Creating vacuum on individual drop lines into bucket

[fisheatingbagel]

I've only used "hung" buckets and bags in the past, but next year I would like to try something different. I can't use a tubing system due to my trees being in a public area. I want to use tubing into individual buckets (one per tree, 1-2 taps per tree) in an attempt to extend my season by reducing tap hole exposure to air. It seems like I should be able to create some natural vacuum as well. I would like to hear from others who have tried this, and if I can expect the taps to remain viable for a longer period. I already have an investment in buckets and bags, but if I could extend the season by a couple of weeks I would go for it.

To maximize the benefits, both of extending the season and creating vacuum, is it necessary to have a loop in the tubing before it enters the bucket to create an air lock? Will 3/16 tubing running straight into a bucket create any vacuum? Would vacuum increase by tapping higher up the tree?

All comments appreciated!

Dave

[mainebackswoodssyrup]

You won't be able to get any vacuum (natural or mechanical) without a closed tubing system, regardless of tubing size. The tubing you plan to run is still considered and "open" system where the tap hole is directly in contact the air from the end of the tubing and surrounding environment so it is essentially no different than a bucket or bag set up in regards to tap hole longevity. Could you possibly put in a closed tubing system and take it down every year? Then you might be able to see some benefits.

[RedMapleCreek]

You can create vacuum by using 3/16" tubing run down from the tap to a bucket on the ground and it will improve tap hole sanitation compared to hanging a bucket on a spike. A 6 ft vertical drop of 3/16 tubing will generate over 5 in of vacuum when full of sap and this can increase sap yield. 5/16 tubing will not generate this vacuum.

[Daveg]

When you hammer a tap into the tree you seal the wood from the air, so your season won't be extended. It's a good idea to use taps smaller than the old fashioned 7/16" due to the damage caused by the larger size. Making a loop is counterproductive because the loop has an "uphill" section that the sap would be forced to climb.

[DrTimPerkins]

It is not as simple as you might think.

Let's say you decide to tap 6' up and place your bucket on the ground, with 3/16" tubing. The 6' of fall in 3/16" tubing will create approx. 4.5" Hg of vacuum. However, if you normally tapped and hung buckets 2' off the ground, you will lose 4' of natural head-pressure in the tree (the pressure in the tree pushing sap out is largely dictated by the height of the sap column in the tree), so you will lose 3.5" Hg vacuum by tapping higher up on the stem rather than lower down. Your overall gain in vacuum by tapping 6' high (vs 2' high) is therefore 1" Hg vacuum (although on a vacuum gauge it might appear to be 4.5" Hg). The question would be, is it worth doing this to gain 1" Hg of vacuum? As you tapped higher in the tree to gain more vacuum, you would correspondingly lose more head pressure.

Basically physics dictates that you can't get something for nothing...

A note of explanation added later....some of you might wonder how I got 6' of drop = 4.5" Hg vacuum when, in theory, the gain should be 0.88" Hg per foot, so 6' would be ~5.3" Hg. In practice (as opposed to theory), the column of sap is not always just liquid. It often contains some amount of air (which doesn't contribute to adding the gravitational force pulling downward) and because of microleaks in the tubing system or spout/tree interface. So while you might occasionally see something close to 5.3" Hg from a 6' drop, more often you'll see something closer to 0.75" Hg per foot of drop, thus 6' x 0.75" Hg/ft = 4.5" Hg vacuum at the taphole.

[Chickenman]

Question, so if you were able to say put 2 taps in said tree, tee'd 1 foot apart and were able to wrap tubing around the circumference of the tree say 2 times then into a bucket would the increased length and gentle slope of the tubing do anything for you?

[DrTimPerkins]

Length does nothing for you, unless it were too gentle, in which case it could have negative effects. The effect of natural vacuum is related to the change in elevation (height), not in the slope or length of tubing over which the drop occurs. Again, you can't cheat physics.

Generally teeing in 2 lines together is not recommended. Flow from one tends to restrict flow from the other.

[Chickenman]

Ok thank you. Trying to put a plan together for next year. Have a cluster of 5 trees that each base has multiple 18 inch plus trunks. From the distance likes like 5 or 6 trees close together then you get closer and realize that is multiple trunks from one root ball times 5.

[fisheatingbagel]

Yes, that makes sense in regards to tapping higher = lose head pressure

Any comment in regards to increasing the season through reducing exposure of the taphole to air? Using 3/16 tubing, I should be able to create a reasonably closed system, no?

[DrTimPerkins]

At the very least, use a new plastic spout each year (or clean and soak for 15 min in chlorine and rinse very well). No loop -- provides a space for microbes to multiply then get sucked back into the taphole during a refreeze.