3/16 laterals into 5/16

[afretired]

This is my first year running 3/16 tubing. Today I ran 2400 ft of new 3/16 replacing the old 5/16. I have a small woods of about 7 or 8 acres with a valley starting and running thru the middle of it. With good drop of probably 30-40 ft. I ran the 3/16 in a zigzag pattern coming down the valley in several locations picking up 20 -25 trees then “T”ed them into a 5/16 and continued 300 ft to my tank farther down the valley. So basically picked up several clusters of trees, combined and then ran 3 - 5/16 lines from farthest areas to the tank and on those areas closest to the tank 3 - 3/16 laterals to the tank. I reutilized some old 5/16 line going to the tank. My question is: Will I get any vacuum in the 5/16 lines? My thought was 2 3/16 lines combined would fill the 5/16 line and generate vacuum. Or do I need to order a couple more rolls of 3/16 tubing and run each separate?

[Bucket Head]

There is such a thing as natural vacuum with 5/16- I've done it- but it isn't constant and by the sounds of it you probably won't see it with your set up. For optimum performance of natural vacuum you'll want all those taps on 3/16 with the required drop below the last tap on each line, and then use 5/16 to take it to the tank if the slope isn't steep. I've found 3/16 on flatter terrain does not help things. And you will be creating resistance by running multiple 3/16 lines into one 5/16 line. Having them go to a "main line" and then to the tank is the way to go but you should put up actual main line to the tank.

Good luck this season!

Steve

[bmbmkr]

Steve, I've read somewhere about how many taps- how much volume it takes to get that 5/16 naturl vac to work but I can't remember the numbers or find the dats anymore.

I'm running a similar setup as Afretired. In my new woods I have several 3/16 laterals up on a bench in a bowl shaped valley that only have 6-10 trees on each. I'm running those laterals down over the steep, 40-50' elevation drop from the last tree, then tee'ing two 3/16 into one 5/16 for the next 50' of drop to the mainline. The 3/16 laterals that I did manage 25-30 on are running over the steep and transitioning to a single 5/16 to the mainline. It's a hybrid system, but from what I gathered from a tubing seminar at the Southern Syrup Symposium, sap can slow down due to resistance in 3/16 if the grade at the bottom is too long and flat.

WVKeith has done some experimenting and data collecting on the subject, and I think there will be more data after this season. Dr. Tim stated that there hasn't been much research on the subject, and using 5/16 as a "mainline" is NOT advisable. However, those of us with very steep terrain, may actually benefit by using a mix of the two tubing sizes.

My 5/16 extensions are about 150-200' long, very tight-and on a roughly 15-20% grade.

There is another thread on this subject that was started back in the fall.

Afretired- I'm retired USAF too, AMMO IYAAYAS!

[Bucket Head]

It takes a lot of taps per line to fill the 5/16 and it takes excellent slope to generate the vacuum, and even with that it isn't as high of vacuum as what the 3/16 generates. I had 34-44 taps on the lines and 8 inches of vacuum is what it could achieve. But it took a good day/run of sap also to keep the lines full. A mediocre run did not support the natural vacuum.

[maple flats]

The issue is, that while 2 at 3/16 may fill a 5/16 (I didn't do the math) a 5/16 is vastly different. In a 3/16 the sap never passes the gasses in the line, the sap thus fills the tubing, you will see a parade of sap/air (gases) sap/air etc. The fall in elevation on the sap is how a vacuum is generated. With 5/16 the sap will pass the gases and will not fill the tubing to allow gravity to generate any vacuum until you have enough taps feeding the line that sap fills the tubing.
You can get vacuum on 5/16 but it will take more than 2 lines of 3/16 and it may only give any vacuum on the better flow days.
First, on your 3/16 you are far better having at least 15 taps on a line, 25 is a good average (15-30). But you need good fall in elevation. If the area where you currently used 5/16 (as mainlines?) is not at least 2% slope, use a 1/2" or a 3/4 " mainline, if it has over 2% slope, remove the 5/16 and tie in 3/16 instead, all of the way down for best performance. The % slope will translate to feet/hundred feet. 2% is 2'per100'.

[afretired]

Well it’s finally sinking in a little. Maple Flats, I understand now how it works, “the sap doesn’t pass the gasses”. That is what I was missing. It’s not having the tubing full with sap as much as having the sap droplets separated by gas bubbles. I see what everyone has been saying, I guess it boils down to the surface tension on the sap holding the droplet together filling the 3/16 tubing, where it can’t on the 5/16 tubing, and basically runs down the tube allowing the gasses to slip by.

One other thought. I’m from a Kentucky, my flattest ground has a lot more slope than 2%, so I guess I’ll be running more 3/16 lines.

[afretired]

Bmbmkr, you must have worked in a WSA. I was in Comm. retired in ‘99

[maple flats]

Exactly, the surface tension makes the sap fill the tubing on 3/16. With more than 2% fall from where you had tied the 3/16 into 5/16 to the tank, going to 3/16 will give you more vacuum on all of the taps (well, not all, just the ones that didn't already have the maximum vacuum for your elevation and that day's barometric pressure).
Besides, 3/16 is cheaper especially when you don't need a bunch of fittings to make it work.
Be careful, it will be hypnotizing to watch the march of sap/air/sap/air etc. flow downhill. I've stood and watched it for maybe 5 minutes at times before I remembered I had things to do.

[maple flats]

Read up on sanitizing 3/16, it becomes very important or you will get a considerable drop off in production in subsequent seasons. You may find it wise to use 5/16 taps, drops and a tee in 3/16x3/16x5/16 (the drop is 5/16) and change them every year for best production.
There is a huge benefit to gravity vacuum, it runs without fuel, needs no pump, never needs to be turned on, makes no noise and never quits.

[VTnewguy]

Exactly, the surface tension makes the sap fill the tubing on 3/16. With more than 2% fall from where you had tied the 3/16 into 5/16 to the tank, going to 3/16 will give you more vacuum on all of the taps (well, not all, just the ones that didn't already have the maximum vacuum for your elevation and that day's barometric pressure).
Besides, 3/16 is cheaper especially when you don't need a bunch of fittings to make it work.
Be careful, it will be hypnotizing to watch the march of sap/air/sap/air etc. flow downhill. I've stood and watched it for maybe 5 minutes at times before I remembered I had things to do.

Ain't that the truth! Fun to watch!