3/16 drops and laterals into 5/16 mainline

[Rodger]

Getting back into the hobby after a couple years absent, Looking to run 3/16 drops into 3/16 laterals to a 5/16 mainline to a collection tank. Two laterals of 300 feet each will have 25-30 drops tied in . Tie in point for both laterals will be at the same point to the 5/16 mainline. The 5/16 mainline will travel a distance of 700+/- ft to a collection tank. 3/16 Drops and Lateral ends to tie in point drops in elevation of 10 feet. From 5/16 tie in to collection point drops in elevation of 25-30 feet. Question is would this be a wise set up to go with?

[DrTimPerkins]

If I understand you correctly, you have two 3/16" laterals that are 300 ft long with a drop of 10' in elevation. That's a 3% slope (10/300=3.3%), which is not really optimal for 3/16". Likely any vacuum created will be lost due to friction in the line, but it isn't terrible....just that the 3/16" isn't going to help you much.

You then are going to run those two 3/16" laterals with 25-30 drops each into a 5/16" lateral that is 700 ft long with a 25-30 ft drop. Your slope would be OK (30/700=4.3%), but that's really on the high end for number of drops on a single 5/16" line, so you'd likely restrict the flow in the 3/16" lines even more.

So the real answer depends upon what your goal is. If you just want to collect some sap and don't care too much about yield, it would work, and might be the cheapest way to go. But using all 5/16" might be simpler (since the 3/16" isn't going to do much for you and is harder to keep clean), might get you a bit more sap (less flow restriction), require fewer fitting types, and would be easier to keep clean. If you want to get higher yields, then run BOTH 3/16" lateral lines all the way to the bottom separately. That way you would likely develop a decent amount of natural vacuum (given your total fall in elevation and the fact that all your taps higher up would get vacuum)...ASSUMING you kept it really tight and leak-free. You'd also have to be sure to sanitize and rinse the 3/16" lines well each year.

[Rodger]

Yes that is correct of what I am trying to do. Would like to get all I can . I can run several 3/16 laterals with about a third of the taps on each lateral if that would yield the result.

Thank you for your insight

[maple flats]

As Dr Tim stated, forget the 5/16 and run the 3/16 all of the way to the sugarhouse. You will get more yield. Make it 2 laterals, the 25-30 taps you suggest, then go the full distance to the sugarhouse. With the 25-30' fall in the distance you would have had 5/16 for will get excellent natural vacuum. In the section where the taps are you would get little or no vacuum gain if you then connected to 5/16.
The big difference is that the air (gases) do not pass the sap in 3/16, but do in 5/16. Thus 3/16 with enough drop gives you natural vacuum.

[Rodger]

That is what I was wondering if there would be enough vacuum. So 3/16 it will be

Thank you

[Tuckeradams2012]

I'll jump on this as well. Lets say you have 10 taps on the total lateral of 3/16" and 9 taps have 20' of drop with the last tap only having a 5' drop. Theoretically you still get vacuum for the top 9 taps but no vacuum for the last tap on the line correct?

[DrTimPerkins]

Vacuum is proportional to the height from the taphole to where sap exits the 3/16” tubing. That assumes your slope is good enough to counteract frictional forces.

[Rodger]

The overall drop from the highest point to the holding tank is about 40 feet

[DrTimPerkins]

The overall drop from the highest point to the holding tank is about 40 feet

At those highest trees you'll get maximum vacuum. At the lower trees you'll get less. This assumes you keep the tubing system very tight (leak-free).

The article located at https://mapleresearch.org/pub/slope2018-2-2/ will help explain the relationship.

[DrTimPerkins]

I'll jump on this as well. Lets say you have 10 taps on the total lateral of 3/16" and 9 taps have 20' of drop with the last tap only having a 5' drop. Theoretically you still get vacuum for the top 9 taps but no vacuum for the last tap on the line correct?

In practice, the trees at the top (20' of drop) will get about 12-18" Hg vacuum (assuming the system is leak-free and the slope is > 5% so friction is not too high). The last tap at 5' drop will get 3-4" Hg vacuum. Trees in between the top and bottom will get something between that depending upon their position (height above the outlet of the 3/16" tubing).

[ADK_XJ]

Hi, I am finding this thread while researching a similar setup in our (small) sugar bush - any report back on how the all 3/16 approach worked out?

We have good slope that is currently tapped with 3 lines of 3/16 with 25 or so taps on each, it then reaches a bit of a "gulley" (as we would call it here, basically a flat depression) and there is moderate to mild slope down the rest of the way to the valley floor. I would say maybe 15-20 feet of drop over 200-250 feet of distance.

I had read before that 3/16 might not be ideal because of the decrease in slope and the build up of resistance due to friction but this seems to suggest the overall drop in height from the top would overcome that?

[Rodger]

The configuration did not work out as I had hoped. We only end up with about 16 gallons of syrup from a total of 175 taps for the 2022 season. The slope on the top section was flatter than anticipated so therefore I had to many taps per line which created a log jam and slowed down the flow before dropping down to the collection tank. This year I decided to pull all the 3/16 lines. Made the decision to run 1 inch mainline throughout and use 3/16 laterals from tree to mainline added another 125 taps for a total of 300 taps. Each lateral will have approximately 5-15 taps each. The laterals longest run to mainline is no more than 100 feet. Installing a guzzler pump to pull the sap. I am excited to see how this improvement is for this season.