Vacuum pumps

[MiMappleMan]

I was in a local surplus store and found a handful of old Labratory vacuum pumps. Models include: Cenco hyvac-2 vacuum pump, cenco pressovac, cenco hyvac, Welch 1399 dualseal. Most of these while researched show that they average 1 cfM and an ultimate pressure (whatever that is) of 1x10^-2 Torr. Another one says guaranteed pressure of 25 microns.

Is this suitable for maple lines? I know a pump is usually rated for 100 taps per a cfM, but the pressure thing throws me for a loop. Thanks


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[blissville maples]

Very low cfm, dental tool vaccum system probably. Not worth your time, not sure what you have for taps but want at least 10-20 cfm for a small Bush. Haha I used a wet vac years ago and a homemade releaser out of a 5 gal bucket and some homemade electric contacts with a Pepsi bottle float!!, gave me 6 inches of vac.

Only thing that needs to be noted is cfm and inhes of vaccum. The torr values from what I understand are performance standards at a certain vaccum level(inches) and cfm rating at that vac level.

[DrTimPerkins]

Not all pumps are rated for continuous operation. Will they work...maybe? Will they overheat at some point and start a fire....maybe?

Ultimate (or absolute) pressure is just pressure rated from a scale of zero. What maple producers generally refer to is vacuum BELOW AIR PRESSURE (standard atmosphere), which we refer to as 0" Hg, but in reality, is 29.92" Hg (at sea level on a standard day), which equates to 14.7 psi, 1013.25 millibar, 101325 Pascal, or 760 Torr. The other oddity is that we refer to it as if it were positive, but it is actually negative (below atmospheric pressure), which makes "high" vacuum kind of an oxymoron (since it is actually low pressure). Yeah...kind of a head scratcher -- best not to overthink it. :confused:

In either case, those pumps will pull high vacuum, but probably not produce a lot of CFM under vacuum.