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!
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!
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 22.214.171.124, 2019 126.96.36.199).
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 188.8.131.52 2002-16, 184.108.40.206 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 13 220.127.116.11 (2007-2013), 18.104.22.168 (2016), 22.214.171.124 (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 13 126.96.36.199 (2007-2013), 188.8.131.52 (2016), 184.108.40.206 (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.
Find this article helpful? Subscribe to more like this here for free.
One project question I very commonly receive from civil engineers is whether a post-indicator valve (PIV) is required.
In short, there are options. I'm exploring PIVs in more detail in this week's article. If you want to get more like this, subscribe for free here.
Purpose of Post-Indicator Valves
Post-indicator valves have long been used to stop the flow of water into a building during developed stages of a fire. Exterior wall collapse of a burning building poses a threat to break water supply mains as well as create many openings to the water supply. Without a valve to stop supply to these areas, firefighters and their efforts could be compromised by the loss of pressure and outflow of water to areas of a site that don't need water.
With the recognized effectiveness of sprinkler systems and cost pressures, the requirement for post-indicating valves have become more relaxed in the last decade. Code references to account for building collapse, for instance, now appear only indirectly in location requirements for hydrants and post-indicator valves to be sufficiently away from a building.
Components of Post-Indicator Valves
The post-indicator valve has several important features - first is the ability to quickly shut the valve with use of the post indicator valve handle. The second is to quickly see whether the system is in the 'open' or 'shut' condition in a protected enclosure. It can sometimes be difficult to see after years of dirt on the glass, but not impossible.
The valve itself is along the water main below frost depth such that only the stem is subject to freezing conditions. It's a simple concept that's carefully crafted to protect the valve and stem in a reliable fashion.
One example of a post-indicating valve - a Mueller Company Vertical Adjustable Post Indicator Valve (see https://www.muellercompany.com/fire-protection/ulfm-indicator-posts/)
History of the PIV Requirement
So is a post-indicator valve required or not? This used to be an easier question to answer.
While not a referenced standard from the International Building Code, the International Fire Code requires that all private fire service mains be installed in accordance with NFPA 24 (IFC 2000-06 Section 508.2.1, 2009-18 507.2.1). NFPA 24, the Standard for the Installation of Private Fire Service Mains and Their Appurtenances, governs system requirements between a water supply main and a building's service entry.
Up until the 2010 Edition, NFPA 24 required a listed post indicator valve on every connection from a private fire service main to a building unless special criteria were met (NFPA 24 Section 6.3). The special criteria included the use of a non-indicating underground gate valve with a roadway box and T-wrench or locating an inciating valve in a pit. Either special case required approval of the AHJ.
Current Valve Options within NFPA 24
Since the 2010 Edition, NFPA 24 gives a series of options for isolating a building's system and does not mandate that a post-indicator valve be used. These options (from 2010-13 6.2.11, 2016-19 6.2.9) include:
While still considered an "indicating" type valve, wall indicating valves are generally less preferred than post-indicating valves as they are more susceptible to a building collapse than post-indicating valves.
Post-Indicator Requirements of NFPA 14
NFPA 14, the Standard for the Installation of Standpipe and Hose Systems, also weighs in on post-indicator valve requirements.
NFPA 14 requires that each water supply (except for an FDC) shall be provided with a listed indicating valve in an approved location (NFPA 14 2000 4-2.6.1, 2003-07 220.127.116.11, 2010-19 18.104.22.168.1).
The prescriptive way to accomplish this is through the use of a post-indicating valve. Annex material within NFPA 14 goes further, stating a list of preferences for outside control valves:
NFPA 14 does give exceptions (as is almost always the case in fire protection), but they require AHJ-approval. Wall-point-indicating valves, or underground valve with roadway box and T-wrench, are alternative options that require AHJ approval (NFPA 14 2000 4-2.6, 2003-07 6.2.6, 2010-19 6.3.6).
Post-Indicator Requirements of NFPA 13
So where does NPFA 13 stand on post-indicator valves? In short, it doesn't. NFPA 13 only states that where post-indicator valves are used, they top of the post must be 32-40 inches above grade, and they must be protected against mechanical damage (NFPA 13 2002 22.214.171.124, 2007-16 126.96.36.199, 2019 16.9.9).
AHJ & Insurer Inputs
Authorities Having Jurisdiction may also want to weigh in on requirements for post-indicating valves. Some municipalities write code amendments to require PIVs, while others may request PIVs be installed for certain building types.
Insurers, such as FM Global, may also want input. FM Global for instance, recommends that each system has a control valve a minimum of 40 feet from the building (with less preferred options also recommended in Data Sheet 2-0 2.6.2).
What's the best course of action for your project? First, check for local or state code amendments that may affect post-indicating valves. If you have a standpipe system within the building, plan to provide a PIV. Last, check with your AHJ for any nuanced requirements you may be missing or to coordinate a location with the AHJ.
Not already getting these free weekly articles? Subscribe here. Found this helpful? Share on LinkedIn.com or send to a friend. MeyerFire is all about helping you do great work in fire protection with tools, tips and resources.
It is a popular and well-established concept that water and electricity don’t mix.
Water is electrically conductive which creates a major hazard of electrocution where a continuous pool of water meets a live electrical feed.
Can We Omit Sprinklers in Electrical Rooms?
On a few occasions I have come across building authorities and building owners who assume that sprinklers will not be installed inside traditional electrical rooms.
Why? The basic tenant that water and electricity don’t mix.
While the concept is important, the intent of sprinkler protection throughout a building is not just for each item within a building, but the building itself.
The primary intent of sprinklers is suppression – or stated differently – to prevent the growth of fire from the room of origin throughout a building. This includes all the rooms and spaces beyond just the electrical room where a fire could begin.
This week I’m digging into guidance surrounding electrical rooms.
NFPA 13 Guidance
NFPA 13 (2002 Section 188.8.131.52, 2007-10 184.108.40.206, 2013 220.127.116.11, 2016 18.104.22.168, 2019 9.2.6) allows sprinklers to be omitted in electrical rooms, but only where each of the following are met:
Concerns with Providing Sprinklers in Electrical Rooms
Providing sprinklers within electrical rooms could:
Prior to the 1994 edition of NFPA 13, important electrical equipment were required to have hoods (or shields) comprised of non-combustible construction to prevent direct contact by sprinkler discharge. All electrical rooms were required to be sprinkler protected.
Beginning with the 1994 edition, NFPA 13 introduced language to address concerns for firefighter safety and equipment damage. Sprinklers could be omitted in electrical rooms where the room contains dry-type equipment (no oils), is dedicated to electrical equipment only, is fire-resistant to reduce fire spread, and the room has no storage hazard.
The 2016 Edition, the requirement for equipment hoods or shields was removed to direct it under the scope of NFPA 70.
Just recently for the 2019 Edition new text was introduced such that no storage is permitted (non-combustible storage had been allowed) and liquid-type K-class (less flammable, non-spreading fluids) would be allowed.
International Building Code Input
The International Building Code (IBC) does not allow the omission of sprinklers “merely because it is damp, of fire-resistance-rated construction, or contains electrical equipment” (IBC 2000-18 22.214.171.124.1).
Within the same code section, the IBC does allow sprinklers to be omitted in “generator and transformer rooms separated from the remainder of the building by walls and floor/ceiling or roof/ceiling assemblies having a fire-resistance rating of not less than 2 hours.” These rooms must have an approved automatic fire detection system.
According to IBC commentary, buildings with sprinklers omitted in one of the sections allowed by the IBC would still be considered fully-sprinklered throughout and in compliance with the code and NFPA 13. This distinction is important as it carries eligibility for code alternatives, exceptions and reductions.
Combined, both the IBC and NFPA 13 require electrical rooms to be protected unless the prescriptive alternative option is followed.
As NFPA 13 commentary outlines, sprinkler systems have been successfully installed in rooms containing electrical equipment for over 100 years with no documented instances of a problem. While still seemingly controversial, most projects designed today include sprinkler-protected electrical rooms.
If you enjoy these articles, subscribe here. If you're already a subscriber, consider forwarding to a colleague.
MeyerFire is all about dissecting real challenges that real people face in fire protection design. I'm thrilled you're a part of our journey for better fire protection worldwide.
I'll start by saying I'm not perfect. I've learned some things the hard way that I could have avoided, which in part spurned this whole blog. This week's topic covers one of those things learned by trial and error (but mostly error).
If you are responsible for fire protection bid plans and you expect a contractor to provide hydraulic calculations, then you should include flow test information on your plans.
"If you are responsible for fire protection bid plans and you expect a contractor to provide hydraulic calculations, then your plans should include flow test information."
NFPA 13 does just about everything but require a flow test to be completed on the preliminary plans.
Annex material, for instance, has long spelled out that preliminary plans should be submitted to the AHJ prior to the development of working plans by a contractor (A.14.1 in 2002 Edition, A.22.1 in 2007-10, A.23.1 in 2013-16, A.27.1 in 2019). These preliminary plans should include test information with date and time, conducting party, location of hydrants, and size of mains.
Water supply information is a critical part of the overall fire protection equation but it's value comes before bidding as well as after.
If it is not a requirement in 13 to have it included in preliminary plans, then why provide it when the contractor can?
Well, there are several reasons.
1. Determine Fire Pump & Water Storage Tank Prior to Bidding
Is a fire pump required for the project?
It’s an important question – the cost impact to an owner is often between $50,000 and $120,000 between the pump, controls, piping and equipment, and possible generator when a pump is required.
The only thing more expensive than a fire pump or water storage tank included on a project
is when they get added as a change order.
Is the available flow to the site low, needing a break-tank or a full water storage tank?
The cost impact to an owner here is even greater.
If a flow test is not included on preliminary plans, how is a contractor supposed to confirm that a pump or a tank are not necessary? Take the word of the engineer? Guess based on past-history?
For flat-terrain areas with little construction activity over time, anticipating the available supply might be possible. For hilly areas where I live with a wide variety of water main sizes, it can be next-to-impossible to guess an available water supply at any given location.
If you are a prudent contractor and you are to bid a job without clear water supply information, what would you do? Bid a price conservatively high to anticipate large pipe sizes with a poor water supply? That’s possible – but then you’re also far less likely to win the job. Bid a competitive price, but exclude larger pipe sizes or a fire pump/tank? That could work to win the job, but what happens when the actual flow test is run and you determine a fire pump is necessary?
I’ll tell you what happens – the owner gets a very large change order they weren’t anticipating and the general contractor, sprinkler contractor, and design team all look bad.
Part of my role is creating upfront preliminary plans for owners & architects that go out to bid, but I also work for sprinkler contractors to produce installation/shop drawings. I’m very fortunate in that I get to see both sides of the industry.
A Real-World Example
One current job that I’m working for a local sprinkler contractor on is a new-construction five-story medical office building. It’s a great building with tall floor-to-ceiling heights and a fifth-story ceiling that’s about 80 feet above ground level.
The preliminary plans call for an FM Global Hazard Category-2 shelled area (0.20 gpm over 2,500 sqft) on the top level. Once the flow test came in, even with good pressure, it wasn’t enough to support this hazard classification.
Could the hazard classification get bumped down to better align with the future tenant use? Possibly. Could a fire pump be added to the project at a significant cost, late in construction? Possibly.
Either case, this all could have been avoided had flow test information been provided on the original plans. Bidding contractors wouldn’t be eligible to claim large change orders based on unanticipated pressure, and they can flag issues before they even submit bids.
2. Reduce Potential for Major Change Orders
Too often the single cost that a building owner is concerned with is the total cost of the job at bid. They should be concerned about the total cost of the project, including change orders and including the lifecycle of the system.
What good does accepting a low bid do if it is later rife with change order cost additions? It happens all the time with poorly prepared bid plans.
Including a flow test as part of the preliminary plans removes a major potential change order opportunity as it enables the sprinkler contractor to do their own pre-bid layout and calculation should they choose to do so.
3. Removes Potential Conflict of Interest
I have encountered misreadings of pressures from a gauge in the field, test results that were incorrectly copied between documents, and flow tests that were suspicious enough to go and re-test.
I (thankfully) have never come across anyone doctoring flow test numbers.
Is it possible that a contractor could fudge flow test numbers to save on pipe sizes and improve their bottom line? It’s possible. Virtually all of the contractors I’ve come across are very proud of their installations and are in the business because they care about life safety. Have I ever seen it happen? No. Could it? Yes.
When an engineer provides the water supply information upfront, however, this potential conflict of interest evaporates.
Including flow test data (or fire pump/water storage tank information) can be a critical piece
for bidders to properly assess and bid a system.
4. It’s Not That Hard to Get
For all the information we expect contractors to produce after they win a job, could we as engineers not produce such an important (and basic) piece of information?
Some water purveyors run hydrant flow tests at no cost. Some jurisdictions will do the same.
Even when both don’t run the tests, you can do it yourself. Read and follow NFPA 291, watch some videos, pickup a flow test kit for $400-$600, and remember to open and close valves slowly. It’s not terribly hard to do.
If you aren’t interested in running the test, hire a contractor. I’ve seen tests run as cheap as $150 and as expensive as $1,200 (a 3-hour drive each way), but they are often between $350 and $550 to have completed. Local contractors are more than capable of providing this service and they can do so quickly.
One of the biggest hassles in running a test early is often the tight design schedule many projects are on, and explaining to the owner why a flow test should be done upfront when a sprinkler contractor could just to it later. This article at least helps you address the later concern.
5. It’s Fair to Bidders
Bidding contractors are often not as concerned about how much or how little you want them to do. If you want schedule 40 throughout, they’ll provide schedule 40 throughout. If you want a nitrogen system, they’re provide a nitrogen system.
What contractors are extremely concerned about is that their bid price is fairly compared to other contractors. They will not provide schedule 40 if they feel another contractor will not provide it. Same with nitrogen or any other upgrades that could otherwise greatly benefit the building owner.
Water supply information is one of those key pieces of information that allow contractors to bid on an even playing field.
6. Retain Data History
How often do you find old building design documents that don’t include shop drawings? If you’re like me, it’s all the time. An engineer’s pre-bid plans don’t often have a wealth of helpful information – but having a little water supply block is a helpful data point when comparing historical water supply points.
Since engineer’s preliminary plans often get stored and tracked with the rest of the construction documents, including the water supply information can be a helpful way to retain that information for designs and renovations in the future.
I’ll slowly now descend from my soapbox by saying again that I’m not perfect. I’ve sent far too projects out to bid without water supply information than I would like to admit, often without any legitimate excuse. As an in-house goal we now try to hunt down water supply information for every project that we expect to see a hydraulic calculation by the contractor. That’s every building addition, occupancy hazard change, and every new construction project. It’s just too important of a data point to leave out for bidders.
Enjoy articles like this? Subscribe here.
Already subscribed? Send to a colleague or friend.
I'm excited to announce a new addition to the Toolkit that has been in development for a long time - the NFPA 13 Edition Translator.
With the major restructuring changes in the 2019 Edition of NFPA 13 - it has been difficult for me to flip straight to the content I'm used to doing. From the feedback I've heard I'm not alone on that learning curve.
As a result, a couple weeks ago I released the first version of the translator, which takes any numerical section from the 2016 or 2019 edition, and returns the matching section from the opposite edition.
Full Tool Now Available
This full version is quite the powerhouse. With over 130 hours of research included, it can now take any numerical section from any edition of NFPA 13 from 1999 through the 2019 edition, and returns the matching section throughout it's history.
A quick search on the edition translator shows the history of the section and where it appears.
Why could this be helpful? If you work across multiple jurisdictions or your local jurisdiction just updated to a new edition of NFPA 13, the shift in organization can be frustrating.
If you use the free versions of NFPA 13 that are supported by NFPA, then this tool could help you quickly navigate equivalent sections.
Probably the most common use I have is finding the back-history of where a section first appeared and where to look for it in past editions. This comes up occasionally for projects when there's disagreement about a particular section of code and searching for the back-history and any clarifications in future editions is very helpful.
If you're a Toolkit subscriber, you can download the latest version of the Toolkit, including this edition translator, here.
I've made it easier to download updates for Toolkit users. You can access the latest version and quickly download it at www.meyerfire.com/download. No sign in required.
Find this interesting? Consider sending to a friend or colleague who might find it helpful.
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 126.96.36.199.2(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!
Get Free Articles via Email:
+ Get calculators, tools, resources and articles
+ Get our PDF Flowchart for Canopy & Overhang Requirements instantly
+ No spam
+ Unsubscribe anytime
Get access to every tool, the downloadable Toolkit, Sprinkler Database, Daily Post-a-Question and more:
Joseph Meyer, PE, is a Fire Protection Engineer in St. Louis, Missouri. See bio on About page.