Agree oren, but it was Sig who brought the loop here, which also was the reason for my earlier discussion with him above. And there seems to be some confusion of which is what in some other comments.
Continuing with the hyperloop.
You would need
a lot of expansion joints, and therefore also get thousands of potential points of failure. This has been mentioned many times before by a lot of engineers. Also upthread.
Remember, we are not talking about the loop = 150 mph on rails here.
We are talking about hypersonic promises at 0.001 atm / 0.015 psi / 750 microns.
Compare to the Swissmetro study above, 310 mph at 0.01 atm / 0.15 psi / 7600 microns.
I'll repeat my personal point of view from upthread:
The main reason for using a vacuum pump on a heat pump installation, is to evaporate and withdraw water from the system, you need at least 500 microns of vacuum. 100Pa is ~750 microns. Lower micron numbers mean a stronger vacuum. 0 microns is a perfect vacuum while 760,000 microns is the measurement of a space with no vacuum at sea level. The main reason for leakage in HVACs is often the copper flare flanges. Stressed installers often fail on those and eventually the refrigerant will leak out. And that is a brass nut tightening on the copper flange itself. That copper flange needs to be perfectly made and the flare fitting must be perfect. Still they can leak. The larger pipes on domestic heat pumps are often 3/8-1/2 inch. Rather thin and they dont have pods at supersonic speeds travelling inside them. Only refrigerant at high pressure.
I would really like to see a real world installation of the Hyperloop that can maintain 750 microns with a pod travelling though at mach 0.8. This would then have to be done many, many times over an extended period without any failiures.
And that with thousands and thousands of welded steel or rubber joints.
750 microns, 100Pa or 0.015 psi equals 99.9% vacuum. Adding an image with the expanded air ratio for temperatures at 60° F or 15.5° C.
Edit; adding the reason for choosing mach 0.8 above, it's from the study posted here:
https://forum.arctic-sea-ice.net/index.php/topic,1094.msg139894.html#msg139894And this section:
https://forum.arctic-sea-ice.net/index.php/topic,1094.msg140010.html#msg140010Those are pretty good reasons to assume that speeds higher than that, are not feasible.