Pump-N-Seal claims that their hand pump by Pioneering Concepts will pump down to 28.9" Hg.
That is 1.1" Hg away from absolute vacuum. If you applied 28.9 Hg to a steel drum you would suck its sides in. I've seen it done with a Sutorbilt 7M Roots Blower. Granted the blower was only rated for 16" Hg dry vacuum; however, was moving about 2000 CFM. (It ran off a hydraulic motor that was powered by a 454 V8.) He guy was showing off his home-made 4- wand carpet cleaning machine that he used for cleaning cruise ships. What he did was to almost close off his vacuum relief valve to show that he could crush a drum and yet his waste tank would not be damaged. If I remember correctly that drum crushed around 22" Hg.
My point is I don't see how with this much Hg a regular can or a glass jar could hold up.
Does this Pump-N-Seal claim make sense to you-all???
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