Is # of required hydrants based on fire flow reductions for sprinklers?

[Yikes]

I have a building that per California Fire Code (CFC) Appendix B, table B105.1 would normally require 3,000 GPM fire flow.

However, because the building is sprinklered, this flow rate can be reduced to 1,500 GPM per CFC 105.2.

CFC Appendix C, table C105.1 shows the minimum required number of hydrants, based on required fire flow.

QUESTION: in my example, do I need 3 hydrants because the required flow was 3,000 GPM, or do I only need one hydrant because the reduced flow requirement is only 1,500 GPM?

In other words, is the number of required hydrants based on the reduced flow allowed when a building is sprinklered?

 

[cda]

Check with each ahj to see how they read it

But b&w: the answer is yes

Exception: A reduction in required fire-flow of 50 percent, as approved, is allowed when the building is equipped with an approved automatic sprinkler system.

Now on top of that there may be spacing criteria or hydrant needed near the fdc , that would drive additional hydrants

 

[Yikes]

Thanks, cda. I don't own a copy of the fire code handbook / commentary, and I was wondering if it addressed this issue.

 

[cda]

Just left the office maybe Monday

Am I missing something in your question??

 

[Yikes]

I was wondering if the Handbook to the Uniform Fire Code actually mentions the reduction in # of hydrants, based on the building being sprinklered. If I want to challenge my local fire official, it would be easier if I had a handbook reference, rather than going through a long appeal / interpretation request to our State Fire Marshal.

I don't own a copy of the UFC handbook, so I don't know if such a clarification already exists in the UFC handbook.

 

[cda]

are you doing a house or commercial??

 

[cda]

on friday will try to get it to you.

 

[cda]

on friday will try to get it to you.

Yikes clean out your private message box, so people can send you private messages

 

[Yikes]

It is a 20 unit apartment building on at the corner of two streets. There is already a fire hydrant across the street, and a second hydrant proposed at the front property line. The fire department wants to add a third hydrant on the other street side, total 3 hydrants, based on the flow rate charts. However, since we have sprinklers, the flow rate reduces and therefore the number of hydrants should reduce.

 

[cda]

We also have a distance requirement along with a fire hydrant within 100 feet of the fdc

So sometimes we get additional hydrants

 

[Msradell]

They are on the asking for two hydrants, the third one is existing. It makes perfect sense to ask for one at the front and for one at the rear of the property. Accessibility is as big of concern if not bigger then flow rate in most cases! Starting a war with the FD is not going to come out well for you. You may win on the hydrant issue but they will become very picky on every other issue in the project!

 

[mtlogcabin]

As others have pointed out the number and location of hydrants is not based on fire flow only. The distance from the hydrant and the perimeter around the building may require additional hydrants.

507.5.1 Where required.

Where a portion of the facility or building hereafter constructed or moved into or within the jurisdiction is more than 400 feet (122 m) from a hydrant on a fire apparatus access road, as measured by an approved route around the exterior of the facility or building, on-site fire hydrants and mains shall be provided where required by the fire code official .

Exceptions:

1. For Group R-3 and Group U occupancies, the distance requirement shall be 600 feet (183 m).

2. For buildings equipped throughout with an approved automatic sprinkler system installed in accordance with Section 903.3.1.1 or 903.3.1.2, the distance requirement shall be 600 feet (183 m).

 

[Yikes]

Our FDC is 20 feet away from the currently proposed hydrant, right near the street corner. The property dimension is about 120'x177'. A fire truck pumper could park on either street, connect to this hydrant, and the maximum distance from the street to any point on the building is 149 feet.

From that hydrant, you could walk all the way around the perimeter of the property, and return to the hydrant, in 484'. Of course our actual building is smaller than the site.

I understand that number of hydrants is based on both flow rate and on access, whichever is more restrictive. n this case, I think I've got access taken care of.

 

[mtlogcabin]

What does the hydrant flow? We have a couple of areas in our city that have 4" dead end lines that the hydrants flow less than 900 gpm's.

2 hydrants should suffice for what you described

 

[Builder Bob]

It is really interesting that ISO bases the required fire flow on the Needed Fire Flow at the base of riser for the sprinkler system.

 

[Yikes]

mtlogcabin:

Flow at hydrants is 2037 GPM at 20 psi residual. Not awesome, but adequate when we are allowed the fire flow reduction for sprinklering the building.