old building, no BFP on current fire system

[sparky9]

This building was a food store and is changing to a library. Straight forward design, no library stacks to worry about and only reconfiguring sprinkler heads to match new ceiling grid layout. FPC wants to add a BFP. Is this required? Is this the liability of designer or should this have been picked up by the FPC before the bids? Is there a code per NFPA or the building codes that mandate this?

 

[TravisMack]

NFPA 13 does not mandate backflow preventers. Actually, they are discouraged in sprinkler systems. However, the local water authority is what drives the backflow preventer requirement.

Since you have an existing system, is the water authority requiring a backflow preventer to be installed now that you are working on the system? Can the hydraulic calculations handle the pressure loss of a backflow preventer? (This should not be a problem since you appear to be going from OH2 to LH for design criteria).

This may just be one of those change orders that the owner gets hit with. Things come up when doing remodel work, simple as that. If it was not on the bid plans to install a new BFP, then the FPC should not be held responsible. This is not really something that I think the engineer/designer would be responsible for either.

 

[cdafd]

would be up to local ahj, and water provider. We require a backflow on major remodels if one is no there.

 

[PEDARRIN2]

The installation of backflow preventors is to protect the water supply which is basically a health issue.

Under normal situations where the water main is pressurized there are no concerns. But if in the case of a water main break or a reduction in the water pressure, such as a fire down the street, then there is the concern of backflow and back siphonage.

It would not be healthy to have the water that was in the sprinkler main back in the public water system.

That is why backflow preventors are required.

 

[LCREP]

I hope if you require a backflow you also require the building owner to do an hydraulic sprinkler review to determine if the device will result in an inadequate sprinkler system. This is requirement of NFPA.

I would hate for the bld owner to have to install a booster fire pump because the AHJ wanted a backflow device. This is a real big concern for RPZ which can eat up 10-15 psi. I see some hydraulic calculation with a 1-2 psi safety cushion. I do not see many systems with a 15-20psi safety margin.

How many documented cases do you have of water contamination from wet pipe sprinkler water?? What about all the check valves we have already in the system, i.e. alarm check valve, detector check??

 

[SprinklerDesigner2]

"How many documented cases do you have of water contamination from wet pipe sprinkler water?? What about all the check valves we have already in the system, i.e. alarm check valve, detector check??"

1978 the year of the great blizzard in Ohio.

It hit on Thursday and I couldn't get out of my driveway until Sunday to go to the store (empty shelves for the most part) and it wasn't until Tuesday I could make it to work.

Power was lost and temperatures dipped to well below zero.

The manager of a national retail chain had plenty of ethylene glycol on hand since they had an attached automotive store so to keep his sprinkler from freezing he pumped over 800 gallons into the overhead system.

Sprinkler risers were straight gut protected with a single clapper check valve between the anti-freeze and city water supply that fed a large apartment complex.

Lucky for corporate and their lawyers nothing ever happened but it could have been a disaster.

Personally I think they should be required. All it takes is one time and we get a black eye.