I'll come out and say it.
I’m a millennial.
I like to think I can opt out of millennial status voluntarily, but I'm told it doesn't work like that. Technicalities…
I like to think that the relentless pursuit of finding better & faster ways to do better work is about innovation and constant improvement. I guess it could also just be considered finding ways to avoid work or wanting the "apps" to do any real engineering.
Today's post covers one of my favorite cheats on checking site elevations and distances. It's super easy and a major benefit when setting up or reviewing hydraulic calculations.
On a side note I'm also told that the kids these days call these "hacks". I'm told that a "hack" is a good thing, so I'll roll with it. Besides - age is just a state of mind, right? I'm cool, I promise. Just don't ask my kids.
Here's the “hack” - just follow these steps:
Get Elevations Between Any Two Points
1. Open Google Maps (https://www.google.com/maps)
2. Enter or zoom in on any address.
3. Right click on any location you wish to get an elevation on. Select "Directions to here"
4. Now right click on any location at least a block away, such as your tap for the building's water connection. Select "Directions from here"
5. Now you'll have opened up the directions dialogue. Instead of car directions, click on the walker icon in white at the top.
6. Click on the very bottom description in gray. It often reads “Mostly Flat”. This opens up an elevation view from your original point (such as your building’s water tap) to your building. This shows your end elevation (against sea level), your original elevation, and the elevation difference between the two.
Measuring Site Distances
While still in google maps, you can also get distances on a site.
Here's a video showing both (click this link if you don't see the video):
Earlier this year I had a project I was reviewing which showed no elevation difference between the flow test and the base of the project. The pipe distance was roughly accounted for, but no elevation.
I checked the test distance on Google Maps and despite only being several hundred feed from the project, the test was at an elevation 32 feet lower than the base of the project.
Did this affect the hydraulic calculations? It absolutely did. The calculations went from having 6 psi safety to being 8 psi over the available water supply.
The measurement tool comes in handy for many projects where site plans are not prepared. This doesn't come up quite as much in new construction, but certainly for retrofits or projects with no site work - a site plan often isn't available. Use of quick measurements can give some guidance towards using conservative measurements for hydraulic calculations.
If you already knew these two tricks, congratulations, you’re probably also a millennial.
If you didn’t, and would like to send money for the gobs and gobs of time these simple tools will save you in the future, please make the check out to “Joe’s Beer Fund.” Actually better yet – just tell another friend about this site. It is always very much appreciated! Hope you have a great rest of your week.
Last week I discussed a common question in residential construction concerning whether NFPA 13R could be used, or whether NFPA 13 had to be used.
If you haven't read it, you might check it out. Here's a link.
The four global limitations to using NFPA 13R include:
The last qualifier is often the most difficult to assess, and is an important question that the architect or code consultant for the building will need to answer.
To help determine whether a building can use NFPA 13R, here's a PDF cheatsheet that shows differences in code allowances using NFPA 13, 13R, 13D, and no protection at all.
All of the references are to the International Building Code 2018 Edition, but this should help offer some quick guidance on different code allowances to check for your project. As always, it's worth using this as a starting point and then exploring the code nuances to be sure your project is up to snuff.
If you haven't already subscribed - you can do so here. This blog is all about promoting best practices in fire protection by providing tools, resources, and helpful articles.
Travis Mack at AFSA
If you're going to AFSA's Conference in San Diego next week, be sure to check out Travis Mack's presentation on this topic. He's an industry leader & expert in everything suppression.
Correction on the Porte-Cochere Logic
A couple weeks ago I discussed the differences between different forms of heat transfer in the context of flame spread. I made a point that conductive heat transfer is the least critical of the three forms of heat transfer, but suggested that fires "jump" across roadways due only to radiation heat transfer. This is due primarily to convective heat transfer - strong winds can promote fire growth far faster than radiative heat transfer can - and it often does for large wildfires.
I mentioned last week - but I'm down to about a dozen copies of the 2019 PE Prep Guide Edition left for the year. If you know someone who is looking for a copy you might suggest they get it sooner rather than later.
Thanks & have a great week!
For the contractor clients I work with I regularly look over jobs pre-bid. I’ll review drawings, read specifications, and compile all my notes looking for red flags that could impact the job from a design standpoint. (The cheatsheets that I use to breakdown a job is now all in the Toolkit)
Last month I reviewed an apartment complex job for a bid where the code summary had conflicts. The IBC Chapter 5 summary indicated and NFPA 13 system while the IBC Chapter 9 indicated an NFPA 13R system. There were no other references to a fire sprinkler system in the rest of the documents or specifications.
These are the projects that I blame my hair loss on. It's another bad example of project documentation. Regardless, the question of NFPA 13 versus NFPA 13R is something that comes up regularly and is the topic of this and next week's article.
Why Does it Matter?
NFPA 13R is not built with the same intent as an NFPA 13 system.
NFPA 13R systems are designed to “prevent flashover (total involvement) in the room of fire origin”. By doing so, they intend to improve the ability for occupants to survive a fire by evacuation. 13R design is primarily concerned with protecting areas of residential buildings where fires cause loss of life. It is not as concerned with fires in areas where fatal fires in residential occupancies do not originate. (Reference IBC 903.3.1.2 Annex)
NFPA 13 systems, however, intend to provide a “reasonable degree of protection for life and property”. In a general sense, NFPA 13 systems are concerned with both life safety and property protection. The goal is to suppress a fire near its' point of origin, regardless of the level of risk to life safety.
Cost can be largely impacted by the NFPA 13 vs. NFPA 13R decision -
especially in wood construction buildings with attic spaces and overhangs.
Aside from having different purposes, NFPA 13 vs. 13R decisions can have major implications on system cost.
NPFA 13R systems allow sprinkler omission in a handful of areas which 13 does not. These include small closets, exterior balcony closets, concealed spaces, elevator machine rooms, garages, carports, attached porches, and attic spaces. I've summarized these with a cheatsheet here.
For wood-construction (a mainstay in residential design), attic sprinkler systems under NFPA 13 can command a major cost premium. These attic systems need dry valves, air compressors, use of steel in lieu of CPVC, special application sprinklers, and design requirements that can require large diameter pipe.
Testing and maintenance is also a long-term ownership concern. Not only do dry attic systems require regular low-point drainage, but they often corrode faster than wet systems .
Attic systems are one area of a building that can be a huge difference between NFPA 13 and 13R.
That said, I’ve also worked on projects where 13R has little to no impact on the project price. A flat-roof building built with non-combustible structure, for instance, offers no major difference. The only impact was the lower density permitted for residential-style sprinklers. Using the 0.05 gpm/sqft in lieu of 0.10 gpm/sqft of NFPA 13 resulted in smaller pipe diameters for an NFPA 13R system.
Buildings must be residential, four stories or less, 60 feet in height or less,
and not use any code exemptions for an NFPA 13 system in order to use NFPA 13R.
When Can I Use NFPA 13R?
There are four global limitations where an NFPA 13R system can be used. These include:
"My project is design/build with deferred submittals. Can’t the contractor determine this?"
No - and I can’t stress this enough – please do not leave this determination to a contractor.
It doesn’t matter if you’re an architect, mechanical engineer, or the expert code consultant. There are a number of code exceptions that can only practically be determined by the design team. The sprinkler contractor is an expert on suppression – not on architectural design decisions and the code paths for those decisions.
What are the building code exemptions that require an NFPA 13 system?
The code exceptions show up for building height increases, building area increases, egress widths, travel distance limitations, occupancy separations, corridor wall ratings, hazardous material increases, inclusion of atriums, unlimited area buildings, allowable area of openings, vertical separation of openings, draftstopping, interior finishes, floor finishes, manual fire alarm systems, and several others.
Sounds like a lot? It is. Fortunately I’ve got a cheatsheet coming next week where I’ll explore these differences in more detail. If you’re interested in getting a copy, subscribe here and it’ll be emailed directly to you.
A couple weeks I posted a link on this month’s sponsor Engineered Corrosion Solution’s whitepapers. Many of you have already checked it out, but if you haven't there's a MeyerFire welcome page here: https://www.ecscorrosion.com/meyerfire-welcome
I had a couple people ask about the whitepapers, so here’s a direct link to them. Specifically, be sure to check out "Industry Myths Regarding Corrosion in Fire Sprinkler Systems" and "Six Reasons Why Galvanized Steel Piping Should NOT be used in Dry and Preaction Fire Sprinkler Systems."
PE Prep Guide 2019 Selling Out
There's been a ton of interest this year in the PE Prep Guide. I genuinely appreciate every single person who's checked out the book for this year's exam - there has been more interest than ever before and I suspect the exam turnout could be the most ever for the Fire Protection P.E. Exam.
Next year's exam in 2020 will go computer-based and have major changes, so the PE Prep Guide will undergo big changes as well. This year's shipment of the 2019 Edition is just about out, and because of the big changes next year I won't be ordering extra copies. We currently have 16 copies available, so the 2019 edition will likely sell out by October's PE Exam. If you'd like to get a copy of the 2019 PE Prep Guide, please consider doing so now.
After the 2019 Edition sells out we'll still have 2018 PE Prep Guides available, and I'll ship an errata list with it. Any questions, please reach out to me at email@example.com.
Last week I discussed across a common misconception with porte-cochere sprinkler requirements and how code addresses sprinkler protection for these structures.
This week I’m diving a little deeper with some estimates of how a porte-cochere fire would actually affect a main building, based on distance from the building.
It’s important to note that this exercise is largely academic: with the calculations below I’m making some gross assumptions that overly simplify the situation. This has not been vetted with Ph.D. experts nor gone through full scale fire testing. I’m just running some basic numbers with big assumptions to illustrate a point.
From what science gives us - heat is transferred by three methods. Conduction, convection, and radiation.
Conduction is the transfer of heat by objects touching each other. The direction of transfer is dictated by hot-to-cooler materials in direct contact.
Convection is the transfer of heat caused by the movement of gas (or a fluid). The direction of transfer is largely dictated by overall movement of the fluid, and for smoke tends to be vertical.
Radiation is the transfer of heat from the emission of electromagnetic waves. The direction of transfer is in all directions, but can reflect and re-emit from other surfaces.
Heat Transfer for a Flame
For a flame, depending on the fuel, most of the heat will be transferred away from the flame source primarily by convection. The chemical reaction (oxidation) of a flame will cause gases to heat. The heated gas’ molecules will become more active and less dense. With less-dense gas than surrounding cooler air, the warm gas will rise up and away from the flame source and carry solid particles forming hot smoke.
Radiation will typically comprise 20-35% of the overall heat release rate for a fire. Radiation transfers heat from the source in all available directions until it contacts another surface. Once in contact with other surfaces, radiation can be absorbed or re-emitted from the surface, depending on the surface material.
Conduction is the least important mode of heat transfer in an open fire. Radiation near a flame’s origin, for example, often emits and heats up adjacent surfaces with more impact than conduction. For wall assemblies, conduction of heat through penetrations becomes important, but for flames in open environments conduction plays only a small role.
Three Porte Cochere Scenarios
Now imagine a porte-cochere that is 100 feet (30 m) from the face of a larger main building to the center of the porte-cochere. If the porte-cochere is completely inflamed, how would it transfer heat to the main building?
It would transfer heat only by radiation; and in very small amounts. Assumptions include a 5 megawatt (MW) fire from a wood-built porte-cochere, a 100-foot (30 m) center distance from the main building, an atmospheric transmissivity of 0.95, and a 30% of the overall heat loss as radiation.
Using the Lawson and Quintiere Point-Source Method, the incident radiant flux (a measure of the heat energy per area) is 0.13 kW/sqm.
This radiant flux is about 10% of the flux for a 1st degree burn on unprotected skin.
Now move the porte-cochere to be 30 feet from the face of the building. Radiation will again transfer heat to the face of the building, but in a much larger amount. Because radiant flux is related to the inverse square of the distance between the targets, this 30-foot distance will actually have a radiant heat flux 10 times greater than a porte-cochere fire 100 feet away. For the same size fire as before but at 30-feet, this could be about enough heat for a 1st degree burn.
At the 30-foot distance, however, heat transfer to the main building is still primarily by radiation. The hot, buoyant smoke is still primarily driven upward from the porte-cochere and would likely not reach the main building unless strong winds directed the hot gases.
Now imagine this same porte-cochere, but this time centered only 10 feet (3 m) from the main building. Radiation heat transfer is now 10 times greater than the 30-foot distance, and 100 times greater than the 100-foot distance.
At only 10 feet from a 5 MW fire, the heat flux is enough easily cause 2nd degree burns for unprotected skin.
Additionally, this heat flux is now approaching the critical heat flux for ignition of some building materials. The critical heat flux is the minimum amount of heat, per area, required to cause ignition. There's several factors that contribute to ignition including exposure time, material thermal properties, surface temperatures, and the actual heat flux versus critical heat flux - but for our purposes I'm only showing this critical heat flux for a couple siding materials.
Wood, for instance, has been tested to have a critical heat flux of approximately 10 kW/sqm. Vinyl siding has a critical heat flux of approximately 15 kW/sqm (both values from SFPE Handbook of Fire Protection Engineering, Table A.35, 5th Volume).
When we look at the heat flux already produced by a fire of this size at 10 feet we can see that we're already approaching the critical heat flux for both wood and vinyl.
Now let's speak in practicality. Porte-cocheres are built to allow visitors to enter and leave cars without exposure to rain or sun. Is a 30-foot or 100-foot separated porte-cochere provide any value to a building? No, of course not. This exercise just shows that with reasonable assumptions, a 10-foot physical separation assuming a 5 MW fire begins to approach the critical flux needed to ignite a nearby building.
Would the actual fire be 5 MW? It's difficult to predict and will vary widely by the materials used and the shape it conforms. A point-source approximation is a large oversimplification given that a wooden canopy would burn in a very different configuration than a condensed pile of wood pallets, for instance.
What about convection? Up to now we've still only discussed heat transfer by radiation. If a porte-cochere is close enough to a building, convective heat transfer from the hot smoke will begin to contact the main building and heat surfaces along the face of the main building. This could also be aided by wind conditions as well.
As I explored a little last week, a porte-cochere that is only separated inches or a couple feet from a building is hardly any different than a porte-cochere that's attached to the building. That's largely because of convective and radiative heat transfer. The further away the porte-cochere is, the less convective heat transfer plays a role and the lower amount of radiative heat will be transferred.
What if we create a firewall or fire barrier? Both would slow the spread of fire and help prevent the main building from burning. The International Building Code relaxes the physical separation with fire-resistive construction, and for good reason. Heat flux becomes much less important when the exterior is of non-combustible construction.
It can be easy to get lost in code minutiae and live by the black and white lines of what code reads. I find that it's important to remind myself about context about each building and where good engineering judgement plays a role in protecting buildings from fire.
This overly-simplified series of calculations just shows the tiers of radiative heat transfer and how much it is affected by the separation distance. The further away a building is from another, the less convective heat transfer plays a role (if any) and the less radiative heat transfer occurs.
If you found this interesting, let me know by leaving a comment here. Always happy to hear other opinions. If you don't already follow the weekly blog, consider subscribing here. Thanks for reading!
In February of last year I put together a flowchart that covered sprinkler requirements for exterior projections. If I had a Top-10 Articles list, it'd be on it.
If you haven’t read it,here’s a link to the original article.
Since I wrote this article and posted the original flowchart, I’ve received some encouraging feedback and thoughtful comments.
I’ve updated the flow chart this week to address specifically sprinkler protection of porte-cocheres:
What's a Porte-Cochere?
First, because I have no idea where the term “porte-cochere” originated, I’m talking about the covered entrance where vehicles can pass through as part of an entranceway to a building.
Not to point fingers, but I’m guessing the term “porte-cochere” was dreamed up by an architect to disguise the fact that they’re sticking a carport on the front of their building. Maybe it’s my Missouri roots, but what we’re talking about here are just fancy carports that can be driven through. Now stepping down from the soapbox…
"If It's Not Touching the Building..."
Stop me if you've heard this one before.
One common assumption I’ve heard repeatedly from architects and contractors concerning porte-cocheres is that sprinkler protection isn’t required for porte-cocheres if they are not connected to the main building.
Unfortunately, that's not justified by code.
It is true that porte-cocheres, on their own, often do not require fire sprinkler protection. They will generally fall under a Type U (Utility and Miscellaneous Group) Occupancy, which do not require fire sprinklers by IBC 903.2.
However, in order to qualify as a separate “building”, the International Building Code requires a physical space separation, a fire-rated separation, or a combination of both.
In terms of a porte-cochere attached to a main building, the porte-cochere would be considered a separate building by any one of the following:
As an example, if the main building is a Type V-B (combustible construction), Residential R-2 Occupancy (such as a Senior Living facility with more than 16 people), then the minimum requirements for a porte-cochere as a separate building would be:
From a practical standpoint, what is the difference between a porte-cochere that’s six inches from the main building and one that is touching the main building?
None. Zero difference.
I’ll explore this from a scientific perspective in next week’s article, but in short - conduction heat transfer makes little difference in the spread of fire from one structure to another.
Want to know why forest fires can “jump” across highways? It’s not because trees are locking branches above roadways – it’s because of radiative heat transfer.
So why do we get so tied to the concept that if the porte-cochere isn’t touching the main building that it’s as if it doesn’t exit? I’m not sure exactly, but it seems to come up quite frequently.
One Note on Concealed Spaces
NFPA 13 has two separate sections that affect porte-cocheres. The first is protection below overhangs, canopies, & porte-cocheres. This article and the flowchart address this situation. The second section is protection within concealed spaces.
If your porte-cochere does not require sprinkler protection per the building code, then no sprinklers are required regardless.
If that's not the case, and your porte-cochere has concealed spaces within it, check out NFPA 13's Special Situations section to see if the concealed spaces require sprinkler protection. These may still be required to be protected even when sprinklers can be omitted below the ceiling. This show ups in Section 8.14.1 of the 2002 Edition, Section 8.15.1 in the 2007-2016 Editions, and Section 9.3.18 in the 2019 Edition.
Losing the Forest for the Trees
I sometimes find that when assessing code it is easy to lose the forest for the trees.
Sometimes I can be so fixated on finding one specific answer that it is easy to step back and assess the ‘big picture’. Addressing overhangs and canopies can get that way.
While I don’t always get the opportunity to address fire protection intent with a building owner, I have to keep in mind that code only prescribes the minimum requirements. We can always elect to improve fire protection & life safety above code minimum.
Two recent local fires come to mind when looking at how sprinkler protection affects overhangs and how different owners were impacted very differently.
The first fire occurred at an apartment complex when a tenant left a lit cigarette on the third story balcony of an apartment complex. The cigarette started a fire on the unprotected balcony, which spread into the apartment attic (without draftstops) and quickly spread across the attic of the entire building. The upper two levels were badly damaged along with the entire attic and roof needing replacement.
Another fire occurred, more recently, at a three-story office with a porte-cochere. A car fire underneath the porte-cochere activated a single sprinkler which suppressed growth until the fire department arrived. The porte-cochere had smoke damage, but the fire had no impact to the main building. No downtime, no multi-million dollar rebuild. From the photos it was difficult to see any impact from just inside the main entrance.
These are two different situations of course; the first likely an NFPA 13R and the second an NFPA 13 system. Nonetheless it raises the issue of making sure that we, as professionals, inform and have dialogue with the building owner to not just determine what code minimums require, but what levels of protection may serve them best.
This Month's Sponsor
I'd like to introduce this month's MeyerFire sponsor with Engineered Corrosion Solutions. They are experts in the corrosion space for fire sprinkler systems and have a long list of helpful resources on their website.
As a side note, some of their original whitepapers and case studies were instrumental for me in my understanding of current corrosion challenges. When should we specify galvanized pipe? Is MIC or oxygen-induced corrosion a bigger concern? What can we do to stop corrosion entirely? They have it all here.
Thanks to the ECS team for helping promote this site and supporting my efforts to develop new resources for the industry.
Next week I'll explore the concept of porte-cochere separation distance, but from a modeling perspective. How much does the distance impact radiative heat transfer? How does convective heat transfer play a role? I'll explore this in more detail and from a calculated perspective next week.
If you don’t already get these weekly articles via email, subscribe here. If you know someone who might be interested, please pass a link along. Thanks and have a great week!
Sometimes the best inspiration for new tools on this site come from basic frustrations with repeated tasks.
The past few weeks I’ve finally come to the point where I needed to scratch an itch – plumbing fixture counts.
What does this have to do for code & life safety? It doesn’t – other than (generally speaking) code summaries will often address plumbing fixture count minimums as part of the overall building code evaluation.
Here’s my scratched itch – a calculator that will populate minimum requirements for plumbing fixture counts based on the 2018 International Building Code & 2018 International Plumbing Code.
Now, with only four inputs you can quickly grab the minimum fixture counts from the 2018 IBC (note: if you don't see the calculator below, click here):
It’s more than likely that something already exists in the vast spans of the internet for this, but in the meantime at least I know we all can stop wringing the calculator for a few basic number crunches.
If you’re already a Toolkit user, you can download this update and use it right away on the downloads page here: www.meyerfire.com/downloads
If you’re not already a Toolkit user, why not? Join in on all the expanded tools we have by getting the Toolkit here.
Is this something you’d use? If you’d find this useful and would like to see it expanded to other editions of the IBC (or other standards), let me know by commenting here. I’d be happy to break this out for prior IBC editions if it’s something that’d be beneficial.
There’s no real way around it: I love cheatsheets.
In a design course in college we received 5x7 index cards to include any handwritten notes we wanted for an upcoming final. I wrote so much on that card with handwriting that was effectively size-4 font that it could have been displayed as a work of art.
Nearly an entire semester summarized to a 5x7 card. It was a thing of beauty.
While I no longer have a need to write so small, I still enjoy having information organized so that it is extremely easy to access.
If you haven’t seen these before, here are a couple cheatsheets I’ve created so far:
Summary of Differences of NFPA 13, 13R, and 13D
Sprinklers & Passive Fire Protection Options
Last week I covered important considerations surrounding fire department connections from a design perspective, which was a joint-effort with QRFS covering the topic.
At some point I’ll compile the best blog posts and resources into a hardcover reference book. For this week, however, here’s a cheatsheet on requirements surrounding fire department connections across NFPA 13R, NFPA 13, and NFPA 14:
Find this helpful? Consider subscribing to free resources like this here.
Have a great week!
I'm very excited to announce that starting this September we will have a monthly site sponsor.
As you may know, MeyerFire.com was created to help you do great things in fire protection. This site was built to promote the practice and empower professionals in the fire protection community. How? By creating highly-visual, high-quality content and resources to support and connect the people who do fire protection the best. You.
Each month we'll showcase an exclusive sponsor that supports our efforts at MeyerFire. The only difference you might notice is a new a sidebar image to the right on the site and a horizontal banner towards the bottom of emails.
I'm very encouraged that the sponsorships will allow me to invest more time and development in content and resources that ultimately will help you continue to do great things.
Sound like a stretch?
Don't take my word for it. I hope you'll see for yourself later this year what the support of the sponsorships will bring to the site.
In the meantime, please consider supporting our sponsors by clicking on the images and checking out their content starting this September.
If you're interested in sponsoring the site with your campaign, don't hesitate to contact Joe directly at firstname.lastname@example.org for more information. Thanks for all of your continued interest and support!
Why are fire department connections (FDCs) so important to a suppression system?
They are the link between initial response and supplemental help.
Despite appearances, sprinkler systems are not intended to discharge forever. Their goal is to suppress long-enough that firefighters can take over and finish the job.
Standpipe systems exist to extend the reach of the fire department in tall, wide or complex buildings. Manual standpipes depend upon pressure and flow from the fire department. What single piece of equipment is relied upon to make the transfer? The FDC.
This week's article is an overview of fire department connections from an engineer’s perspective. It is one part of a two-part series covering fire department connections. Read more from a supplier’s perspective at Quick Response Fire Supply here.
Authority Intervention Needed
Fire department connections are a unique piece of a suppression system in that they’re not just governed by the designer and code. NFPA 13 and 14 require that fire department connection type and location is coordinated with the Authority Having Jurisdiction.
Early in design, prior to bid, I’ll call the local fire marshal and coordinate each of the following big-picture elements:
Coordination Item 1: Type of Fire Department Connection
The most popular types of FDCs? Siamese (2 x 2-1/2" threaded connection) and Storz (4" or 5" with or without 30-degree elbow).
In my very unscientific study of jurisdictions I call (nearly half are local to my area), I've found the following; 73% use Siamese-type 2-1/2” fire department connections, 11% use 4” Storz connections, and the remaining 16% use 5” Storz connections.
Of these, 13% have special requirements such as Knox Locking caps, 30-degree elbows, or irregular threading.
There’s no right or wrong answer here – I just want to be sure what I’m calling for or showing on plans match what the jurisdiction uses.
Large diameter Storz-type fire department connections have become more common for their ability
to quick-connect a single hose and flow large amounts of water.
Coordination Item 2: Location of Fire Department Connection
The most obvious coordination during design is the location of the fire department connection.
My design preference, driven by installation effort and cost, is typically in the following order:
1. Wall-mounted FDC, adjacent to the sprinkler riser
2. Wall-mounted FDC, remote from the riser (such as the front of the building)
3. Freestanding FDC, downstream of a site backflow pit or hotbox
4. Freestanding FDC, connected underground into the sprinkler riser room
The first couple options are not always workable and depend on the building.
Sometimes the water supply and riser room are in the back of a building inaccessible to the fire department. This would be a bad place for an FDC.
Sometimes the front face of a building is "grand view" with large glazed curtain walls and no room to mount a fire department connection. This comes up with large offices or modern schools.
Sometimes a building-mounted FDC doesn’t make sense with major hazards; why risk firefighter safety in these cases? High-rises, for instance, require multiple FDCs due to the potential for falling glass that could injure firefighters or sever hoses. If there's potential for wall-collapse (think high-hazard warehouse wall) then a wall-mounted FDC also may not make sense. Freestanding FDCs can make a lot of sense for projects like these.
Considering most of my work is two stories or less and light commercial, it may not be surprising that roughly 85% of projects include building-mounted FDCs. The remaining 15% have necessitated freestanding FDCs.
Some jurisdictions require freestanding fire department connections, but it typically
depends on the type of building and hazard presented.
Coordination Item 3: Distance of FDC to Nearest Hydrant
As a designer it would be great if I could operate in the dark. Send me all the information I need to do a design, I do it, and everyone’s happy.
If it were that simple, though, we’d probably already have machines design and do it without downing two bags of Doritos and a half hour of facebook each day.
Back to the topic: FDC-to-hydrant distance has an impact on the tactical approach in firefighting.
Many designers & installers in our field are current or former firefighters. They could readily speak to this. I’m not one of them, but I can imagine that having to shut down a major roadway or cross a parking lot with hundreds of feet of hose quickly during an emergency is not exactly the easiest thing to accomplish.
As a result I like to ask AHJs what distance the FDC should be to the nearest hydrant.
Of my highly unscientific and locally-biases results, 41% of jurisdictions require a hydrant to be within 100 feet of the FDC or less, 47% require a hydrant to be within 150 feet, and only 16% of jurisdictions require a hydrant within 200 feet or more of the FDC.
These three elements are a part of my code calls. Next week I'll distribute my FDC Cheatsheet that outlines requirements for FDCs across NFPA 13, 13R and NFPA 14. If you haven't already subscribed, consider doing so here.
What do you look to coordinate with the AHJ? Discuss your experience here.
Want more coverage on fire department connections? See the other half of our two-part series on fire department connections here: Quick Response Fire Supply.
Since the entirety of fire sprinklers systems normally depend on heat to actuate a sprinkler – it is an important topic.
Before I ever started in shop drawing design. I prepared bid packages that specified important aspects of system design. One of the luxuries of living on the front-end (some say "theoretical") side of design was delegating the sprinkler temperature selection.
Selecting appropriate sprinkler temperatures is not difficult. That said, making an egregious error with a temperature too low could cause an inadvertent discharge. Considering how much damage this could do, there’s quite a bit of liability there.
Temperature is one of the three concepts I look to address when designing sprinkler systems in commercial kitchens.
Consideration #1: Heat
In high school I worked a few years in a kitchen. I hated it. It was stressful, always hot, and the cook line seemed to play the same six songs on repeat.
Even now when I hear The Hand that Feeds by Nine Inch Nails, my palms start to sweat. I get thrown back to that smoky, steamy kitchen and getting yelled at for bringing out entrees while the salad course wasn’t finished. Despite it being in a country club, it was awful.
Maybe I’m sensitive (if not dramatic), but when I design sprinkler systems for kitchens I’m acutely aware of how hot those spaces can be.
We want sprinklers to operate early enough in a fire when they can be effective. We also don’t want unintentional activation with a temperature too low.
NFPA 13 directs sprinklers to be ordinary or intermediate temperature unless specific heat-producing sources or hazards exist.
For commercial cooking equipment, if a sprinkler could experience ceiling temperatures over 100 degrees F (38 C), then they must at least be intermediate temperature (NFPA 13 2002-16 220.127.116.11, 2019 18.104.22.168).
I’ve never measured temperatures on the cookline but I would suspect this would be easy to achieve.
NFPA 13 also directs temperature selection to be based on nearby heat sources (in 22.214.171.124 2002-16, 126.96.36.199 2019).
NFPA 13 identifies temperature guidance for similar residential heat-producing sources. Sprinklers located 9 to 18 inches from a kitchen range, for instance, should be intermediate-temperature. Sprinklers 18 inches or more away from a kitchen range can be ordinary-temperature. Wall ovens have the same rules.
I've often located sprinklers within the center of cooklines as intermediate-temperature sprinklers. This allows a little grace from the edge of heat-producing sources. I'll then check specific appliances for anything that could cause higher temperatures and adjust accordingly.
Kitchen hoods that would otherwise form large obstructions can be excluded from sprinkler protection
when they contain a separate fire extinguishing system.
Consideration #2: Spacing Near Hoods
Exhaust hoods are required above cooking equipment that produces grease-laden vapors. NFPA 96 goes further to require that the equipment and exhaust system must also be protected.
One way to achieve this requirement is by sprinklers, but this method is rare. Pre-engineered wet chemical systems are designed specifically for cooking hazards. They are also often supplied directly with hood equipment.
If a fire extinguishing system is a part of the hood, NFPA 13 relaxes nearby sprinkler protection:
NFPA 13 188.8.131.52 (2007-2013), 184.108.40.206 (2016), 220.127.116.11 (2019) Hoods containing automatic fire-extinguishing systems are protected areas; therefore, these hoods are not considered obstructions to overhead sprinkler systems and shall not require floor coverage underneath.
NFPA 13 18.104.22.168 (2007-2013), 22.214.171.124 (2016), 126.96.36.199 (2019) Cooking equipment below hoods that contain automatic fire-extinguishing equipment is protected and shall not require protection from the overhead sprinkler system.
In regards to sprinkler spacing, the front-edge of a protect exhaust hood is essentially a solid wall.
If portions of a hood are not protected, the hood would be considered an obstruction and coverage would need to be provided below the hood.
Consideration #3: Obstructions & Conflicts
Commercial kitchens are often tightly-designed areas intended to maximize the preparer’s efficiency. End result: high-density of equipment and appliances in small areas.
This is the case along the ceiling as well. Lights, diffusers, and sprinklers become secondary and must shift to the narrow remaining ceiling. With hoods and the need for cooling comes large ductwork. These can limit the pipe layout serving sprinklers in kitchens and requires careful coordination.
It’s not always easy to tell from plans, but floor-to-ceiling storage is common.
Reflected ceiling plans often show a continuous ceiling between one cookline and its adjacent counter. However, there are often heat lamps, pot and pan storage, and a myriad of boxes and other food supplies stored above head height to the ceiling.
I try to space sprinklers in these areas directly above walking spaces that can tolerate storage in-between the cooklines.
What has been your experience with suppression systems for commercial kitchens? What challenges have you come across? Let us know here.
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Joseph Meyer, PE, is a Fire Protection Engineer in St. Louis, Missouri. See bio on About page.