Where to place isolation valve(s) on manual dry standpipe system 1

[sl3656]

We have a single floor structure that is protected by a Class-I dry standpipe that runs a partial loop around the periphery edge of the structure, with short (~5 feet) tee-offs to fire hose valves every 150 feet. This ensures that the entire structure has hose coverage. The dry standpipe is fed from multiple FDCs at street level, spaced every 300 feet (or part thereof) around the structure.

In this situation, how would you comply with NFPA 14, clause 6.5.2? See below:

"Valves shall be provided on all standpipes, including manual-dry standpipes, to allow isolation of a standpipe without interrupting the supply to other standpipes from the same source of supply."

Where would one place the valve(s), given the multiple sources of supply via FDCs?

 

[cdafd]

Thought there was something for horizontal??

Will have to look.

So how many feet of standpipe??

How many total hose valves??

 

[cdafd]

Maybe not required?

 

[sl3656]

See attached sketch of the system for reference. We have around 10 nos. 2-1/2 inch FHVs.

 

[cdafd]

Very interesting.

And the reason for so many fdc's??

I am thinking no isolation valve required.

Maybe if one is added in the middle on the 200 feet side?

 

[sl3656]

Local AHJ requires street level FDCs every 300 feet of a building frontage or part thereof. Same reasoning for the quantity of FHVS, based on the 150 ft FHV-to-FHV spacing requirement.

I am thinking the same that an isolation valve isn’t required. Putting one on the 200 foot side would essentially stop an FDC on the northern street feeding FHVs on the southern street and vice-versa, contravening 6.5.2 of NFPA 14, no?

 

[cdafd]

Yes but same thing happens when an isolation valve is required and installed.

Will look at 14, plus other smarter people will also respond

My lean to no, is because it is only one standpipe

 

[sl3656]

Thanks cdafd!

 

[cdafd]

""""""""without interrupting the supply to other standpipes """""""

Does not appear you have an ""other""

All one standpipe, unless they count the tee as another

 

[stookeyfpe]

Nothing against the design but my Operations firefighters would call me every week to ask which FDC do we pump to if there is a fire. The design is fairly unorthodox but if it's how the jurisdiction specifies it, that's what's they want. May be some firefighters own stock in a FDC manufacturer. That's also a nice little ITM gold mine.

 

[sl3656]

Thanks for the replies guys. The local AHJ has a requirement that the standpipe be filled in no more than 10 minutes. Based on the volume of the system, anything from a fire apparatus greater than 500 GPM would satisfy this requirement, so any FDC can be used to fill.

Glad there is no requirement for an isolation valve.

 

[LCREP]

Putting on my prefire planning hat on you better put signage at each FDC indicating all FDC’s are interconnected. As stookeyfpe said this set up is crazy BUT if that is what they want they got it....