As plan reviewer any authority I applied was adopted codes, including standards 
adopted by ordinance through codes. 

Also I was expected to pass on local conditions that a designer working in a 
much bigger regional area would not have at fingertips.

Calculation to the right of the curve is code complying. Rare exception might 
apply if it is known or reasonable to expect pressure/flow curve to degrade at 
a given point. I only remember this applying at one isolated area. (See recent 
talk about tank sizes). This would have been supplied to project team at first 
meeting, with near complete surety that information would not be passed onto 
sprinkler bidders.

Hydraulically calculated systems all have safety factors built in. Somewhere I 
had to take a test that I had to list five or seven. Two that immediately come 
to mind are: Test setups at FM’s test building, and later UL’s, are designed to 
maintain as much as they can a constant pressure at the heads as more heads 
open. In our world the first couple heads flow more at higher pressure than the 
minimum design flow when all heads in the calculated area are flowing. Another 
is that the every part of the system outside the worst (selected, calculated) 
part of the system has better flow/pressure, although with grids delta is often 
not much.

We did not include by ordinance a safety margin. So I can’t understand 
authority to require one. Again above example where we knew an area was going 
to lose one end of a loop, and become a long dead end (~3,000’) during major 
road construction. 

Best.

Bruce Verhei 


> On Jun 15, 2018, at 11:59, Parsley Consulting <[email protected]> 
> wrote:
> 
> Richard,
> 
> If my memory is accurate of the issues raised in the discussion that 
> ambiguity was a part of the differing viewpoints.
> 
> Some argued that 10 psi was not workable in their locale as their pressures 
> were so limited that an imposition of 10 psi was simply to drastic and would 
> result in much larger pipe sizes as a result.
> 
> Others argued that 10 psi was not enough, and in their area 10 psi didn't 
> equal 10%, and there was some reluctance to base their designs on a pressure 
> greater than 90% of the available.
> 
> It was quite a discussion.  
> Ken Wagoner, SET
> Parsley Consulting
> 350 West 9th Avenue, Suite 206
> Escondido, California 92025
> Phone 760-745-6181
> Visit the website
>> On 06/15/2018 10:23 AM, Richard Carr wrote:
>> Even though it is not in NFPA most AHJ’s require some sort of safety margin, 
>> 10%, 10 psi which we have had to provide for a long time so most designers 
>> know to leave safety margin in the calc’s. it would be nice if they all used 
>> the same amount.
>>  
>> Richard M. Carr, SET
>> Project Manager/Design
>> Diboco Fire Sprinklers, Inc.
>> 325 Jackson Loop Road
>> Flat Rock, NC  28731
>>  
>> [email protected]
>> 828-696-3400
>> 828-696-2288 Fax
>> 828-708-9118 Mobile
>>  
>> <image001.jpg>
>>  
>> <image002.png>
>>  
>>  
>> From: Sprinklerforum <[email protected]> On 
>> Behalf Of Parsley Consulting
>> Sent: Friday, June 15, 2018 1:22 PM
>> To: [email protected]
>> Subject: Safety Margin
>>  
>> Scott,
>> 
>> Based on the material which was presented to the -24 and -291 committee 
>> meetings I believed the proposed safety margin and the means to calculate 
>> that margin there was some merit in the proposal. 
>> 
>> For reasons I don't quite remember the PI was voted down at the 2nd draft 
>> meeting.  I listened to some of the discussion, and there were some good 
>> points made.  I'm not terribly surprised it failed at the convention level.  
>> Perhaps the attendees were following the lead of the technical committees, 
>> and declining to overrule their decision.
>> 
>> sincerely,
>> Ken Wagoner, SET
>> Parsley Consulting
>> 350 West 9th Avenue, Suite 206
>> Escondido, California 92025
>> Phone 760-745-6181
>> Visit the website
>> On 06/15/2018 8:09 AM, Scott Futrell wrote:
>> Only that the 'safety margin' inclusion in the 2019 edition of NFPA 13 
>> failed, so it won't be included or required.
>>  
>> I consider this unfortunate, but I'd guess that not everyone on the forum 
>> would agree.
>>  
>> Scott
>>  
>> Office: (763) 425-1001 x2
>> Cell: (612) 759-5556
>>  
>> -----Original Message-----
>> From: Sprinklerforum [mailto:[email protected]] 
>> On Behalf Of [email protected]
>> Sent: Thursday, June 14, 2018 5:46 PM
>> To: [email protected]
>> Subject: NFPA Vegas Convention
>>  
>> I didn't make it again this year.
>> "Caputo" is the only speaker name I recognized.
>> Anybody have any earthshaking epiphanies?
>>  
>>  
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>>  
>> 
>> 
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