Whose job is it to calculate the required fire flows for a project? 1

[SprinklerDesigner2]

I know what a fire flow test is and it has always been my understanding this test should be performed at the very beginning of any project design.

This said I am not asking for help in performing the fire flow calculations because if I am asked I will flat out refuse. How would someone size the mains and place hydrants if they didn't perform the fire flow calculations? If the water wasn't there before I ever got involved with the project how the heck am I supposed to fix it now?

Project consists of a set of four three story residential buildings with the bottom floor, open on all four sides, used for parking cars (OH1) while the second and third floors where residential units. Four units per building.

Civil drawings, prepared by a professional engineer, detail underground mains, sizes, run-in and fire hydrant locations were prepared in early January as were the architectural drawings.

I was invited to bid the job at the end of January and applied for a flow test from the local fire department. My contract begins at a connection 1'-0" AFF of each building.

I asked for a flow test in late April and because of COVID I didn't receive results until the very end of May. The results were:

Static: 55 psi
Residual: 25 psi
Flow: 632 gpm

Certainly not great but as far as sprinklers, and sprinklers only, go it's adequate.

For sprinklers I got everything to work with a minimum 8.4 psi safety factor and that was the OH2 area with 250 gpm hose. My sprinklers worked just fine so I submitted the drawings.

Well, it appears my fire sprinkler drawings have not yet been approved because the project lacks fire flow calculations.

From fire department feedback I am getting the feeling they are looking at me to do the fire flow calculations which is something I have never been asked to do and, in my strong opinion, should have been done by someone else well before the project got started.

How could anyone lay out the site utility drawings without having performed the fire flow calculations? I would have to think a the fire flow calculations would be the very first thing done on any project well before the fire fire sprinkler contractor showed up to bid the project.

I got the feeling I am going to be blamed for the project not having the required fire flow. It appears I have enough for the residential units alone but I am worried about the parking area under the building that is OH1.

Reason there is such a difference in BOR and source pressures is the use of a RPZ backflow assembly.

Oh, and I wouldn't stake my life on it but I think the fire flow for the OH1 area is 1,500 gpm? If I am right someone has a real problem on their hands seeing as how the site utilities have already been installed.

Sorry for the ramble but it is upsetting that someone might be looking at me as if it were my responsibility.

 

[cdafd]

Fire flow to do fire sprinkler hydraulic calculations with???


If so I normally see the fire sprinkler company do it.

 

[SprinklerDesigner2]

cdafd,

ISO fire flow calculations.

 

[UFT12]

... but I think the fire flow for the OH1 area is 1,500 gpm?

Not easy answer. ISO methodology relies on a different hazard classification than the standard three (LH, OH, EH) of NFPA 13. The fire area also maters.

About your question in the sheet you posted, if you are feeling sure that NFPA 13R is the applicable standard for the parking garage, then why not apply the ISO methodology there too? Note 2 should apply there too. You would need to run the methodology for each construction type, each occupancy, each fire area, each side of the area if the occupancies are separated or in case they are mixed, look into the recommendations of the methodology to determine how do define occupancy and construction type as a whole.

 

[SprinklerDesigner2]

UFT12,

The parking area is OH1 while the units themselves are Residential. The parking area is shared by the four units.

These are beach houses sitting on the Gulf of Mexico beach. Everything is sand.

I don't have any problem conducting a flow test for the fire sprinklers as I have been doing it for close to 50 years now (I'm older than dirt). The problem I have is being made responsible for the ISO Fire Flow calculations which is something that should have been done well before I ever showed up on the scene. As my contract calls for me to start 1'-0" AFF, the land has been purchased and all site utilities have been installed before I won the contract what am I supposed to do if the ISO fire flow isn't there?

I am not certain but if I have to meet the fire flow for an OH1 it's not going to pass because my guess is the minimum fire flow will be either 1,000 or 1,500 gpm. Not sure but it's clear either one would fail.

If it doesn't meet fire flow requirements what am I supposed to do about it?

In any case I maintain meeting the ISO Fire Flow requirements, not to be confused with anything to do with the hydrant flow test for fire sprinkler calculations, is not my responsibility but should have been done well before I ever showed up on the job.

Another point to make is if the building was a single story without fire sprinklers ISO Fire Flow Calculations would still have to be performed.

In my mind this isn't unlike a situation where a structural engineer for a building makes the fire sprinkler designer responsible for insuring his building will support the fire sprinkler system.

 

[MGXFP]

Fire flow is typically based on building size and construction type. Methods to calculate it can be found in Appendix B of the IFC and Chapter 18 of NFPA 1 among other resources. This is the available flow at 20 psi residual pressure. Typically fire flow is reduced for a building equipped with a fire sprinkler system. There are other ways to calculate fire flow for rural areas using standards such as NFPA 1142. Also other methods exist such as ISO. The local building code should establish what method is used.

I believe an engineer should be establishing the minimum fire flow for the building; usually a civil or FPE will have this task to make sure the water supply is sufficient before construction begins. In my opinion it should not be the responsibility for a fire sprinkler technician. Like you said your work/contract is for inside the building.

Generally speaking the minimum fire flow for just about anything is 1,000 gpm for IBC/IFC. It can be reduced to 600 gpm if quick-response fire sprinklers are used throughout the building per chapter 18 of NFPA 1 if that is the adopted standard.

 

[cdafd]

Sounds like a Stookey input question

Or a set down and clarify what is being asked of you

 

[TravisMack]

Art:

I have found there is a very large gap in this. As Newton said, the most common way we see it done is with the IFC Appendix B. It is pretty straight forward based on building size and construction type. IMO, this should be the responsibility of whomever is doing the site development drawings. How can you know the infrastructure needed for the site water lines if you don't know the minimum flows required and the minimum pressures?

But, as with all things, it seems to get thrown in the sprinkler guy's lap. I used to play the nice guy and help point the civil engineer to the appropriate location in the IFC and basically show how to do it. I never did the final stuff and always insisted the civil seal their own work scope for it, but I basically put it all out there for them. I had a colleague "educate" me on this. The civil guys are getting paid quite well to do their work and there is no way we should be giving it to them for free. So, we have started charging a pretty penny to help get this resolved on projects. We have actually been brought in quite early on projects and then been given the opportunity to do the sprinkler system as part of the design documents because of us being in on the fire line sizing and calculations.

I would say we run into at least one a month where the civil guy didn't have the site fire flow and it has caused some major issues. The most recent is a project we go brought into because the sprinkler contractor couldn't get the plans approved with all the AHJ required. The project was out of the ground already. It turns out one of the requirements was to do the site fire flow calcs. Well, as you can imagine, the site fire flow calcs would not work based on the water supply. The project is going to end up needing a break tank and a pump. You can imagine how happy everyone was at this stage of the game.

Travis Mack, SET, CWBSP, RME-G, CFPS
MFP Design, LLC

http://www.mfpdesign.com

 

[SprinklerDesigner2]

I would say we run into at least one a month where the civil guy didn't have the site fire flow and it has caused some major issues. The most recent is a project we go brought into because the sprinkler contractor couldn't get the plans approved with all the AHJ required. The project was out of the ground already. It turns out one of the requirements was to do the site fire flow calcs. Well, as you can imagine, the site fire flow calcs would not work based on the water supply. The project is going to end up needing a break tank and a pump. You can imagine how happy everyone was at this stage of the game.

EXACTLY MY CURRENT SITUTATION!

Since we don't have the ISO Fire Flow calcs my sprinkler drawings will not be approved and some people might think this is all my fault as I should have conducted the ISO fire flow calculations six months before I ever heard of the project.

The owner, a wonderful person to know, is already under stress and I feel horrible about the entire situation. Florida, COVID and these being high end vacation rentals you can only imagine the stress.

120,000 gallon tank @ $1.00/gallon plus pump?

 

[fel3]

This is long, but perhaps my narrative will be helpful to you.

Over the years, I have been the site civil engineer for a variety of buildings and building clusters, ranging from a small medical office building to four full prisons (three federal and one state). I have also established water system design requirements for proposed residential and commercial developments while consulting for a good-sized water district in Southern California early in my career and later several cities and small water districts in Central California.

In my experience, fire flow requirements for hydrants and sprinklers and fire hydrant locations are usually established by the local fire jurisdiction. Their requirements are in turn based on the governing fire code (e.g., the California Fire Code for most of my projects), sometimes with local modifications for special circumstances, guidance from NFPA, ISO, and other sources, and so on. The main exception to this was the prisons, where the fire flow requirements were based on agency standards, not local requirements, plus the recommendations of a fire protection engineer who was part of the design team. I sized the supply, storage, and distribution elements of the water systems based on these requirements. For the prisons, I selected the fire hydrant locations, subject to approval by the client.

As an aside, I also designed the fire protection system for a petroleum tank farm. Here, the City Fire Department established fire flow requirements based on published accounts of fires at similar facilities and studies related to those fires, then allowed me and my client to determine what combination of water and foam injection would meet these requirements. In this case, we chose to drill two 2500-gpm wells, size the fire water distribution system for 5000 gpm, then make up the rest with foam injection. I selected the fire hydrant locations, subject to approval by the City.

For residential developments (both single-family and multi-family), the fire flow requirements are (in my experience) usually tied to zoning categories, but the zoning-based requirements are founded on the Fire Code. For commercial/industrial, the fire flow requirements are (in my experience) usually based on zoning plus building size(s), building type(s), and occupancy(ies). The last three items require input from the design team. What I have seen is preliminary fire flow requirements based on a preliminary description of the project provided to the fire jurisdiction, then final requirements based on the submitted design. Depending on the project, the architect and/or the mechanical engineer and/or a fire protection engineer handled the coordination with the fire jurisdiction, although I was often part of the discussion because of my civil experience in this area.

When I consulted for the SoCal water district mentioned above, the developer would provide a project description, a parcel or tract map, and (for commercial/industrial) a building plan with size, types, and occupancies. I would then work with the Los Angeles County Fire Department to establish the fire flow requirements. In the end, the LACFD would provide me with a map showing preferred fire hydrant locations and a letter that provided the fire flow requirements and any other fire-related requirements. I learned a bunch working with the good people at the LACFD.

With the cities in Central California, it has been a mix of the city setting the requirements and me setting the requirements for the city's approval. For the bigger cities, it has been the former; for the smaller cities (and for the small water districts), it has been the latter. For example, one city of 18,000 people that I worked with for a few years has a volunteer fire department and the chief and his very limited staff had no experience setting fire flow requirements so turned to us as the contract City Engineer to do that.

When I have had to establish fire flow requirements, I have based them on the Fire Code and what I learned from the LACFD. In a couple cases, I also had to temper the requirements because the local water system was incapable to providing a reasonable fire flow and nobody had the money to fix the problem. On the other hand, one small water district was able to get grant funding to implement improvements based on my analysis of the system and its lack of capacity.

In the end, I think the local fire protection agency should ALWAYS establish the final fire protection requirements: including hydrant flow requirements, hydrant locations, sprinkler flow requirements, and any other applicable requirements. However, the design team needs to be involved because every project is different and a one-size-fits-all set of requirements from the agency may not be the best solution.

============
"Is it the only lesson of history that mankind is unteachable?"
--Winston S. Churchill

 

[OremusFire]

I've been involved in these sorts of situations as well and I always deflect it back to the civil engineer or architect since my scope of work is the interior piping and if I can get my system to work with the hydrant flow test alone then my work is done. My understanding is that building's fire flows is for MANUAL fire fighting operations via fire hydrants, whereas fire sprinkler systems are AUTOMATIC fire suppression. That being said, as a design technician, this has nothing to do with us - until it does - it's all infrastructure.

I think if the city cannot provide fire flows for parcels that they have zoned all this should be on them and not the private property owner. It seems overkill that as a municipality you would expect every business on such and such street to each have a large storage tank and pump to provide their own fire flows.

That said, I've come across so much confusion in this area from both AHJ's and civil engineers that it's unreal. I had an AHJ tell me I couldn't use a 1500 sq. ft. design area because the fire flow calculations say I have to calculate everything under the roof! I told him that fire flows have nothing to do with my design area for determining pipe sizes based on friction losses for the fire sprinkler system.

Any thoughts on my understanding of things? I would like to know if I'm wrong and always look forward to being educated.

 

[stookeyfpe]

Fire flow ultimately rest with the Building Owner. They are bringing the hazard to the jurisdiction and based on the building's construction classification, height, area, and fire protection, they are responsible for providing the fire flow. In my jurisdiction, we address this at the site plan phase. In my town (approximately 1,000,000 population over about 312 square miles) a site plan is required for most commercial and residential development. Part of building a site is to provide a water supply for sanitation and fire flow.

Fire flow is not sprinkler demand. The Civil Engineer of Record for the Site Plan is responsible for getting the required volume and pressure based on the adopted jurisdiction's fire flow provisions, which can be significantly reduced by the installation of an automatic sprinkler system.

In my world, if the Owner doesn't want to comply, move out of town, build whatever you want however you want to do it because in Texas, many small towns don't adopt a building code and the Legislature prohibits counties with a population of <250K people from adopting a fire code because we're business friendly. Don't get me started on sacrificing firefighter lives for the purpose of the free market.

Maybe I should write a book on fire flow.