what are the spec. vacuum requirements for thermos bottles?
I know that a vacuum is needed but how much?
I heard that the thermal retention value only works below a certain vacuum level but I don't know what it is. any small vacuum won't do.
I also would like the answer in regular terms.
I found out that solar tubes use
P<5x10-2Pa of vacuum. I don't know what that means in inches of vacuum. I need to know more, so that I can buy the right vacuum pump.
What other equipment will I need?
will a regular check valve and epoxy work for testing?