Reds on tubing:vented or not vented

[The Sappy Steamer]

I have some 3/4" tubing runs with mostly reds on them.They have great slope, short laterals, 30" drops and about six taps to a lateral. I have seen a marked reduction in my volume compared to when I had the same trees on buckets. Would I benefit by venting my tubing system with the reds? If so how and where should I vent it? I don't and probably never will have vacuum. I thought I would have an increase in volume due to natural vacuum with the amount of slope I have, but lost ground instead. I got about the same amount of sap with twice the amount of trees. But that was last year and we know Ma Nature didn't cooperate. I don't have the time to collect from buckets after work.

[royalmaple]

Here's some information from an old research paper I have: This is NOT my take on it.


In 1967, Blum reported that 43 percent more sap was obtained from closed tubing installations on slopes than from open or vented tubing. He associated this increase with vacuum created in the closed tubing. Gains in sap yield from natural vacuum are especially important since the collection of sap is the most costly and least profitable phase of making maple syrup. Moreover, sap costs for a tubing network are mostly fixed costs; increased sap flow from natural vacuum represents added profit with little or no added cost. Recently, Laing et al. showed that sap produced under high vacuum conditions differed little in chemical composition from sap produced without vacuum. Both produced a syrup of comparable high quality.
While Blum's research results were exciting, they prompted numerous questions to which answers were needed prior to successful field application of natural vacuum and tubing techniques:
1. How do number of tapholes per tube line affect natural vacuum?
2. How does slope affect natural vacuum?
3. How do results vary by season and locality?
4. Where should vacuum be measured?
5. Is natural vacuum more effective at slow or fast flow rates?
6. What limits the production of natural vacuum?
7. What are optimum conditions for natural vacuum?
8. How does production with natural vacuum compare with pumped vacuum?
Our research commenced in 1968 with an initial attempt to answer the first two questions. In succeeding years it was extended to three localities and broadened in scope to gain information on the other questions. Altogether some 4,500 experimental tapholes were used. In addition, tests were made of water flow through tubing in 1970 and 1971 to gain theoretical knowledge concerning vacuum and flow rates so that results of field tests could be properly interpreted. All tests were made with commercial tubing with approximately 0.3 inch inside diameter.
Conclusions
Good natural vacuum in closed maple tubing needs the following:
1. A good, leak-free installation and freedom from rodent damage.
2. A high column of sap to make a good head. An elevation difference of 50 feet or more is best. This can be obtained by steep slopes and/or long lines, as well as sufficient numbers of tapholes per tube line.
3. A fast flow rate, obtained by numerous tap holes per line; vigorous trees; good climatic and weather conditions for sap flow; etc. Within the range tested, vacuum increased with larger numbers of taps; ten taps per line were too few, while best vacuums were obtained with 50 or more taps.
4. Minimum sag in tube lines. Changes in elevation which restrict continuous downhill flow of sap will reduce vacuum in either aerial or ground tube lines.
5. Suitable slopes and proper numbers of tapholes. Five-percent slopes had good vacuums with 50 taps per line; additional taps would likely overload the line. Ten-percent slopes had the best vacuums; 50 to 80 taps were best. Fifteen-percent slopes were not as good as ten-percent slopes, probably because there were too few taps. We believe that a hundred or more taps per tube line are necessary for best results with 15 percent or steeper slopes. On such steep slopes, tubing can be installed at lesser slopes simply by angling it away from the direction of steepest topography. On the other hand, good installations are difficult on slopes of less than 5 percent, and we recommend the use of pumped vacuum where feasible. It is also important to avoid shallow slopes in the lower and middle portions of tubing installations.
Gains in sap production tended to be proportional to increased vacuum, whether natural or pumped. Both experimental and commercial results suggest seasonal sap gains of 1 to 2 quarts per taphole for each inch of vacuum (33 to nearly 100 percent). The lower gains are associated with natural vacuum, poor seasons, and low-producing localities and bushes. The better gains may be achieved with pumped vacuum, good seasons, and high-production trees.
Both the requirements for and potential sap gains from natural vacuum indicate the need for evaluation and proper use of slope for maple tube installations. Steep slopes, poorly regarded in the past, may now be considered assets.

[royalmaple]

Now my .02, which is worth much less than that.

I don't have 10% or 15% slopes, and certainly not with 50 or 100 taps per latteral. So my take on natural vacuum is going to be different than someone trying to get it. But even in the research paper is states it was "associated" to be natural vacuum. And at no point did they make any remarks to specific vacuum levels.

So smoke and mirrors? I have no idea. But I have done a test using a shop vac and they pull 2.5 inches of vacuum and I think we have all put our hands over a shop vac so you know what that feels like. And there is research out there that shows that sap yields are not increased significantly until around 10 inches. I would love to have someone show me a vacuum guage at the end of a gravity tubing system pulling 10+ inches of mercury(4x stronger than a shop vac). Even 5 inches. I just don't see it happening. But that is just my take on it, I am more than willing to say I am wrong, but I have nothing to test it on.

Has anyone ever had a vacuum guage on the end of a latteral? I'd really like to know what you found on a good flow day.

[WESTVIRGINIAMAPLER]

Even with any sap flow, you are creating a very small amount of vaccum which means it is sucking air into the lines and that means pulling bacteria and other foreign substances inside the system.

[PATheron]

Sappy steamer- Ive run small number of taps hobbying for many years. My experiance has been this. I got more sap running buckets than I did using tubing. Im not sure why but that has been my experiance and Ive had others tell me the same thing. Id use 4 gal buckets and the sap yield varied for sure from tree to tree but quite often there was quite a bit more than a gal per tap. Some taps would fill a bucket. When I went to tubing on a good run day I get a gallon per tap. That is pretty much how it has worked for me. I ran my tubing with a max of 15-20 taps per lat and always did it nonvented. I believe that is pretty much to book standards. I do think that youll do better for sure not venting it. I know some producers say to run the tube like its for vac with fewer taps per lat so theres varying opinions but I doubt youll do much better than that yield no matter how you do it. What Ive done when I did buckets is used a dumping station by taking a 55 gal drum and putting a nipple on the bottom to go to water line and running that off the hill to a drum closer to the road etc to collect. That worked good. The advantage of the tubing is makes it piece of cake to get the sap but im thinking use the gal per tap figure and if you want more sap put in more taps. Theron

[royalmaple]

Sappy I was going to ask you if you were using 7/16 or 5/16 because it has been proven that 7/16 on gravity will run more than 5/16.

Whole different story on vacuum.

[gmcooper]

From a session with Glenn Goodrich this fall, unless less my hearing totally failed me. The opinion was to not vent. The one big issue was that venting introduces air in to the system which inturn introduces bacteria. Introducing air also can lead to tap holes drying faster. The bacteria is the biggest issue and that alone will cause the taps to stop sooner and also lead to poorer quality sap.

Having gone from gravity to vacuum several years ago 2 things that come to mind are:
1) when the vacuum started I found several leaking fittings and taps that I never would have found. So I did have some unintentional venting.
2) I also found a few plugged fittings that had some kind of "junk" in them or wood chips.

Just my 2 cents
Mark

[The Sappy Steamer]

Thanks for the posts guys. I did alot of reading about tubing installation and believe I've got things just about ideal. I just didn't know if reds responded differently on tubing than sugars or if the pressures they generate were less than sugars, or maybe they don't flow heavy enough to create a natural vacuum. I would think ANY flow would create some natural vacuum on a steep slope like mine(maybe 15%) Well, I did add another 75 or so taps for this year, so maybe I'll be pleasantly suprised. I guess the bottom line is to not vent and enjoy the convenience of being able to collect from just a couple of tanks.

[royalmaple]

Sappy-

You got it, you have to look at it that way. When you get a good run you'll have sap. And all in one spot. Super savings.

I will say from experience that on great run days I got sap from reds on buckets, some very decent, but unless I had ideal conditions it was dismal going to collect buckets on reds, sugars always did better. Gravity tubing on reds was about the same, but I looked at the collection aspect and not screwing around with a five gallon bucket in waist deep snow going bucket to bucket collecting.

Now add a vacuum pump to them and you'll fall back in love in a few minutes. Ahhh you just want to reach out and give them a big hug. Gotta think vacuum, you won't believe the difference. And until you take the jump you'll think we are just giving you another line of BS, but that one is the truth. 99% of the rest is bogus.

[The Sappy Steamer]

Matt,
Is the difference between using 5/16 and 7/16 taps a substantial difference? Now that you brought that up, I did change over to all 5/16. Maybe there's more to the equation than just going to tubing. Very interesting. I wonder if it's worthwhile swapping back. I'm half tempted, especially if I still have some taps. I was under the impression that 7/16 were sort of being phased out. Is that true? I did see a big difference in the time it took for the tap holes to heal. I did find a couple small vacuum leaks where the tubing meets the fittings and I did fix those. The other thing I did was sterilize all my tap holes and now I read in the Maple Syrup Producers Manual that they have found that has a tendency to dry out your tap holes sooner. Well, I've got some stuff to mess around with and compare.

[Breezy Lane Sugarworks]

I haven't read any studies but have heard that the 7/16 on gravity can produce as much a 20% more sap than the 5/16 on gravity.

[The Sappy Steamer]

Man, 20% is quite a bit of sap increase for the little work it is. I don't know if I'm going to get around to it before I tap this year, but I would sure like to. I'm going to order some taps anyway, just in case I get my act together early and get a chance to change things. I sure wish I didn't just buy two new 5/16 tapping bits last week. That's o.k., throwing away money is one of my favorite things to do. And gosh darn it, I'm just plain good at it!

[PATheron]

Sappy- I think the 7/16 will do a bit more on gravity too for sure. I like your attitude. Im not bragging or anything but I think ive taken wasting money to whole new level. You come down to Pa and Ill show you what wasting money is all about. Theron

[mountainvan]

When they first came out with 5/16 I experimented with them vs 7/16. 3 taps/tree going into a 5 gal bucket. They 7/16 did give a little more sap, but... 7/16 dryed up sooner, so without reaming the 5/16 gave as much sap throughout the season, and the 5/16 hole healed up in a year or less vs two years for 7/16. I switched over the next year.

[WESTVIRGINIAMAPLER]

There you have the final word from the expert himself! I'm like Van, I like to experiment with things. Guess that is why I am always changing or trying to improve something.

[Breezy Lane Sugarworks]

That's the only way that new and better things get developed......EXPERIMENTATION!!!!

[The Sappy Steamer]

Yeah, I really enjoy the experimentation part myself. That's what got me roped into this sugaring thing in the first place. I know... I'll just hang a couple buckets on maple trees, just to see if I can make maple syrup. What the...why the...how the...what happened? Gotta love that experimentation stuff!

[Sugarmaker]

Theron,
You dont have a corner on the wasting money thing.
And experiment, well you guys got me completely changed over to gravity tubing (not vented) using 5/16 splies this year if this doesn't work your going to hear about it!:) Hoping for 2 gal. per tap on a good run and easier collection on all runs.:D

Chris

[PATheron]

Chris- Your right. It just seems that way at times. I hope you get the two gallons. The roadsides like you tap should run better than anything else so hopefully well get a good season and youll have tons of sap to boil. The main thing is itll be way easier for you to collect. Theron

[jemsklein]

now i have about a 150 foot drop from the top of the main line to the end of the main line but i don't think i need to vent cuz there is lots of natural vacumme