On Jun 26, 9:18*am, "Ed Pawlowski" wrote:

They can go off accidently, but it is very rare. *I've seen sprinkler pipes
banged by errant fork lift drivers and nothing happened. *

Maybe if you bang the pipes, but if you hit the head there's a good
chance.

I've seen it happen several times, once in a hotel room where somebody
hung a clothes hanger on the head. (Doh!)

That little glass piece is fragile - it handles a good compressive
load but any sideways pressure will trip it, and an impressive amount
of water will come out.