NFPA- Storage water size for Sprinkler system 2

[farid2176]

We are desiging a builidng in remote area. this builing have boarding, labs and little office spaces i think the majority of builindg will be light hazard area. There is no city water in this area and we have to provide storage tank for sprinkeler system. I am woundring if any body can point out the NFPA section to size the storage tank. we are thinking that we have to design the tank based on water quantity to provide water to 10% of builing for 60 minuts
by the way our builing is 29000 sq-ft and in Manitoba Churchill the weather is too cold in winter for that reason the tank needs to be inside the builing. can any body help pointing out the NFPA section that provide the guide line to size the storage tank
I will appreciate your help
Thanks

 

[MechEng2007]

See Table 11.2.3.1.2 in NFPA 13, 2007. This lists Water Supply Duration Requirements by occupancy type.

 

[farid2176]

Thanks for the quick response
the table you mentioned will give me the Hose allounce and the duration. should i consider density/area curve to figure out the water demand for sprinklers. have you used this density/area curves before, can you explain how to use these curves
Thanks I appreciate your help

 

[SprinklerDesigner2]

You say the building will have labs so it's impossible to tell what the hazard would be without more information.

Most high school chemistry labs are designed for Ordinary Hazard Group I but, depending on what your 'labs" are they could be more.

The industry has "sprinkler system layout technicians" supported by FPE's or Fire Protection Engineers. To become a qualified certified layout technician takes a minimum of five years and passing about three days worth of tests. Layout technicians are qualified to do just that, we can layout systems, perform all the necessary hydraulic calculations and, in most locations, assign hazard groups but while some hazard groups can be easy you really need the expertise of an FPE when it comes labs and chemicals.

Most of the labs I've done were spec'd out or, most often, the criteria was developed by Factory Mutual which made my job safe and easy.

A case in point was discussed on the forum a year ago concerning chemicals used at a public water treatment plant. I barely made it through high school chemistry and who would ever guess a water treatment plant would use volatile chemicals needing Extra Hazard protection? I certainly wouldn't which is exactly why FPE's are needed on more projects than they are used on now.

If you already have the job on a design build basis I would strongly suggest you obtain the services of an FPE or at least a competent layout technician who has the common sense to know when contact an FPE is needed.

You want to spend $500 or so now or $50,000 later after you have egg on your face?

Based on the level of your questioning you really need to make contact with someone who is experienced. I'm not trying to be nasty or unhelpful to you but trying to keep you from stepping in it.

Best of luck to you.

 

[farid2176]

We are not trying t design the system, the project is in planing phase we need to allocate the space for storage tank, i like to have some storage tank size the fire protection will be performance spec item
Thanks any way

 

[MechEng2007]

Assume Ordinary Group I occupancy due to the labs. To find the amount of water needed you would take 0.15 gpm x 1,500 sq ft (as shown in Figure 11.2.3.1.1) which comes out to 225 gallons. The amount of water multiplied by 60 minutes comes out to 13,500 gallon. This would be your tank size. Section 11.2.3.1.2 states that you only need to take the minimum duration.

In NFPA 13, 2002 you have to account for outside hydrants if you water service is energizing outside hydrants. Not sure why this was removed in 2007 but it was (or it was placed where I didnt see it).

 

[farid2176]

Thanks MechEng2007, Do we need to include hose stream allownce for storage water calculation

 

[TravisMack]

If you are supplying outside hydrants, you may need to look at site fire flow requirements in the IFC. That could be significantly more volume than the fire sprinkler demand.

If you are not feeding hydrants from your tank, then you don't need to include the hose allowance.



Travis Mack
MFP Design, LLC

 

[MechEng2007]

Not sure if you need to figure the hydrants. I didnt see it in the 2007 edition. If you are supplying hydrants and the applicable standard is 2003 you have to. You may need to use IFC if the local AHJ requires it.

 

[TravisMack]

Assuming that this project is in an area covered by the I-codes, you first look to the IFC to see what to do, as the codes will override the standards.

Often times, we sprinkler guys, don't worry about the site fire flow requirements because that is being handled by the civil guys. But, if you are in a rural area and the tank for the sprinklers is to supply the hydrants, then you may need to get into site fire flow requirements. That is in Appendix B of the IFC, if I recall correctly.

There were some threads on here a while back about the site flow demands vs sprinkler demands. Traditionally, site flows are much greater than sprinkler, but sprinkler pressures are much greater than the site pressure requirements.

Anyway, good luck with the project.

Travis Mack
MFP Design, LLC

 

[ContractorDave]

This project will not be covered by IFC and it's highly unlikely outside hydrants will be an issue either. The NBC will reference NFPA 13 1995 edition. I have done many projects throughout NWT and Nunavut that are almost always tank based. The tanks will invariably be installed in a heated mechanical crawlspace, usually multiple tanks where you would have say 3 x 5000 gallons for fire water and 1 x 5000 for domestic depending on the building occupancy. We've also installed tanks where one of the fire water tanks is fitted with floats to allow for a percentage to be used for domestic purposes but we are getting away from that. We are also getting away from installing hose cabinets for occupant use in the Territories, but your AHJ will have to address this and if they are required, then you will have to allow for hose streams.

Regards
Dave