Douglas Krantz - Technical Writer - Describing How It Works
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Do I Have to Use a PVC Pipe That's Listed?

The PVC pipe that is used in any air sampling type detector is part of the whole air sampling detector system. The manufacture has this tested as a system, so the manufacturer's pipe, along with the manufacture's design method has to be used to have a listed air sampling detector.

The air intake and the air exhaust piping system is a part of a listed VESDA air sampling smoke detector

Greetings Douglas,

I am working as a fire-safety engineer. In part of job responsibilities, I have to do inspections at various factories to give them fire-safety compliance certificates. A factory that I visited wants to install an aspiration system. My question is, should the PVC pipe be listed or not, as per NFPA 72?

Thank you, MR

The word Listed means that a nationally known, third-party testing laboratory like UL, ULC, CE, FM, etc. has tested the pipe for use in Aspiration Systems for Air Sampling. Once the testing laboratory knows that the pipe is going to be adequate for this purpose, they say that it is adequate by Listing the pipe For Use with an Air Sampling Aspiration System.

The reason that Listed For Use is so important is that a PVC pipe of one type might have been tested to be adequate for use in a garden sprinkler system, but that same PVC pipe may be highly inadequate to be used in an air sampling aspiration system. A pipe sold for use in a garden sprinkling system may not be good enough for air sampling for an aspirator.

Also, if you can, check with the technical support people that make the aspirator. If the technical support people aren't available, there's some chance that their website has further information.

Douglas Krantz


Further Question

Mr. Krantz

Thanks a lot for your answer. But one thing is not clear to me that NFPA 72 does not mention that piping shall be listed. Them how can I say that it shall be listed? Do you have any reference that pipe shall be listed for the system?

Thank you, MR

Because the NFPA Code itself is designed to be used by the government in the government's set of laws, the NFPA Code is written as a set of laws. The NFPA Code, though, in order to stay current keeps changing every three years or so.

In the year 1999, for instance, in their definitions at the beginning of the codebook, the NFPA 72 Code basically says that a detector is a device suitable to be connected to a circuit that detects smoke or heat.

In the year 2007, though, the NFPA 72 Code says the same thing in their definitions, but it goes on in a sub-paragraph saying that an Air Sampling-Type Detector consists of the pipe or tubing network connected to the detector where the air is then analyzed. That means that in order to be listed as an air sampling-type smoke detector, the manufacturer's PVC pipe is listed to be used with the specific air sampling system.

According to the NFPA Code, it's an air sampling-type smoke detector system - it's not just the detector box mounted on the wall.

In other words, the manufacturer has their pipes designed specifically for their detection system. Not only that, but the design of the piping system (length of pipe, air sample holes, area covered by each sample pipe, elbows in the pipe, etc.) has to be designed using the manufacturer's own design system (usually in the form of computer software) to make sure the system, including the air sampling, will detect all fires, and do this detection in a timely basis.

I'm not sure which version of the NFPA Code you are using, but the definitions in the front of the NFPA Code will specify that the Air Sampling-Type Detector consists of a network of piping attached to the detector. In other words, in order to be a listed detection system, the piping and the piping design is part of the detector.

Further information can be found by googling "VESDA" (Very Early Smoke Detection Apparatus) and looking at: VESDA by xtralis.

Also look at: VESDA-E Aspirating Smoke Detection .

Further information can also be found by googling "air sampling system" and looking at: AspiratingSmoke Detection.

Douglas Krantz


Mr. Krantz

Thanks a lot for your answer. Your answer always helps me. Again, thank you for your knowledge sharing.

Thank you, MR


facpdoug@douglaskrantz.com
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