Following the interest and popularity of the ceiling-mounted obstructions tool, I've been working on some new tools that cover other obstruction situations which we often encounter. This week's post is a quick demo of the progress for one of these obstruction situations, which is the soffit against a wall condition.
One way NFPA 13 addresses soffits is by shifting a sprinkler away from the wall, which allows water from the sprinkler to throw below the soffit. With only two input values this tool will quickly determine the horizontal distance a sprinkler needs to be located away from a soffit in order to meet NFPA 13 Figure 220.127.116.11.2(b) (2016 Edition).
Give this demo tool a quick try and comment below with any concepts you'd like to see added to this tool or the site. Thanks in advance!
When I was six years old, I came home from school unexpectedly excited one day.
I ran up our driveway, pushed wide the door and yelled to my mom.
“You won’t believe it! There’s this place at school where you can go through shelves and shelves of books and pick out anyone you want –
and it’s free! They call it a library.”
It wasn’t one of my mom’s proudest parenting moments, but in our house, we never pretended to be great readers… or apparently even pretended to introduce kids to a library.
I guess I’ll just come out and say it… Both of my parents are accountants.
Now, I know what you’re thinking, and yes, the accountants are where my well-rounded sense of humor comes from.
But there’s another big benefit to having parents as accountants –
and it’s having a love for spreadsheets.
I’m not sure if little excel formulas naturally run through my veins or whether it was every family calendar my parents ever created, but one way or another I thoroughly appreciate the power a spreadsheet has.
Even if your parents are not both CPAs, there’s a place for Microsoft Excel in your engineering life.
Excel isn't just made for your uncle accountant anymore - there's potential any engineer can love.
For one, Microsoft Excel is not called
the “Swiss Army Knife of Software” for naught. Excel is a blank canvas for any calculation you need to make. You can quickly create and repeat repetitive calculations to speed up and organize your workflow. You can complete reports, forms, create charts, tables, organize content, or use any of a myriad of highly powerful tools.
Here are a few of my most often used formulas:
That’s pretty much all of my secret sauce. About 95% of the tools created combine those formulas alongside mathematical operators (like max(), min(), sin(), sqrt(), etc.).
One of the best parts about using Excel is that you may already have access to it. If your company has a Microsoft Office suite (or what’s now their subscription model with Office 365), you already have access to these tools.
Creating helpful resources is what we’re all about, and Excel is the epitome of giving you, the rockstar designer or engineer, the ability to create and flourish with the tools you need.
You didn’t get into the industry to do poor, sloppy work. You came here to help save lives. We shouldn’t have to wait for programmers to create the daily tools we need to do great work. Excel is one way you can organize and validate the great work you do.
There came a point near the end of my undergraduate work and at the beginning of graduate school where I realized I needed to create a clean, organized method to show details within calculations. The method I slowly developed needed a single logic path, had to be easy to follow, would thoroughly explain the process, and had to allow the easy repetition of the work.
What’s resulted is the standard format that’s used in the PE Prep Guide and on many of the tools you’ll see around this site. Concepts are researched, painstakingly created, tested, refined, tested, refined, beta tested, and refined more.
Standard formatting for MeyerFire tools - note the equations and worked examples with references cited.
If you’ve followed the blog for a while, you already know the blog, daily forum, and even the PE prep materials are all created to help foster discussion that leads to shared expertise and knowledge.
Outside of a few major players and organizations, the fire protection industry is comprised of thousands of thousands of small outfits that welcome this shared expertise. Our industry thrives on the contributions from a wide spread of individual parties.
Don’t let me or anyone else douse your enthusiasm to create resources that improve your ability to impact the industry.
Keep on keepin’ on.
Oh and remember to take your kids to the library.
Looking for an opportunity to turn a basic concept into a controversial one on a project? Great! This week I'm exploring the quick-response remote area reduction that's provided in NFPA 13.
Suppress Early, Suppress Less
The concept behind reducing the calculated hydraulically remote area in a fire sprinkler system is entirely based on fighting a smaller fire earlier in the development of the fire.
There's a handful of factors that contribute to the timing of sprinkler response (a good future discussion), which include the thermal sensitivity, sprinkler temperature rating, distance of sprinklers relative to the ceiling, sprinkler spacing, ceiling height, and dynamics of the fire itself.
The reduction in the hydraulically remote area is based upon comparative tests of quick-response against standard-response spray sprinklers. According to the NFPA 13 handbook, the tests demonstrated that the earlier the water is applied to the fire, the smaller the fire and ultimately the less number of sprinklers needed to activate.
Not Universally Accepted
While the remote area reduction has been included in NFPA 13 for years, it's not universally accepted. Many engineer specifications don't allow the reduction, and design standards for major organizations such as the Department of Defense (UFC 3-600-01) don't permit it either.
Why not accept the remote area reduction, if NFPA 13 includes it? Like other elements in hydraulic design for fire sprinkler systems, not using the remote area reduction provides an additional safety factor to the system.
Additionally, since the quantity of sprinklers relates to the quantity of water flowing in the system, main sizes are directly impacted by using or not using the quick response area reduction. Building owners may opt to not want to reduce the remote area to preserve reasonable (larger) main sizes and give themselves flexibility on building modifications and sprinkler system changes in the future.
Quick-Response Area Reduction Calculator
This quick calculator is in part a checklist of prerequisites to reduce the remote area on a fire sprinkler system, in part a method of showing your work, and in part a quick calculator on determining your final remote area size. Don't see it below? Give it a try here.
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Determining fire flow can be a tricky subject. This week I'm breaking down one common method of determining fire flow requirements and hopefully exposing some myths about the process.
Not an Exact Science
First, determining the exact amount of water required to manually suppress a fire is dependent upon so many variables. The amount of water used could depend on the building size, hazard, outdoor conditions, speed of fire growth, fire department response time, whether the building is protected by sprinklers, and on and on.
The methods used to calculate fire flow are different methods at estimating the amount of water required to manually suppress a fire. It is not an exact science.
What is Fire Flow?
I'll start by what fire flow is not. Fire Flow is not the volume of water required for the fire sprinkler system. I couldn't count the number of projects where Fire Flow has been assumed to be sprinkler-related.
Fire Flow is formally defined as the "flow rate of a water supply, measured at 20 psi (138 kPa), that is available for fire fighting." (IFC 200-2018 Appendix B Section B102)
Fire flow is used to determine the quality of a water supply to an area. It's used as an aid to determine pipe size and arrangements to delivery water to a specific area.
Fire Flow is important for emergency response at it is the total capacity of the system that the fire department has available for use in response to a fire.
How Is Required Fire Flow Determined?
In short - it depends.
There are many methods for determining fire flow. The most common cited in US circles include the Insurance Services Office (ISO) Method, Iowa State Method, and the Illinois Institute of Technology (IIT) Method. At least a dozen other methods exist (for more on these, the Fire Protection Research Foundation provides great analysis in Evaluation of Fire Flow Methodologies research paper).
The International Fire Code (IFC) offers Appendix material that provides guidance for determining the required fire flow, which is based on the ISO Method. It is not a mandated code requirement unless a jurisdiction adopts the Appendix.
Many jurisdictions I've worked with do not have an ordinance that adopts the appendix, but when asked they are typically open to using the IFC Appendix B method of determining fire flow. The International Fire Code, which is widely adopted in the US, only requires that an approved water supply "capable of supplying the required fire flow" be provided to buildings.
This process will be explored in more detail here.
1. Determine Baseline Fire Flow
The first step in this overall determination of water supply to a site is to determine the required fire flow.
Using the IFC Method, Appendix B has a reference table that stipulates a minimum fire flow and flow duration based upon building size and construction type (2000-2012 Table B105.1, 2015-2018 Table B105.1(2)).
2. Reductions & Increases
Once a baseline value for flow and duration is taken from the table, it can be reduced based on the presence of sprinkler system.
Section B105 details the adjustments that are available for buildings with a sprinkler system. A reduction of up to 75% can be permitted for buildings with a fire sprinkler system.
It's important to note that up through the 2012 edition of the International Fire Code, a reduction of fire flow had to be approved, meaning the AHJ must agree on the reduction. This may not make a difference if a jurisdiction hasn't adopted the appendix and the entire calculation has to be approved anyways, but in the case where Appendix B is adopted and you're under IFC 2000 through 2012, you'll need AHJ buy-in to use the reduction.
The 2015 and 2018 edition of IFC removed the approval necessity for sprinkler flow reductions.
As part of this process the Fire Chief is also authorized to decrease the required fire flow, based on building isolation or impracticality. Alternatively, the Fire Chief is also authorized to increase based on unusual susceptibility for the facility. These stipulations come with Section B103 of Appendix B (all editions).
Fire Flow is used to quantify the available water supply for manual firefighting operation.
3. Verify Provided Fire Flow
The best way to verify fire flow for a location is to conduct a flow test at the site itself. This of course can be difficult to impossible for new-construction projects on virgin sites.
For developed areas or building expansions, this may not be difficult to accomplish.
I have a current project we're working on that is a major building expansion. Fire flow needed to be assessed based on the new expanded building and whether a single 8-inch feed would still meet the minimum requirements. A flow test on the site itself confirmed that we are just short of required fire flow which prompted a healthy discussion with the AHJ.
4. Calculate from Flow Test to Site (if necessary)
Sometimes a flow test can't be conducted on the site itself.
When this is the case, a hydraulic calculation can be run between the water supply source (nearby flow test, a water tower, reservoir, or pump) and the project site to estimate what the available fire flow will be. This calculation incorporates the pressure loss of the pipe network as water is constricted between a source and a project site. The best way to confirm actual fire flow (in my opinion) is to verify with a flow test once any extension is installed.
Easy Tools for Fire Flow & Water Supply Analysis
There's a new tool in the arsenal around here that directly addresses fire flow requirements.
It's the Fire Flow Calculator that's now a part of the Toolkit. If you're already a Toolkit subscriber, download it today.
The Fire Flow Calculator uses the IFC method based on your project parameters to quickly grab the baseline fire flow and duration, and make adjustments for sprinkler protection. Now you have extremely quick access to determine required fire flow, and the documentation to support your process.
This is a tool I'm happy to debut and have used with great client feedback.
On a side note, Toolkit subscribers also now have access to last week's Design Checklist with user-provided feedback. The download update includes both tools. Give them a download and let me know what you think!
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What's not to like about a Top 10 list? If you know someone who may enjoy reading about this, please consider forwarding to a friend.
Here's the top ten most popular articles and posts in this past year:
I hope you've had a great 2018 and are looking as forward to the coming year as I am.
If you've found any of this helpful, consider sending this to a friend or encouraging them to sign up for these weekly articles here. Thanks in advance and have a great holiday and happy new year!
Things are busy around here - despite the PE Prep "offseason" beginning, I've been working on improvements and construction of a handful of promising tools.
One basic but very much needed update is an improvement to the Obstruction Calculator. Now, you can enter either the horizontal distance of a sprinkler or the vertical distance of the sprinkler, and get minimum and maximum feedback based on each.
During design, many of us know the depth of the sprinkler and depth of the obstruction prior to determining where (horizontally) the sprinkler is going to be located away from an obstruction. Now the tool helps support that effort.
If you're a Toolkit user, you have immediate access to these updates and can download the latest updates on the dashboard here.
As always, thank you to those who have sent ideas and feedback! Stay tuned for next week on a new database launch for Toolkit users.
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Based on some feedback and good ideas I've been experimenting with graphing fire pump & flow test curves with usable data outputs. Below is the first iteration for drawing a fire pump curve alongside a water supply curve.
Determining ideal fire pump configurations for sprinkler and standpipe systems can be
an important part of optimizing fire suppression design
Here's the help I could really use from you - what else would be included in your ideal pump curve?
Would you prefer this be on a logarithmic x-axis?
Want 175 & 300 psi limit lines shown?
Would you want to see at what height in a building the 175 psi threshold would occur - on this graph?
System demand and hose?
I'm open to any and all ideas - in the end I think it'd be great if this tool was the quickest & best method for summarizing and analyzing fire pump output. Share your ideas in the comments here, thanks in advance!
When conducting or reviewing hydraulic calculations, I very often face scenarios where the initial (very first) hydraulic demand exceeds the potential for the water supply.
At that point I lose all hope and add a fire pump to the job.
Just kidding, of course - there's at least a half dozen hydraulic elements I analyze and refine to better match the capabilities of the water supply to the design of the sprinkler system.
Refining Hydraulic Calculations with K-Factors
One of the more fine-tooth aspects I look at is the k-factor used on the sprinklers.
The k-factor for a fire sprinkler is the discharge coefficient, or in normal human terms just relates to the amount of water that is permitted through the sprinkler.
The k-factor is dependent upon the orifice diameter of the sprinkler - a low k-factor (such as K2.8) restricts the flow of water, while a larger k-factor (such as K22.4, K25.2, or K28.0) permit much more water to flow through. K-factors were originally created to be multiples of the discharge of a K5.6 sprinkler. A K2.8 sprinkler, for example, is 50% discharge of a K5.6 sprinkler, while a K11.2 sprinkler is 200% of the discharge of a K5.6. NFPA 13-2016 Table 18.104.22.168 shows this well.
Use In Design
We find K5.6 sprinklers in light hazard all the time. Residential sprinklers often have k-factors less than 5.6. ESFR and CMSA require minimum K11.2 (NFPA 13-2016 22.214.171.124). ESFR are tied directly to the hazard it protects.
Back to refining the hydraulics in a system - increasing the k-factor of a sprinkler allows more water to flow through a sprinkler with less pressure loss. This becomes very important when trying to reduce pressure loss in a system.
Light Hazard Example
A light hazard system (0.10 gpm/sqft) with widely spaced sprinklers (at 225 sqft each) would require a minimum flow through each sprinkler of 22.5 gpm (0.10 gpm/sqft x 225 sqft = 22.5 gpm).
In order to flow 22.5 gpm, a sprinkler with a k-factor of 5.6 now requires 16.1 psi to do so (Q=k√p, or rearranged, p=(Q/k)^2). This is 9.1 psi higher than 7 psi, or the minimum that NFPA 13 requires.
In order to flow 22.5 gpm, a sprinkler with k-factor of 8.0 only requires 7.9 psi to do so, or less than 1 psi more than the minimum NFPA 13 requires.
In this scenario, flowing the same amount of water (22.5 gpm) results in a 8.2 psi difference in the pressure required at the most remote sprinkler. Can 8.2 psi be important? Absolutely!
Similarly, consider Ordinary Hazard Group 1 (0.15 gpm/sqft) and Ordinary Hazard Group 2 (0.20 gpm/sqft) systems.
For Ordinary Hazard Group 1 and sprinklers spaced at 130 sqft, a K8.0 sprinkler requires 5.1 psi less than a K5.6 sprinkler (7.0 psi vs 12.1 psi).
This same methodology applies to extended coverage sprinkler requirements, specific densities for traditional storage design, and more.
The K-Factor Selector
Want to quickly compare fire sprinkler k-factors across different design densities and sprinkler spacing? Easy. Here's the calculator I've created that quickly compares pressure requirements and flow rates across different sprinkler k-factors.
Want all these tools in a downloadable, printable & PDF-saving capability? Great! The MeyerFire Toolkit will include this tool as well. You can download and try it out now through September for free.
Other than the Toolkit, users of the comprehensive Fire Sprinkler Database can sort & search among k-factors as one of the parameters when comparing sprinklers.
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Know someone that might be interested in these tools or articles? Please do me a favor and send them a link or email to share these resources. Thanks!
Last week I introduced a new Thrust Block Calculator and explored some of the concepts around the design and function of Thrust Blocks.
Here's the new expanded thrust block calculator. With similar inputs as before, we're now able to calculate the thrust block volume required, as well as determine the height and width required for the thrust block.
Toolkit is Here
Well it's here! The MeyerFire Toolkit is past a beta version and ready for you.
To celebrate here's the latest version I've created and free access that runs through the end of September. You can download the complete Toolkit with installation instructions below:
Don't Get These Updates?
You can subscribe to all the tools and resources we discuss and create by following the blog here: Join In
As promised I've been busy developing all of the tools available from this site into a downloadable software package, where you can quickly run calculations, save, and print your work. I'm calling it the MeyerFire Toolkit.
Here's the info page about the MeyerFire Toolkit.
The Toolkit is a downloadable software package with an assortment of basic tools for the fire protection professional.
I have the software to a point now that I'd love to gather feedback from you - if you're interested.
If you'd like to beta test the software (try it out and poke around for free), please just reply to this email or shoot me a quick email at firstname.lastname@example.org letting me know you're interested. I'll send a link for a trial version of the software.
While it would be great to get a gauge on where the software is now, I'm far more interested in where it can go in the coming months and couple years. I've been very encouraged by the interest and support to date and I think what these tools are now hardly scratches the surface of what could be developed to help fire protection professionals like you work faster and smarter.
If you'd like to give it a try, all I ask is that you let me know your thoughts about it - usefulness, ways it can be improved, your level of interest - anything that might help build a better resource going forward.
See more about it all here: MeyerFire Toolkit. Thank you!
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Joseph Meyer, PE, is a Fire Protection Engineer in St. Louis, Missouri. See bio on About page.