POLAND_SPUD wrote:when will you switch to metric units?
We pretty much do. There are only three common uses of Imperial units in the UK - road signs (yards and miles), milk/cream (usually in pints, although increasingly less so), and beer (pints, of course).
The really daft one is road signs. As fuel is only bought in litres, it means either of the common fuel consumption figures (MPG or litres/100km) is easily used.
As far as "civilising us"... not really. These were originally from a stage, and the black ones were far more ideal - as they weren't quite so bleeding obvious.
The fact they were black also helped prevent
an accident. Stopped a totally brain-dead actor finding and using an extinguisher they were completely untrained to use (CO2 extinguishers are pretty dangerous if misused). There's always going to be an idiot who doesn't listen to the "If there's an emergency, tell the stage crew" instruction.
Anyway they would make a nice hybrid chamber or air reservoir for a fridge compressor.
I've considered both.
The hybrid chamber idea can't really happen unless I can get the valves out of the neck - and they appear to have been mechanically tightened, so it's going to take some more ingenuity.
But the restriction of a valve is less of a problem for a high pressure reservoir - it's perhaps even desirable to be able to close it off.