Increase Capacity of Existing Sprinkler System?

6/11/2021

I'll preface this that I'm not a engineer. There is 17-foot storage with an existing sprinkler design of 0.20 / 1,500 sqft.

Based on NFPA 13, I believe we would need 0.21 / 2,000 sqft for a Class II commodity (non-encapsulated rack storage).

How would you recommend going about increasing both the remote area size and the density on an existing system?

Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe

8 Comments

Glenn Berger

6/11/2021 08:36:29 am

Start off by having new hydraulic calculations prepared on the existing system. The result and this analysis and understanding the age of the system would determine my next move. There are too many variable to discuss at this time.

Dan Wilder

6/11/2021 08:49:14 am

Too many storage questions, but assuming your density & area scenario is accurate, just putting a new remote area on the drawing at the new size and density is all you need (along with a current flow test) as long as you have the system surveyed/verified for layout.

The density is still below .26 so 5.6K sprinklers are still acceptable, only better if you've got 8.0K's, you can still keep the 130ft² area max but I wouldn't think they are 286° so I question the reduction to 2000 but there are some tricks I probably don't know about.

Mike

6/11/2021 09:07:54 am

Survey the system. Do a complete hydraulic design. Hopefully, the underground is 6". Start with increasing 1" pipe at the end of lines, then do an analysis of high friction loss pipes and work backwards.

Brian Cockburn

6/11/2021 09:32:25 am

I would survey the existing system and do a hydraulic calculation to see how much capacity there is. It is possible that the existing sprinkler system could deliver higher amounts of water.

I would also confirm precisely what type of storage occupancy you're dealing with. As others have said, there are many variables to consider. Once you know the occupancy type and system capacity, then you can look at reconfiguring the system as required.

A qualified engineer and sprinkler contractor could do this for you.

CJ Bonczyk

6/11/2021 09:39:31 am

There are still some factors about the storage arrangement & commodity in the occupancy to confirm if adjusted your remote density area calculation is allowed. However, if you have fully surveyed the existing system, and completed a RECENT flow test including any appurtenances back to the hydrant location you can determine the actual hydraulic capability of the system. You might get lucky and see that the water supply availability actually got better since the original design was installed (but most of the time this is not the case). Complete a total survey of the existing system. Prior to completing any calculations have the owner fill out to its entirety an owners commodity classification form. This information is critical so that if/when you modify the existing system you can place with the new hydraulic placard the additional sprinkler system general information placard as required per NFPA 13.

If your commodity is correct as you state above then verify the spacing of the exact spacing of the sprinklers, types, temps, K factors etc. when performing your calculation based on the new density only apply the minimum density required based on the spacing installed and not the maximum spacing allowed. For example you have a .20 density with 5.6 sprinklers for a commodity allowing sprinklers to be spaced at 130ft². But the actual max spacing installed is at 120ft². In lieu of flowing 26gpm for a 130 sq./ft. layout flow the bare minimum required which is 20gpm. Normally I try to calculate the max flow because spacing in the field doesn't always end up being perfect and i want some fluff for field adjustments. Analyze what is the simplest portions of the system that can be modified to accommodate your calculation requirements. Ensure this is submitted to the AHJ for approval so that they are aware the of the changes in the building system capabilities and hazard classification.

Jon Sullivan

6/11/2021 12:39:54 pm

Recent being within the past year.

Wes

6/11/2021 09:59:53 am

We partner with local sprinkler contractors and help perform these calculations regularly. If the capacity of the existing system won't match the new storage arrangement, we'll find ways of economically upgrading or replacing the system to get it to work.

It's nuanced on the hydraulic side, so doing an actual survey and hydraulic calculation is important here.

My only recommendation/contribution to this question is that I strongly suggest you don't do this work for free. Contractors get roped into enough "free consulting", and when they give an owner advice the owner doesn't like what do they do? They shop around the job and all that upfront calculation work is lost.

If you're a contractor, consider charging for the design or getting a quote from a local engineer to calc up the system so you don't have to be the bad guy, and don't get roped into important work like this without compensation. Free or underpaid work in this area could (not always) try to justify only a quick look or sloppy engineering. The win-win is to get it right, thoroughly, and get paid for your work.

Off my soapbox now.

Dorg T

6/17/2021 03:01:27 pm

As mentioned you cant do anything without a hydraulic calculation.

I do these all the time. You wont get above 12' without going to a larger remote area and potentially density.

As for what to do, after you do hyd calcs, options are:
up sizing the pipe, using high temp spks (I doubt current ones are HT), up sizing the K-factor, grid the system, and likely up-sizing the back-flow preventor.

GL
DT

Leave a Reply.

Home
Our Cause

The Blog
The Forum

PE Exam Prep
The Toolkit
MeyerFire University

Pricing
Login
Support
Contact Us

MeyerFire.com is a startup community built to help fire protection professionals shine.
Our goal is to improve fire protection practices worldwide. We promote the industry by creating helpful tools and resources, and by bringing together industry professionals to share their expertise.

MeyerFire, LLC is a NICET Recognized Training Provider and International Code Council Preferred Education Provider.
All text, images, and media Copyright © 2016-2024 MeyerFire, LLC

We respect your privacy and personal data. See our Privacy Policy and Terms of Service. The views, opinions, and information found on this site represent solely the author and do not represent the opinions of any other party, nor does the presented material assume responsibility for its use. Fire protection and life safety systems constitute a critical component for public health and safety and you should consult with a licensed professional for proper design and code adherence.

Discussions are solely for the purpose of peer review and the exchange of ideas. All comments are reviewed. Comments which do not contribute, are not relevant, are spam, or are disrespectful in nature may be removed. Information presented and opinions expressed should not be relied upon as a replacement for consulting services. Some (not all) outbound links on this website, such as Amazon links, are affiliate-based where we receive a small commission for orders placed elsewhere.

Increase Capacity of Existing Sprinkler System?

Leave a Reply.

ALL-ACCESS

SUBSCRIBE

COMMUNITY

YOUR POST

PE EXAM

FILTERS

ARCHIVES

PE PREP SERIES