One of the labs where I first had those (also chip fabs have them) attached to a high flow water supply - normally triggered by standing inside them.
Our top H&S guy decided that as he was responsible he should be the one to test it he did cheat a bit by wearing swimming goggles to protect his eyes. He commented it was like being sand blasted with small ball bearings and "fracking hurt"
A long time ago (late 70's) a lab I worked next to had an emergency shower over each worker and there were straps on their wrists. If they jerked their arm back the shower would go off.
