NYC and NFPA 14 - Combined Auto wet Sprink / Manual wet Standpipe

[DHEngineer]

Hello All,
I am new to the forum and have the following question regarding Combined Automatic Wet Sprinkler / Manual Wet Standpipe systems in NYC under the latest code. For some reason the code does not address this.:

I am working on a low rise I1 occupancy building that requires an automatic sprinkler system as well as a standpipe system due to the area floor limitations. According to the NYC code, I can install a class 1 standpipe system in leu of a Class 3 system provided the usual requirements are met (lobby cabinet ect..)

After then reading NFPA 14 as modified by appendix Q, it states that in low rise buildings, Class 1 standpipes may be automatic wet or manual wet. So Far so good. At this point I have decided to go with the combined automatic wet sprinkler / manual wet standpipe system.

Based on the above, I assume that I will only have to provide a pump to satisfy the load of the sprinkler system and size the system pipes to accomidate the sprinkler system fed from the building pump and standpipe load that will be fed from the FD siamese connection. Again, so far so good.

Here is where it gets tricky. Since my building pump will only be providing the supply for the building sprinkler and only maintaining the water in the manual standpipe system, am I then allowed to use a sprinkler booster pump with one source of water? Or am I required to provide a fire pump with two sources of water?

I can not find this in the code anywhere and have yet to find a difinitive answer from a NYC code official.

Please let me know if anyone has had any experience with this in NYC or if any of my Logic seems off on any of the above.

Thanks,
DHEngineer

 

[pipesnpumps]

Your logic is sound for NFPA 13 and 14 as I see it, although I can't speak to NYC code.

FDC is the 2nd source of water supply, and it connects downstream of the pump, but upstream of the combined system standpipes.. The pumper truck provides the supply pressure in that case.

The NFPA 14 requirements are as follows:
"9.1.2 Manual standpipe systems shall have an approved water
supply accessible to a fire department pumper."

The NFPA 13 requirements are per NFPA 13; imagine that the requirements are completely separate. It just so happens that your NFPA 13 and NFPA 14 systems share a common pipe.


A second supply would only come into play for multi-zoned high rise buildings (not the case according to your low-rise description).

NFPA 14:
9.1.4 Where a secondary water supply is required by 7.9.4, a
single water supply shall not be permitted.

7.9.4 For systems with two or more zones in which portions of the second and higher zones cannot be supplied using the
residual pressure required by Section 7.8 by means of fire department pumpers through a fire department connection, an
auxiliary means of supply shall be provided.


The only thing that didn't seem 100% right, is I believe that the term "low-rise" is more appropriate for <4 stories. "Medium rise" is normally what is used for >=4 stories but <75ft from lowest level of fire department vehicle access.. Are you saying NYC requires standpipes for <4 stories? if so, that's interesting.

hope this helps.

 

[DHEngineer]

Thanks for the reply pipes and pumps.

Yes In NYC the following is true:

1) Standpipes are required based height and size of floors. I am way under the 75 ft mark but am required to provide standpipes because the building is 3 or more stories high and larger than 7500 sq ft on any one story.

2) The second supply I am refering to in my question is regarding the fire pump suction line (not the system supply). In NYC all fire pumps are required to be fed from two seperate street mains unless it is an R (residential) occupancy.

3) Lastly, in NYC they differentiate between Sprinkler booster pumps and Fire pumps. Sprinkler booster pumps do not require two sources of water on the suction side.

My question comes into play when deciding to use a sprinkler booster pump (when normally reserved for sprinkler use only) or a fire pump (usually required for standpipe systems).

In this case, with the combined auto wet sprinkler / manual wet standpipe, I can not find anything in the code that states if I can or can not use a sprinkler booster pump to supply this system based on the fact that it only be required to meet the demand of the sprinlker system and not the fire standpipe system.

In NYC this poses a problem because it is a huge cost to install a second 6" water service for the building fire pump if I can use a sprinkler booster pump instead.

unfortunaley I can not get an answer as of now.

 

[NJ1]

I did not understood the part where you said "require to provide a fire pump with two sources of water"

Is there a water source already in the building?
If you are designing a Fire Sprinkler Standpipe Combo in NYC in a building that is classified a low rise you will need a fire pump however 6" seems a bit overkilled. The main problem you will encounter is water pressure specially in Manhattan.

 

[DHEngineer]

NJ1, Read above.

In NYC Fire pumps are required to be supplied by two seperate street mains. (two sources of water on the suction side of the pump),

Sprinkler booster pumps are not. (one street main)

It is a brand new building. I know I need a pump but the question is if a sprinkler booster pump can be used in leu of a fire pump for a combined auto wet sprinkler / manual dry standpipe due to the fact that the supply is only meant for the sprinkler system and to maintain water in the standpipe system.

They do not talk about this situation in any NYC or NFPA code I know of at this point in time.

 

[NJ1]

Ok I see. Well I have installed over 100 sprinkler systems in NYC and I have seen installations where only one supply line is brought inside the building to supply a Fire Pump. I never came across a situation where a booster pump has being approved in leu of a fire pump. Maybe I should start doing more work in NYC so that I can be familiar with such application.

 

[DHEngineer]

Hi NJ1
In NYC all fire pumps except those that serve Residential or old J2 occupancys require two sources of water from seperate street mains. (just in case one street main is shut down for service, ect..) Sprinkler booster pumps are allowed in certain situations usually to supply sprinklers only and have certain requirements (min 5 psi at top of system without pump or emergency generator ect)and are almost the same as fire pumps except they only require 1 source of water and a few other exceptions. It's possible that the fire pumps you installed were for Residential occupancys, they only served sprinklers (no Fire standpipes) so then they were actually considered sprinkler booster pumps, or they were fed by suction tanks in the celler of the building providing the minimum demand for a half hour of supply to the system at the rating of the pump.


Either that or you may have installed those system under the old code which may or may not have been a bit different.

-DHEngineer

 

[NJ1]

You probably right. I was just a fitter with the 638 local so I was not involved with the design.