Mix Standpipe Types in Same Building Complex?

3/22/2024

In a 15-story highrise building, can the standpipe system be zoned with an Automatic Dry in the 1st -5th floors of the unheated Parking Garage, and an Automatic Wet in the 6th- 15th floors of the heated office portion?

Are we allowed to mix types?

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5 Comments

Casey Milhorn

3/22/2024 08:17:55 am

I've designed one that way before. I don't think I've ever seen anything that says you can't unless there is something in the applicable building code. Below is from 2013 edition of NFPA 14.

3.3.17.3 Class III System. A system that provides 11⁄2 in.
(40 mm) hose stations to supply water for use by trained
personnel and 21⁄2 in. (65 mm) hose connections to supply
a larger volume of water for use by fire departments.

5.4.2 Class II and Class III Standpipe Systems. Class II and
Class III standpipe systems shall be automatic wet systems unless
located in a facility where piping is subject to freezing and
where a fire brigade is trained to operate the system without
fire department intervention, in which case an automatic dry
or semiautomatic dry system shall be permitted. (newer editions might have cut out the "fire brigade part". I don't have a newer edition in front of me at the moment.

Of course check with the AHJ. They will be the one using it and may prefer dry throughout (to avoid confusion). But if you can arrange for one FDC to feed both standpipes that would cut down on the confusion. Make sure you check valve is listed for dry system and I believe the newest NFPA 14 requires supervisory air pressure on the automatic dry systems.

With the height of your building, you may also need (2) FDC's facing different streets where possible.

Also make sure to take into consideration the pressure listing on the dry valve and determine if you will need master PRVs in series, or if individual PRV hose valves are the way to go. I would double check the listing on those as well to be used on a dry automatic system (probably fine but have never checked that before).

Don't forget the proper signage at the FDCs and to what pressure the fire dept needs to pump up to to get 100 psi at the top most hose valve.

Lot's to think about....

Dan Wilder

3/22/2024 08:43:00 am

You've used the correct terms....automatic...for both. Just make sure they comply with the Class I requirements. No different than providing a sprinkler system that is wet for a portion and dry for a portion.

Some items to think about (along with Casey's comments):

FDC signage
Hose valve signage (so the FD isn't expecting water immediately or they have provisions to exhaust the air while waiting for the lines to prime)
Heated paths for the wet feeds through the lower portion along with heated rooms for the valves.
System volumes limitations and/or water delivery within 3 minutes
Accelerator/Exhauster to reduce delivery time or some integration with the fire alarm system to trip the valve and allow some pre-filling of the system
Compressor location
Drainage (garages are really not known for their abundance of vertical clearance)

Kelly Brooks link

4/2/2024 03:39:24 pm

DAN WILDER- Do you know where I can find the 3 minute delivery requirement you are referenceing? Thanks,

Jack G

3/22/2024 01:31:33 pm

In my opinion the above statements are correct.
The only thing that I d add, that is not required for safety :
1. I ve installed manual trip stations ( device like a fire alarm / deluge systems ) on the dry standpipe above each of the hose valves. Pulling the handle rotates the handle on a half inch valve.
This would start a release of air at the hose valves.
2. I would install an automatic air vent above each of the standpipes.
This could be a request for additional work. Most owners would accept the request.
Reasoning:
Maint personal in most buildings, when they shut the system down, for work in the building, never bleed the air from the top, Fill the system using the fire pump, which causes a Water hammer , when using the system.
A serious problem in buildings where tenants renovate areas or change.
In Philadelphia. there have been cases where the top of standpipe cap, and or hose valve have been blown off, flooding the building.
Add signage at the pump ( for wet standpipes) to bleed the tops of wet standpipes ( if air vents are not installed). Even though this is a no brainer- trust me no one bleeds them .
An automatic air vent is an easy piece of mind.
Same for the dry standpipes “ manual pull stations “!
You are required to install them per nfpa 13, on all wet systems.
As the system fills with air over time, and the fire pump is used to fill it or the system is used, operates, the psi of the pump is amplified 3-4 times the pressure and could prove a disaster..
A tell tale signal would be ( system pressure ) gauge would show this additional pressure.
In my career I ve designed over 400 high rise buildings.

Glenn Berger

3/23/2024 01:05:51 pm

The design appears to be compliant.

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Mix Standpipe Types in Same Building Complex?

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