CV's and Dropline changing

[palmer4th]

I was wondering if anyone can explain why people are saying changing drops can be beneficial if your using check valves? I thought the point of the check valve was to prevent sap in the line from re entering the tap holes, thus no bacteria from the lines should enter the hole??? what am I missing?

[mapleguy]

Interested in hearing some comments on this. I've been using cv's with old drops and have had unbelievable success and I'm all gravity too.

[WESTMAPLES]

yeah im interested in hearing what others have to say on this topic also. maybe dr Tim could shed some light on the subject.

[CharlieVT]

[QUOTE=palmer4th;239026]I was wondering if anyone can explain why people are saying changing drops can be beneficial if your using check valves? I thought the point of the check valve was to prevent sap in the line from re entering the tap holes, thus no bacteria from the lines should enter the hole?,,,,QUOTE]

Here's some Proctor research published in Maple Digest in 2010:
http://www.uvm.edu/~pmrc/aging.pdf

A quote from the above article: "Based upon that work, as well as
our own previous work (Perkins 2009, Perkins unpublished), we anticipate that
CV adapters will show significant improvements in sap yields when used on old
drops as well as when used in combination with new drops."

If there is research that specifically compares new CVs on new drops to new CVs on old drops, I don't recall seeing it. Anyone have a link to such a publication?

[palmer4th]

That is a good article, I thought there was a newer article also published in the maple digest. I may be mistaken but I thought from the information I have read they are saying for the highest sap yield you have to replace the tap and drop? (I know there are lots of factors involved in deciding when drops need to be replaced).... My question is if you use a new CV spouts every year how can your sap yields go down in comparison to using new CV's and new drops drops. I understand that if your not replacing or cleaning your tubing the quality of your sap could suffer. However if the check valve is working properly why would it matter if its brand new tubing or old tubing?

[DrTimPerkins]

I was wondering if anyone can explain why people are saying changing drops can be beneficial if your using check valves? I thought the point of the check valve was to prevent sap in the line from re entering the tap holes, thus no bacteria from the lines should enter the hole??? what am I missing?

There is an article in the current Maple News with information about dropline replacement interval if you are NOT using CV adapters or spouts. While there have been several papers written with related info, and I've specifically addressed this in many presentations, I can't at the moment think of something easy to point to that answers your question about changing droplines with CVs. With that in mind, see the attached figure (below). It shows sap yields in 4 sections of our "main bush" area over the 2013 season. All were dual-conductor systems on one common pump (separate releasers so we can quantify the sap volume) running an average of 25.7" Hg over the season....and not shut off at any point during the season. The different sections have droplines that are new (0 yrs old), 2 yrs old, 4 yrs old, and 10 yrs old. All were tapped with CV2 spouts at the same time and operated exactly the same. There was no significant difference in sap yields on these systems, with sap yields averaging 30.5 gal/tap. There is no apparent slowdown of sap flow (as we would expect with contaminated systems without CVs) right through the end of the season. In a nearby section of our woods with 8 yr old spouts/drops (non-CV spouts), we got 23.5 gal/tap. In short, age of dropline had no impact on sap yield if using CV spouts, at least out to droplines that were 10 yrs old. At that point it might begin to make sense to replace droplines just due to tubing or fitting breakdown. This would be indicated by breakage or tubing coming off fittings.

CV2 and dropline age.jpg

[CharlieVT]

Isn't it pretty amazing that a bunch of sap suckers can ask a question online, and shortly get our own resident PhD maple-ologist to reply? Sweet!

Thanks to you Dr. Perkins.

[WESTMAPLES]

thank you dr Tim, that was everybit of information I was looking to have answered . I like to read your responses, they always make sense out of hard to answer questions.

[cur dog]

Wouldn't the best numbers be taken from a bush that shuts its vacuum off, during periods of freezing weather. When the vacuum never stops, it seems you would get good results on regular spouts. Is there data available showing a bush using CV's with new and older drops, and an on, off vacuum routine, like many producers use?

[sjdoyon]

thanks Dr. Perkins, we're coming on our fourth season with our CV drop lines and wasn't looking forward to replacing them next summer. We now can wait a few more years.

There is an article in the current Maple News with information about dropline replacement interval if you are NOT using CV adapters or spouts. While there have been several papers written with related info, and I've specifically addressed this in many presentations, I can't at the moment think of something easy to point to that answers your question about changing droplines with CVs. With that in mind, see the attached figure (below). It shows sap yields in 4 sections of our "main bush" area over the 2013 season. All were dual-conductor systems on one common pump (separate releasers so we can quantify the sap volume) running an average of 25.7" Hg over the season....and not shut off at any point during the season. The different sections have droplines that are new (0 yrs old), 2 yrs old, 4 yrs old, and 10 yrs old. All were tapped with CV2 spouts at the same time and operated exactly the same. There was no significant difference in sap yields on these systems, with sap yields averaging 30.5 gal/tap. There is no apparent slowdown of sap flow (as we would expect with contaminated systems without CVs) right through the end of the season. In a nearby section of our woods with 8 yr old spouts/drops (non-CV spouts), we got 23.5 gal/tap. In short, age of dropline had no impact on sap yield if using CV spouts, at least out to droplines that were 10 yrs old. At that point it might begin to make sense to replace droplines just due to tubing or fitting breakdown. This would be indicated by breakage or tubing coming off fittings.

Attachment 8686