First year tapping- big question about pumps

[Michele Barlau]

Hello folks,
I've been reading the other posts about what type or what size pumps people are using. I'm having a hard time finding a clear answer for my trees. All our trees are about 950 feet from any type of road. No motorized vehicles are allowed to cross the pastures or use the trails due to the mud and the terrain. In addition, the trees themselves are on the rims and hills of deep ravines. Its our first year trying this, we're all completley dependent on improvising to come up with what we need to make this work. NO money in the budget to purchase new equipment or fancy equipment.

My thoughts are, the only way to get the sap out, is to set up tubing that can run into a mainline and deposit to a collection bin. Then the sap would need to be pumped, or suctioned, from there to a collection container at the top of the hill, in the back of my truck. The problem I'm having is figuring out the pump. after trying to do the math, it seems I need a pump able to send the sap 160 feet up hill, over a distance of 950 ft.

What can I use to get the power I need, without spending 100.'s of dollars. I have a guy who might have a motor I can rent or borrow, but then what kind of pump attachment works with that?

Can anyone help ?

Michele

[spud]

A gas powered pump is really the only thing I can think of. If you have no money to buy one then try to borrow from a friend.

Spud

[Darkhollow Sugar Bush]

i have a honda gas powered transfer pump with 2" inlet and outlet and i necked down the exit side to 3/4" and pumped water straight up a huge hill for three thousand feet..

[CampHamp]

My neighbor got a gas pump from Harbor Freight and likes it. Click Here to see it. (http://www.harborfreight.com/1-clear-water-pump-with-79cc-ohv-gas-engine-69747-8849.html)

Use THIS COUPON (http://www.harborfreight.com/affiliate17551-05.html?utm_source=cj&utm_medium=aff&utm_campaign=wts-coupons&hftref=cj) to save another $30 for just over $100 bucks, you get a good deal even if it last only a few years.

It won't go your whole distance though (read manaul on the product page to see chart). So you'd need to pump it up to a mid-way tank 80' up at 18 gal / min then pump again to your head tank.

If money were less tight, you could find a more powerful engine to go the whole way, but get the performance specs to make sure it will work before laying down your dough!

[Michele Barlau]

I was wondering if this was the method I was gonna have to use. Thank you so much for the info!

[Maplesapper]

Dark Hollow-
Is that pump safe for food etc? Or is it a simple trash pump?
Most of those suckers aren't stainless inside...
I want to do the same thing but wasnt sure if the pump would be safe.....


In Maple Sap terms.....Problem is, your 3000 feet would have approx 1 gallon of raw sap every 26' of hose, how would that NOT spoil ??

[motowbrowne]

I changed my plans, but northern tool and supply has a belt-drive food grade pump that is pretty big. They have two actually, I think they use 1.5 and 3 hp electric motors respectively, but you could power it with that botrowed motor. I can't look up the link right now, but I think I've linked to it before, so if you search all of my posts you'd find it. Or you can get on their website and search for food grade pumps. I think they're only 89 or 100 bucks and seem to get good reviews.

[timmeh87]

Hey everyone, Ive been lurking for a while, but I joined specifically to offer some insight into this pump question.

Pumps are specified by the amount of head they can produce. (waits for people to stop snickering about "head"). The head being the vertical height that the water is being pumped. The horizontal run distance has no effect on the pump's rating, provided it is not so long and thin that friction becomes a factor.

So what I'm saying is, it takes zero work to move a liquid horizontally in a tube. That should make intuitive sense; water will naturally flow (slowly) to the other end up the tube if it is perfectly horizontal.

Also, the flow rate decreases as the head increases, so the max head specification on a pump may be at zero flow, or some number far below the rated max flow.

I noticed that the original head spec was 160' and one of the gas pumps linked to can only produce 105' of head. It probably would not be able to pump any liquid to the top.

And all that discussion is assuming the pump is at the bottom of the hill. It is much less effective to put it at the top of the hill, as it is physically impossible to produce more than about 25 feet of head (of water) using a vacuum. (this is because you cannot create a pressure lower than zero. Also, water begins to boil at very low pressures.)

The same theory applies to gravity vacuum lines - its not how long the run is that matters, its how far vertically the outlet is from the inlet.

If the tube runs all the way down a hill, but then back up the other side, it cancels out and the calculated head is 0. This is all assuming there are no leaks in the tube. Leaks add or subtract pressure depending on whether there is vacuum or pressure inside the line.

More info:
http://www.onestopfire.com/head.htm

[Maplesapper]

Hello Timme-

You seem to have flushed out some interesting facts.
Here is a question for you.

I have a 2" Gas-powered Trash pump. 128 gallons per minute outflow.
Can I neck down the 2" outflow to 3/4" to push my sap out the food grade poly pipe horizontally for 400' to my shack ?
I would of course only let the pump idle vs full power- that would surely blow the pump.
I only need to run the pump for 2 minutes or so to empty out my 55 gallon holding tanks

[timmeh87]

Crap, I had a whole reply typed out then I accidentally fat-fingered my keyboard and lost it.

Ill try to remember the main points I had, maybe this time it will be less rambling. :lol:

- Im not an expert on this, I'm just going to try to work it out using some science
- As far as I understand, the vertical height the fluid flows up can be expressed as a pressure, and the line resistance can also be expressed as a pressure, and those two pressures are simply subtracted from the pump's pressure to give you the pressure at the output. If its lower than 0, theres no flow.

Source/more info: http://www.augusta.k12.va.us/cms/lib01/VA01000173/Centricity/Domain/396/Resistance_in_the_Fluid_System.pdf

- There is a law that says the drag is proportional to the square of the velocity of a fluid, in general
- there is a law thats says if two sections of pipe have different diameters, the ratio of the velocity is proportional to the ratio of the areas

- The ratio of areas of a 2" and 3/4" pipe is ~7. Therefore, I concluded that the fluid resistance for the small pipe would be 49 times higher than the resistance in a 2" pipe.
- This conclusion does not really say anything definitively, but it suggests that the pump will have to work a lot harder than it would for the same run of 2" pipe
- I wonder aloud what a gas pump does when overloaded. Does it stall? Do the RPMs increase, or decrease? An electric motor would stall and then overheat because of the massive electric current stalled motors draw. A stalled gas engine is not a broken engine. If the RPM's increase, but you are limiting them to a low number, I don't see how that could be a problem, the engine should be able to operate at any throttle anywhere within its RPM range right? (again, not an expert on engines)

- So I say, give it a shot, like you said, keep the throttle low, but you might find it needs to be higher to stop from stalling

Also, if you add more 3/4" tubes in parallel, the resistance will drop significantly. Three 3/4" pipes would only have 5.6 times more resistance than a 2" pipe, according to my very simple math.

[timmeh87]

Ok Im going to double-post here cause I feel this deserves its own section, I was thinking about this problem some more, and I realized they probably have standard tables for this type of thing. So voila:

http://www.engineeringtoolbox.com/water-pressure-loss-hose-d_1525.html

These are just rough estimates, real values will depend on a lot of factors, hose material, number of kinks, number of couplings, etc. But basically you just read a point off this chart. the bright yellow line shows valid combinations of pressure and flow. I need the head rating (ie, max pressure) of the pump to do this right, cause you just kind of have to guess at where the balance point between flow and pressure is.

If we assume that the pump's operating curve is a straight line with a flow of zero at the head rating (not a very safe assumption), and a pressure of zero at the flow rating, then its a matter of finding the intersection of that line and the one on this chart. Ill just randomly guess that the pump is rated for 100 feet of head, so 43 psi.

I get two lines with the equations

y = 2x + 0.2 (slope of line on chart is x4 to get 400 feet)
y = -43/128x + 43 (slope of line is just head psi/gpm, intersect is head psi)

No promise that that is right, but I tried to double check.
Putting that into www.wolframalpha.com gives an intersection point of x = 18gpm and y = 37psi

So there you go. I think that 18gpm is a decent ballpark figure for the expected flow on 400 feet of 3/4" tube, with that pump, and zero head

edit for math.

And I guess the answer to the original question is "yeah, thats fine". The pump can handle it (remember: I made up a number for head), although it is near the max amount of length it can handle. It should take 3 minutes to do 54 gallons, which checks out with what you said.