bubbles on 3/16.

[cjf12]

Can anyone give me a rough idea of how many bubbles you should have on a 3/16 vacuum line? I have what I would call a string of pearls about 4" long every 18" or so. Seems like a lot. What is something I should look for? I am going to rig up a vacuum gauge but may be a week or so till I get to it.

[maplenutter butter]

I have the same problem. I'm thinking since, Im in Minnesota and its a little early there isnt enough sap yet?? Anyone know what may be going on?

[Mini_Maple_Men]

Same thing here in Maine, the better my flow the less bubbles i get. I have a cold north facing bush that is slow to get going, on my last good run day I had few bubbles and 27" of vac at my gauge, today a colder day and overcast had 18" of vac and lots of bubbles.

[Russell Lampron]

I see that all the time on pumped vacuum. As long as the bubbles are moving slowly it is normal. If they are moving fast you've got a leak.

[n8hutch]

On my 3/16 a leak tends to look like really small bubbles, like you get when checking for a leak on a tire with soapy water. Almost foamy in your tubing if that makes sense.

[maple flats]

That is perfectly normal on 5/16 with vacuum and 3/16 natural vacuum and unless they are moving fast it is not indicating a leak. As sap comes out of the tree it is a combination of sap and "air". The longer the bubbles in the tubing the higher the vacuum is. This is why in a pumped vacuum system the wet/dry can help so much, because it separates the sap and the "air". In a 3/16 method, the real elevation fall at any time is the length of the sap portion in the line relative to the elevation change.

[Maple UP]

I've found that occassional bubbles in a 3/16' vacuum line are pretty normal. I've had them in my lines while still pulling maximum psi and getting great sap flow. To determine the cause, I'd suggest you walk your line from bottom to top, checking each drop line for bubbles. I've found that the drop lines containing lots of bubbles are usually due one of 3 things: a loose tap, a poorly sealed T fitting, or tapping into rotting wood. (I"ve tapped trees before that look good on the outside but are dying from the inside, happens a lot in my location). Make sure the tubing on all your connectors and T fittings goes past both barbs and seats well. A vacuum gauge will really help you monitor your lines.

[Sandersyrup]

I get bubbles as well in my 3/16. I am using SAP Star 6.22mm spiles which are supposed to form better to the tap hole and prevent air and sap leakage. I do think it is working, I have less bubbles than last year and my holes are completely dry around the spile. My line runs at about 18lbs of vac and is almost 2000' long with only 25 taps.


~ John Sanderson

[cncaboose]

A small amount of gas comes out of the tree in the sap so a small amount of bubbles is normal and lets you observe sap flow in the lines. If you have a point in your line where there's a lot more bubbles all of a sudden, then you have a leak.

[peteinvermont]

Can anyone point me to some youtube videos of moving bubbles in a system without leads, and then another to compare?
Or are the bubbles only used to determine if there's a leak when a vacuum gauge isn't used?
Or, if using a gauge and readings are lower, do you use the bubbles to determine the location of a leak?