But Horror stories have been the basis for ‘safety margins’ in our codes
and standards since their inception... including NFPA 13.
There have been amazing strides made in understanding and quantifying
the dynamics of sprinkler performance, limitations, etc. over the past 30
years and incorporating that knowledge into NFPA 13. A defined safety
factor in hydraulic calculations is but one logical step in the continuing
maturation of 13 and will eventually be in the standard. The more useful
discussion is how it should be quantified and Incorporated. I agree with
Scott and share his experiences....NFIRS stats are not helpful in
justifying technical stagnation.
I absolutely understand and agree with the position that a safety factor
is already baked in the standard but what is it? Saying it’s “enough”
without being able to eventually define it doesn’t help further progress.
... 2 cents from a lurker (usually 😉)
Daniel Arnold, PE, FSFPE
Seneca Fire Engineering, LLC
Atlanta, Georgia
Daniel L. Arnold, PE, FSFPE
Sent from my iPhone
On Jun 18, 2018, at 11:34 AM, Mark Sornsin [FAR] <[email protected]>
wrote:
All of the horror stories in the world do not change the fact that
requiring a specific safety margin for calculations is difficult to justify
in an internationally recognized standard. I could see Annex language
offering pros for a margin and maybe giving examples of when one might be
considered.
In my view it’s the responsibility of the person engineering the system to
make this call. In this industry 99% of the time that is the designer
working for the low-bid contractor. The designer who may or may not be
NICET certified, depending on the rules of the jurisdiction in which they
are working. The point is the person with the most knowledge of the local
conditions should be making this call. In an ideal world, when you have
someone specifying the design parameters for a bid project, it would be the
specifying engineer. I also realize that this is fantasy 98% of the time,
which is a stain on the engineering profession, but that’s a different
rant. We can’t expect to codify a requirement like this in a standard that
needs to apply throughout the world. It would require specific numbers and
these will vary on local conditions. Instead it is the engineer/designers
responsibility to become familiar with local conditions and adjust
accordingly. The example of reduced water levels in municipal water towers
is a great one. Not all cities engage in this practice, but where they do
the designer needs to know what the minimum static pressures can be. Or
the local reviewing authority needs to adopt specific requirements to match
their local conditions.
But the real problem comes when a contractor is bidding on a job with no
real engineering guidance and no local amendments to account for special
local conditions. The low-bid contractor or will be the one who assumes
their water test is valid despite having taken it at the highest possible
pressure of the day/season. And a specific safety margin requirement in
NFPA 13 cannot guarantee proper correction for this error.
<image1fad98.JPG> <http://www.SummitCoUS.com> Mark Sornsin
Sr. Fire Protection Engineer
Direct: 701-499-1391
Cell: 701-526-8585
*From:* Sprinklerforum [mailto:[email protected].
org <[email protected]>] *On Behalf Of *Scott
Futrell
*Sent:* Saturday, June 16, 2018 9:51 AM
*To:* [email protected]
*Subject:* RE: Safety Margin
As a plan specifier, plan reviewer and an investigator I see designs right
to the supply and then as-built conditions far worse (read more demanding)
than the design submitted with the calcs. This is not a regional
observation.
Additionally, I am aware of communities that lower elevated tank levels
20’ in winter to lower heating costs. Contractors in those areas do NOT
adjust flow tests for this seasonal variation.
No safety margin what-so-ever in NFPA 13 is unreasonable for a design
standard.
Arguments on the floor including ‘requiring all systems to have back-up
power’ were ridiculous.
Scott
Office: (763) 425-1001 x2
Cell: (612) 759-5556
*From:* Sprinklerforum [mailto:[email protected].
org <[email protected]>] *On Behalf Of *Steve
Leyton
*Sent:* Friday, June 15, 2018 2:16 PM
*To:* [email protected]
*Subject:* RE: Safety Margin
That was the conversation on the floor of the code hearing. The concerns
underscored by the CAM were not about whether safety factor is a good
practice, it was that a fixed minimum value as high as 10 PSI could trigger
all sorts of cost-impact consequences, particularly in areas where
pressures are middling to poor – in Rhode Island, 10 PSI could be 25-30% of
the available pressure.
In the West, due primarily to the politics of drought, water districts are
using models in lieu of physical flow tests. Prudent and conservative
programming makes it possible for them to issue safeguarded values from
which it’s not necessary to reduce the available pressure. For ex., City
of San Diego uses a three-level safety factor in their (highly accurate)
models: starting with legacy drought water levels in the reservoirs, then
factor the highest seasonal demand, then the highest peak day demand of
that season. The values we’re getting are usually significantly lower
than what can be measured on the hydrant, and this practice isn’t without
controversy because there are obvious complications that can and do occur,
particularly with existing systems based on 20-year old (and older)
pressures that were physically measured (with crappy equipment) when first
designed and built.
But if modeling becomes the new normal, prudent water district engineering
departments and fire departments they serve can coordinate manipulating
data to include reasonable safety factors. The range of variation in
pressures, accuracy of flow test equipment, the use of modeling in many
areas … there are too many variables to set a fixed minimum safety factor
based on PSI, IMHO.
SML
*From:* Sprinklerforum [mailto:[email protected].
org <[email protected]>] *On Behalf Of *Parsley
Consulting
*Sent:* Friday, June 15, 2018 12:00 PM
*To:* [email protected]
*Subject:* Re: Safety Margin
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 <http://www.parsleyconsulting.com/> *
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]>
<[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 <http://www.parsleyconsulting.com/> *
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]
<[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?
_______________________________________________
Sprinklerforum mailing list
[email protected]
http://lists.firesprinkler.org/listinfo.cgi/sprinklerforum-firesprinkler.org
_______________________________________________
Sprinklerforum mailing list
[email protected]
http://lists.firesprinkler.org/listinfo.cgi/sprinklerforum-firesprinkler.org
_______________________________________________
Sprinklerforum mailing list
[email protected]
http://lists.firesprinkler.org/listinfo.cgi/sprinklerforum-firesprinkler.org
______________________________________________________________________
This email has been scanned by the Symantec Email Security.cloud service.
For more information please visit http://www.symanteccloud.com
______________________________________________________________________
_______________________________________________
Sprinklerforum mailing list
[email protected]
http://lists.firesprinkler.org/listinfo.cgi/sprinklerforum-firesprinkler.
org
_______________________________________________
Sprinklerforum mailing list
[email protected]
http://lists.firesprinkler.org/listinfo.cgi/sprinklerforum-firesprinkler.
org
