Sprinkler Head Location

[RonShap]

When designing sprinkler head locations, our FP Engineer locates the heads to protrude through a suspended ceiling tile, so all are essentially on the underside of the suspended ceiling. No sprinkler heads are located above the suspended ceiling which is used as an air plenum for return air back to the air handlers (no return ductwork, just registers in the tile). There are no combustibles above the suspended ceiling, which is why the FP Engineer says none are required above the suspended ceiling.
There is a data center installation, where there will be a tremendous amount of heat load and thus many, many return air registers in a similar orientation as mentioned above. The ceiling registers will amount to be approximately 1/3 of the total suspended ceiling.
The FP Engineer is considering adding sprinkler heads above the suspended ceiling, on the underside of the ceiling above. He is worried that heat will zip past the heads below the suspended ceiling and not be detected.
It wouldn't be too much of a a problem, except it is a pre-action system, which would mean detection would be required above the suspended ceiling too, which would have to be accessed every year for testing (clear for smoke entry).
What are your thoughts for this requirement?
I think there is so much air flow in a data center environment, that the sprinkler system will only operate in a "real" serious fire, or if the air flow is shut down anyway.

 

[LCREP]

Is the sprinkler system a pre-action system, which activates via smoke detection?? If so, have the hvac shut down on 1st smoke head.

 

[RonShap]

I sort of want my cake and eat it to.
It is a data center. Without airflow the computer equipment will fry, most likely due to a false smoke alarm.

 

[SprinklerDesigner2]

I believe your FPE is correct. With an amount of openings you suggest sprinklers should be installed in this non-combustible plenum space.

From NFPA #13 2002

8.14.1.2* Concealed Spaces Not Requiring Sprinkler Protection.
8.14.1.2.1 Noncombustible and limited combustible concealed spaces with no combustible loading having no access shall not require sprinkler protection. The space shall be considered a concealed space even with small openings such as those used as return air for a plenum.

The key here is "small openings". 33% is not a small area and I would figure sprinklers in that area.

I can't find it but I seem to remember somewhere defining what "small openings" were. I think it was around 5%, one out of 20 ceiling pads, but I can't remember if I saw that in an NFPA publication or HPR guidelines somewhere.

This highlights an area where sprinkler contractor's and their designers get into trouble.

We are profit driven and I do not believe many outside the industry appreciate how competitive we can be.

To get jobs we need to be competitive and if you take a sample of 5 contractor's bidding such a project I would be willing to bet 4 of the 5 wouldn't figure sprinklers in the plenum space.

If one were just to bid the project, which included sprinklers in the plenum space, the estimator did the right thing but he isn't going to get the job.

So what to do? Be honest, bid it both ways suggesting the owner get in touch with his insurance underwrite and/or code enforcement people to ask their opinion. With 33% open a quick phone call explaining the situation to the building official will usually solve the problem who will tell the owner you were correct, that sprinklers will be required in the plenum space which does a lot making you look like the "best" bidder on the project.

I would feel strongly in this situation the last thing I would ever want to endure is the failure of a sprinkler system I designed. Talk about bad press. I would bid the job both ways but refuse it if offered to install sprinklers below the ceiling only but, if you do a little extra work, I doubt it will go that direction. Considering the money invested in a data center I would have to feel the insurance carrier would side with you as well.

 

[cdafd]

do not think they are needed. if you want some comfort level maybe put some heat detectors above the ceiling.

the other thought is if you do put the spinklers above the ceiling and one activiates is it going to do any thing for the fire if the fire is below the ceiling??????

 

[LCREP]

Are you sure they are putting a wet sprinkler system in the computer room?? Most IT folks I talk to do not want water above computers. So most rooms that have sprinkler protection are double interlocked pre-action sprinkler systems. 1st smoke detector shuts off the HVAC, 2nd smoke kills power to the room and trips the pre-action valve and NOW you have a wet system. If it gets hot enough to set off a sprinkler head u have one heck of a fire. If we have a raised floor we will also look for a gas fire suppression system under the floor when we start to have values above $25M.

Most losses we pay for computer rooms is water damage NOT fire. We also require water detection in the room.

As someone said better to talk to the insurance carrier, they will have requirements not listed in the Building code. Take a look at NFPA 75 for what many insurance companies will be asking for and then add onto it depending on how much $$$ are at risk including business interruption a huge number a lot of times IF they have no disaster recovery plan that includes a hot site.

 

[SprinklerDesigner2]

"Are you sure they are putting a wet sprinkler system in the computer room??"

This is such ancient history but I remember doing a computer room back in the late 70's for IBM in Kentucky. Yes, they did have computers in the 70's one as large as a covered wagon wouldn't have the power your laptop does today.

It was a regular wet system and what IBM was saying it wasn't the water that did the damage but "improper drying" after an event.