Vacuum level at high flow

[blissville maples]

I have seemed to notice that when the sap is flowing really hard, my vac level seem to drop a couple inches? Wondering if this is normal from the extra tree gas, or if the warmer weather is exposing a leak I cannot find??

[spud]

Tree gas will bring vacuum down on a hot sunny day. Also if your mainline system is too small for the amount of taps you have that can cause poor vacuum transfer. I have a section of my woods that has a booster tank 1000 feet from the sugar house and then goes another 1000 feet to a second booster tank. In all there is 2500 taps going into both boosters. I started out with a 1 1/2 inch wet/dry line system. After my first season I noticed the first booster in line was always full of sap and shaking on the stand. I then added a back-up wet line that is 1 1/4 inch and that took care of the problem. On good runs both wet lines are running strong and my vacuum went up 1-1 1/2 inches. With the big monster trees you have you might need bigger pipe to handle all the sap your getting.

Spud

[DrTimPerkins]

Yes, as Spud indicated, tree gas production increases on warm days. That, combined with decreased vacuum transfer due to all the sap coming down the lines competing with air trying to also come down the same lines, will decrease the vacuum level at the taphole.

[ennismaple]

Agreed with the above - plus if you are using a mechanical releaser it introduces air into the system every time it dumps. When our sap runs very well our releaser in our New Bush (2000 feet from the vacuum pump) dumps every 90 seconds or less. The vacuum was dropping by up to 8" on good days because we only had a 1.25" vacuum line to the releaser so we couldn't get the air out of the system fast enough. We've replaced that with a 2" vacuum line which should allow 4x the air through per minute and will increase the vacuum level.

[Ivyacres]

I had a helper tell me he couldn't see any sap flowing so he grabbed the tap and twisted it a few times and then he could see sap and air flowing. I totally believe he broke the good seal the tap had with the tree and only let air in now. What is your take? There are about 20 -30 taps on each line and I wondered if some weren't getting overloaded?
Thanks,
Bob

[ennismaple]

If you are on 3/16 it absolutely must be a tight system with no air leaks. Your helper introduced a leak - meaning the 3/16 natural vacuum effect has been lost.

I know people expect to see sap moving quickly in the lines but for a tight system the sap should barely be moving - it means there are no leaks. People used to vent their gravity tubing to allow the sap to drain thinking it helped production. The opposite is true. Over the duration of the season. I believe the sap in 3/16 lines flows faster.

[blissville maples]

Agreed with the above - plus if you are using a mechanical releaser it introduces air into the system every time it dumps. When our sap runs very well our releaser in our New Bush (2000 feet from the vacuum pump) dumps every 90 seconds or less. The vacuum was dropping by up to 8" on good days because we only had a 1.25" vacuum line to the releaser so we couldn't get the air out of the system fast enough. We've replaced that with a 2" vacuum line which should allow 4x the air through per minute and will increase the vacuum level.

I have not checked at the tap hole however the releaser tends to be around 25 whereas normally 26-27+.

And I guess the mechanical releaser dumping every 90 seconds versus 3-4 minutes makes a loss that I guess maybe I overlooked.

I do not believe it is from leaks as the sap movement is still slow as it always is.
I kind of thought the extra flow and gas was culprit, However I thought my lines were larger enough, except for one sugarbush undersized mainline and dryline may the culprit it's rather flat also.

From now on all of my wet lines will be inch and quarter minimum, I think they resist ice plugging and ****ing also compared to 1 inch.

Good info as it's hard to see every angle by yourself sometimes

[blissville maples]

I had a helper tell me he couldn't see any sap flowing so he grabbed the tap and twisted it a few times and then he could see sap and air flowing. I totally believe he broke the good seal the tap had with the tree and only let air in now. What is your take? There are about 20 -30 taps on each line and I wondered if some weren't getting overloaded?
Thanks,
Bob

I've wondered this about "overloading" on 3/16..... I've also seen a big enough air leak from a spout not set good that absolutely no sap from tree is present and all air is going thru, when I hammer the spouts back in you can see the sap start to come and gas bubbles under vaccum then appear.....