Dry Pendent Sprinkler for Outside Dust Collector?

I have a project involving an outdoor dust collector. My firm specified a dry-pipe sprinkler system for it.

The contractor asked if an antifreeze loop would be acceptable as a substitute, and we said no, as the AHJ does not want to deal with the maintenance side of an antifreeze loop long term.

The contractor states that the head connection in the collector is pendent instead of upright, and they can't go with the dry system because of trapped water concerns. I think a dry pendant sprinkler would work as it's allowed (even required if an upright is not used) by FM Data Sheet 2.0.

​Anyone install a dry pendent in a dust collector, and have any drainage issues or had to add a drum drip or other means of drainage to make the system work long term?

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