jim rozen wrote:

In article , Grant Erwin says...


Hmm. Often when someone from an industry whose revenue source depends on
scarcity says "oh no you surely cannot do that" what it really means is
"oh my if everyone did that I'd be out of work". I vaguely remember the
letter, probably was HSM. I'd welcome it if anyone knows which -- since 1982
there have been over 135 issues, that's a LOT of reading.


If you do what you are proposing, you are making a boiler.

The requirements for boiler blow-offs are different than
ordinary pressure vessels, and you should understand the
differences before you put it to work, and see that you
have followed the requirements.

I seem to recall a boiler explosion in a vintage tractor
at a farm fair recently that killed a number of people.

It was a crown sheet explosion. Apparently when a boiler
breaks open, the pressure lowers rapidly which causes the
liquid remaining in teh boiler to flash to steam.

A little more detail - if you let the water drop
very low and the tractor is standing still, it's
possible for the crown sheet to get red hot even
though there's still some water in the boiler.
As soon as the engine lurches forward, the the
water splashes on the crown sheet and flashes
to steam. No safety valve can vent the pressure
surge in time, not to mention the stresses on the
crown sheet from the temperature changes.

The engine in Ohio did have a very erroded crown
sheet that contributed to the explosion, but I
also suspect there was operator error.

The first rule of operating those old engines
is to always keep plenty of water in the boiler.


Jim