Linear Heat Detectors 1

[EEJaime]

Hello all,

This is both a code question as well as a technology question. Recently, I started doing some work for another of our offices where I noticed a fundamentally different approach to Fire Alarm System design.

This is for public schools, K-12 in California. We are required to install a fully automatic fire alarm system.

Many buildings will have dropped ceilings which will result in smoke detector coverage on the ceiling and heat detector coverage above the ceilings. Still basic stuff. Where I saw a difference is when I noted that this office was specifying the ceiling space heat detectors as "Linear Heat Detectors". These are lengths of multiple conductor cables of known resistance which initiate an alarm when temperatures exceed their temperature rating. Much of this is very similar to spot type detectors and the provisions of NFPA 72 are still referenced. For the system specified, "

http://www.protectowire.com"

the installation seems to be a lot more complex and hence costly than using spot type detectors.

I am not sure we are using this in its intended application.

It seems that once the system goes into alarm the "sensor" is permanently damaged and must be replaced.

It seems a complex and first cost intensive system.

And appears to be a maintenance and servicing nightmare.

Does anyone have experience with these systems? Another manufacturer is "FARENHYT", (at least the manufacturer's used the same marketing/branding company-LAME NAME INC).

Do any of you AHJ types have any issues with these systems, especially the detector wire laying directly on top of the ceiling grid and tiles? Is this code compliant? There appears to be no codes directly speaking to linear heat detectors. This even according to the Installation Guide on the Protectowire site.

Look forward to any information available.

Regards,
EEJaime

 

[cdafd]

ahj

have seen it used a few times, no problem with accepting it.


and, I did not do the plan review, but I would look at the listing, installation instructions to see if it can be used for this application, and can be installed as you stated.

I do not see why you think it is more labor intensive, basicaly just strech the wire out like you would have to do anyway to connect the heats.

and if the building does not burn then just semi annual testing needs to be done

http://www.protectowire.com/documents/ds-6592.pdf

maybe missing if you can just lay it on top of the ceiling tile:::

http://www.protectowire.com/documents/man-2001.pdf

http://www.protectowire.com/documents/ds-7877.pdf

call maker ans ask the question

 

[cdafd]

I guess a different way of getting there????????????

 

[stookeyfpe]

I've seen linear heat detection systems used in three different applications:

-- Heat detection for cable trays in telephone switches and nuclear plants
-- Heat detection for foam water systems protecting storage tanks from ground spill fires
-- Heat detection in cold storage warehouse and used to activate pre-action sprinklers

In the case of the warehouse, the installation was completely FUBAR and was extremely problematic. Neither the installer or the approving agency knew what they were doing. I've had good success for cable trays and outdoor applications.

My question is why do you need heat detection above a lay-in ceiling? Is it the building construction type (Type V or III) or is this a specific California DSA requirement?

 

[EEJaime]

stookfpe,

California requires a complete coverage system, and NFPA 72, 5.5.2.1 states:

"If required and unless otherwise modified by 5.5.2.1.1 through 5.5.2.1.5, total coverage shall include all rooms, halls, storage areas, basements,attics, lofts, spaces above suspended ceilings, and other subdivisions and accessible spaces...."

We and all our AHJ's have as long as I can remember protected these spaces with heat detection. Are you saying that that is not required? I'd like to know how that works.

Thank you,
EEJaime

 

[pipesnpumps]

I use that clause from NFPA 72 also to enforce putting heats through-out the space where our adopted criteria requires "complete coverage". I am still learning, and totally missed the suspended ceiling part of it.. That is kind of excessive for non-combustible construction, but thanks for pointing it out! Now I am worried I missed alot of it on plan reviews.


The relevant 2010 code:

17.5.3* Detector Coverage.
17.5.3.1 Total (Complete) Coverage. Where required by laws, codes, or standards, and unless otherwise modified by 17.5.3.1.1 through 17.5.3.1.5, total coverage shall include all rooms, halls, storage areas, basements, attics, lofts, SPACES ABOVE SUSPENDED CEILIINGS, and other subdivisions and accessible spaces, as well as the inside of all closets, elevator shafts, enclosed stairways, dumbwaiter shafts, and chutes.

17.5.3.1.1 Where inaccessible areas are constructed of or contain combustible material, unless otherwise specified in 17.5.3.1.2, they shall be made accessible and shall be protected by a detector(s).

17.5.3.1.2 Detectors shall not be required in combustible blind spaces if any of the following conditions exist:
(1) Where the ceiling is attached directly to the underside of the supporting beams of a combustible roof or floor deck
(2) Where the concealed space is entirely filled with a noncombustible insulation (In solid joist construction, the insulation shall be required to fill only the space from the ceiling to the bottom edge of the joist of the roof or floor deck.)
(3) Where there are small concealed spaces over rooms, provided that any space in question does not exceed 50 ft2 4.6 m2) in area
(4) In spaces formed by sets of facing studs or solid joists in walls, floors, or ceilings, where the distance between the facing studs or solid joists is less than 6 in. 150 mm)

 

[EEJaime]

pipesnpumps,
Yes that is the same language as in the 2007 NFPA 72 I quoted, and none of the excepting conditions apply in my case.
EEJaime

 

[cdafd]

EEJaime

which fire code was this designed under???


Is the base fire code admended to require complete coverage, or is it getting there because of 72 reference???

 

[EEJaime]

cdafd,

In California, we are under the California State Fire Code which currently consists of the 2006 International Fire Code with 2007 California amendments. It basically is a referenced in version of NFPA 72. The 2010 version will soon be in effect, but these schools are already submitted.

However, the fact that all California Schools, K-12 must have a full coverage fully automatic system is due to Senate Bill 575-2003. Which makes it a requirement. Basically a political response to a legislator's family member being lost to a school fire in the early part of this decade.

We have found that almost regardless of the specific code in effect, we seem to always go back to NFPA by reference as it is by far the most extensive, detailed and vetted code available, (IMHO).

Thank you and regards,
EEJaime

 

[cdafd]

well, but

would say IFC states what is needed, along with Senate Bill 575-2003

not sure of the specfic langauge in Senate Bill 575-2003, but would look to IFC first on what and where it says what is needed, if Senate Bill 575-2003 adds to that so be it,

but to me 72 just says how to install something

does the great state fire marshal have an interp of what is required???


do you have a link to a copy of the senate bill??

 

[EEJaime]

I do not have a link to the Senate Bill. There was a "Finding of Emergency" in April of 2002 regarding the "Green Oaks Family Act". In a document issued by the Office of the State Fire Marshal, "Emergency-Express Terms, 2001 California Fire Code", where individual code sections are amended, the following appears:

SECTION 1006.2.4.2.2.1 [FOR SFM] PUBLIC SCHOOL-SMOKE DETECTORS

1006.2.4.2.2.1.1 [For SFM] Automatic Detection. Smoke detectors shall be used as the primary method of automatic alarm initiation except in areas where the environment or ambient conditions exceed smoke detector installation guidelines; another method of automatic detection shall be used. In areas containing sprinklers, heat detectors may be omitted. Smoke detectors shall be designed, installed and maintained in accordance with NFPA 72 as amended in Article 91.

Well in the original hard copy I got that was all underlined, but mine didn't take. Anyway, that is the genesis of the current requirements.

Hope that helps,regards,
EEJaime

 

[pipesnpumps]

This is similiar to my situation. A blanket "complete detection throughout" statement is made in another governing criteria, but it doesn't specifically define the term. Therefore, the most conservative interpretation is to use the "total coverage" language above from NFPA 72, and its hard to argue against the validity of that when the governing language does not define the terms.

In your case you can only omit detectors where there are sprinklers installed, which implies they must be installed everywhere else.. That is an over-zealous code official's dream, because he gets to play Giver Of Determination (GOD) and fill in the holes with his personal thumbprint of interpretation.

Sorry can't help with the original question; I will ask around with the EE's but I doubt it will yield much.

Just speaking out of the side of my mouth, I would be concerned the linear heat detector will not respond unless it is sufficiently close to the fire.. i.e. the plume from a fire will rise in the plenum. Only about 30% of the total heat release is radiative, and quickly heats only adjacent surfaces.. The rest of the heat goes straight up in a cone and hits the ceiling.. I'd be surprised if the linear heat detector works very well as an early fire detector (for a fire in the plenum) in the way you describe.. personally i would reject your plans unless the manuf. stands behind it in a letter, or it is published in their literature.

 

[Arsnman4]

We have had six installations over the years in our jurisdiction for various occupancies from Business to Industrial and using stand alone, pre-action and deluge protection schemes with specific spacing and have experienced no issues fortunately. We have had two historic activations one in a foundry and the other in some bag houses which prevented building loss and regarding the need to replace all the wiring if initiated; the only replacement necessary is an affected section and or zone and since approved splices/junctions are permitted if a zone is lengthy or test locations are necessary, affected sections can be replaced relatively easy in the event of an initiation event. Regarding the allowance for lying on top of suspended tiles; the listing requires the wire to be fastened to prevent un-necessary sag and must be affixed using an approved fastener and there are lots of them. It also has the ability to be used by other fire alarm control units provided the panel is capable of recognizing its initiation means.

"Fire suppression is a failure in prevention"

 

[EEJaime]

pipesnpumps,

Thank you, you are so right. It is even worse when we have a politician with I understand a small amount of technical background, creating a law requiring codes to be amended and forcing others to interpret the exact implementation of those amendments.

Once we have the omnipotent "Giver" establish this 'requirement', (and here it's been de riguer for 7 years), there is no way that a plan checker or field inspector is going to countermand that directive. We end up with over-engineered facilities with large quantities of equipment that will rarely be serviced and which drive up the cost of construction unnecessarily without, in my opinion, adding much to the overall life safety of the facility.
Thank you,
EEJaime

 

[cdafd]

Mandated items without direction ,,,, never have heard that before

 

[Arsnman4]

I like the "Giver of Dtermination" also.

Regarding the usefulness of LHD. In my experience it works very effectively and all of them are pretty much the same where as there are varying thermal detection devices throughout the wire to account for lag time v. inintiation and there are also specific wire applications and temperature ratings to protect all types of enviornments

"Fire suppression is a failure in prevention"

 

[pipesnpumps]

What can I say, you are in the 2nd most democratic state in the country.. there are so many laws there, they probably contradict themselves.

I can't copy since the PDF was encrypted, but it very clearly states in the installation an O&M manual (page 5) that the detector should be placed at the ceiling, or along the side-wall within 20 inches of the ceiling.

Reading the O&M manual, this device uses a polymer that melts at a specific temperature, so fundamentally it is the same as a fixed temperature heat detector.. Any heat detector that activiates (in this case melts) along the circuit sounds the alarm. But you need a temperature quite a bit higher than the 135 F melting point (the lowest temp available) for an amount of time sufficient to melt it.

In my opinion, you ain't going to get there with a wire run along the top of a ceiling grid, covered by dust and CAT5 cable runs, three feet below where the hot gas plume is.. It may eventually melt, but this will likely happen well after somebody is able to smell the fire and activate a pull state..

Bottom line, if you use this product, I personally interpret that you must mount it to the underside of the decking. You could also run it along the side wall within 20" of the underside of the decking where it doesn't exceed the listed spacing. Think of this wire as pre-wired heat detectors strung together, because that's what it is, and then ask yourself, would you mount a heat detector on the floor of a room??

 

[EEJaime]

Pipesnpumps,
Thank you, I think that is the best advice if we are going to use this. But as you said, the proper installation would be at the top of the volume.

That is why I am so hesitant to use this system. In a typical 30'x 30' classroom, we have a loop consisting of a large "S" in the center of the room with both ends run back to the point of connection. If we mount this tight to the deck, we need to do so before the Mechanical, plumbing, etc..., get there. If the detector ever fails or is activted by a small fire or other heat source. It must be replaced. It cannot be spliced. How are we to replace this 120 lineal feet of detector? It will be above lighting, ductwork, roof drain piping, ceiling and fixture support wires, etc.... It will never be re-installed as designed and listed.

I just wish I could get some input from someone whom has used this in a similar application. It makes sense in applications such as noted by stookeyfpe, but it seems to me as if we are using a shotgun for a flyswatter.

Thank you,
EEJaime

 

[stookeyfpe]

To the specific questions, every school in the region I've worked on is generally Type IIB construction so we apply Section 5.5.2.2 on the 2007 edition because we so no real value in providing detection in a noncombustible space. Maybe it helps that I'm a taxpayer and we've worked closely with the design community to write solid specifications for fire alarm and detection systems for the school districts.

 

[EEJaime]

Stookeyfpe,
But therein is the dilemma. 5.5.2.2 says that where "Where codes, standards, laws or AHJ's require the protection of selected areas only, the specified areas shall be protected in accordance with this code." Where did you get anyone to specify such areas?And who specified them? The DSA Life Safety plan checker? No code, standard, law or AHJ that I know of has specified only selected coverage in a school. I have yet to meet one that would go out on that particular limb.
Thank you,
EEJaime