First, a big thank you to those who commented and emailed ideas and topics that contributed to the latest tool for this site - the Trapeze Calculator. 

Quick Calc
With only a few "knowns" (pipe diameter and schedule, and distances to nearest structure), you can now quickly calculate the section modulus that's required, visit options for the trapeze bar, and see these options schematically in a to-scale detail.

Multiple Pipes
Have multiple pipes on a trapeze? Calculate the section modulus required for each, add the two moduli together, and simply override the Section Modulus Required value below to see your options.

Get CAD Details
Want a CAD version of the detail? Sure thing - the downloadable All-Access Toolkit allows you to save and print these calculations as PDFs, which can then be imported directly into AutoCAD and use the ALIGN function to scale it to your drawing.

​Toolkit Users
Already a Toolkit user? Install the latest version from your dashboard to get the updates to this tool. No new activation code is necessary.

​Don't see the tool below? Try it out here - 

This site is all about finding ways to help you be the office hero with quick and helpful fire protection tools. 

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The Toolkit package is here! 

This week, as part of the big launch, you can get every tool we have available: Get access to the Sprinkler Database, downloaded tools, post-a-question and more today. ​The Toolkit is a downloadable package that allows you to PDF, print and save your calculations as well as get access to the Sprinkler Database and a host of other benefits.

Vote on New Tools & See What Else is Coming Soon
Around here we're always in development on new and improved tools to help designers, reviewers, inspectors, installers, and engineers in the fire protection industry.

​You can now see, and vote, on upcoming tools that are in development for MeyerFire.com. The "Coming Soon" page is now live under "Tools" on the website header.

​Take a look at upcoming tools, rate each, and share ideas that we can work towards on this new area of the website.
​

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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 6.2.3.1 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 6.2.3.5). 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! 

Other Scenarios
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.
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Toolkit Update
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.

Sprinkler Database
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.

Please Share
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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.

​Expanded Calculator
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.

I just wanted to take a quick moment and thank you for the great response to this three day launch of the Sprinkler Database. 

If you haven't checked it out already - the deal for the Sprinkler Database is here.

I look forward to continuing to create helpful tools to help you do exceptional work, and the launch of the database is one way that helps me keep those efforts going. 

Have a great weekend and a Happy Easter, thank you!

It's almost here! The MeyerFire Sprinkler Database goes live tomorrow at 9am Central. Check out more detail about our long-awaited project with our video:

Can't see the video? View it here.

Estimating Pipe Sizes for Sprinkler Systems

Occasionally when designing fire sprinkler systems I'm interested in approximately sizing a specific run of pipe early in a project.

That point of interest is often an underground service entry, a main for coordination, or even standpipes. Prior to doing a complete set of hydraulic calculations, running a quick calc using the Hazen-Williams formula can help give an order of magnitude pressure loss that is helpful with initial sizing.

Here's the calculator I use for these estimates. Don't see the tool below? See it here.

​Example: Underground Service Main Sizing

Consider a new project with an Ordinary Hazard Group II fire sprinkler system.

What should the underground service size be? 

A 4-inch fire main can be permitted under special circumstances (see NFPA 13 2002 Section 15.1.3, 2007-2010 23.1.3, 2013-2016 24.1.3). A 6-inch fire main is common. Is an 8-inch necessary? If the length of the service main is 10 feet, my answer can often be quite different than if the service main is 1,000 feet.

For this exercise I often run a quick calculation to judge the pressure loss in this single pipe as opposed to running calculations for a full system, to get order of magnitude pressure loss. Let's assume a long service main length of 750 feet.

Hazen-Williams Formula

NFPA 13 stipulates the Hazen-WIlliams formula be used for pipe friction loss calculations for systems other than antifreeze (NFPA 13 2002 Section 14.4.2.1, 2007-2010 22.4.2.1, 2013-2016 23.4.2.1).

The Hazen-WIlliams formula, while generally considered conservative, only requires the flow, friction loss coefficient (or C-Factor), and the actual internal diameter of the pipe.

Estimating Flow for a Sprinkler System

For an Ordinary Hazard Group II example, I can roughly estimate the flow for the system simply based on density and area (assuming the density/area calculation approach). A density of 0.20 gpm/sqft over the most remote 1,500 sqft begins to look like:

​Approximate Flow = Density x Area x Overflow Rate + Hose Allowance
Approximate Flow = (0.20 gpm/sqft) x (1,500 sqft) x (1.3) + (250 gpm)
Approximate Flow ​= 640 gpm
​

Why include the Overflow Rate? Naturally a fire sprinkler system is not going to be perfectly balanced.

While my most remote sprinkler can be calculated at exactly 7 psi and it's k-factor that throws exactly 0.20 gpm/sqft, the feed to that sprinkler will have friction loss. Due to that loss, the adjacent sprinkler will experience a slightly higher pressure than 7 psi and thus will throw slightly more water. This process repeats where sprinklers closer to the riser will provide more than the stipulated density.

For order-of-magnitude estimates, I've found that a 30% overflow will be generally close to the final flow result.

Pipe Schedule

The pipe thickness affects the actual internal diameter of the pipe, so I've included it here. I typically will use Schedule 40 pipe for sizes 2-inch and smaller (so that they may have threaded ends), but I've left the schedule type open to users as I know these preferences can vary.

C-Factors

The C-Factor relates to the friction-loss due to the surface of the interior of the pipe. NFPA 13 stipulates C-Factors for fire sprinkler systems depending upon the type of system and pipe material. These can be found in NFPA 13 2002 Table 14.4.4.5, 2007-2010 Table 22.4.4.7, 2013 Table 23.4.4.7.1, 2016 Table 23.4.4.8.1.

Note that important and impactful changes to the c-factors occurred in the 2013 edition for use of galvanized steel, which has been found to accelerate corrosion by focusing the corrosive action at specific weak points in pipe.

Friction Losses

With only a few inputs (Flow, Pipe Thickness, C-Factor, and Length of Pipe) you'll now have a comparison of pressure loss across a handful of pipe sizes. Punch in 640 gpm, a Global C-factor of 140 for underground pipe, and a 750 foot pipe length to test this example.

If there is plenty of water at high pressure available to the site, perhaps a 48 psi drop on the service entry could be tolerable and a 4-inch main could be used where it meets other NFPA 13 requirements.

For the vast majority of projects I cover this loss (48 psi) would not be acceptable. The 6-inch service main shows a pressure loss of under 7 psi, and an 8-inch shows under 2 psi loss. Depending on the water to the site, either of these begin to look much more reasonable.

The Friction Loss Calculator

This tool is designed to give quick-comparisons of pressure loss for a run of pipe and compare it against other pipe sizes.

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I'll be posting the weekly article tomorrow but before then I have a question and a favor.

Over the past two years I've been working on a long-awaited resource involving literally hundreds of hours of research and development, but before I wrap up the project I have just one question that will help create a better resource: Learn more and provide input with my quick one-question survey here.