Very Simple Sap Lines

[berkshires]

5/16" tubing will develop natural vacuum if installed properly. This has been known for some time. https://ecommons.cornell.edu/bitstre...=1&isAllowed=y It is more difficult in some ways, requires more taps per lateral line, is less consistent, and the vacuum will "collapse" at certain times and not persist well during low or no flow periods, but it certainly can be done.

3/16" tubing will develop natural vacuum much faster and will retain it far longer during a flow. This is because the internal diameter of 3/16" tubing is small enough that a column can develop (due to cohesion of water) and be held within the tubing. That's not the case with 5/16" tubing, in which the water (sap) column will naturally drain unless maintained by continuous flow of sap.

The biggest advantage with 5/16" natural vacuum systems over 3/16" is that there is less clogging.

Seems to me the best of all possible worlds would be 5/16 lateral lines from the top tap to the bottom tap, and then a 5/16 to 3/16 converter and at least 75 feet of 3/16 tubing (with no drops in it) down to a collection point.

Then all the lateral line with drops cut into it are on 5/16, and less prone to clogging, but you get the benefit of a sap column in 3/16.

Thoughts?

[Sugar Bear]

I am not entirely sure what you mean. If the sap column rises higher in the lateral line than the lower taps (which should only happen if the drain end gets blocked, the tubing at the end with the lower taps is on flat ground or below the lateral line at that elevation, there is a clog or blockage in the line restricting flow, or the line is seriously overloaded with taps), then the problem is with the installation somewhere.

In a well functioning 5/16 gravity vacuum setup, how long in feet should the sap column be expected to be?

If mine is 60 feet long and rises 15 feet vertically above the collection barrel and their is a tree suddenly available to tap next to my line that is 20 feet from the barrel and 5 vertical feet above the barrel and I put that tap on my run, wouldn't I have back pressure into that tap from the 60 foot sap column and also be corrupting my sap column at that point where I put that tap in.

[DrTimPerkins]

In a well functioning 5/16 gravity vacuum setup, how long in feet should the sap column be expected to be?

It isn't that simple. Depends upon several factors, slope, number of taps, rate of sap flow from taps. However the sap column in a non-pumped system can be several feet long. The reason that natural vacuum doesn't build as well in 5/16" tubing compared to 3/16" tubing is that air slips by the sap (upward) more readily in larger tubing. In 3/16" tubing, the air is trapped (better) and is pulled/pushed down and out of the end of the tubing, which creates the vacuum.

If mine is 60 feet long and rises 15 feet vertically above the collection barrel and their is a tree suddenly available to tap next to my line that is 20 feet from the barrel and 5 vertical feet above the barrel and I put that tap on my run, wouldn't I have back pressure into that tap from the 60 foot sap column and also be corrupting my sap column at that point where I put that tap in.

If the end of the tubing were closed, you would develop pressure quite readily at those taps. Given that the end is open (to drain), and you have vacuum above that point and the sap is moving downward, and there is (presumably) pressure within the tree pushing sap outward, there is relatively little net pressure (or vacuum) generated at that point. A good deal will depend upon the conditions of the moment.

Pressure variations within the entire system (trees and tubing) can be quite complex, variable, and change a lot during a flow period. Trees can have positive pressure up to 30-40 PSI when the first thaw, and vacuum can propagate in them (from the tubing system) down to -29" Hg+. The pressure/vacuum within the tubing system is also quite variable depending upon a lot of things.

[DrTimPerkins]

Seems to me the best of all possible worlds would be 5/16 lateral lines from the top tap to the bottom tap, and then a 5/16 to 3/16 converter and at least 75 feet of 3/16 tubing (with no drops in it) down to a collection point.

Then all the lateral line with drops cut into it are on 5/16, and less prone to clogging, but you get the benefit of a sap column in 3/16.

Thoughts?

While it could work, the problem with this type of setup is that there is a LOT more air in a 5/16" line than in a 3/16" line. Vacuum is generated in the line by pushing or pulling air out of the line. In this arrangement, you need to move all the air out of the larger 5/16" line through the 3/16" line at the end. Air slips past the sap in a 5/16" line better than in a 3/16" line, so it would be less efficient in moving air out, and because there is also more air, it would take more time for the vacuum to build up. It will work, just not as well as a system completely constructed of 3/16" tubing. Now some people do use 5/16" drops. This is less of a problem because the total amount of 5/16" tubing (and air within it) is not large.

[berkshires]

While it could work, the problem with this type of setup is that there is a LOT more air in a 5/16" line than in a 3/16" line. Vacuum is generated in the line by pushing or pulling air out of the line. In this arrangement, you need to move all the air out of the larger 5/16" line through the 3/16" line at the end. Air slips past the sap in a 5/16" line better than in a 3/16" line, so it would be less efficient in moving air out, and because there is also more air, it would take more time for the vacuum to build up. It will work, just not as well as a system completely constructed of 3/16" tubing. Now some people do use 5/16" drops. This is less of a problem because the total amount of 5/16" tubing (and air within it) is not large.

Hmm... I might have a basic assumption that's wrong.

Let's take a simple setup where you just have a 100' 3/16 line, running tight down a constant slope, and you're running enough sap in it to create a column of sap in the bottom 50' of it. For the sake of argument, let's say you get 10" of vacuum at the top of the line.

Now compare that to a 200' 3/16 line. Everything is the same - running down the same slope, same volume of sap running through it, same column of sap in the bottom 50' of it. Only difference is there are 150' of line from the top of the column to where you measure vacuum at the top, instead of 50' of line.

Would the 200' line also have around 10" of vacuum? Or would all the extra air in the line somehow decrease the vacuum at the top?

Thanks,

Gabe

[Swingpure]

I purchased 500 more feet of 3/16” line today, as well as the single handed tool.

I kept thinking of slope as degrees, but it is two different things, which helps.

I have two runs where I can have about 8 trees then a 75’ run on a steep grade, to the collection barrel.i have a third run, that I have about 6 trees on a 40%+ grade that goes to a 7th tree also on a steep grade below. I could put a collection barrel there, but it would be the hardest one to get to. I could run to a group of another bunch of trees. It would be a 100’ run with no taps on a 3 to 5% grade, before meeting up with 5 more trees on a 5%+ grade and I could have another 75’ finishing run on a 5% grade to the collection barrel. My fear is after a very steep initial run, that the sap would bog down in the 100’ shallower run.

[Sugar Bear]

It isn't that simple. Depends upon several factors, slope, number of taps, rate of sap flow from taps. However the sap column in a non-pumped system can be several feet long. The reason that natural vacuum doesn't build as well in 5/16" tubing compared to 3/16" tubing is that air slips by the sap (upward) more readily in larger tubing. In 3/16" tubing, the air is trapped (better) and is pulled/pushed down and out of the end of the tubing, which creates the vacuum.



If the end of the tubing were closed, you would develop pressure quite readily at those taps. Given that the end is open (to drain), and you have vacuum above that point and the sap is moving downward, and there is (presumably) pressure within the tree pushing sap outward, there is relatively little net pressure (or vacuum) generated at that point. A good deal will depend upon the conditions of the moment.

Pressure variations within the entire system (trees and tubing) can be quite complex, variable, and change a lot during a flow period. Trees can have positive pressure up to 30-40 PSI when the first thaw, and vacuum can propagate in them (from the tubing system) down to -29" Hg+. The pressure/vacuum within the tubing system is also quite variable depending upon a lot of things.

To Clarify ... In your reply above can your words "at that point" be replaced with "at those taps" as to reference the previous "at those taps" in the same paragraph.

If so that would make sense to me and had not considered the relative indifference of the hydro dynamics at that location.

But somehow the effectiveness of the sap column and or the flow of the lower taps/drops within the column seem like they are being hindered.

[Swingpure]

When you hook the line to the very first tree of the run, do your drop line(s) connect to the 3/16” tubing after the intersection with the end line hook and the tubing, or just before it?

Thanks

[DRoseum]

Did you get the end line hook with the built in drop line barb? Like this: https://bascommaple.com/collections/...ducts/laelh316

If so, drop line goes down to the top barb and your lateral comes off the side barb.

[Swingpure]

Did you get the end line hook with the built in drop line barb? Like this: https://bascommaple.com/collections/...ducts/laelh316

If so, drop line goes down to the top barb and your lateral comes off the side barb.

No I got one that plugs the end and hooks onto the hose on the other side of the tree. I never saw the other ones, and these are the ones that CDL gave me.
The ones you showed in the link, would have been slick to use.

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