Bzzzz
I was taught to relieve pressure from the regulator diaphraghm by backing the pressure adjustment off (to zero pressure) after each use. I do so after the tank valve is closed and the line is purged (out of habbit)

It's critical that the tank valve be opened SLOWLY for safety... the worst that can happen is the gauge explode and send pieces of it flying into your or someone else's eyes or face... ghe gauge face, therefore, should be pointed away from you when opening the tank valve... I keep mine pointing at about a 45 degree angle toward the cieling to help keep me (and others) out of the line of hazard just in case we get distracted and become careless, but this would depend on the size tank you're using and how tall you and coworkers are (not to mention your ability to read the gauge when you want to) sometimes I aim it slightly downward, and the face stays cleaner longer as well; no matter as long as you pay it some mind.

I believe the regulator is engineered safely enough for confidence, but if you've ever read the little paper enclosed with replacement gauges, including application directions and cautionary notes, you'd probably see the gauge itself as the primary weak spot. Select replacements with great care. Take an old one apart to see how it can fatigue, split and explode it's bourdon tube (I believe that's the name of the curved metallic bladder inside that tends to straighten when pressurized; the face is calibrated to that charicteristic of the tube, and a linkage/gear mechanism moves the pointer to read the pressure); there's a lot of small parts to go flying.

regards,
d