Gravity Releaser?

[mapleman3]

Tell ya what, if you can get that thing to work, you could probably make a fortune, it's amazing what they get for some plastic tubes, plastic cement and O-rings. the main thing is .. can it withstand the Vacuum, negetive pressure sure is an amazing thing, look at what it does to an 18 wheeler stainless milktank if the milk is let out with out venting, implodes like a tin can. I had drawn up a few things too but got nowhere fast, I couldn't think of how to overcome the vacuum and when it did, how to have it close tight enough to start it again.. all with being able to not have the vessel implode 8O :wink:

[Maple Hill Sugarhouse]

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[Maple Hill Sugarhouse]

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[Maple Hill Sugarhouse]

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[Russ]

If you go to my album, you can see a crude drawing of the gravity releaser that has been discussed here. I talked to the user of the system last night; here are the specs that go with the picture:

- 3" PVC tower is 30' high.
- Four 1" mainline fittings are 5 feet down from the top of the PVC tower.
- Barrel is a 55 gallon drum, cut in half.
- A 1/16" hole is drilled at the beginning of the upslope on each mainline to allow the vacuum to grab some air to lift the sap.
- They run 20" of vacuum at the pump.
- It takes about 15 gallons of sap in the barrel to prime the column, plus have some left in the barrel to prevent sucking air from the bottom of the PVC tower.

My brother has attempted to build a 8'high 8" wide PVC tower, but recent research on how vacuums work may indicate that a wider column does not make a difference in the height required. Plan B is to have a 30' 3" tower built by next weekend, so we can test that as well. As I stated earlier, I will post our findings and perhaps some pictures as well.

[Mr Bill]

The gravity releaser is a clever idea. Unfortunately, you can't get something for nothing in this world and this is no exception.

If the trees are significantly below the height the mainline connects into the releaser pipe/tower, you will not have much vacuum at the trees.

So, if the tower is 25 ft. tall,
the ground is flat so the tower/pipe base and tree bases are all at the same elevation,
the main line connects at the 22 ft point,
20 in-Hg of vacuum is pulled at the top of the tower
and the trees are tapped 3 feet above the base,
then when the mainline is full and dumping into the releaser tower, the vacuum at your trees will only be about 3 in-Hg.

It's just like trying to run a drop line uphill. With sap, roughly 1 inch Hg of vacuum equates with 1 foot of height. If the drop line runs uphill to about 18 feet elevation difference and the vacuum at the top of the hill is 20 inches of mercury (in-Hg), then you will only have about 2 in-Hg of vacuum at the tree tap.

If the releaser tower can be positioned at the bottom of a hill such that the mainline connection to the pipe is at or below the elevation of the taps on the trees, then there won’t be any compromise in vacuum at the trees. Of course you wouldn’t need a vacuum system either since with full tubing that runs to the base of the tower, the gravity flow could pull 20 in-Hg or better anyway.

With respect to the notion that using a bigger diameter pipe will allow it to be shorter, unfortunately it doesn't work this way. Vacuum is a pressure – that is force per unit of area. The height a given vacuum will raise the sap in the pipe is irrelevant to pipe diameter. Sure, the fatter the pipe the more the sap weighs but since vacuum is a pressure, the fatter the pipe the more area the pressure has to work on and this offsets the increased weight exactly. Sorry.

[brookledge]

Physics 101 good point

[Russ]

I'll concede on the wider diameter pipe point. As for the rest of the concept, with the 30' PVC tower and the rest of the design, I have been told that it does work. I'll have to check on the slope versus level ground point; our implementation will be on a slope. We still want to apply vacuum to improve the flow, and will utilize Kevin's vacuum booster design to help in that regard as well. I thought sap ladders were a crazy idea too, until I heard of all the people that are using them. I guess it's wait and see.

I better get to bed. I'll be up at three; son #1 and I are headed up to the sugar shack (210 miles) for the test boil tomorrow. Got the camera and camcorder packed already.

[mapleman3]

210 miles 8O you must stay there the whole sugar season WOW my hats off to you Russ :wink:

[Brian]

I have about 60-70 taps below the sugar house and also to far down for a sap ladder. They run gravity into a tank, so I am going to hook vacuum from the releaser and run 1 inch plastic down to the upper side of the main line and put in a check valve at the bottom of the main line and i hope as the sap runs down and fills the main line, in time the weight of the sap will overtake the check valve and dump some sap every once in awhile. Then at night when the vacuum is off it will dump out.