another 3/16" slope question

[peteinvermont]

Installed a test run of 3/16" over the weekend. 28 taps on a run. First tap is about 40ft above the where it enters the mainline, so we won't get full vacuum on all taps, but its a good starting point for us. It ran full throttle from when I finished it 4pm yesterday until everything froze up last night. Those 28 taps never produced more than 100 gallons or so in a season before, when they had 5/16" on them, so I'm hoping for some improvement, but with realistic expectations, being this is the first 3/16" I've set up before.

Here's the question - in the next install I want to test on, they are virgin trees, so I don't have any benchmark to go by. Here's what it looks like, if I can do a decent job explaining...

- 600ft from first tap to collection tank.
- first 450' or so only has a slight slope on it. MAYBE 8-10ft.
- 90% of the 60 taps are in this first flat section.
- the last 100ft of line will drop another 20ft in slope.

My plan was to start at the first tree and continue tapping until I hit around 30 taps - at that point, I'd run the line past all the other trees, and going all the way down to the tank.
I'd then start where I left off, tap the other 30 trees, and run that line all the way down to the tank.

Is the last 100ft dropping 20ft going to be enough slope for a pair of 30 tap runs to pull vacuum? I know I won't get max vac, but even if I get 5-10" on them, I'm thinking it will still be more productive than 5/16".

Thoughts anyone?

[jmayerl]

With 20 feet of drop after last tap I think you will get a min of 15" at lowest tap on very possibly much more. Sounds like a good plan

[seandicare]

i am going off memory here, so i might be slightly off....

Steve Childs from Cornell did a lecture at our local maple expo 3 weeks ago.........he had done some tests and figured (kinda theoretically) that the max taps on a 3/16 line would be 43ish....

also for every foot of drop on the line, you should get roughly 0.8psi natural vacuum.

with the low grade area, i'm not sure what kind of affect that will have on things though.

[peteinvermont]

i am going off memory here, so i might be slightly off....

Steve Childs from Cornell did a lecture at our local maple expo 3 weeks ago.........he had done some tests and figured (kinda theoretically) that the max taps on a 3/16 line would be 43ish....

also for every foot of drop on the line, you should get roughly 0.8psi natural vacuum.

with the low grade area, i'm not sure what kind of affect that will have on things though.

Agreed, which is why I'd only tap up to 30, run the rest of the line strait to the tank, then start a new line with the other 30 on it.

I could make the number lower or higher, but based on the reading I've done, I'm choosing 30 for these reasons:

1. With a 600ft run, and minimal slope, I'd need a high number of taps on each line to produce enough sap to fill the column - creating the continuous "weight" of sap necessary to pull vacuum when there isn't a lot of slope and its a long run.
2. I could push one run up to 40 taps or so, and the 20 taps closer to the tank on their own run. But I'm afraid in a heavy sap run, I might overload the 3/16"

[DrTimPerkins]

...also for every foot of drop on the line, you should get roughly 0.8psi natural vacuum.

Correction to that....for each 1' drop you get roughly 0.8" Hg vacuum.

[markcasper]

Not to hijack the thread, but someone please explain why T'ing in 3/16 is a bad idea. I have a couple areas where I used 5/16 and had some tee'd together to take it to the collection tank. One spot has about 200 feet to the first tree with minimal slope and the line just lays on the ground going through the pasture to get to the road. There is maybe 45 taps coming off a steep sidehill and I had always joined them into one 5/16 "mainline" that was on the ground. The sidehills are steep with probably 60 feet of drop from top of hill to last tree, and then there is another 15 feet of drop from the lat tree to barrel over 200 plus feet. Why can I not do the same with 3/16? I have not tapped these trees for a few years.

[peteinvermont]

Correction to that....for each 1' drop you get roughly 0.8" Hg vacuum.

So the ratio of flat to slope doesn't affect vacuum in any way. As long as I have 30ft of drop at the end of my run, all the taps will get full vacuum, even if the flat run above the drop is 500+ft long?

[peteinvermont]

Not to hijack the thread, but someone please explain why T'ing in 3/16 is a bad idea. I have a couple areas where I used 5/16 and had some tee'd together to take it to the collection tank. One spot has about 200 feet to the first tree with minimal slope and the line just lays on the ground going through the pasture to get to the road. There is maybe 45 taps coming off a steep sidehill and I had always joined them into one 5/16 "mainline" that was on the ground. The sidehills are steep with probably 60 feet of drop from top of hill to last tree, and then there is another 15 feet of drop from the lat tree to barrel over 200 plus feet. Why can I not do the same with 3/16? I have not tapped these trees for a few years.

This thread is about the ratio of flat to slope, but I was just searching for some documentation on T'ing into 3/16" as well. So its not hijacking in this case.

[DrTimPerkins]

So the ratio of flat to slope doesn't affect vacuum in any way. As long as I have 30ft of drop at the end of my run, all the taps will get full vacuum, even if the flat run above the drop is 500+ft long?

I think that is still questionable. 3/16" tubing on flat land is not indicated. I can't say for sure how it'll work in this case.