Horizontal Standpipe

[jjmoore73]

I have a single story 100,000 sq. ft. concrete fitness center project. It will have automatic sprinklers and a Class I Standpipe system with 13 2.5" hose valve locations.

According to 7.10.1.1.1 the minimum flow rate should be 500gpm at the most remote location through two 2.5" outlets at one location, then 250gpm at the next two remote hose connections in accordance with 7.10.1.2.

Based on 7.10.1.1.2, AHJ said I only need to flow 750gpm total for this project because it is a horizontal standpipe. (250gpm for 3 different hose valves) What say you?

Based on 7.10.1.1.3, leads me to believe I should not only have 1000gpm total, but 500gpm should be at the two most remote locations.

Based on 7.10.1.2.2 says I need to calculate 250gpm at the three hydraulically most remote hose connections on the standpipe AND at the topmost outlet of each of the other standpipes. Say what?

I need some help determining how many and which hose valves need to be calculated. Based on the attached plan, I am thinking 250GPM at F,G,H,L. I am also showing where I am planning on the isolation valves. If I need to calculate 500gpm at one location, do I need to provide 2 hose valves at that location?

Thanks - J





J. Moore
NICET III - Water Based

 

[cdafd]

Not an engineer or designer, but if you took this layout and stood on end, as in vertical position, I think than apply 14 for required flow

And that is the answer

 

[3cio]

Good day!

Just to be clear, NFPA-7.10.1.1 discuss about the flow rates and NFPA 7.10.1.2 discuss about the hydraulic calculation procedures.

Base on your attached drawing, you only have one standpipe.(NFPA-14 clause 3.3.14 - Standpipe is the system piping that delivers the water supply for hose connections and for sprinklers on combined systems, vertically from floor to floor.)
In this case, you need only to satisfy NFPA-14 clause 7.10.1.1.2 & 7.10.1.2.2. the word "and at the topmost outlet of each of the other standpipes" is not applicable to your design since you only have one standpipe. that is why it will arrive only at 750GPM.


As an advised, kindly go through chapter 3 for the definitions because it helps a lot.

Hope it helps,

 

[jjmoore73]

CDAFD... Yes this is how I was looking at it. However, there appears to be different guidelines for horizontal standpipes. I wonder what Stookey and Travis think?

3CIO... This is very similar to the thoughts of the AHJ. I want to purchase a 750GPM pump but my gut is telling me I need a 1000GPM.

 

[cdafd]

Not near the book and this is from 2003. I was looking for the definition of standpipe

There are also special hydraulic calculation procedures for horizontal standpipes. They will require that where a horizontal standpipe on a Class I and Class III system supplies three or more hose connections on any floor, hydraulic calculations and pipe sizes for each standpipe shall be based on providing 250 gpm at the three hydraulically most remote hose connections on the standpipe and at the topmost outlet of each of the other standpipes at the minimum residual pressure required. The total flow is still required to be up to 1,250 gpm (1,000 gpm when sprinklered.)



The definition for a standpipe will now include both vertical risers and the horizontal portions of standpipes that are the water supply for more than two hose connections on a single level. Prior to this change, horizontal standpipes commonly used in locations such as stadiums, transit system tunnels, and malls were not explicitly addressed. The intent of these changes collectively is to distinguish between a secondary line to one or two hose connections on a single floor, and the primary distribution system of risers and mains that may, occasionally be run on a horizontal orientatin. Where unique conditions require more than two outlets on the same level that can only be fed by a horizontal distribution system, the arrangement shall be considered a "horizontal standpipe."

http://www.firesprinkler.org/sprinkleragesite/sprinklerage.cfm?id=484

 

[TravisMack]

I will take a stab at this.

First, you only have a single standpipe. It is truly a horizontal standpipe per the definitions in Chap 3.

Now, looking at Chap 7, we have to decide on flows. I understand your issue about floors greater than 80k sq ft, but that is when you have multiple standpipes. You only have ONE standpipe, so that does not apply. Using NFPA 14, 2010, section 7.10.1.2.2 states when you have 3 or more outlets on a single floor, you flow 250 gpm at a maximum of 3 outlets, then you pick up any additional flows you need at the top of additional standpipes. Since you don't have this situation, then the additional flows don't apply.

This gets me to where you need 750 gpm total at your F,G&H.

There is also another interesting question that arises in this scenario. You obviously do not have a high-rise building. As such, manual wet standpipes are allowed in non high-rise buildings. So, could you just calculate this to the fire dept connection. Per the appendix in NFPA 14, a typical truck will be delivering about 200 psi at 700 gpm and 150 psi at 1000 gpm. So, you have somewhere in that range to get your 175 psi. If the AHJ will accept a manual wet standpipe in this case, and if your water supply is adequate to supply your sprinkler system, you may be able to eliminate the on-site fire pump as well.

Travis Mack
MFP Design, LLC

http://www.mfpdesign.com

 

[jjmoore73]

And now the rest of the story...I didn't want to make things more confusing, as I didn't think the 2nd floor would matter. AHJ wanted me to calculate the 2nd floor as a separate calculation. Travis, does your opinion change if part of this building has a 2nd story? The middle of the buildings has a 2nd floor. C,D,E,H,I,J,K each go vertical to supply hose valves on the 2nd floor.

The jurisdiction does not recognize manual standpipes. Standpipes must be Automatic per local amendments.

J. Moore
NICET III - Water Based

 

[TravisMack]

Yes, it does change. Because now, you do have more of a traditional standpipe system. You have verticals that are fed by a common horizontal bulk. I would have a sectional valve for each of those standpipes that feed 2 floors and call them a "traditional" standpipe. At that point, because you are now having standpipes with multiple verticals, I would flow 500 gpm through 2 of those and get to 1000 gpm.

Question:

Are these "vertical" standpipes located in a stairwell, or how are they located?

Travis Mack
MFP Design, LLC

http://www.mfpdesign.com

 

[jjmoore73]

Travis....Attached is a link to the CAD file. The hose valves don't "stack" like traditional standpipes. The only place this happens is in a stairwell near the fire pump. This stair has the only access to the roof, and the AHJ wanted one on the roof at this location. There are (3) valves at this location, 1st, 2nd, roof. The other stairwell only has a valve on the 2nd floor. It is a 2nd floor exit stairwell, with no reason to have one on the 1st floor since there is no access to the 1st floor from this stairwell.

It is a funky layout. I am used to more traditional vertical standpipes. I'm not sure which hose valves to calc, how many to calc or what gpm to calc.

I appreciate and respect your input!!

 

[stookeyfpe]

The drawing should be posted as a Adobe file so we can all review it.

 

[jjmoore73]

Good idea Stookey....Attached is the standpipe showing the 1st and 2nd floor plan on 2 pages. In RED is where I have a hose valve. I can't figure out which hose valves to calculate and how many GPM at the valve. Jurisdiction requires standpipe to be automatic.
I am thinking 250@A 250@B 250@C and 250@E 1000 Total.
AHJ said 250@A, 250@B, &250@C 750 Total.
Coworker said 500@A, 250@B, 250@C.

I still have to get the plans stamped by a PE for the general contractor. Specification list a 1000 GPM fire pump.

Thanks - J

J. Moore
NICET III - Water Based

 

[cdafd]

3.3.14.1 Horizontal Standpipe. The horizontal portion of the system piping that delivers the water supply for two or more hose connections, and for sprinklers on combined systems, on a single level.

 

[cdafd]

7.10.1.1.2* Where a horizontal standpipe on a Class I or Class III system supplies three or more hose connections on any floor, the minimum flow rate for the hydraulically most demanding horizontal standpipe shall be 750 gpm (2840 L/min), and the calculation procedure shall be in accordance with 7.10.1.2.2.



7.10.1.2.2 Where a horizontal standpipe on a Class I and Class III system supplies three or more hose connections on any floor, hydraulic calculations and pipe sizes for each standpipe shall be based on providing 250 gpm (946 L/min) at the three hydraulically most remote hose connections on the standpipe and at the topmost outlet of each of the other standpipes at the minimum residual pressure required by Section 7.8.

 

[TravisMack]

I would shoot conservative and do A/B/F @ 250 gpm / 100 psi and then pick up L at an additional 250 gpm. This would be a total demand of 1000 gpm.

That may be overkill, but you already have a 1000 gpm pump specified in the project. When things look to be in a grey area like this one is, I tend to err on the side of caution. AHJ's can be wrong. He may be right about 750 gpm demand as the most needed. However, if something goes wrong, it will not be the AHJ that has his butt in a sling...it will be you having to defend why you chose what you did.

Travis Mack
MFP Design, LLC

http://www.mfpdesign.com

 

[mellis1967]

I'm following this thread with great interest. I'm currently working on a similar project, with a 140,000 sf covered sports facility with a 20,000 sf mezzanine. I understand the fire pump sizing portion of it, but I'm questioning where to find the code that requires a horizontal standpipe system in the first place. I'm under IBC and I can't find anything requiring them. Can anyone help? Thanks.

 

[stookeyfpe]

It's not required. The only time a horizontal standpipe is ever prescribed by the 2006, 2009 or 2012 IBC is at a horizontal exit. The fire code official may prescribe to reduce hose lay distances inside a building, but I won't speculate on this.

 

[CarlosMN]

Jjmoore73, could you please send again drawing?