Colliam7 - 5/19/2017 12:09 PM
This is a worthwhile video. But, but the viewer needs to pay particular attention to what is said beginning at 2:41, which is, turn your face away from the gauge, to prevent facial injury from EITHER type of blow-out - plexiglas gauge face OR relief port blow-out. And, that is what I tell students - look at the gauge before you pressurize, to see if the needle is zero’ed, then turn your face away from the gauge, and move the gauge down and away, when turning on the air. If you are holding the SPG in your hand when reading it (palm behind / below the back of the gauge, palm facing your face), and you extend your arm away from your face, the natural rotation of your wrist is likely to rotate the SPG face down and away.

I happen to be one of those instructors who has seen a face plate blow off, fortunately nowhere near a diver’s face. We were on a coastal NC charter ~ 5 years ago, and were sitting around during a surface interval, most of us seeking shade under the canopy. The cylinders were in their racks toward the stern. We heard a (very) loud pop, as the face plate on a SPG on a rig on the starboard side of the boat (sitting out in the sun) blew off, across the deck and richoceted off a rig in the port side racks, before landing on the deck. That image has stuck with me. :)