Two Early-20th-c Engineers Invent Vacuum Technology



A: So, the rough vacuum for the system is provided by a mechanical rotary vane pump, sealed with an oil that has a very low vapor pressure. 

B: Makes sense. 

A: This only gets us down to twenty microns or so. Our high vacuum pump works by spraying a jet of oil vapor downward through the vacuum chamber, which blows the extra air molecules out of the way. 

B: Won’t the oil vapor jet kind of make the vacuum not a vacuum any more?

A: No, it’s fine. We condense it. 

B: That sounds fake but ok. 

A: So, we make all of our pipes and hoses very large in diameter, often more than 75 mm. 

B: Doesn’t that make it clunky to fabricate and hard to keep airtight?

A: Yeah, but it’s necessary. You need big pipes for the vacuum to be able to flow through them fast enough. 

B: I’m pretty sure that’s not how it works. 

A: That is totally how it works. 

B: Why is there a fan connected to our vacuum chamber? I thought fans only worked for moving atmospheric pressure air at low pressure differentials

A: It’s not a fan, it’s a turbo molecular pump. It only works at really high vacuum, but it basically just swats individual air molecules out of the way. 

B: Okaaaaaaayyyy, so basically it’s an air molecule fan

A: It’s not a fan

A: Let’s call this fitting style “Quick Flange”, or QF. 

B: I vill kall it Kleine Flansche, because it ist so kleine

C: (smoking dope) I will call it NW. 

A: Why does it smell like honey and trees?

B: I’m mixing molten beeswax with rosin to make a vacuum sealant wax suitable for rough vacuum use (down to one micron or so)!

A: That’s a great idea!

A: (using a blowtorch to melt wax sealant coating that is the only thing making a hardware store water valve usable for vacuum) I had this thought. Suppose we went into business, making a special line of valves with metal bellows to make them usable for vacuum straight away?

B: And suppose we manufactured them out of some kind of super-material that, while hard to work with, is somehow cheaper than copper and bronze?

A: I dunno if it’s that good of an idea. With the low demand for such a thing, the prices would be through the roof. I can’t imagine many people buying that when they can just hack water pipe valves with bellows and wax. 

B: Also, it’s not like anything could ever be cheaper than copper and bronze. 

Explanation of Jokes below cut

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B: Go on?

A :HAVE YOU CONSIDERED: We’ll put a metal wire in the chamber

B: Won’t that make the volume smaller, therefore the pressure higher?

A : Well yes but HAVE YOU considered: Then we run a current through it

B: OK that sounds more scientific

A: We run a high current through it! So high that the wire starts evaporating a metal gas into the chamber! More gas equals lower pressure right?

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