Sap Ladder/Lifting sap on a lateral line?

[DaveB]

I have a few trees that are below the grade of where one of my mainlines under vacuum goes. I've always avoided tapping these trees because the are below the line but last year I put a couple of buckets on them to see how they would produce and they did pretty good so I'd like to see if I could include them. I've attached an image showing what I'm thinking about but basically I'm wondering if I could lift the sap a couple of times in the 5/16" lateral line to provide good slope between trees.

If I create a slope between the furthest two trees, the line would be near the ground at the third tree and I still have two more trees to go. So, I'm wondering if I put a 90 degree fitting and lifted the sap about 4' and then continued the slope to the third tree and on to the mainline. Since the line is under vacuum, would the sap lift up in the lateral line like that? I know sap ladders go up sections of 5/16 tubing and I'm thinking that if there's only about 7 taps on the line that it should work but I thought I would see if anyone has any experience doing this.

Hopefully my picture explains better what I'm trying to do.

[maple flats]

While you won't get the most sap possible, in your case I suggest you use 3/16 lateral, and 5/16 taps and drops. That, with good vacuum will give you a fairly good sap flow at minimal cost.
The reason for 3/16 and not 5/16 is because in 3/16 the air (gasses) do not pass the sap, thus a vacuum will pull both uphill to the mainline.
I did this exact thing on about 200 taps, in about 8-9 laterals running up to 500' each and lifting up to 12' in elevation for 4 years. Yes I got less sap than if I'd gone a more conventional method, but my thinking was justifying it in terms of investment vs sap collected. If you tried the same using 5/16 you would always have a pool of sap at the lowest trees that would not move much if at all. To do mine I had a piston vacuum pump with 27" of vacuum. I never put a vacuum gauge near the last tree, but I know it was low, but I always had a nice constant sap flow where the laterals entered the main linesany time the sap was flowing.

[DaveB]

Thanks for the observations. I hadn't thought about using 3/16 tubing like that. My thought was that the 5/16 would be like a mini mainline and because there only 3-4 taps on the low ladder and 7 at the second one that one 5/16 line should be sufficient to lift the sap but I can see what you are saying. Appreciate the feedback!

I'm also going to take a look at the line and see if I could get a minimal slope from as high as I want to comfortably tap and see where that brings me. I may just have to do one lift at the end but we'll see. I thought I remembered seeing something similar going over another sugarmakers driveway but he may have used 2 5/16 lines in the lift.

[buckeye gold]

deleted text-got off topic

[GeneralStark]

Two schools of thought here. Some just run the lateral uphill (inverted lateral) from the end tree to the mainline the same way you normally would. Others prefer the variation you have drawn where the lateral is sloped downhill and then lifted with a vertical section to the mainline. Those that prefer the second method argue that keeping the lateral sloped for the majority of its length allows it to more effectively drain to the point of being lifted so there is less line loss to competition between sap and air and therefore better air removal. The physics seem to make sense with that argument but I don't think it has been tested empirically. This is the method that many producers in Quebec prefer where very flat land is common... I have tried both methods and the sap moves through the line effectively in each case but I haven't measured vacuum levels at the end tree. In my mind the goal is the highest vacuum level at the taphole possible.

I would personally argue against using 3/16 for lifting sap in any vacuum type application. It is designed for gravity slope applications and the smaller diameter will limit air removal.

[buckeye gold]

Removed text, misunderstood question

[Super Sapper]

I would also do the 3/16 and just run your lats up to the mainline. I have gone to all 3/16 lines to a manifold on shurflo pumps. Some lines have good slope some very little and even go up and down without problems. I consistently get more sap than when I ran a 3/4 mainline and 5/16 lats. It may not be the optimal setup but takes very little attention to maintain your yield. Any little dips with 5/16 or the 3/4 mainline kills your vacuum where it does not seem to have a measurable loss on 3/16.

[GeneralStark]

I'll expand on my position a bit. As long as you have plenty of fall and distance after the lift I don't think it will matter.

Maybe I'm missing something but I think we're talking about different things. My impression is that DaveB is describing a situation in which he has a mainline under vacuum (with a pump removing air from the mainline I'm assuming) and would like to lift sap up to that mainline. You're describing a situation in which a long run of 3/16 below a lift is creating enough vacuum to lift the sap. In DaveB's scenario, air removal from the system is done mechanically and in your situation, a long column of sap moving down hill is essentially creating a siphon and pulling sap uphill.

Like I said, I may be missing something from DaveB's description but I don't see how the situation he is describing is at all similar to the one you are describing.

I don't at all disagree with what you are saying in terms of the ability of a gravity 3/16 system to create enough "vacuum" to lift sap. What I'm saying though is that 3/16 will not be as effective as 5/16 in maintaining high vacuum at the taphole in a mechanical pumped vacuum situation in which (I believe but could be wrong) DaveB is describing.

3/16, as you describe, works on the premise of liquid flowing down hill in the tubing creating vacuum. A pumped system works on a completely different principle and while there may be some similarities, the physics are indeed different.

[GeneralStark]

I would also do the 3/16 and just run your lats up to the mainline. I have gone to all 3/16 lines to a manifold on shurflo pumps. Some lines have good slope some very little and even go up and down without problems. I consistently get more sap than when I ran a 3/4 mainline and 5/16 lats. It may not be the optimal setup but takes very little attention to maintain your yield. Any little dips with 5/16 or the 3/4 mainline kills your vacuum where it does not seem to have a measurable loss on 3/16.

You're talking about "vacuum" with a shurflo pump in both 5/16 and 3/16 systems? Or did you use a different type of vacuum pump with the 5/16 system?

[buckeye gold]

My bad, I removed my comments.