Linear Heat Detector

[TMMB]

inside underpass/tunnels , what kind of fire alarm detector required ( above cables tray or electrical services ) , normal heat detector can be used? or we have to use the linear heat detector , as per NFPA72

please advice me

 

[TMMB]

there is no single reply ??/

 

[TMMB]

no body here?

 

[gadfly56]

inside underpass/tunnels , what kind of fire alarm detector required ( above cables tray or electrical services ) , normal heat detector can be used? or we have to use the linear heat detector , as per NFPA72

please advice me

NFPA 72 is not a design document. If you choose to use linear detectors, then you must follow the prescriptive requirements.

That said, I would suggest the use of linear detectors for your cable trays. You will likely need multiple segments, as the distance for the detectors is limited, depending on how you install them.

 

[ron]

Does the building code require any detection at all for that occupancy, or maybe this is a contract requirement.

When needed, depending on the criticality of the tray and the ambient environment, i've used many things from linear heat detectors through air sampling smoke detectors.

 

[TMMB]

please this case in drive way tunnel not in building , i can ask the same question as follow , can we use the normal heat detector inside the drive way tunnel (closed as tube) or we have to use the linear heat detector in this location

please advice

 

[ron]

please this case in drive way tunnel not in building , i can ask the same question as follow , can we use the normal heat detector inside the drive way tunnel (closed as tube) or we have to use the linear heat detector in this location

please advice

It is not that easy. There are lots of variables. The linear heat detector is easier to install along the tray. Spot type heat detectors may be cheaper depending on the ceiling environment. Both alarm at approximately the same temperature ranges, although the linear will go up higher 155 F to 356F.

Whether they are required at all is a building code or contractual question.

 

[gadfly56]

please this case in drive way tunnel not in building , i can ask the same question as follow , can we use the normal heat detector inside the drive way tunnel (closed as tube) or we have to use the linear heat detector in this location

please advice

As Ron said, lots of variables. Whether you must or not depends on your local building code and the project specification.

Design issues to consider: How long is the tunnel? Are the cable trays covered? What are the environmental temperature extremes? What is the air velocity in the vicinity of whatever you're protecting? The more information you give the more unsupported speculative solutions...er, I mean, advice, we can give you.