Problem solving: pressure in the lines

[Thad Blaisdell]

Last year was crazy how many days I had as much as 30 lbs of pressure in the lines. Spouts out everywhere. This is the creation I came up with to solve this issue. I have sensors in the woods so I also made these so that the sensor would connect to it making it so that no liquid could get in the line.

These will be attached at the far end of every main line. Connected to mainline with 5/16. The check valve will be horizontal. Bottom saddle to mainline, top saddle will go to sensor.

Sharing so that makes be someone else might be helped by this

19546

[hogisland42]

What is creating the pressure in your lines? I am curious, I have never had that problem

[GeneralStark]

What is creating the pressure in your lines? I am curious, I have never had that problem

Lines freezing and trees still running...

Interesting concept. Keep us posted in how it works.

[blissville maples]

With proper slope of lines, this really shouldn't be an issue too bad. As tree builds pressure from getting warm, the frozen sap in the drops starts thawing and frees up allowing pressure not to build. However If your mainline is not sloped correctly and you have a low spot that freezes, this will not thaw as the trees build pressure, could be hours before a mainline unthaws.

[blissville maples]

Do you drive your taps in hard enough? Sometimes ice can push mine out if a hard freeze after a heavy run, but only maybe a few a season out of 3000+taps. Pressure usually blows a cap off a star or something similar for me, which is how I usually can tell if it was pressure or ice expansion that did it.

The tree is losing pressure to build vacuum inside as the temps go down and droplines and lats start to freeze, so usually no pressure issues this side of the cycle. The pressure usually happens on the other side of the cycle, in the morning when things are warming and sun is on trees.

[Thad Blaisdell]

As I have the H20 sensors on all mainlines I can see exactly what is going on in my woods. Last year was a complete head scratcher. Never seen anything like it. On many days/nights I would have as much as 30 lbs of pressure. This had nothing to do with slope or sags. Everything to do with tempature. Longer story. Normally I will only see a 12 or so a year. But last year I would have that many on any given day. I ahve talked to many sugarmakers that experienced this same thing last year.

[doocat]

Thad we had it down here in Pennsylvania and many producers I spoke with in new York as well last year. Hope it's not a repeat this year.

[blissville maples]

So you had 30 psi in your lines during a freezing night? Do you run vaccum? I know when I shut my pumps off after it freezes the lines, especially mainline, stay vaccumized in deffinantly until I turn pumps on or lines dethaw and expel all the vacuum into pressure.

[blissville maples]

If you don't run vacuum then the open end of your main line should release all the pressure unless you have an ice blockage somewhere this is obvious, since to have pressure or vacuum the line must be airtight.
If you're running vacuum I would have to assume that the vacuum pump would reduce the pressure in the lines to a negative pressure environment unless again there was an ice blockage....

Maybe I'm missing something

[Walling's Maple Syrup]

So you had 30 psi in your lines during a freezing night? Do you run vaccum? I know when I shut my pumps off after it freezes the lines, especially mainline, stay vaccumized in deffinantly until I turn pumps on or lines dethaw and expel all the vacuum into pressure.
He said he has h2o sensors. I believe that would mean he runs vacuum.......

[Thad Blaisdell]

If you don't run vacuum then the open end of your main line should release all the pressure unless you have an ice blockage somewhere this is obvious, since to have pressure or vacuum the line must be airtight.
If you're running vacuum I would have to assume that the vacuum pump would reduce the pressure in the lines to a negative pressure environment unless again there was an ice blockage....

Maybe I'm missing something

Yes I run vacuum.

This was a very strange situation. Most years I too have vacuum lasting all night into the next day. But here the trees would start running at 33 degrees way before the lines thawed out. I believe it had to do with the pressure in the roots. The mainline fills..... creates pressure. Too much pressure and something has to give. In ten years I have seen this only once before. And that was only a one or two day event. Last year was almost every day.

[blissville maples]

I assumed had vacuum but you never know. I guess I'm not sure why the main line would be filling with sap and making pressure- something doesn't add up to me, I'm assuming u run a vacuum pump not an air compressor!! . Other than a low spot or an ice blockage between trees and the pump.....but good luck

[DrTimPerkins]

Yes I run vacuum.

This was a very strange situation. Most years I too have vacuum lasting all night into the next day. But here the trees would start running at 33 degrees way before the lines thawed out. I believe it had to do with the pressure in the roots. The mainline fills..... creates pressure. Too much pressure and something has to give. In ten years I have seen this only once before. And that was only a one or two day event. Last year was almost every day.

Hi Thad...We see the same thing occasionally....not real often, but every now and then. It is easier to see with a vacuum monitoring system (we also use H2O Smartrek and have since they started selling them). Last year this phenomenon was more common. Temperature is quite variable across the sugarbush. I think slow sap runs in some sections of the bush (more southern-facing areas) and would run down and then freeze in the lower sections (with more west-facing slope) where it was still cold and the cold-air drainage kept things well below freezing longer. The lateral lines and upper sections of the mains would pressurize due to the higher trees on the slope starting to run. Every now and then the pressure would get high enough for a spout to pop out (or the tubing to push off the spout), but that was quite rare. We interpret it as just very highly variable temperatures across different parts of the bush. Gets pretty exciting at the releaser when it all finally lets go. :D

[GeneralStark]

I guess I'm not sure why the main line would be filling with sap and making pressure- something doesn't add up to me....Other than a low spot or an ice blockage between trees and the pump

You answered your own question. A blockage in the line, usually due to ice, allows pressure to build up when the trees are still pushing out sap. At some point the pressure has to release and a spout pops out or a drop comes disconnected, or fittings pop. I heard reports last season of mainline fittings coming apart...

Blockages can occur for lots of different reasons, with leaks being a common cause. We all like to think our systems are tight, and they are, but there are still micro leaks and at those places a blockage is common. Any one that uses a leak with sap ladders knows what I am talking about.

Last season we had lots of runs when it was at or just above freezing. I attributed it to the warm weather in February really thawing the trees and ground out, and then marginal freeze thaws after as well as some real cold snaps. The trees would run well but the tubing would freeze earlier than the trees. I see this effect most when the tubing freezes up after a good run. Last season it was one area in particular with a mainline that had been repaired several times but had some micro leaks. After every good freeze I would walk the whole woods before it thawed again to find the dangling drops and then I would be good until another good freeze.

In addition to temperature variations throughout the woods as Dr. Tim mentions, I think it is also worth noting the temp. variation between trees, the air, and the sap in the tubing. Trees have high thermal mass so stay thawed much longer than the air temp. or the tubing/sap temp drop below freezing.

Dr. Tim. I remember when TREEMET was operating, and perhaps it still is, being really impressed by the variations in air temp. and tree temp. as well as tree pressure. Do you guys still have temp. and pressure probes in trees?

What else can be measures with the mainline remote sensors besides vac. and pressure? Sap temp?