So why not boil/clean/sterilize adapters and reuse them?

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Originally Posted by blissville maples

So with this pressure you speak of is this in a gravity or vacuum system? There wouldn't be pressure if the vacuum pump has created a 25+ inch vac inside tree, there would be vacuum? So when the line freezes wouldn't the tree pull back not push out?

QUOTE=DrTimPerkins;339058]Although that could happen, it seems like a fairly unusual (at least not common) type of thing. Seems like perhaps your mainline either runs through a really cold spot or maybe has a high spot somewhere that doesn't allow it to drain properly. Either way, yes, it could result in backflow. However, keep in mind that if the trees are still thawed and sap is running then it means that there is PRESSURE within the tree for a good period of time as the lines freeze up, thus there should not be much of any sap moving backward at this time.

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As Dr. Tim stated, if the tree is thawed, it is under pressure from the column of liquid above the taphole pushing down under gravity. When the tree freezes an internal vacuum is created. The situation he was referring to is when the tubing will often freeze before the tree does.

Under freeze/thaw sap flow conditions, sap is flowing from the taphole under pressure, even with vacuum tubing. Without a freeze, then sap then begins to be extracted from the tree under vacuum.

Yes the tree will build pressure, I guess what I meant is after 3 days of vacuum pump wouldn't that reduce the pressure in the tree to minimal or a vacuum(as was previously stated in this forum) and when this happens the tree will tend to pull sap back in and not push it out- so when an ice jam forms in the lateral or mainline the tree(behind the ice jam) will at some point have more vac in it than the line......I have been told to leave pumps on to reduce sap back flow but in the above situation leaving the pump on wouldn't necessarily reduce backflow, or itleast that's how it would seem to me......

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Originally Posted by blissville maples

I have been told to leave pumps on to reduce sap back flow but in the above situation leaving the pump on wouldn't necessarily reduce backflow, or itleast that's how it would seem to me......

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"Don't waste money on checkvalves, leave the pump run, does the same thing". has been cropping up more and more by non-Leader salesmen.

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Originally Posted by markcasper

"Don't waste money on checkvalves, leave the pump run, does the same thing". has been cropping up more and more by non-Leader salesmen.

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I've had quite a few interesting lessons on the way business works in the last 7-10 years. It basically comes down to "all is fair in love and sales." :rolleyes: What else are they going to tell you....go shop at Leader Evaporator?

The reality is that different people with a range of operations, equipment, and pump/leak management styles will have different experiences and a range in the amount of benefit they will experience. What is telling (I think) is that all three major maple research organizations have done studies showing that they do work.

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Originally Posted by blissville maples

... and when this happens the tree will tend to pull sap back in and not push it out- so when an ice jam forms in the lateral or mainline the tree(behind the ice jam) will at some point have more vac in it than the line......I have been told to leave pumps on to reduce sap back flow but in the above situation leaving the pump on wouldn't necessarily reduce backflow, or itleast that's how it would seem to me......

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You are exactly right. That is one of the reasons why putting a check-valve in the lateral line near the mainline (as some have recently suggested) might help a bit under certain circumstances, but doesn't solve the problem entirely. The only way to ensure sap won't flow back into a tree is to put the valve as close as possible to each individual tree. All the things people have suggested (leaving pumps on all the time, use an electric releaser, use new spouts each year, replace droplines periodically) will HELP to reduce backflow or the consequences of backflow, but none of them eliminate (at least to a substantial degree) backflow into the tree like the CV does. Power going off and squirrels chewing lines are pretty common things....leaving your pump on if the power goes off doesn't do much for you. Unless you've got extra nice squirrels who only chew the laterals before the inline check-valve, then you'll have backflow. Maybe branches only fall on your mainlines...but never your lateral lines and pull fittings off.

The CV system is insurance...some people like the extra protection (and higher sap yields that come with it), some don't, but for vacuum users, I don't ever recall a scenario where the CV system didn't pay off in terms of extra yield and extra net profit to the producer beyond that of replacing spouts alone. The one exception might be gravity producers (I'm not talking about natural vacuum here....backflow occurs in 3/16" systems too...even more so than 5/16" systems). In some years the sap yields on gravity are just too low to justify the added cost, so the net economic benefit is close to zero or even slightly negative occasionally), but there is no way to predict when that'll happen ahead of time. It is more a simple matter of low yield in that case than the CV (which was designed for vacuum use) not doing its job.

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Originally Posted by markcasper

"Don't waste money on checkvalves, leave the pump run, does the same thing". has been cropping up more and more by non-Leader salesmen.

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Leaving the pump on continuous and having an electric releaser will work most of the time. There are however, situations throughout the season that backflow will still occur. I have seen it. What happens when a fitting pulls apart and you instantly lose a few inches of vacuum really fast? Where is that sap in the lateral lines going then? Definitely not toward the releaser. When a manifold or fitting freezes because of a leak before it reaches freezing. When you lose power when the sap is running and the pump is off for some time. Releaser freeze ups and malfunctions. Pump breakdown. These are the times when check valves do their job. I use them. They work. Not only do you gain at the end of the season, but the small gains start somewhere about midway through the season and grow bigger with each run. It's pretty much the same every year. The first half of the season (early), you get small to medium runs, then somewhere around halfway through the season the trees get totally thawed and you get a major temp swing and a blowout run. After this run, cvs keep going strong, while traditional spouts slowly start losing yield. It's almost unnoticeable at first, but with each run the difference is greater and greater. Our best run last year was on Mar 30 and we started tapping on Dec 30. I know that would not have been the case without using cvs.
I just wish quality control would get better with them. Each year I find an issue. I'm not done tapping yet, but I already have over 600 out of 7,000 that are not going in the tree. They are going back to leader. The balls do not move freely in them. They stick. I inspect and shake every one before it gets put on the dropline. I feel for the price of them, you should be able to pull them out of the bag and use them without a thorough inspection.
Neil

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Originally Posted by DrTimPerkins

You are exactly right. That is one of the reasons why putting a check-valve in the lateral line near the mainline (as some have recently suggested) might help a bit under certain circumstances, but doesn't solve the problem entirely. The only way to ensure sap won't flow back into a tree is to put the valve as close as possible to each individual tree. All the things people have suggested (leaving pumps on all the time, use an electric releaser, use new spouts each year, replace droplines periodically) will HELP to reduce backflow or the consequences of backflow, but none of them eliminate (at least to a substantial degree) backflow into the tree like the CV does. Power going off and squirrels chewing lines are pretty common things....leaving your pump on if the power goes off doesn't do much for you. Unless you've got extra nice squirrels who only chew the laterals before the inline check-valve, then you'll have backflow. Maybe branches only fall on your mainlines...but never your lateral lines and pull fittings off.

The CV system is insurance...some people like the extra protection (and higher sap yields that come with it), some don't, but for vacuum users, I don't ever recall a scenario where the CV system didn't pay off in terms of extra yield and extra net profit to the producer beyond that of replacing spouts alone. The one exception might be gravity producers (I'm not talking about natural vacuum here....backflow occurs in 3/16" systems too...even more so than 5/16" systems). In some years the sap yields on gravity are just too low to justify the added cost, so the net economic benefit is close to zero or even slightly negative occasionally), but there is no way to predict when that'll happen ahead of time. It is more a simple matter of low yield in that case than the CV (which was designed for vacuum use) not doing its job.

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Ok so during freeze/thaw sap flow, there is an internal vacuum in the trees tissue when it freezes, and when it then thaws, pressure builds in the trees tissue under gravity as the tree thaws. I'm sure there is nuance to this, but that is my general understanding of the mechanism. When a tree is freezing can it overcome the mechanical vacuum induced at the taphole? And if a tree is thawed for several days and one is still getting sap flow under mechanical vacuum, at this point is the vacuum level in the tree equivalent to that in the tubing?

It seems that some of this discussion is more related to mechanics occurring in the tubing system as it freezes, but I know you have a better understanding now of what is going on in the tree during sap flow and how it is affected by vacuum.

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Originally Posted by DrTimPerkins

I've had quite a few interesting lessons on the way business works in the last 7-10 years. It basically comes down to "all is fair in love and sales." :rolleyes: What else are they going to tell you....go shop at Leader Evaporator?

The reality is that different people with a range of operations, equipment, and pump/leak management styles will have different experiences and a range in the amount of benefit they will experience. What is telling (I think) is that all three major maple research organizations have done studies showing that they do work.

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I have had dealers from non Leader outlets say they know the CV2 spouts are best but they have to push their product instead. I have dealer friends that would love to use the CV2 spout but they want to keep their jobs. We tease each other about it. When a dealer or sugar maker tells you that leaving the pump on is just as good as using a check valve then you know they have little understanding in the sap extracting process.

Spud

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Originally Posted by GeneralStark

It seems that some of this discussion is more related to mechanics occurring in the tubing system as it freezes, but I know you have a better understanding now of what is going on in the tree during sap flow and how it is affected by vacuum.

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Both the mechanics of the tubing/vacuum system and the mechanics (physiology) of the tree are involved, and there are so many different permutations that it is difficult to generalize enough to cover all of them, however there are certainly times when a freeze-up can result in backflow of sap. Leaving the pump on will minimize it to some degree...but probably never eliminate it.

Essentially, all the different things that people do have some effect in term of minimizing backflow. Not shutting off pumps helps. Using an electric releaser compared to a mechanical releaser helps. Using new spouts helps. Cleaning (chemical sanitizing) helps. Periodic replacement of drops helps. Use of CV helps. In all cases, the goal is to have a very clean taphole and to keep it clean by minimizing (or eliminating to a high degree) the entry of microbes from the tubing system (primarily the dropline in 5/16" tubing, both dropline and lateral line in 3/16" tubing) back into the taphole where they will collect and grow, inducing a wound-response in the wood tissues which will physically and chemically "wall off" the surrounding tissues (resulting in the "stain" or brown wood we see around the taphole). This renders that area non-conductive of sap, starts to happen fairly quickly, and is progressive during the season. The reason trees do this is to prevent infection from spreading throughout the wood tissue. By "walling off" or compartmentalizing the affected tissues, the tree prevents the infection. The result that is more important to the maple producer is that this zone of affected tissue is less, and eventually, non-conductive to sap. In effect, the taphole has "dried out."

Some (most) of the backflow occurrences are very small/short, only a matter of an inch or two max. That is why simply replacing spouts has a sizeable effect. Most other backflow events are a bit larger, such as when the tree freezes up, or you have a small leak, or any of a number of other things. In those cases, backflow can be from several inches to a foot...but usually not more than 15" (5/16" tubing) or several feet (3/16" tubing). This is why changing the dropline helps so much. In some cases, if you get a major leak or the pump shuts off or your releaser fails, you can have sap flow back tens of feet, although this is quite rare, and should be avoided as much as possible. In all these cases though, no matter the source, the CV and its position as close to the taphole as possible, largely prevents backwards sap movement, thus providing some level of protection to the taphole.

With all of these approaches, there is a range of cost and benefit (both in terms of sap yield and net profit) in any strategy or combination of strategies. Some of it due to material cost, some of it due to labor costs. CV adapters/spouts cost more up front for the material. The other approaches (cleaning, drop replacement) cost some for the material, but generally cost quite a bit more on the labor side.

I can say that while our early studies were mostly done with a mechanical releaser, we've used an electric releaser for the past several years, and for a long time we have hardly ever shut off a pump during the season unless we get a good freeze that is forecast to last several days. Most of the time it gets turned after we tap, and shut off after we pull spouts. We still see a positive benefit to using CV in that setting...and we don't tend to make much of any commercial syrup. We stop before getting to that point. About the only time we use non-CV spouts is if the study calls for that, or if we want something to compare CV to, or if the tubing system is new. In a good chunk of our woods, we have drops that are 5-8+ yrs old now that produce as well as 2 yr old drops. We don't see much need to change them out unless the fittings start to fail.

HOPEFULLY we will have the final report of the joint UVM/Cornell sanitation study out shortly after the 2018 sugaring season. It will include a spreadsheet tool to allow producers to plug in their own values and play around with the different approaches and see what the estimated effect is on sap yield and net profit. Stay tuned.

Thank you Dr. Perkins for your explanation. I have trialled the CV spouts since they were available and continue to see benefits when the system is on its second year or more. My experiments have always been small in nature due to the small amount of taps I have. The CV spouts continue to amaze me, they run longer and the difference can be seen in the tap hole when you pull the spout. I look forward to the report.