I can think of one or two brewers who might come up with this.
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Thanks Mick for the link to the item about the Flojet pump, which I don't think I've heard of before.
I thought this would be something to do with the use of the cask breather? It puts a blanket of carbon dioxide on top of the remaining beer in the cask, so that when the hand pump operates and pulls the beer up the pipe to your glass, the volume of the cask vacated by the beer is filled with CO2 instead of air. If the CO2 cylinder is empty, the beer will not rise up the pipe.
I thought this thread was for jokes - I was waiting for the punch line. :)