Typical vacuum/pressure in a domestic vacuum/Thermos flask
Typical vacuum/pressure in a domestic vacuum/Thermos flask
(OP)
I am trying to replicate a vacuum flask (on a low budget) with a 1m long 8 inch UPVC pipe forming the outer shell. A search of the internet suggests that the influence of convection stops around 10 Pa, however the vacuum pump I have, a two stage rotary 3 cfm advertised to achieve a vacuum of 2 PA, can only achieve around 350 Pa. My question is, what is the typical vacuum/pressure in a domestic vacuum/Thermos flask and how is it achieved? i.e. a vacuum pump or creating a void in the manufacturing process.
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RE: Typical vacuum/pressure in a domestic vacuum/Thermos flask
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RE: Typical vacuum/pressure in a domestic vacuum/Thermos flask
For large bulk storage tanks the limit is not as low, I recall using 0.05mbar (5Pa, ~40mTorr).
There also contain multilayer aluminized mylar foil in the vacuum space to reduce heat transfer.
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P.E. Metallurgy, consulting work welcomed
RE: Typical vacuum/pressure in a domestic vacuum/Thermos flask
RE: Typical vacuum/pressure in a domestic vacuum/Thermos flask
It is twofold, there are limits on what is practical with that size installed outdoors, and they make up much of the difference with the layered aluminized mylar film.
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P.E. Metallurgy, consulting work welcomed