Who is responsible for Fire Flow?

[StoneCold]

I am building a chemical facility campus. I represent the owner of the facility. I have architechs, and mechanical engineering firms and sprinkler design firms all under contract. They are all telling me that I need to tell them the design fire flow for the campus. I am wondering why is that my choice. I have had FPE's do some overviews of the facility but I did not get a fire flow from them. Do I just need to pick it out of appendix B of the 2006 IFC compare it to my sprinkler flow + two hydrants and call it good? I feel like this should be coming from one of the people on my design team, but who?

Thanks
StoneCold

 

[stookeyfpe]

Your fire protection engineer needs to make the determination. The fire flow will be based on the building area, the construction type, and which buildings are or are not protected by a NFPA 13 compliant automatic sprinkler system.

If I was your FPE I wouldn't burden you with making the determination.

 

[TravisMack]

Typically, if you have an FPE on board, they will do it. It seems like you have done a design / build and have the fire sprinkler contractor as the designer on board. They may or may not be familiar with site fire flow as most sprinkler contractors do not deal with site work.

Many times, the civil engineer will do the site fire line and determine the site fire flow if an FPE is not part of the design team.

I will often show the civil guys where in the IFC it is and give them the information to properly size their site fire lines. It is really just a simple look up in the IFC.

Good luck!

 

[stookeyfpe]

Stone Cold

If you will provide me the area of the largest building on your campus, its method of construction, and if the building is sprinklered or not sprinklered, I can run the numbers. If you have unsprinklered buildings, please provide the construction type and area for comparitive purposes.

Also, am I corrrect to assume this facility is in the US?

 

[StoneCold]

stookeyfpe
Thanks for the offer. I believe I have a plan worked out but I would really like to see your comments.

We are currently building two buildings. The first is a 15,000 sq ft mixed use building. Office space, boiler room, compressor room. Building shell is a prefabricated metal building with metal studs and drywall internals. Should fall under IBC Type IIB. Sprinkler Design is 0.3gpm/ft2 over 5000sqft.

The second building is a batch chemical production building utilizing Class 1A flammables. It is 10,000 sqft with a 3000 sqft mezzanine. It is a tilt up concrete building, so under the IBC it is also a Type IIB. Sprinkler design is 0.3gpm/ft2 over 5000sqft.

We are also building a tank farm that has a foam suppression system with a coverage requirement of 0.16 gpm/ft2 over a total of 11,400sqft, and two fire monitors that require 750gpm each. (Covers seven 30,000 gallon tanks, two 8000 gallon tanks, and a railroad tanker unloading bay.)

The rest of the campus is set out in the future. It will consist of more of the production buildings and some warehousing of chemicals.

Fire hydrant demand is set a 750gpm.

In the 2006 IFC appendix B it sets the flow at 2500 gpm for a 15000sqft Type IIB building, before you take credit for the sprinklers.

However if you look at our current largest demand you get 1824 gpm for the tank farm and 1500 gpm for the two fire monitors that go with the tank farm suppression system. That gives me a flow of 3324 gpm with no fire hydrants running. If I add one fire hydrant (750gpm) to the mix that puts me at 4074 gpm.

So I don't think that it is unreasonable to set the fire flow demand at 4100gpm.
However that means anything else I build has to fall within this envelope.

What do you think?

Thanks
StoneCold.

 

[stookeyfpe]

Stone

A couple of things to consider:

A) Your calculations are treating fire flow as additive. The IFC does not consider fire flow to be used for simultaneous events. In other words, the design basis for fire flow is based on the greatest single demand, not the sum of all of the demands. For your buildings I would approve them with a 1,500 GPM fire flow.

B) I'm not sure how you derived a 750 GPM hydrant flow rate. The minimum flow rate allowed in 2006 IFC Section B106.5 for a site such as yours is 1,500 GPM.

C) Why was the flow rate for the tank farm and the nozzles summed? The nozzles are protecting the tank farm so I am not sure how one is going to deliver the 1,824 GPM value - unless that's the wetted area of the tanks and the exposed area of the dike. If it is, I would use that as a basis for the tank battery fire flow.

D) As buildings are added, the fire flow for the new building needs to be considered. Again, we do not aggregate the total areas of the buildings.

Also, you should search this website for a posting very similar to your question. That thread stayed open for over a month and goes into even greater detail.

Let me know if you have additional questions.

 

[StoneCold]

Stookeyfpe

I think I am missing some details that will bring this thing together and then maybe things will seem more clear to you. My site is a remote location and my fire flow is defined as the amount of water coming on to the property from the city. It will supply all the hydrants and building sprinkler systems and the tank farm. The fire flow number is going to be used to size the booster pumps and the underground fire protection loop piping.

Point A . 1500 gpm for the buildings is probably an acceptable value. However if I have to have 1500 for fire hydrants as well then I am up to 3000 gpm of demand for a single fire in one building. Right?

Point B. I only allowed 750 gpm per hydrant , I did not allow the 1500 for two hydrants running and the tank farm fire suppression running. Which will become more clear as you read point C.

Point C. This is an overkill on the design and I think that is causing some confusion. The insurance company and the fire marshal wanted deluge foam fire suppression on the tank farm. The plant is in a very small town with virtually no fire fighting capabilities. The insurance company also wanted four fire monitors covering the tank farm with the ability to educt additional foam from drums to cover the tank farm. I was able to talk them down to two monitors. That is how a single tank farm fire would pull the 1824gpm for deluge foam plus 1500 gpm for two fire monitors. Then I only added one hydrant to that number because we are running out of water here, that and there is barely anyone available to use it anyway.

Point D. I realize that I need to consider future expansion but I have to cap the water flow at ~ 4000 gpm because that is all I can get out of the city infastructure and I am not interested in adding a tank and pump to get any higher. I will just break my future buildings or tank farms up to keep there needs under the 4000 gpm.

I did read the other posts so I think I am still on the right path.
Do you think I am way off base here or am I getting pretty close.

When you tell a city planner that you want 4000 gpm they get a kind of sick look in their eye.

Thanks
StoneCold

 

[stookeyfpe]

Stone

Thank you for the clarification and the additional information.

From what you explained I think the focus needs to be on the tank farm. Realistically, the automatic sprinklers (when properly maintained) and assuming compliance with NFPA 30, will control and eventually suppress the fire.

I understand you have an AHJ and insurance company to deal with and you have a limited water supply. I believe I understand that you have a deluge foam system protecting the tank farm (I am assuming a dike flooding AFFF-water system). Based on your explanation, your going down the correct path.

One thing to consider in the future is to install a static H2O tank and use this as a supply source for the fire pump. Given the community's lack of firefighting resources (not an uncommon problem) and the hazards you are dealing with, having your own water supply will improve the reliability of your fire protection systems.

I will further extend myself by giving you an alternate e-mail account where you can e-mail me your phone number if you think it will assist you in obtaining resolution. Sometimes a 20 minute phone call solves our dual efforts of writing detailed analysis. Its afdhm@yahoo.com

 

[LCREP]

Stone,

Yep I agree with Stookey you really need to consider a tank and pump for your water supply. It will be a lot of $$ but given the hazard you have an adequate and reliable water supply is critical. A tank and two fire pumps, either two diesels or an electric and diesel depending on the reliability of the electric supply should be considered. Sizing of the tank would be critical, NFPA will only require a 120 minute supply. However given the hazards and possible long duration during an emergency you may want to double the duration it the local water supply is not adequate in volume. The FD can supply the required pressure, just make sure your FDC have several connects because the FD will need to connect more then 1 engine to the connection given your high flows. Most FD engines are in the 1500-2000 range.

 

[FFP1]

I agree with Stooky and LCREP. With regard to the two fire pumps...........it would probably be best to arrange one as a booster pump from the city supply and one from a suction tank. This approach requires both fire pumps operating simultaneously to meet the tank farm demand, but solves the volume issue because you will supply some from the city supply and some from the suction tank. During a catastrophic scenario, you will have the entire volume of the city supply available (even if it does not meet the full demand, you will be several hours into the incident and at least you will not be completely out of water. By this time the tank farm is a total loss and the fire fighters will be in a defensive mode anyway).