Following a link from Instapundit, I read a Popular Mechanics article on Extreme Plumbing by Jamie Hyneman of MythBusters fame. Jamie makes the following point about pressure tanks:

The forces at play with high-pressure tanks can be huge. If the energy stored in a workshop air-compressor tank is released all at once, it can hurt or kill a person. I once complained to our insurers, “Why are you so fussy about the explosives we use on the show? Every day we make rigs using pressure tanks that are just as dangerous.” Big mistake. Now they fuss about pressure tanks, too.

As it happens, I was reading this shortly after I got home from Raleigh Little Theatre, where I spent all day working on the first technical rehearsal of House of Blue Leaves. I am assistant stage manager for this play, and one of my responsibilities is to handle the special effects that are used when, halfway through Act 2, a bomb explodes just offstage. One of those special effects is a compressed-air cannon that fires a load of fuller’s earth through a doorway onto the stage, simulating the cloud of dust and smoke produced by the explosion. The cannon fires when I open a valve that releases air from a pressure tank.
In fact, one of the last things I did at RLT before coming home was to repressurize that tank to 80 psi so that it’s ready for tomorrow’s dress rehearsal. Then I came home and read Jamie’s explanation that pressure tanks are dangerous and can kill you.
Actually, I’m not worried. If you read his entire article, you’ll see that that paragraph is scary only when taken out of context. Sure, pressure tanks can be dangerous if you use them in a reckless or irresponsible way, but the MythBusters don’t do that, and neither do theatre techies like me. Jamie’s article is really about how many of the challenges on MythBusters have been solved with plumbing and pressure tanks, and what that tells us about how useful and powerful that technology is. And fun, of course. I’m certainly going to be careful operating my cannon over the next several weeks, but I’d be lying if I said it won’t be a big thrill to set it off.