check valves

[FunnyFarm]

I could be beating a dead horse here but I am curious if anyone has tried instead of using the check valve taps just putting one on the lateral lines? this could possibly save a few bucks and might work as well.

[mapleack]

Yes they have. Research has shown that with a check valve farther down a lateral there will still be sap re-absorption from the drop line, leading to contamination of the tap holes.

[maple flats]

The first test by Cornell was with in line check valves on gravity systems. They proved to be an improvement over just gravity. One problem is that there is no check valve Cornell could find at the time that even came close to what has now become the CV adapter. What are you going to use that costs less than $.35, and is it food grade?
Last year I used CV's on gravity and I was not impressed. The taps didn't dry up sooner but the sap flow was less (because of restriction?). I might be wrong, but I'm thinking I will use CV's on my vacuum but not on my gravity. On the gravity I plan to use all new drops.

[DrTimPerkins]

The first test by Cornell was with in line check valves on gravity systems. They proved to be an improvement over just gravity. One problem is that there is no check valve Cornell could find at the time that even came close to what has now become the CV adapter. What are you going to use that costs less than $.35, and is it food grade?
Last year I used CV's on gravity and I was not impressed. The taps didn't dry up sooner but the sap flow was less (because of restriction?). I might be wrong, but I'm thinking I will use CV's on my vacuum but not on my gravity. On the gravity I plan to use all new drops.

The CV spout adapter was designed for use with vacuum. We've (UVM) never studied it on gravity, but as described, Steve Childs of Cornell University has. Any benefit seen on gravity system is just naturally going to be far smaller on gravity than on vacuum.

Theoretically, the only time that gravity tubing systems would be conveyed any protection by the CV spout adapter from microbes moving back in the system would be during the water absorption phase during freeze-ups when sap might be sucked back up the dropline. Given the very small number of re-freeze periods we had last season (2010), any benefit would have been correspondingly very small. In a more typical season, a larger benefit might be observed, but again, this would be smaller than that seen on a vacuum system.

[red maples]

so then it you might as well use a seasonal spout which run roughly $.25 each instead of a stubby and seasonal adapter then for gravity. Thats what I am doing anyway. Even though there is a +- vacuum at site of the tap hole when the sap flows slows there is stilll more of a chance for sepage past the check valve.

[adk1]

I bought the CV's for my taps, and this is my first year. everything new and I am on gravity. But I am also only tapping 120+ trees. I just like the idea that it "might" prolong my season. I need a long season with only tapping 120!