taps per lateral and lateral length

[leaky bucket]

Hello all i am having a new installation done and had the mfg rep and installer came out to lay it out and do my material list.
They are proposing a single line system 2 1-1/4 mains at approx 1200'ea and 1 1"main at approx 600' 1300 taps on high vac.
Terain is well sloped. Installer says he can put up to 20 taps on a 5/16" lateral and laterals can run up to 400--500 ft.
When i questioned this ,( as i cannot find any evidece or anyone else that agrees with this) they claim that Cornell univ. has done studies on more taps on 5/16" . And 5 taps per lateral and 100' limit lateral run is old school .
I would love to hear Dr Tims take on this and anybody elses thought.
Other suppliers i have asked for a quote from thinks this is crazy talk. Right or wrong ?

Thank You
Mike

[ennismaple]

This is contrary to what I've read. Maybe if you were doing 3/16" laterals on vacuum but not 5/16". The vacuum will ensure you keep 25" Hg+ on the lower taps while the long steep 3/16" laterals will get you max vacuum on the upper ones.

[fred]

I cant find the link. But steve childs has done testing on this. 25-30 on 3/16" somewhere around 125 on 5/16. The point at which the flow cant get any faster through the tube. If i remember right the tests were also 1500-2600' in order to get that many taps on a line.

[DrTimPerkins]

I cant find the link. But steve childs has done testing on this. 25-30 on 3/16" somewhere around 125 on 5/16. The point at which the flow cant get any faster through the tube. If i remember right the tests were also 1500-2600' in order to get that many taps on a line.

Those were the recommended numbers...up to about 1990. We've learned a lot since that time.

For 5/16" laterals ON A VACUUM PUMP, the rule of thumb is "strive for five, no more than 10." That comes directly from research done at UVM PMRC (see the first graph below). Production drops off with added taps per 5/16" lateral. I'm not aware of any newer research at Cornell or elsewhere that disputes this. The best production is with ONE tap per lateral, however that is too costly, so 5-10 taps/lateral is a compromise between production and cost. Length of laterals should be no more than about 150' if at all possible.

The problem is that in 5/16" lines, gas can't move past through the sap. Liquid (sap) in fairly incompressible -- gases are very compressible, meaning that they "stretch out" (the bubbles expand under vacuum). This limits the transfer of vacuum in those lines. A decent analogy is two bricks connected by a rubber band. If you have a very rigid rubber band (little or no bubbles), you can pull on one brick and the other moves easily...the force was nearly completely transferred. Now if you replace the rigid band with a very loose rubber bands (more or bigger bubbles, warm day = more tree gases, small microleaks), when you pull on one brick the other doesn't move very well at all until you pull a lot more on the band. The sap (bricks) in a lateral line act the same way when you have air (rubber bands) in the line. This isn't the case in mainlines since the bands (air) moves over the top of the bricks (sap) and the two aren't connected together very strongly (or at all) unless you have a lot of turbulance. Same reason a wet/dry line system works better. The sap and the gases are separated and each is allowed to move at the natural rate of flow (gases can move 10X faster or more than liquid). Thus the inability to remove the gas (produced by trees or by leaks) in lateral lines reduces the vacuum level at the taphole, especially at certain phases during a sapflow period. Fewer taps and shorter lines mean less gases in the lines and better vacuum at the taphole. Can you put 20 taps on a lateral line? Sure...but your production will be lower.

20169

Our tubing systems at UVM PMRC average about 3.5 taps/lateral. This is how the companies (CDL, Leader, D&G, and an independent professional installer) all installed them in 2004, and largely we told them to put in their recommended systems to produce high yields.

The following two graphs/text are out of the Cornell Tubing Notebook, and are based upon the research at UVM PMRC.

20170

20171

Now, it is entirely possible some newer information is out there on the subject that I don't yet know about, but I'd need to see it in writing.

For some other weird vacuum-related stuff, check out https://mapleresearch.org/pub/m0216vacuumtubingresearch/

Recommendations for 5/16" laterals on gravity are different. 3/16" tubing systems are a TOTALLY different animal, and the recommendations are quite different.

[fred]

i wish i could find it. but i also was in one of his classes which showed a chart where he had a series of lines with different tap counts and showed no difference until reaching 120+.

im installing up to 20 in a 5/16 line under high vacuum and achieving .5-.8 syrup gallons per tap in various systems with optimum foresty practices giving as much as 35-38 gallons of sap per tap hole.

i do have 2 producers near me following intense guidelines getting over a gallon of syrup per tap every year. 95% of your money is made in the woods