Why Aren't Added Standpipe Flows Balanced?

6/19/2026

When adding flow of additional standpipes (vertical standpipes with a horizontal connecting main), the NFPA 14 handbook (NFPA 14 10.6.1.2.4) explicitly says that flows shall not be required to be balanced.

I get the logic of balancing the calc, and it's not terribly hard to do - but what's the difference?

Is not balancing the calculation more conservative?

Is it insignificant, and therefore doesn't really matter?

Why aren't we required to balance the calc by code?

Thanks in advance.

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

7 Comments

Dan Wilder

6/19/2026 08:24:14 am

Good Friday question! The current/former fire fighters can better speak to a lot of below but in my searching...

Best I can provide looking into this is that the flow calculation is performance based to provide that the minimum flow and pressure is available at the flowing points because the actual flow and pressure requirements are unknown at those points. They are all independent of each other (the hose valves) and are not setup with any predetermined requirement (this hose valve supports these hose and nozzle types)...

Will a single 2½" nozzle be used with a wye and feed smaller 1½" - 1¾" attack line needs stream and fog capabilities separately? Not a clue... Will a single 2½" hose be used with a nozzle, likely not but there is a possibility (can't drag that around very well). Will they pull lines from separate hose valves to the same area to provide better coverage. Again, not a criteria we as designers are required to align with as we are just providing what seems to be the best overall approach to most of the responding department's needs.

6/19/2026 08:56:47 am

The hose allowance for a fire sprinkler system in NFPA 13 is based on providing the fire department water for final extinguishment (assuming that the fire sprinkler system is controlling the fire like it's designed to).

The standpipe hose system demand in NFPA 14 is for manual firefighting operations which can either be in a non-sprinklered building, or in a sprinklered building where the sprinkler system control valve is closed for the fire department to manually intervene to extinguish the fire.

If everything works correctly, there really shouldn't be a situation where you have a fire sprinkler system fully activated over the entire remote AND a hose allowance for final extinguishment AND need an additional 1000gpm of water at 100psi for fire fighting operations. I'm not saying this always happens, but the codes and standards are based on everything working as designed, not incase things fail. If the expectation was that things were going to fail, it would be very hard to standardize anything.

Mark Harris

6/19/2026 09:06:46 am

Not sure if this is the question but if is about balancing flows for additional vertical standpipes (NFPA 14 not sprinklers NFPA 13) my interpretation is if it flows at hydraulically remote standpipe any closer less hydraulic demand standpipes or connections would provide more flow and or pressure. Like the worst case remote design area for a closed head fire sprinkler system.

Jose R Figueroa

6/19/2026 10:17:10 am

It is presumed that the fire protection system incorporates automatic sprinklers. These standpipes shall not be considered in the balance calculation for gridded or looped systems. Omitting the balancing of added standpipe flows (referencing NFPA 14, section 10.6.1.2.4) represents a deliberate and code-compliant simplification, which is generally more conservative for the supply piping and remains pragmatic due to the performance-based requirements of standpipe demands.

Mike Russell

6/19/2026 10:47:38 am

Without getting into the inherent differences between a sprinkler with a fixed k-factor and a hose valve, the intent of NFPA 14 is that you balance the pressure, but not the flow.

The code requires 250 gpm for each hose connection, starting with 100 psi at the remote connection. Depending on the edition, you add 250 gpm for each additional standpipe at the balanced pressure. Essentially, your remote connection should be discharging at 100 psi while each additional connection would have the same 250 gpm at slightly higher pressure.

Jack G

6/19/2026 01:52:44 pm

While it’s not recommended or referenced, I usually perform a “ supply calculation “ on the standpipe system with the 500 plus 250 plus 250 at the top ( 3 standpipe) and the program will calculate the pressure available at each valve. I then tweak it if needed, and then perform the required demand calculation.
I also initially do a supply calc on remote area calculations, tweak the pipe sizes if needed, then do the demand calculation.
In my opinion, the supply calc is what you are going to see , say when a remote area goes off( accuracy wise ) as it uses all the water.
In the past, when I do a demand calculation with the normal 10 psi safety factor, that 10 psi puts the demand over the curve ( doing a supply calc on the calculation with the safety factor)
Real life or “ demand?”

Jack G

6/19/2026 01:58:35 pm

I initially was in special hazards for anbout 7 years. Transformers
and deluge systems.
The goal was to “ let the pipe sizes “ regulate the flow to prevent sometimes massive overflows. If that occurs the sprinklers involved will not deliver the required density.

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 © 2016-2025 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.

Why Aren't Added Standpipe Flows Balanced?

Leave a Reply.

ALL-ACCESS

SUBSCRIBE

COMMUNITY

YOUR POST

PE EXAM

FILTERS

ARCHIVES

PE PREP SERIES