Sap ladder

[SWEETSAP]

I made a 6 line star sap ladder with a 10 foot lift. My system is really tight 25" at the releaser and there are no gas bubbles in the ladder. When I start the vacuum there are tons of gas bubbles (of course) then as the gas clears all 6 lines fill with sap and slowly climb the ladder to the top. I am wondering if this is how it is supposed to work. I haven't had a chance to check the vacuum at the end of the line yet but I assume that if it is 20" or better that the ladder is working OK.

[3rdgen.maple]

How many taps before the sap ladder. I was wathcing 6 star ladder today and it was full of bubbles and surging sap right up it. Fun to watch. Also make sure the bottom star is facing down and the top star facing up.

[ennismaple]

I made a 6 line star sap ladder with a 10 foot lift. My system is really tight 25" at the releaser and there are no gas bubbles in the ladder. When I start the vacuum there are tons of gas bubbles (of course) then as the gas clears all 6 lines fill with sap and slowly climb the ladder to the top. I am wondering if this is how it is supposed to work. I haven't had a chance to check the vacuum at the end of the line yet but I assume that if it is 20" or better that the ladder is working OK.

That's what you're looking for. If you don't have surging in the lines it means you have a tight system on the lower mainline. I'll admit to staring at a sap ladder for long periods of time just watching the sap move around!

[3rdgen.maple]

Yes you are right Ennis I walked lines this morning and found a very small leak and once i fixed that up ladder is looking good.

[SWEETSAP]

Today we checked the sap ladder and the liquid was only 3/4 of the way up the ladder. The vacuum downstream of the ladder was 24" and upstream 17" no bubbles at all. If we crack a tap at the bottom of the ladder the sap moves up the ladder and the upstream tap pressure goes from 17" to 22" and this is with a tap leak. It seems that all lines of ladder fill with sap and then cut off the the transfer of vacuum to the upstream side. Yes the ladder is constructed properly star up on top, down on bottom.

[maple sapper]

I saw something, it may have been on utube about putting a valve in the lower line with one end open. Then cracking the valve ever so slightly to allow air in. This made the ladder work better. Not an expert just repeating what I saw.

[red maples]

I am a newbie to sap ladders as well but If you have sap sitting in the ladder just steady, yes you have a nice tight system, which is good, problem with that is you have no vacuum/ air transfer past the lift. So you need that little air leak in order to get better vacuum after the lift. thats why when you intorduced the leak the sap could move and the air could flow through as well increasing your vacuum further up the line. So anyway you need that little vac leak. You just need to dial it in so that your ladder will work at the least loss of vacuum.

And yes I love just sitting there and watching that sap pulse up there.

[red maples]

Speaking of sap ladders (no to steal you thread) I made an adjustment to mine that I hope will work.

I have a 2 pipe sap ladder and I was watching it (like I said I am new ot the sap lift) and 1 side is favored over the other which I was told is normal. But what I did notice is that sap shoots up 1 side and almost everytime came back down the other side. and only a small percentage is continuing down stream past the lift.

So what I did was I rebuilt the top of the lift with PVC and cut a small groove in the top of the Tee(I have the Tee facing down just like the star ladder set-up) and cut a piece of flat pvc out of a square drain pipe adapter. and slide that into the channel to act as a stop and direct the sap down instead of across into the other pipe.

just finished it letting it dry so I can put it back on. we'll see. hope this will work better. I just saw time after time that sap going into the other side and back down didn't make much sense to me.

[mapleack]

Speaking of sap ladders (no to steal you thread) I made an adjustment to mine that I hope will work.

I have a 2 pipe sap ladder and I was watching it (like I said I am new ot the sap lift) and 1 side is favored over the other which I was told is normal. But what I did notice is that sap shoots up 1 side and almost everytime came back down the other side. and only a small percentage is continuing down stream past the lift.

So what I did was I rebuilt the top of the lift with PVC and cut a small groove in the top of the Tee(I have the Tee facing down just like the star ladder set-up) and cut a piece of flat pvc out of a square drain pipe adapter. and slide that into the channel to act as a stop and direct the sap down instead of across into the other pipe.

just finished it letting it dry so I can put it back on. we'll see. hope this will work better. I just saw time after time that sap going into the other side and back down didn't make much sense to me.
I wonder why you couldnt use an T and an elbow at the top, so the lines weren't coming in directly across from each other.

[red maples]

that would probably work just fine but every one that I have seen is set up to way I explained. I bought it that way, Afriend was getting rid of his because he was changing his set up so I set it up exactly the same way. and being that I had already spent the money to rebuild it the same way the divider in the middle was the cheapest easiest way I could see to fix it.

And it was just warm enough with just enough sap in the main line from a few running trees to test and man it works greeeaaattt.!!!!! sap... well Ice crystals you could here them going right down the where they were suppose to!!!:) Big sap here we come!!!

it wasn't a good enough test but it almost looked like there was a more even distribution of sap going up both sides....hmmmm. I think I might be on to something!!! but it is what it is for this year!!!

[SWEETSAP]

Well today after the sap started to flow we installed a leak valve in the sap ladder. The results with the leak valve are good, we now have 22" upstream and the ladder is chugging away. The valve has a very fine adjustment to it and we have set it for the minimum leakage necessary to allow for vacuum transfer.

[markct]

i remember seeing a study that said the leak valve or pinhole just made the vac level go down, and kinda believed it till i started watching my 6 way star sap ladder with about 55 taps on it. it appears that with the good tight system i have i end up with more sap than air and the sap tends to fill the mainline at the bottom before it can be drawn up the ladder. it would seem logical this would happen as when there is not enough air coming in then of course the sap cant be drawn up, basicly air locked. so i think i will add a small valve to bleed a tiny bit of air in to help it flow, wondering where it should be, near the ladder or at the far end of the lower mainline? was thinking maybe just a saddle with a 1/8 in pipe valve on a short piece of tubing

[markct]

so today i went out and looked at my sap ladded, it was backed up about 15 ft in the lower mainline, and only about halfway up the sap ladder, had about 18 in vac above the ladder and about 12 below, i took a saddle and a length of tubing and a small valve and installed it a few feet up the mainline a few feet from the lower star of the ladder. cracked the valve open just enough that you can hear a leak if your ear is less than a foot from it, so a very minor leak, and the sap ladder is working much better and not backing up the mainline. i guess i had too tight of a system on the lower part!

[twitch]

how many feet can you pull sap up a sap ladder

[markct]

well i have always heard that you use roughly 1 in of vac per ft of water column, ie sap lift, so i guess in theory if you had say 20 in vac you could lift almost 20 ft but would have likely no vac at the bottom for the taps

[twitch]

so 56 feet would be asking a lot !!

[markct]

as far as i know thats not possible, as vac maxes at something like 29.9 i think? so seems that would be about the limit. just curious why ya would need a ladder that tall?

[twitch]

got permission to tap an orchard of about 1000 runs down hill away from the road. Think i will run it down hill and pump it back a project for next year just thinking about it.

[Beweller]

It seems this comes up again and again.

There are two sources of vacuum "loss" in sap ladders. First is the friction drop caused by flow of the liquid and gas. Second is the column of liquid.

The intent of sap ladders is to reduce the loss caused by the column of liquid. To do this you must have air/gas flowing in the system. For example, if you have a 10 foot ladder with no air/gas, you have a "solid" column of liquid and this column will cause a vacuum loss equivalent to 10 feet of liquid--about 10 inches of vacuum. However, if for example, the average column content is half gas and half liquid, the liquid column is only 5 feet high, and the loss is only 5 feet of liquid--about 5 inches of mercury.

But if the flow of liquid is fixed, adding gas increases the velocity of the liquid and this increases the friction loss.

Finally, if you are adding air, there will be an effect on the vacuum pump, which depends on the capacity and characteristic curve of the pump.

All this suggests that there will be an optimum quantity of gas/air, and you will have to find that optimum by experiment. Note that the optimum will depend on the quantity of liquid flowing.

The friction loss can be reduced by increasing the cross section of the ladder, which reduces the fluid velocity. However, as the cross section increases there is a tendency for the gas/air to "slip" past the liquid, causing the liquid quantity in the ladder to increase and thus increase the vacuum loss. There is very little slip in 5/16 in tubing, but slip increases rapidly in larger pipe/tube.

Lots of things to think about and diddle to reach an optimum.

[3rdgen.maple]

I thought I read Dr. Perkins say that 1 inch of hg = 7 feet of lift of water.

[Beweller]

The density of mercury is 13.5462 gm/cc. The density of water is 0.998203 gm/cc. (20 C, Chem Rubber Handbook)

Hence 13.5462/0.998203 = 13.5706 inches of water per inch of mercury = 1.0439 ft of water per inch of mercury.

[red maples]

yeah you just have to fiddle with the right vac/air ratio and dial it in the best you can!!! and sap flow changes things alot if you have a heavy run day your going to need to adjust things a bit same with a light flow day.