can go through the codes and simplify
the rest of the stuff. Be sure to break it down into words with no more
than 2 syllables.
By the way, I think that velocity had something to do with the name
Velociraptor. However, its been a long time since I saw Jurassic Park.
Thank You
Rahe Loftin, P.E.
Region 7 - GSA
Office - 817-978-7299
Fax - 817-978-8644
Cell - 817-371-3102
<craig.pr...@ch2m
.com> To
Sent by: <sprinklerforum@firesprinkler.org>
sprinklerforum-bo cc
un...@firesprinkl
er.org Subject
RE: Underground flushing velocities
03/31/2010 01:14
PM
Please respond to
sprinklerfo...@fi
resprinkler.org
The local AHJ wouldn't know the difference between Velocity and
Velociraptor so no point even going there.
So for the next NFPA 24 go-round they need to change the wording in the
flushing section to just say "that the minimum rate is whatever you can git
outta the pipes" and be done with it.
Craig L. Prahl, CET
Fire Protection Specialist
Mechanical Department
CH2MHILL
Lockwood Greene
1500 International Drive
PO Box 491, Spartanburg, SC 29304-0491
Direct - 864.599.4102
Fax - 864.599.8439
craig.pr...@ch2m.com
http://www.ch2m.com
-----Original Message-----
From: sprinklerforum-boun...@firesprinkler.org
[mailto:sprinklerforum-boun...@firesprinkler.org] On Behalf Of Roland
Huggins
Sent: Wednesday, March 31, 2010 2:06 PM
To: sprinklerforum@firesprinkler.org
Subject: Re: Underground flushing velocities
What it actually says is: shall not be less than ONE of the following. So
as long as you meet ANY one of the following you comply.
As for why all the discussion on 10 ft/s, that is the golden rule and
they had to talk about something so they talked a lot about that.
What about all the discussion in the Handbook about sizing the remote area
by counting sprinklers despite the fact that even with the right number,
the actual size can be too small and NOT be in compliance.
What about the Handbook text that states: "In the field, actual
flushing is normally done without measuring the flow rate. Flushing
is normally accomplished at the maximum flow rate AVAILABLE from the water
supply as permitted by 10.10.1.2.3(3)."
So yes, 2 fps is acceptable as long as it is what is produced by the system
demand and has nothing to do with a call by the AHJ. You guys are
unnecessarily beating yourselves up. Now having said that, what you put in
your spec's (especially where stuff glows in the dark and the DOE is happy
to apply the golden rule), is a different story.
Roland
On Mar 31, 2010, at 10:37 AM, Law, Kevin W wrote:
> The key is the requirement states it shall not be less than ANY one of
> the following.
>
> Therefore, the very minimum flow rate will be 10ft/sec line velocity.
>
> If your system cannot under any condition flow a minumum of 10ft/sec
> then you would have to get a ruling from the AHJ to allow that.
>
> Nuff said
>
>
> Kevin Law, PE
> Bechtel National, Inc.
> Waste Treatment Project
> Fire Protection Engineering
> Work (509) 371-3280
> Cell (509) 531-5715
>
>
> -----Original Message-----
> From: sprinklerforum-boun...@firesprinkler.org
> [mailto:sprinklerforum-boun...@firesprinkler.org] On Behalf Of
> craig.pr...@ch2m.com
> Sent: Wednesday, March 31, 2010 10:20 AM
> To: sprinklerforum@firesprinkler.org
> Subject: RE: Underground flushing velocities
>
> So if the max. velocity is only 2fps there's no issue?
>
> Then why the talk of 10fps in the appendix with mention of high
> velocity and Table relating to 10fps?
>
> If any velocity was acceptable then why not just say it doesn't matter
> or say nothing at all?
>
>
> Craig L. Prahl, CET
> Fire Protection Specialist
> Mechanical Department
> CH2MHILL
> Lockwood Greene
> 1500 International Drive
> PO Box 491, Spartanburg, SC 29304-0491 Direct - 864.599.4102 Fax -
> 864.599.8439 craig.pr...@ch2m.com http://www.ch2m.com
>
>
> -----Original Message-----
> From: sprinklerforum-boun...@firesprinkler.org
> [mailto:sprinklerforum-boun...@firesprinkler.org] On Behalf Of Roland
> Huggins
> Sent: Wednesday, March 31, 2010 12:51 PM
> To: sprinklerforum@firesprinkler.org
> Subject: Re: Underground flushing velocities
>
> The 10 fps applies only to option 2, not all the options. As long as
> you meet any ONE of the options, where's the beef?
>
> The objective is to keep loose objects in the main from potentially
> blocking the sprinkler system. Option 2 assures us that we will
> remove the loose objects. The other options assure us that the
> objects will not reach the system since the maximum possible velocity
> (being less than 10 ft/s) has removed the objects that will move at
> system demand (which would be the likely lowest velocity). Option 3
> allows us to simply open multiple outlets and let it flow whatever
> flows without having to prove anything.
>
> Roland
>
> On Mar 30, 2010, at 1:47 PM, <craig.pr...@ch2m.com>
> <craig.pr...@ch2m.com > wrote:
>
>> NFPA 24 says the following:
>>
>> NFPA 24: 10.10.2.1.3 The minimum rate of flow shall be not less than
>> one of the following:
>> (1) Hydraulically calculated water demand flow rate of the system,
>> including any hose requirements
>> (2) Flow necessary to provide a velocity of 10 ft/sec (3.1 m/sec) in
>> accordance with Table 10.10.2.1.3
>> (3) Maximum flow rate available to the system under fire conditions
>>
>>
>>
>>
>>
>> Debate is whether that means that the flow rate dictates the velocity
>> and it has no absolute requirement or the minimum is 10fps.
>>
>> Based on wording in the Appendix it would appear that 10fps is the
>> desired minimum.
>>
>> So for example I have a flow rate of 8000 gpm (fire flow per local
>> AHJ) and the line size ends up being 24" Vel= 6.74 fps. Is that
>> acceptable per NFPA 24, 10.10.2.1.3? There are issues with the
>> distance between source and pump suction and larger pipe equal less
>> friction loss but also lowers velocities.
>>
>> I read it that it can be less than any one of the following with
>> 10fps being the minimum. Sometimes simpler wording for non-FP
>> types would make life easier. <sigh>
>>
>> Thought, comments, etc?????????
>>
>> Craig L. Prahl, CET
>> Fire Protection Specialist
>> Mechanical Department
>> CH2MHILL
>> Lockwood Greene
>> 1500 International Drive
>> PO Box 491, Spartanburg, SC 29304-0491 Direct - 864.599.4102 Fax -
>> 864.599.8439 craig.pr...@ch2m.com http://www.ch2m.com
>>
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