Increasing yield with larger mainline

[WestfordSugarworks]

Those wishing to attain high sap yields install tubing systems that have wet and dry lines (usually larger than 1"), with mainlines (usually 1") that connect to the wet and dry line. I am wondering if any of you have thought of using mainline larger than 1" instead of a traditional 1" mainline, with the intention of maintaining higher cfm and being able to keep a higher level of vacuum, and getting more sap. I don't have Steve Childs' vacuum book in front of me, but I do believe that when pulling high cfm, you lose a considerable amount of cfm due to line loss over a 1000' length of 1" mainline. A 1 1/4" or 1 1/2" mainline that branches off from wet dry lines would be capable of maintaining a higher level of cfm. Perhaps it wouldn't matter much at the beginning of the mainline, but at the end there would be less line loss. Using larger diameter pipe as mainline would be expensive, i'm not sure how much more expensive, but if sap yields are higher than it would pay for itself, especially since mainlines often sit in the woods for 15 or more years and don't get replaced often. Anyone tried this or know of someone who has? Most of our mainlines are under 1000' in length but on some of the longer ones that stretch all the way to the property line, I wonder if we could have used a larger diameter pipe and attained a higher long term yield and profit.
Thanks and good luck to all as you begin/continue tapping.

[DrTimPerkins]

Not sure of your question exactly, and apologies for the brief reply (I'm traveling and using my phone to reply).

If you are suggesting a single-pipe, but larger size mainline, keep in mind that a 1.5" pipe half filled with sap carries far less CFM than the full open pipe will. In addition, any areas with turbulence or worse, sags, or worse still, frozen sections, will suffer from quite high sap and air transfer resistances, resulting in yield reductions. A dual-pipe system is less susceptible to these problems. Although there is far more research to be done on the precise reasons, dual-pipe systems are associated with an increase in sap yield of about 10%.

[WestfordSugarworks]

Dr. Tim,

To be specific, my question is about using larger mainlines that branch off of the wet-dry lines (dual lines). For example, we installed a 3 inch dry line and 2 inch wet line system that connects to 1 inch mainlines. I'm wondering about using larger mainlines- instead of 1 inch perhaps someone would use 1 1/4" or 1 1/2" to allow for better cfm movement. With our 3 inch dry line, we are providing great cfm to the bottom of the 1 inch mainlines, but because of line loss the cfm is much lower at the end of the mainline. If on some of our longer lengths of mainline we had used a larger diameter pipe, maybe that would have been better and resulted in a higher yield.

I have heard bad things about using a large single pipe instead of a dual line system. We installed dual line systems and are happy that we chose large diameter pipes.

Thanks

[DrTimPerkins]

Mainlines should be "right-sized". Going too large means hotter, and thus lower quality sap.

[WestfordSugarworks]

Okay, this is because sap moving in an over sized pipe is more spread out and therefore more easily heated by air/the sun?