Flex-Fire Sprinkler Heads

[NJ1]

I am not an expert when it comes to design so I would like some opinions and advise when it comes to these types of sprinkler heads.

I am currently bidding in a federal job that states on the fire sprinkler specs the use of flex heads. I question the contractor why such requirement since this could impact the hydraulics and the integrity of the installation.
Questions:
1) How much flex heads can affect the existing hydraulics of the systems by converting from ridgid pipe to flex.
2) In the case where a fire pump is employ why used flex heads. Could this affect the installation and performance of the system?
3) Has anyone seen a flex head come loose from drop ceilings?
4) would you recommend not to use this type of head in applications such as Hospitals, Educational Institutions, Medical Labs, ect.

 

[chevy4x4trucks]

1- You'll have to check the cut sheet for the flex heads, but the type I typically use you need to include 45' of 1" sched 40 pipe in your calculations for them. So, yes, they will have an impact on your calcs. If you are in a light hazard occupancy and using standard coverage heads it does not normally have that much of an impact on your calcs. Once you get to extended coverage heads and/or ordinary hazard occupancies you will definetly see it on the calcs.

2-There is no drawback to using a flexhead when you have a pump. The one plus is that now you don't have to worry about hangers on your arm-overs that are greater than 12". You can go up to a 60" flex without having to worry about a hanger. NFPA 13 2010 edition requires a hanger to be installed on a flexible drop if it is 72" or longer.

3-I have not seen or heard of this happening. The flex drops really aren't that flexible. If you can get a hold of one to try it out they do not bend that easy.

4-We install these everywhere. They are a great labor saver and are a no brainer when the job requires center of tile.


We don't use the Flex Head drops, but we typically use Aquaflex drops (distributed by Victaulic). Flex Head has a nice product, but in this competitive market, there prices are just too high.

 

[NJ1]

In regards to #3
Have you or anyone seen a flex-head come loose or unclipped from its ceiling installation since its not drilled into the ceiling.

 

[SprinklerDesigner2]

IMO They are the only way to go.

#1) Depends greatly on the model. I use Flex Head

http://www.flexhead.com/pdf/product-data-sheet.pdf

and as you can see a 3.0 foot flex head has an equivalent length of 4.8 feet.

As I said it depends greatly with the model used.

#2) In my opinion no.

#3) No.

#4) Absolutely!

 

[cdafd]

Someone will need to check alot of the brackets to assure they are installed Properly per installation instructions

http://www.flexhead.com/pdf/SubmittalPackage.pdf

 

[pipesnpumps]

Sounds like you are bidding on a healthcare occupancy (hospital) which have higher seismic design requirements. If it is seismic design category D or higher the flex heads are necessary, along with heavy t bar ceiling grid with a 2" perimeter angle... This is to allow the ceiling grid to swing during a seismic event without snapping off a head. I have an installation that I'm going to have a run in with soon because the local fire chief bans flexible drops.. I can't justify directing a contractor to use multiple flexible couplings vs the braided drops so I'm going to have to overrule the local rule which shouldn't have been made anyway... If you are seismic design category C flex is not required in the drops, but like others say alot of people use to hit CL of tile.

So that's why they are used in a nutshell. As for question 3, realize that the head is installed into a bracket system that keeps the head in place and resists the forces of the "spring" of the braid.

 

[MGXFP]

Be sure to use the manufacturer's specifications when doing your hydraulics. Each brand of flex drop has a different equivalent length of friction loss it seems. Also make sure what gets ordered is what was calculated.

Fitters will likely throw away the instructions so I copy three sets; two to lose and one to use.

 

[NJ1]

Absoluteley. I love the responses here.
I think my issue is that when using flex heads you are also depending on who ever install the drop ceiling. My field technicians wont inspect how the ceiling was installed but they must install the heads accordingly. I just feel this is an application where you depend on someone else craftsmanship to work accordingly.

 

[pipesnpumps]

That is a good point NJ. Luckily the non compliant ceiling grids I've caught on plans reviews were design build, so the prime DB contractor had to eat the cost to bring the ceiling up to snuff. If I hadn't caught it the sprinkler contractor would have still put the heads in and it would have met NFPA 13, its just that the ceiling grid didn't meet ASCE 7 which is the resp. of the architect.. Bottom line you aren't dependent on someone else to meet NFPA 13. And it is rare as hen's teeth to have category D or higher anyway, where ceiling grid has these special requirements. In eastern US this usually this means near a fault ANd its a hospital etc.

 

[ryano669]

I cannot stress enough that you must pay attention to the manufacturers data sheet for whichever hose you choose. Each one has different requirements for the minimum bend radius, as well as maximum number of bends. Getting the minimum bend radius in many installations is next to impossible due to the limited above ceiling space.

 

[NJ1]

Trust me. If I get the job the first thing is to verify manufacturer's data sheets. You must do this not only for this application but for all applications. I greatly appreciate all comments and hopefully this will serve as a great help for other jobs in the future.

 

[SprinklerDesigner2]

Paradise flex heads are being fazed out something about patent infringement, lawyers and a settlement. Appears Flexhead Industries won out.

Paradise flex heads were definitely cheaper but hydraulically they stunk.

From ICC Cafe

http://www4.iccsafe.org/cgi-bin/ultimatebb.cgi?ubb=get_topic;f=1;t=001941

"The calculation should include an equivalent lenght of pipe for the flex drop. The one I am reviewing this week as an equivalent length of 17 feet of 1 inch pipe for the length of flex they are using."

and that was the shorter one if memory serves me right the longer 59" Paradise Flex Heads had an equivalent length of 33' of 1" sch. 40. Much of the time I could pay the $12 more using a Flex Head Industries and save money by not having to compensate so much but I wonder how many were used without considering the losses.

 

[pipesnpumps]

How many AHJs check the calcs close enough to notice that... Not many, I am too busy catching major items just trying to squelch gross incompetence. Finding would require comparing cutsheet to that line in the calc which isn't an equivalent branch line k factor... But thanks for pointing that out guy.. One more thing I'll worry about missing! :S

 

[stookeyfpe]

More than you would believe in my neck of the world. Don't disregard the competency of AHJs. Maybe I don't understand your answer Pipes and Pumps. In my world, AHJs review plans fairly closely.

 

[pipesnpumps]

Not disregarding their competency, but it is a matter of how much time there is available to review. On the contrary, AHJ's are exceedingly good at what they do.

Consider an inspector for a municipality. He/she has to master virtually all NFPA codes and standards, and performs plans review in addition to physical inspection and acceptance. He/she would have to be of superhuman intelligence and speed to be 100% successful in catching everything.

All I am saying is I can't possibly look at everything in the short amount of time available to review these things, and I am focused on only a very small area of NFPA codes/standards. Now besides that, consider that I snoozed through engineering school with a cum laude, have two PEs and have been outshining vastly more experienced engineers during my 16 year engineering career. I put every single ounce of effort possible into it, and I often take plans home and review them on my own personal "free" time after putting the kid down, just to make sure they are done right.

So given this, I am 100% certain that a former fire fighter turned inspector with a high school degree cannot possibly ever under any circumstances catch 100% of all designer mistakes, particularly if they are related to easy to overlook and difficult to find things like equivalent length of a flex head on one line of a 30 page hydraulic calc. No offense intended. That is just reality. I readily admit I've probably missed one of these before.

Sorry for the overly wordy response, but you used the right troll bait this time, and I wanted to be clear on my comment.





Real world knowledge doesn't fall out of the sky on a parachute, but rather is gained in small increments during moments of panic or curiosity.

 

[Arsnman4]

Ditto and thank you SS!

"Fire suppression is a failure in prevention"

 

[NJ1]

I totally agree with pipesnpumps

He probably sounded a lil overly wordy but that fact remains that these type of evaluations could leak thru the cracks. There are many, many individuals out there that are in the position to evaluate specs that do not have the extensive experience or qualifications to do so.

This is really important.

 

[Arsnman4]

This may be true in some areas of the country but let’s not stereotype since the sword can cut both ways. The majority of fire service professionals I encounter whom are obligated to evaluate these and other design schemes are well versed in many methodologies of fire protection design and installation schemes, standards and practices seen and proposed in the built environment with specific emphasis on fire service professionals.

Many have achieved continued professional training for their related duties that go far beyond the "HS Degree" in relative subject matter including but not limited to hydraulic calculations, layout and code knowledge, unlike many contractors encountered in the field when asked to break out their technical documents to verify why the fire service professional is wrong in their assessment of field corrections.

"Fire suppression is a failure in prevention"

 

[b1ueshift]

I saw a contractor use these in a high rise office fit-out once. They obviously saved a lot of time which helps the overall construction program as well, but the price puts most contractors off. A good pipe fitter can fit off a sprinkler drop to centre of tile in about 30 minutes which works out cheaper than a flexible head.

 

[NJ1]

Blueshift
Your comment/opinion represents a whole different argument.
I agree that a good pipefitter can relocate a sprinkler head to center of tile in 30 minutes and yes maybe such fitter makes about 30-40 dollars an hour which raises labor cost. Maybe such contractor rather puts a helper to assemble such flex heads for less labor cost.

I would like to get back to the original questions:
1) How much flex heads can affect the existing hydraulics of the systems by converting from ridgid pipe to flex.
2) In the case where a fire pump is employ why used flex heads. Could this affect the installation and performance of the system?
3) Has anyone seen a flex head come loose from drop ceilings?
4) would you recommend not to use this type of head in applications such as Hospitals, Educational Institutions, Medical Labs, ect.

I think the answers provided by forum members are quite accurate and in fact true.
I obtain some valuable information on how to properly bid on this jobs in the future.

Thanks