3/16 tubing on a 2% grade your opinion please

[killingworthmaple]

I have a 400 ft long narrow patch of woods with about 100 taps. What do you think would happen if I used 3/16 tubing on a 2% grade slope. Is a little vacuum better than no vacuum at all? I am interested in any and all opinions. It will be an all gravity set up.

Thanks
Nathan

[BreezyHill]

Production wise some will be better than none. The issue will be if you will get enough to make a difference.
from gravity to 15"is an increase of 151% in production with an additional 5-7% for every inch over 15" of vacuum.

My crystal balls tells me that you will end up putting in a pump of some sort down the road. So what I would suggest is to design the bush so that you can install a mains and hook up a pump. Weather it is a diaphragm pump or a vacuum pump and releaser system or a zero tank...time will tell.

It is just more and more producers add on a pump to a gravity system to feed their addiction to maple boiling.

[maple flats]

According to a post by Dr. Tim, it does not matter much what the % drop in elevation, as long as you have 30' fall after the lowest tap. If you can't get that, then some vacuum is still better than no vacuum.

[WESTVIRGINIAMAPLER]

I think Dave meant 30' fall after lowest tap, not 30".

[maple flats]

Thanks Brandon, I corrected it. Someday I should but likely won't proof read after I type, you are correct, 30' fall after the lowest tap gives the best vacuum.

[killingworthmaple]

I don't have any drop after the last tap to the tank it's a long flat area. Thanks for the replys and keep them coming.

Nathan

[maple flats]

Nathan, that may be an issue. Let's see if Dr Tim can give some input on this.

[DrTimPerkins]

2% grade is quite low. Although there has not been a lot of research with 3/16" tubing on low slopes, it should probably not be used on minimal slopes because it can cause backpressure, reducing sap yield. Same thing can happen with 5/16" tubing, but there is a little more room for error with 5/16" on low slopes.

[asknupp]

I had the same concerns earlier in the week and got some of the same replies. I'll be using 5/16 from here on out. The only places I have 30' of fall is down water cut ravines to the rivers edge. I'm not hauling sap up out of there.lol

[Thompson's Tree Farm]

You do not need 30 feet of fall to get a big improvement. You need 30 feet of fall to get maximum vacuum. If half of my taps had 15 feet of fall or more, I would figure the natural vacuum created would create enough extra sap flow to be well worth doing I would use the 3/16 on the top half and then run that line to my tank and a separate line for the lower trees.

[DrTimPerkins]

You do not need 30 feet of fall to get a big improvement.

That is correct. However minimum slopes will cause some backpressure whether in 3/16" or 5/16" lines, but there will be more backpressure in the smaller lines on flat ground due to the increased friction in the 3/16" lines.

If you had low slope, but with a good fall at the end of the line, then it wouldn't be a problem. But a long stretch over flat ground without much of any slope is not suitable for 3/16" tubing.

[maplejunction]

Is there a good rule of thumb, say from the last tap there is 10' or 15' elevation drop to your tank, but the tank is 100' away. Would this be a better 5/16 or 3/16' situation?

Richard