Propane

[Warrior372]

Wow!! KaBoom!  I wonder if the blow-off valve got too scaled up to work?

That would be a fine piece of scale if I have ever seen one! None of the 50-60 year old machines I have restored had stuck pressure release valves and I have seen some pretty nasty and neglected machines! When I cracked the boiler on my '52 Conti it had at least 3" of solid scale in the bottom of the boiler

[grinderz]

Whoa! That's a lot. What could make a one stick? Corrosion? Being stored in a damp environment?

What is that machine anyway?

[Tex]

Whoa! That's a lot. What could make a one stick? Corrosion? Being stored in a damp environment?

What is that machine anyway?

One simpleton and an unfortunate confluence of events, most likely. The pressure stat diaphragm leaks, ancient bi-metallic safety tstats fail to open, boiler pressure rises, popoff valve releases steam, some idiot removes the popoff's safety seal and tightens the valve, and eventually enough pressure builds until the boiler ruptures.
BOOM!

See, it's pretty simple to turn a safe espresso machine into an IED.

[Ascholten]

Ouch,  and for the record,  when water turns to steam it actually expands about 1700 times it's original volume.  It does just as much damage collapsing back into water too.

Tanker Implodes

Aaron

[Tex]

Ouch,  and for the record,  when water turns to steam it actually expands about 1700 times it's original volume.  It does just as much damage collapsing back into water too.

Tanker Implodes

Aaron

It's all about positive and negative pressure in a vessel, relative to the ambient pressure. Which is why a stalled vac pot change be so entertaining!