Return on Vacuum level chart? [Archive]

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Dill

01-05-2017, 08:55 PM

I know I've seen one but now I can't find it online. Looking for a chart,graph etc, showing the increase in sap for inches of mercury of vac level.
Thanks

lew

01-05-2017, 09:36 PM

I believe it's 5-7% per inch of vacuum.

DrTimPerkins

01-06-2017, 09:05 AM

I believe it's 5-7% per inch of vacuum.

That is correct and is based upon a couple of different research studies we've conducted at the UVM Proctor Maple Res Ctr. Since the relationship between sap yield and vacuum is based mostly upon the physics of pressure differential, it is quite linear, meaning that the more vacuum you pull the more sap you get.