Ultra-High Temp Dry Pendents for Exhaust Ducts?

12/29/2025

We have a project that is modifying an existing dry pipe sprinkler system to protect exterior paint-booth exhaust ductwork at a vehicle manufacturing facility, with large and complex ducts exposed to extreme temperatures. The owner prohibits the use of upright sprinklers.

Are there any listed dry pendent sprinklers available at 650°F (or comparable) suitable for exhaust duct protection?

Is the use of dry pendents inside high-temperature exhaust ducts acceptable or recommended by manufacturers or NFPA standards (NFPA 13 / NFPA 33)?

The owner is not allowing uprights on this project. Are there any viable alternate sprinkler or suppression methods that meet listing and code requirements?

Is this application better addressed outside standard sprinkler protection?

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5 Comments

Jesse

12/29/2025 08:19:51 am

I can't find a dry-pendent with a thermal rating that high. What about an explosion suppression system?

Jesse

12/29/2025 08:26:05 am

By the way, quick plug for the Meyer Fire Tool Kit. One of the functions is the Sprinkler Selector. In those weird cases where we we can't seem to find that obscure sprirnkler that does what we need it to do, this Tool Kit has saved me a ton of time. If you're not subscribing to it, I highly recommend it!

Dan Wilder

12/29/2025 09:22:03 am

Couple of options I can think of...

Use a dry pilot line to trigger a deluge system with the ultra-high temp pilot sprinklers. May want to discuss with the duct guys, the owner, and likely someone structural about the amount and weight of the water with a trip.

Talk to the AHJ/Insurance about utilizing NFPA 13 2025 9.4.1.2 (or previous versions with the same language) to utilize the alternate installation with the sprinkler needed. This seems like a good example of what the below section was meant for.

"Where no sprinklers are specifically listed for construction features or other special situations that require unusual water distribution, the requirements of 9.4.1.1 shall not apply and listed sprinklers shall be permitted to be installed in positions other than anticipated by their listing to achieve specific results."

Thomas Jones

12/31/2025 02:32:05 pm

Per NFPA 33, the booth cannot exceed 200F.

13.3.1.2 For fully enclosed spray booths and spray rooms, a high temperature limit switch shall be provided to automatically shut off the drying apparatus if the air temperature in the spray area exceeds 93°C (200°F). When industrial air heaters are used to elevate the air temperature for drying or curing in a closed-top, open-front, or open-face spray booth, as described in 6.5.2, a high-limit switch shall be provided to automatically shut off the drying apparatus if the air temperature in the spray booth exceeds the maximum discharge air temperature allowed by the standard under which the heater is listed or 93°C (200°F), whichever is less.

Therefore, a 286F sprinkler should work.

But, if they aren't following that requriement, as long as your pipe is in a heated area, you are allowed to use non-dry type pendents off a dry system as long as you have a return bend.

Anonymous

1/14/2026 11:00:21 am

Could you elaborate on the explosion suppression system? Also the Owners just responded back and said the sample temp comes out to be 618° which means we wont meet the 50° above requirement. So it sounds as if we will have to do Deluge?

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Ultra-High Temp Dry Pendents for Exhaust Ducts?

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