Fire sprinkler system, Back flow preventer?

[Paddy]

NYbirdman,

A friend of mine hit a sprinkler while working and it went to town. Stinky nasty water flowed. But I'm guessing it was iron pipe. I'd guess Cu and pex would not have near the effect on the water to make it so nasty?

But in any case, my local Pb-ing supply house has a Wilcons double check valve for $27. Not sure if it has a port between to check for back flow. I wanted to presure check to system before Drywall went up so I installed two shutoffs, one above and one below where the backflow preventer would go. The one above/beyond the backflow preventer has a drain back port. I supose I could replace the lower one to have the drain port and consider it to a backflow check point. It would have to leak past both though.

Patrick t.

 

[dfkrug]

The big difference between a residential system and a commercial system is the residential system is for life safety, the commercial is for property protection. Residential systems only cover areas that are normally occupied, such as bedrooms and living spaces. There are not heads in closets or storage areas.

I have residential fire sprinklers in the house I built 9 years ago. It was
required, and it had to be designed/installed by a contractor with a very
specific license. I found a guy who did my design, but allowed me to do
the install under his license.

The design requirments are very detailed, and I WAS required to have
heads in any enclosed space over a certain volume. This included closets,
attic spaces, attached garage, water heater closet, and my pantry.

The manifold for my house (1.25" copper) is sized based upon my static
pressure and the flow requirement for my max room size (# of heads on at
one time).

There is no check valve in the system, but there is a valve that allows
me to drain whole system to the outside. The main shutoff valve is located
BEFORE the manifold, so I cannot disable the sprinklers without turning off
the domestic supply.

Around here, most domestic sprinklers are done by contractors who use
CPVC pipe, and THEIR choice of heads. I wanted to use copper pipe, and
flush-mount heads.

The inspection can be problematic: 250psi for one hour. Yikes. I borrowed
a hand pump and got some seepage at a union coupling. These couplings
don't do well at that pressure. My static pressure is 74psi.

My house is also all-concrete (except roof), but I get no ins rate redux.

 

[NY_Yankees_Fan]

Paddy,

The standard to use is NFPA 13D Standard for the Installation of Sprinkler Systems in One- and Two-Family Dwellings and Manufactured Homes 2010 Edition. You can buy the document from NFPA at www.nfpa.org.

You can use PEX piping for the system. See this web site they have sprinklers that are used with PEX which connects into your domestic water system. If you do this no back flow required.

Uponor - Fire Safety Systems

 

[RobertBrown]

Paddy,

The standard to use is NFPA 13D Standard for the Installation of Sprinkler Systems in One- and Two-Family Dwellings and Manufactured Homes 2010 Edition. You can buy the document from NFPA at www.nfpa.org.

You can use PEX piping for the system. See this web site they have sprinklers that are used with PEX which connects into your domestic water system. If you do this no back flow required.

Uponor - Fire Safety Systems

13D will refer back to 13 for spacing and location requirements. It's unlikely the LAHJ has adopted any standard more current than 2007.
At any rate, your concerns should lie in the pipe freezing in cold weather. If you plan on running pipe in areas such as an attic that is subjected to temperatures below 32F, your asking for problems.

 

[NY_Yankees_Fan]

Antifreeze systems make the entire install more difficult. Also the use of antifreeze is a real problem. It can ignite, resulting in flash fires, NFPA is limiting the % and how the product is mixed, no more on the job, has to be mixed at the factory.

 

[MikeD74T]

I'm in fire protection at a nuclear power plant. I perform maintenance & testing on wet sprinkler, preaction, & deluge systems daily. An option for residential, especially homeowner installed, is an air pressurized dry system. After the double check valve install a schraeder valve & precharge the sprinkler piping with air to about 10 lbs above water pressure. This will hold the check valve closed holding the water back until there's an actual demand and eliminate stagnation & freezing concerns. You can also install a pressure switch to monitor the air to reveal small air leaks before water enters the piping. If hooked to an alarm system or loud horn/bell it also serves as occupant notification of an actuation. Commercial dry systems usually have a piped air makeup through a small orifice or low flow regulator again with pressure monitoring. Another condition this prevents is hydraulic actuation. This is where water in a completely filled system expands due to temperature increase with no place to go (because of the checkvalves) & heads fail open resulting in flooding.
Sprinklers in both residential & commercial applications are primarily for life safety and property protection secondary. It is true that sprinklers left running beyond the suppression of the fire often cause more property damage than the fire. Sprinklers knock down the elevated air temps & some of the smoke that cause death to occupants providing an escape route. MikeD74T

 

[Larry Caldwell]

The big difference between a residential system and a commercial system is the residential system is for life safety, the commercial is for property protection. Residential systems only cover areas that are normally occupied, such as bedrooms and living spaces. There are not heads in closets or storage areas. They allow the occupants to escape if a fire occurs. They do not have enough coverage (fireflow) to extinguish a fire if it gets beyond the incipient stage.

I am in a fire district, but am about 7 miles from the fire station, estimated response time about 10 minutes. I am also buddies with the local Fire Marshal, who says if I want to have a house left after a fire, install a residential sprinkler system. It only takes 5 minutes for the interior of a house to "flash" to total involvement. FD response time in town is under 4 minutes, and at that they only manage to save about 50% of the structures, mostly depending on if they are built to modern building codes. Drywall will give you 20 minutes, but exposed wood goes up like a matchbox. Burning furniture and carpet is so toxic it will kill you just breathing the smoke.