Sap Ladder vs. Sap Lifter

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Originally Posted by TapTapTap

I can't see how the Cornell system will help with vacuum loss. The only way to lift the sap is to use up the vacuum (about 13" of water for every inch of vacuum). Sap ladders will slurp the sap which allows some vacuum to slip by during low flows which is the action you observed. When the flow is high, the flow is continuous through the sap ladder and the vacuum loss will be equal to the 1" of Hg for every 13" of sap.


Ken

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The problem I’m having has been a loss of vacuum due to the lines being full and backing up behind the sap ladder.
I have 300 taps on that section and the ladder is right at the releaser. So when it pools up I’m losing vac to 300 taps.
I’ve got 15x 5/16 tubes on star fittings running that ladder and still backs up at 25” vac.
I have a valve at the end of my mainline that if I crack a bit it will dance the ladder a bit and get it going, but adding a leak in a not something that should need to be done on 300 taps.

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Originally Posted by Bricklayer

The problem I’m having has been a loss of vacuum due to the lines being full and backing up behind the sap ladder.
I have 300 taps on that section and the ladder is right at the releaser. So when it pools up I’m losing vac to 300 taps.

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Ignoring friction losses (and leaks), you should have vacuum below the sap ladder equivalent to about:

Releaser vacuum (inches of Hg) - Lift height of Sap ladder (inches)/13.6

For example, if your releaser is at 27" of Hg and your ladder provides a 72" lift, you should have about 27-72/13.6 = 21.7" of Hg.

Note that mercury is 13.6 times heavier than water (specific gravity 13.6) - there is no fuzzy math here.

I have a vacuum gauge on each side of one of my ladders and they show pretty close to the calculated differential. The gap gets closer as the 5/16 lines slurp which is the benefit of any ladder like system but only occurs when the ladder keeps up with the sap flow. On a heavy run the differential is pretty close to the calculated amount since there is sap pooled up in the mainline above the star. Once the flow decreases, air on the lower side gets slurped up the 5/16 lines.

Have you measured vacuum below the ladder? You will get times with zero if the mainline below the ladder is frozen full or if you're ladder was so overwhelmed that there's sap backed up for a height equivalent to the lift capacity of the vacuum.

There is no need to vent since the ladder is already made to vent to the lower vacuum below the ladder. That slurping action is the venting.

Ken

Quote:

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Originally Posted by TapTapTap

The only way to lift the sap is to use up the vacuum (about 13" of water for every inch of vacuum).

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Quote:

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Originally Posted by TapTapTap

I have a vacuum gauge on each side of one of my ladders and they show pretty close to the calculated differential.

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Yup. The laws of physics....everybody tries to break them...nobody succeeds.

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Originally Posted by DrTimPerkins

Yup. The laws of physics....everybody tries to break them...nobody succeeds.

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They apply equally to everyone whether you believe in them or not!

We have a "triple" sap ladder that lifts close to 20 feet from a swamp edge up to the mainline. The first lift is 7 feet followed by 50 feet of mainline sloping towards the upper mainline, another 7 foot lift and more mainline sloping towards the upper mainline and finally a last 7 foot lift. We have about 120 taps on that section so we used 2x "spiders" at each lift. When our vacuum is low we don't get a lot of vacuum on the end of the mainline along the swamp. When we've got 24" Hg on the upper mainline we get 15 or 16" at the far end. Not perfect but it's better than not tapping those trees.

I have a triple ladder to using 3/4 mainline. The first two lifts are S shaped with another 3/4 line going over top spliced in with Y,s and lifting about 6 feet each. The third is a two pipe system made with 1/2 inch tubing going up 10 feet. I had very good results with this. Especially the two pipe lift. That mainline has around 100 taps on it and vacuum at the releaser was 25”. I didn’t measure vacuum below the lifts but monitoring the laterals it kept the sap evacuated. I also monitored it coming into the releaser. It compared to the other mainlines with similar amount of taps.

I was able to fix the ladder.
I have 2” manifolds on the top and bottom of the ladder. With only a 1” wet line going from top manifold to releaser. I installed a dry line from releaser to the top of the top manifold and it seemed to work way better. Just a nice steady stream to the releaser now. Not a full line with big glugging air bubbles and big blasts of sap.

I have a problem with about 200' of 1" mainline in one section of woods, just not enough slope.
Sap will fill the line just like Bricklayer says and then slug on over to the lifter.

Going to be looking at it tonight to see what we can do to solve.
Only 3 more months of boating so it's time to start thinking Maple...

Does anyone know if Cornell was able to replicate their 2021 results on the "s" bend flatland system in 2022? We have a double CDL lift on 400 taps lifting 17 feet and it's the biggest maintenance issue we have in the woods -- very open to trying something else...........