Physics Question

[Dave Y]

I am going to build a bucket dumping system in a camp delvelopment. I am using 4 33gal plastic trash cans for collection points in the woods I will have them connected together with 1" mainline. They will be distributed at aproxamitley 75ft intervules down the slope. I want to put a valve on the bottom so I can dump it into the dump station on the back of my truck.
From top to bottom it is 320 ft and the elavation change is approx.15ft.
My question is ,how much sap can be put in the system up hill befor the head pressure causes the bottom can to over flow? keeping in mind the cans are 29" high. Any math genuises out there?

[RileySugarbush]

If I understand your set up, the answer is 33 gallons. That's asssuming there are no shut off valves between them and they are evenly distributed on the 15 foot elevation change. The up hill barrels well drain into the downhill until they empty and the bottom one overflows.

To see this, forget the 300 foot distance and imagine a barrel on a table and one on the floor. Connect a hose from the top one to the bottom one, at the bottom of both containers. There is nothing stopping the upper container from completely draining, and the bottom one will overflow.

You could accomplish your goal with a separate mainline all the way down from each. with a separate valve on the bottom of each line.

[parsissn]

To solve this we first have to make some assumptions about your setup. The main assumption is that the 15 foot vertical drop is linear and spread evenly over the 320 foot distance. If that is true, then this becomes a ratio. Divide 320 by 15 and you get the multiplier constant of 21.33. So, for every 21.33 feet along the ground, the hight drops 1 foot. This works for inches too, for every 21.33 inches along the ground the height drops 1 inch. So if your barrels are 29 inches you can go 29*21.33 = 618.57 inches (51.55 feet) along the ground before you reach the top of the barrel. What this means is if your second barrel up the hill is more than 51.55 feet from the first barrel, your maximum sap storage will be 33 gallons - the capacity of the bottom barrel.

If the trees are dumping into the four barrels along the way you might want to put valves into each of them. When you collect, collect the bottom barrel first, then walk up the hill and just open each valve in turn till you reach the top. When the top barrel is empty, close it's valve and walk back down the hill closing each one as you go. This will give you 132 gallons of storage in the woods before you have to collect.

Note: this math does not come with any warranty and my not be suitable for your situation. Your mileage may vary. We know you have a choice in airlines and we're glad you chose MapleAir, sit back, relax and enjoy the in flight boil!

Happy sapping,

Mark

[hydrogeo]

Don't claim to be any sort of physics wizard but here's my stab at it:

If the valve is open at the bottom and the system is flowing continously (pretend youv'e got a fire hose overflowing the upper most can) I think the head in the pipe would roughly equal the head in the top can minus the friction loss in the pipe. However you will be dumping intermittently and therefore have a moving target head-wise as the head in the pipe will rapidly disipate. Because it is a transient system, I think it would be a little tricky to actually calculate it out. Qualitatively if you are dumping in the top can some sap would likely back up into the lower cans but in my mind unless you have a large army gathering for you I don't think you could get the flow high enough, and I would think it would work fine. Someone else may have a better handle on this though. It would be neat to try it and see what happens.

[HanginAround]

Why not just put all your pails at the bottom of the hill, and put manifolds on the mainline? Then you have full capacity of your storage, and never have to go up the hill.

[Dave Y]

Ok here is the way I see it. If I have a valve on the bottom only and fill from the top down I will over run the bottom barrel ,because it has an open top.that is if I collect from the top down. Now if I had a closed top barrel on the bottom I could hold twice as much. I will probaly put 2-valves in line, one after the second barrel ,and one at the end of the line. I will shoot the elavation to make sure the top of the second barrel is not lower than the bottom first,and the bottom third is not higher than the top of the fourth.
Hangin,
Im not sure what you are getting at. please explain

[parsissn]

If your bottom barrel is a closed top and water / air tight you may need to put in some kind of vent to get it to fill. Otherwise you'll just compress the air in the bottom barrel. If the flow in the main line is small enough, you may have room for sap to flow down the main line and displaced air to flow back up the main line at the same time. This would require the main line to enter the closed barrel near the top. Otherwise, you will not get your closed barrel to fill up all the way. If you were to put in a vent, it would of course have to stick up in the air above the height of the top of the second barrel.

[HanginAround]

I went back and re-read your orginal post, and see that I misinterpreted... you want the pails in the woods to dump your cans into, so ignore what I said.

Like parrissn said, if you have a closed vessel at the bottom, it needs to be vented as high as the top of the second barrel. If you're dumping cans, you won't have enough vent within your mainline to accomodate both southbound sap and northbound air.

[Gary in NH]

As far as head pressure goes every 2.31 ft. of elevation in a column of water will result in the addition of 1 psi at the lowest point, sap will be a little heavier. The diameter of the column doesn't matter. At low flow rates in a 1" pipe the friction loss is almost non-existent.

[RileySugarbush]

Best yet may be to have lot's of storage at the bottom (a big tank or a bunch of 33 gallon barrels connected at the bottom) and no valves anywhere. As long as all the upper barrels can empty down hill, and each is higher than the next, you should be able to dump into any of them and have them drain down through to the collection barrels at the bottom. How you get the sap from the collection barrels at the bottom is a different issue, whether you pump, bail or drain with a valve if you have enough head below the collection tanks.

The allowable collection rate at each barrel will be limited by how fast they drain to the lower ones. One risk is if the elevation difference is not the same between barrel pairs, one may fill from above faster than it can drain to the next one down. They actual math is possible but complicated. I'd just measure and try it. For fun you could make a little scale model in your kitchen (with permission, and towels on hand) and check it out conceptually. Flow rates will not be scalable but the concept will be the same... Let us know how it works out!

[hydrogeo]

In re-reading the original post, I assume you have a good sized tank on your truck. why can't you just forget about valves all together with and let the line run directly into your truck tank. It sounds like you have the elevation. As it was stated, the math in a system with such an irregular flow rate is a take home problem for an advanced physics final exam. However, with an open line on the bottom and a couple of 5 gallon pails dumped every five minutes or so I wouldn't think any of the barrels would overflow.

[royalmaple]

I was just going to say do like what rileysugarbush said. Gang up 3 or 4 cans at the bottom, you can take a 3/4 pipe and drill a slightly smaller hole than that and push the tubing through can to can to can. Then as long as you are not dumping more than your lower capacity who cares. Take your trash cans down from up the hill and hang 5 gallon buckets and tie them into the pipe line like you were going to with the trash cans and let them be the dumping station. And if you want a bit more pitch, hang the highest one up the hill a bit higher in the tree.

[oneoldsap]

Plastic garbage cans are made from recycled material. To my knowledge there are no food grade garbage cans available. I wont eat out of a garbage can and I would rather not eat syrup from one. Our syrup should be as pure as we can possibly make it. Get yourself a decent tank and pipe your sap down into it. Sap collected in a larger tank will stay cooler longer because of the volume,the more there is the slower it warms.The cooler the sap the slower bacteria will grow.Anything worth doing is worth is worth doing right. Good luck and I hope you have a fine season.

[Dave Y]

Well heres what I figured out.# 1 the system as I have designed it, will only hold as much as one container 33gal be for the head pressure will cause it to over flow. Kinda new that but wanted it confirmed by some one smarter than me. #2 I don't normally have an army of sap gathers. I am only dumping about 100 buckets in this system. It only needs to hold it long enough for me to get the buckets emptied, and down the hill to turn the pump on in the truck. Snow is Knee deep here yet and looks like it may still be for awhile. #3 I have a very limited time to get my sap collected. So I am saving time and energy for the next chore. I have over 400 taps that I have to lug out of the woods by hand in five gal buckets. I would love to have tubing but most locations are not somewhere I could put up tubing and leave it.
I also agree that any job worth doing is worth doing right. New plastic garbage cans wont hurt anyone the are no differnt than plastic buckets that had drywall spackle in them and there are thousands of them that have been used to collect sap. Thanks to everyone for there input, it is appreciated

[tapper]

Dave,

Do you have enough elevation to run the bottom of your line directly into the big tank on your truck? So that when you dump in the 1 or 2 cans uphill it goes directly to the main tank so you dont even have to mess with the small tank at the bottom? Your discussion here gives me the idea to try this in some of the rugged terrain I gather in Thank You!!! With all the snow I wish it was in place now.

[Dave Y]

Jon,
The elevation slopes off low at the bottom. I t is just high enough to put in to my dumping station on the back of the 1ton dump. If it was high enough I could just back the truck under it and let it fly.But it isn't that's why I need to manage the flow some.I dont want to run the battery down on the truck and I don't want to have it running all that time either.
This is my frist year at this location and I am try to find out what works best. Who knows the owners my allow me to put up tubing next season. Wouldn't that be special! I have some road side trees that I am going to try to hang tubing on next year also. This is a growing process.

[hydrogeo]

As long as the bottom of your lowest can on the hill is slightly higher than your truck tank couldn't you just send everything directly to the tank. The little bit of sap remaining in the line from the can to the tank could then be dumped to your dump station when your done collecting, no?

[maplehound]

You could also leave your pump in the bottom tank and let it run with a float switch. Then it would turn on and off as needed and you wouldn't have to be right there when it filled up.