No Real Grade Tubing

[argohauler]

From the steep hill tubing thread. This needs a new thread. I've realized with all the comments made on the non venting of gravity tubing, that I'm a venting sinner. Yes I vent my lateral lines and I vent the end of the mainlines.

I have next to no grade. There is a bit in places. My mainlines slope at an inch per 4 feet, so a foot in 48. I have 2 mainlines going across a big swamp full of soft maples. They eventually rise when they hit dry land and do slope some. Quite often towards the back end of the mainlines I use a 7 foot step ladder to tap. My lateral lines have next to no sag, so they should drain properly to the mainlines.

I should add I went by uncles setup. He has some really nice crick hills that give him slope. He only vents his mainlines. When he was "taught" to set up gravity tubing, they told him to only put a max of 10 taps per lateral. I made mine to that rule and sometimes there are less. I also do not branch off my laterals with tees.

You'll say get vac! I've no money for that yet. Arch needs to be rebuilt for next year.

I would like to know if i should also eliminate the vent at the end of the mainlines?

[3rdgen.maple]

Im no expert on tubing but was always told a tree can push sap the height of the tree. I am wondering if it is possible a vented line with little slope you could be losing sap out the vents. If the sap is not draining out the lines as fast as it is coming it could it not push it out the vented ends?

[PerryW]

My theory is:

With a a properly sized, properly set up gravity mainline with no sags; it will not make a difference either way. The sap only runs in the bottom of the pipe like water in a gutter, so you will never fill the pipe enough to get any natural vacuum.

But I still vote for no venting of the mainline just to reduce the chance of a frozen pipe causing sap to flow out the vent and to reduce the possibility of foreign objects getting into the pipe.

[argohauler]

The vents on the laterals is a piece of tubing almost as long as the end drop with a splicer on the end and a piece of string to tie it to the end tap.

I've seen it leak out the end tap, but not very much till the line unfroze. My mainline vents are fairly long and are tied to the tree the mainline anchors to. I've never seen those leak.

[farmall h]

argohauler, not tell you what to do but...you have plenty of grade. Be sure your mainlines are tight with very little sag and put a plug in the end of the them (be sure to clamp plug). If your laterals are vented (which I do not understand how and why you do this)plug them off as well. It does not cost much $ to do this and very little effort. With as many taps that you have there should be no reason for not having natural vacuum. Trust me..when the sap starts to flow (mind you it is a drop at a time) and fills your laterals you will see the natural vac occuring. It is a wonderful sight to see!:) Any questions feel free to post 'em.

[maple flats]

argohauler, he is right. You have 1 in 48 which is just over a 2% grade. Do not vent, it lets contaminants in. The only time it helps is when you first open the vent, you then get a very short surge but then the flow falls back to actually less than you were getting without the vent. As far as mainlines, it would be rare indead to get much if any natural vacuum but the latterals are different. Whatever it is, run the latterals as steep as possible, even if you need to tap high in the tree as you get farther from the main. That is what I do. In my smaller bush, at my sugarhouse a topo map has 5' contour intervals and my whole 15 acres only have one contour line in it (thus my name, maple flats). The actual change from the highest to lowest on any line I have is about 8' in 500. My main on the longest runs about 500' and goes at a 2% grade. However, when I do my laterals I get about 3-4% grade by going higher in the tree. My extreme is where the land drops off at the rear of the property and my 2 highest taps are done from a extension ladder with the tap about 13' off the ground. Just do what you need to to get sap to flow.
Refer to Dr Tim's reply in another thread about venting, he gives actual percentage loss from real world scientific study, it should convert you. If nothing else, venting causes holes to dry up earlier in the season.

[farmall h]

[QUOTE=PerryW;110525]My theory is:

The sap only runs in the bottom of the pipe like water in a gutter, so you will never fill the pipe enough to get any natural vacuum.

Perry, this is untrue. Why then is it that when my sap is gravity flowing in it comes in charges of full pipe flow(1 1/2"). That is the result of natural vacuum during sap flow. I have (3) 3/4" mainlines entering this 1 1/2" line that enters the sugar house. Mind you I have very steep grade to the sugarhouse but that should not matter. The natural vacuum does occur once the lines are flowing..we just never see it 'cause it is a slow action. I was a disbeliever in the past until I called the guys at Leader as to whether or not to cap or not to cap. They recommended to CAP. That was years ago. I was always skeptical about that theory as well because I was thinking it was like putting your finger over the end of a garden hose and unscrewing it from the faucet. You do not lose the water in the hose when your thumb is over the end. But in the case of mainlines you have enough release so to speak from the taps that the "thumb" is not as tight as it should be, therefore that amount of release allows the fluid to move which in turn creates a vacuum. That's the best I can explain it....Maybe Dr. Tim has the "scientific" theory behind this. ps: 1st year on any sort of vac (started in 1978).

[PerryW]

Farmall,

I have three 3/4 inch mainlines, each with roughly 200 taps. On a good run, each pipe has a stream of sap about the size of one of those grade-school pencils, but the pipe never gets close to being full. Maybe I need more taps??

But I may bite the bullet and put in vacuum if the power company will do it reasonably.

[argohauler]

I know my mainlines need reworking. There's some sag in places and I hate it where a star comes and it's raised up because the wire has to run beside the pipe. I thought of weighing it down somehow. My biggest challenge will be getting the mainlines tighter.

I replaced my swamp tank this year with a bigger tank and it is actually lower than the old one, so I can lower the lines at the tank.

The venting system came from an experiment I did over in the neighbours bush. I was lining into barrels. I'd find a central location with a lot of taps and set it up. I had 5 barrels. I'd set the runs out opposite each other. Each set of 2 runs had 3 drops going into the barrel. I was going to gather a barrel 1 day and I had to go under a line. The sap was just sitting there. I looked at it and I could see some junk in the line and it wasn't moving. I even tapped on the line to see if it was flowing. Nothing. That's when I pulled the cap and away she went. I never figured that system even with vents run as good as the buckets, so I ended going back to buckets. I spent some time observing how the sap ran out of the lines. I found that if one side was a strong running line, the other side wouldn't run. I put them out across from each other attatched because I wasn't sure how I'd attach them to the barrels and keep the lines tight.

[farmall h]

Argo, well..yes of course..you drained the system! PerryW...tap them all. Even the neighbors!! Seriously Argo, it sounds like you got discouraged. Either try it again with a tight system..more taps on laterals or take the plunge and go with vacuum.