Flow Test Reports and the N^1.85 Supply Graph

4/11/2018

A few weeks ago I received a call from a sprinkler contractor who needed to provide a water supply graph for a flow test he conducted.

I had a canned sheet I had developed for my own flow tests, but it was a basic graph that showed a curve and didn't match the traditional N^1.85 hydraulic graphs common for water supply curves. Since then I've tinkered and come up with an accurate chart that takes flow test input values, calculates total flow and draws the curve along the N^1.85 chart.

The N^1.85 chart is particularly useful for fire suppression systems because the Hazen-Williams formula is based on the relationship that pressure relates to flow to the 1.85th power.

Take a look at the N1.85 Water Supply Curve tool here and let me know what you think in the comment section below.

Download this Tool

When the x-axis, or the hydraulic flow is then scaled to the 1.85th power, hydraulic curves become straight lines which becomes easier to graph and compare. Prior to everyone carrying a computer in their pocket, these graphs were likely much easier to use for summaries and comparisons.

The water supply information is what is provided as part of a two-hydrant flow test. The design input information would be the system demand side and can be used for quick comparisons.

Personally, I only use this setup for flow test reports and water supply comparisons. Fire sprinkler hydraulic calculation software takes care of the graphs and outputs I need after I've completed the hydraulic calculations.

On a side note, I've had several people ask about getting access to all of the tools I've created to use on their own computer with the ability to produce printable output for record keeping. Thanks again to those who asked - that concept is in the works and I'm hoping to bring about some version of all-inclusive software in the next couple months.

Don't get these free weekly articles? Subscribe here. My goal with creating this website and tools is to support those who want to create great fire protection.

22 Comments

David Reynolds

4/11/2018 09:06:36 am

I am trying to come up with a logarithmic graph form that we can plug in hydrant flow and it plots the curve / with a google map location for the hydrants / forms for fire hydrant insp. (5 year)

John Kallenbach

4/11/2018 12:02:30 pm

I keep getting failed to download chart. Is that just me or are others getting that as well?

Joe Meyer

4/11/2018 04:04:46 pm

Hi John, yes this is not yet available for download. I'll post back here when it is.

Thanks John,

Joe

Gerardo pantoja

4/21/2018 02:57:03 pm

Deseo recibí r información

Daniel

4/11/2018 12:35:37 pm

Thanks for putting this out! I just wanted to confirm that this is a web based tool only (like Ping Fire). My group has been looking to create an excel version for a while but has been running into issues with the N1.85 semi-log scaling. Do you have an excel version available?

4/11/2018 04:01:47 pm

Correct, yes this tool is only currently available online similar to Ping Fire.

That being said I'm working on an excel-based downloadable resource with every tool I've created. I hope to have it all ready in the next couple months.

Thanks Daniel!

Brian Harris

4/11/2018 01:42:43 pm

Will this be available for download?

4/11/2018 04:03:31 pm

It will be a part of a software package with every tool I've created to date, but I don't have it ready quite yet. Should be posted in the next couple months.

Thanks Brian!

Cindy Gier

4/11/2018 04:05:25 pm

Great tool! We've been working on a KCMO hydrant map with hydrant flow tests -- since the city will no longer give the information out. This form can replace my hand drawn flow test graphs using scanned N1.85 graph paper. Thanks!

4/11/2018 04:23:44 pm

The example showed up.. I have a free excel spreadsheet in my group on facebook - non-union fire sprinkler group. Feel free to join.

MICHAEL CHARBONNEAU

4/14/2018 05:58:59 pm

why are flow tests on log graph but fire pump data sheets on regular graph? Since most water flows are from pumps, would they look the same if plotted differently?

Merle Hittle

5/11/2018 09:56:04 am

If I am not mistaken, pump tests not plotted on log graph are actually curves and when plotted on log graph are straight lines like flow tests. I have seen flow test data and pump test data plotted on the same log graph to visually verify boost pressures.

jorge h garcia link

4/23/2018 04:22:33 pm

when you have some calc program for download i'm interested to get one, on the other hand, I use before a software for NFPA 25 pump flow test... very usefull and easy, but unfourtunally does not run on windows 10, jut on XP. Did you Know some software to do that calcs and track the history maintenance.
regards

Jeffrey Wong

4/24/2018 06:20:09 pm

Great tool! Is it possible to change the SI to metric? I'm from that part of the world.

JOE MEYER link

4/26/2018 05:32:25 am

You mean you're from almost any single country on the planet other than the US? We completely missed the boat on metric.

I appreciate the idea, it's in the works and I'll plan to put it up in the next few weeks. Thanks Jeffrey!

John Vergara

5/10/2018 05:21:01 pm

Looks good. Can the units be modified to metric?

JOE MEYER

5/11/2018 06:29:47 am

Yes! The metric version is now available here: https://www.meyerfire.com/blog/fire-suppression-n185-supply-graph-now-in-si

Thanks!

Joe

MEL

5/17/2018 01:25:14 pm

What have all of you been using
to use for hanging from Cold Form Trusses
And for the seismic bracing for Cold Form Shapes

Hanging just the sprinkler pipes?

KEN

7/5/2018 12:21:19 pm

Can you explain in your blog or to me how to adjust for Hydraulic Low gradient. There is nothing on the Web. No one seems to know, and I think my adjustments are too much?
thank you

Edriane Leonard Gabriel

12/20/2018 10:08:57 pm

Hi,

Do you have an example of hydraulic calculation for building construction and space expansion?

I believe that fire protection system design for building construction and expansion are different calculation?

Looking for your fast and positive response.

Thanks.

1/5/2019 06:20:10 am

Hi Edraine,

I don't currently have an example calculation - there's some basic starting hydraulic calculations with many of the fire sprinkler hydraulic calculation programs. That being said, each calculation is very specific to the actual design of that system so having an example calculation wouldn't be of any help.

Joe

JUSTIN D STIRLING

1/5/2019 10:32:46 pm

I also have developed my own sheet with a basic graph that shows a curve. Can you provide any guidance on how to adjust the x-axis in Excel to make the N^1.85 chart? Thanks in advance!

Flow Test Reports and the N^1.85 Supply Graph

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