Vacuum Puzzle

[Grand Square Acres]

I have 150 taps on vac. & 65 taps with bags the bags our out producing the vac. Now my sugar bush is on a 3.5 acres hill side (north slope) it is 320 feet from my tank to the top. The GPS tells me that there is about 130ft drop in elevation. I am getting 23" hg on pump and 21.5" at the last tap. I am running a 1" conductor line down the hill to my releaser with 3/4" tube branching off to my drop lines. 3/4 tube is running 2-3% slope from the conductor line, following the topo of the hill. 5/16 drop lines with no more than 6 taps on them. Now my I am just wondering if the slope is to steep for my system? Is it locking up some where? Would a wet/dry system work better on this slope? 4yrs and still trying to figure it out. Any ideas would be helpful. I want to put another 175 to 200 taps on this system but not until I can get it figured out.

[mapleack]

It may be as simple as difference between gauges if you aren't using the same one to check both places. What you're describing should work fine for 150 taps. For 300 you may want 1" pipe.

[maple flats]

The difference in sap flows could be as simple as the vac trees are frozen and the bagged trees thawed.

[BreezyHill]

We too are having issues with sections of the same bush running while others are not. It is all temp.

The size of the system is less important than the slope of the flattest point of the mainline run.

Flow rate of 3/4" on 2% slope is 195 gallons/ hr. Peak production per tap is .2 gallon/ hr. This is strictly flow rate and not for vacuum transfer(vt). For vt you will need larger line if the flattest 50' is pooling sap.

More slope, increases the flow rate quickly... 6% is 336 g/hr, 10% is 444g/hr.

The vacuum will eliminate the chance of a vapor lock or air lock since the gases will be drawn to the pump easier than does liquid.

Due to the extreme slope there is a every so slight chance that you could get a bubble that would be slightly hindering the flow. This would be very slight as the liquid will go to the bottom of the mains and the gas to the top.

The fact that you are only dropping less than 10% to the last tape hole it is not very likely there is any problem.

I would suggest a wet/dry (w/d) system for any one using vacuum to increase the vac to the tap holes. The more vac to the tap hole the more production you will realize. A dry line will also benefit you on those days that you just cant get the temp to stay up. The wet line can freeze and the dry will keep the sap coming to and the vac going to the taps. The steep slope does reduce the affect the dry line will have but it will still be a benefit.

We keep our mains separate into the sugar house so that people can see first hand the difference in orientation to the sun, wind, elevation has on production. We use a glass releaser that has 1.5" glass tees connecting to the main lines. Each line will have a short section of glass to connect the tee and the mainline next season as we are removing the clear tubing we currently use. This season I have noticed that the colder areas are either flowing slow or not at all. While the more protected and warmer areas are flowing well. Every season I like to do a preseason check of all the gauges on a section of pvc connected to the vac system. It really sucks when you think there is an issue and it is only a faulty gauge. They don't last long now days if they get sap into them.

I would suggest adding the taps and you should see an increase in flow due to the number of taps.

It is the location that is your biggest contributing factor mixed with this poor weather we are having.

Best Wishes!

Ben

[Grand Square Acres]

Thanks for replying. I talked with a local producer that come over walked my woods and checked out my system. One thing he noticed right off was my 3/4" branch lines were full of sap with the vac on, but almost nothing in the conductor line. So we played with the vac level and dropped it to 15" it was like he flipped a switch and opened a flood gate it just poured through the conductor. We came to a conclusion that with higher vac it wasn't allowing the sap to enter the conductor it was like the vacuum was blocking it. He said if I want to run higher vac that I need to go with bigger tubing. So that is what I am going to do next year,but for the rest of this season I'm running lower vac level. Thanks again guys and may your pans run full of liquid gold.

[markct]

Thats the most misled thing i ever heard, too much vac not allowing the sap in? That doesnt make any sense at all. I would bet more on the change in vac dislodging an ice blockage in a line and then sap behind it rushing in. And your 3/4 lines should never be full unless they have a blockage like ice or a sag in them

[mapleack]

Vacuum cant block anything, vacuum is "nothing".

[Grand Square Acres]

After reading the last two post I went out and turned the vac back up didn't see any change in flow. Could have had a ice block. I don't know just thought maybe the other producer knew what he was talking about but maybe he is full of BS. But it does make since to go with bigger tubing next year with more taps.

[markct]

bigger mainline or wet dry never hurts but you have adequate size even if you triple the number of taps on it.

[BreezyHill]

Vacuum is force...pulling sap. Our problem was the dry line was pulling the sap to the larger line.

Vacuum is a very strong force that increases the atmospheric pressure and can easily cause a blockage of a line.

I have only seen it happen a few times in my over 40 years of working with vacuum.

[BreezyHill]

To see how strong vacuum is bing vacuum silage from the 1960's.

Farmers would pile loss silage in piles and cover with plastic film. Then they would apply the vacuum pump to remove all the air. The 20 foot high pile would be sucked to a few feet in height with 18-20" of vacuum.

Vacuum is very powerful. No BS

[Quabbin Hill Farms]

I have been having problems with nothing moving in the laterals I have -20 " at my sap puller but only -5" at the end 1800' away. I have walked and walked that line looking for leaks but nothing shows. My lateral aren't racing leaving me to believe there no leaks but the laterals don't seem to be moving either they are full of sap. I thought maybe ice blockage but there is some vacum at the end and it was +8 here yesterday 40f so I don't think its ice. Any help would be appreciated.

[BreezyHill]

Quabbin Hill,

You may be surprised how long ice can stay in 1" mains. I had an ice issue at 42 degrees in a blue line. The blacks had been running for three hours and the blue was just sitting there. Finally I found the issue. About 12 feet in the air there was a ice jam where a large maple about 25 feet away had shadowed the mainline. I went to the next ladder past the issue and opened a bleeder to get more sap flow thru the blockage. I only had 14" so it was not much air but in 10 minutes the blockage was moving.

If this is not the case then you likely need to allow a tiny...very tiny amount of air in to clear the system of... well I call it a slug of sap. The entire system is full and there is no gases coming from the tree. These gases are what helps a ladder work well. If you have as tight of a system as this problem is showing; then you did a great job installing taps and lines! BUT know you need to inject some air to clear the system and get things flow as they should.

I inject air in several places to get things moving faster to get more vacuum past ladders. This goes against common practices but we are going against gravity so common practices is out the door. To master these things you need to experiment and watch the results. You will find very quickly that you will have two sets of rules. Those for a conventional bush and those for the ladder bush. It gets really confusing when a conventional bush flows into a ladder bush. The speed of sap flowing in hitting the ladders will pop saddles loss on the mains. Max seal with screw kit is the only answer I have found that works.

Last night my ladders with the new dry line added were still running at 31 degrees???? Last year they would have been frozen solid hours before that. At 11:30 pm things were still running as I was crashing and it was 30.1. Not making any sense when compared to the last century of lines freezing well before the bush; but I am happy to get the sap in the tank.

Let me know what you find.

Best wishes

Ben