Comment: not a wet pipe

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In reply to comment: I kid you not friend, (see in situ)

not a wet pipe

If you run a sprinkler system in a freezer or cold environment (usually outdoors under canopies) then they are usually dry pipe systems.

A fire would melt the device in the sprinkler head causing the air pressure inside to be released which opens a valve and water flows down the pipe to the sprinkler head.