vac transfer line

[Acer]

Quickie here
800-1000 taps max ever possible on this line
releaser located 2000' from vac pump.
what size vac line from the pump to the releaser?

thanks

Dean

[Jeff E]

I would use 1.5 inch for a run of that length. Line loss is the issue you are trying to overcome. I have 1400 taps on a releaser that is 1300 feet from the pump, with a 1.5 inch vac line. Works great.

[Amber Gold]

This situation sounds familiar...

1" vacuum line from pump at the house to the releaser 2000' away should do it. A 1 1/4" line would give a buffer, but is going to cost more.

My vacuum line for my sugar bush last year was 3/4" and 800' away with little vacuum loss from pump to releaser. A 1" pipe has almost twice the cross-sectional area so I'd think it should be fine.

[Jeff E]

Here are my thoughts:

1000 taps can produce 2000 gallons of sap, +gases, in an 8 hour time period. Say 3000 gallons of volume. That is 377 gallons per hour, or 6.3 gallons per minute for a flow rate that needs to be displaced by the vacuum. That assumes NO LOSS or leaks. for minor leaks, lets round up to 7 gallons per minute.

A 1 inch line losses 3.2 ft of head in every 100 ft of line, so a 1000' line would lose 32 ft of head. To me, that is about 1 hp worth of work lost to friction. I don't know how this corrilates to loss of vacuum capacity, but it is significant!

Compare a 1.5" line, same flow rate only loses 0.4 ft of head/100' of line, or 4 ft in 1000.

To me this says higher vac at the releaser. If you can afford the larger line, I would go for it.

Also this is averaging the volume through the day, and we know there are really big hours, with much higher flow rates to account for. I want to be able to take advantage of those big days, big hours.

My 2 cents worth....

[maplwrks]

I'm with Jeff---1 1/2

[Haynes Forest Products]

Im sticking my neck out and saying NO you dont need the 1 1/2. Vacuum does not act like pressure and I dont believe Head pressure has anything to do with the equation. Friction in a vacuum line decreases as the vacuum increases. As long as the vacuum reading in your releaser reads 20 or 25 it doesnt matter how long a run you have. What line loss do you have in a sealed line 2000 ft long that connects to a releaser. All the action starts at the releaser. Full sap lines into the releaser do not require alot of CFMs. I would install a vacuum tank inline as close to the releaser to smooth out the highs and lows. The bigger line is not needed.

[Thompson's Tree Farm]

I do not know the physics of it but I do know that on a 1400 foot run from my vacuum pump to a remote releaser I was getting a 3 inch vacuum drop using 1 inch pipe. Switching to 1 and 1/4 inch and my loss was less than 1/2 inch. As far as I can tell everything else remained the same. I only use the bigger pipe now. I'd agree with Haynes, a balance tank will help with fluctuations.

[PATheron]

Guys- This seems to be an issue that has been bantered back and forth for a long time. Its always the same old issue between cost and pipe size. Why cant we get a chart with real numbers that says how much vacuum will be lost in a matter of distance with certain size pipes? There must be one somewhere. Im dealing with this issue this year myself bigtime. Ill have to get real measurements but Ive got taps on the Booy line that Im guessing are darn near 2 miles from the pump and I ran one inch line for everything. I did try it at Im guessing 6500' from the pump and I had 27" at the pump and when I checked it it went instantly to 18" or so and then in a few minutes it kept climbing till it hit around 24". So I dont really know what to think either. In this instance the tap count didnt really justify anymore. It comes down to competing theories. The Governor says you can run mainline around the world basically and if theres no leaks your good and Jerry says the distance will mess you up with pipe friction and both of those guys are sharper than myself so ???? I want to see a chart, not head pressure or anything else but actual effect of the friction of the pipe and how it corrolates to vacuum or cfm loss. Theron

[Acer]

Thompson how many on that line?

[Gerryfamily5]

I had a Bernard double 1900' from the pump w/ 700 taps on it,a buffer tank,and a 1" transfer line and a tight system above it.Like Haynes said on a "sealed system" (sap frozen) there was no vac loss,but when the sap started running vac level would drop 3"hg from pump.The harder the sap ran the more the differential never more than 4"hg but that was enough.
I swicthed it to 1 1/2",added taps,it works perfectly,no differential from pump hg's,no big drop when extractor dumps.If I had to do it again I would put up the 1 1/2" first,would have saved me all the way around.lol.

[Russell Lampron]

The larger pipe will buffer the changes in vacuum level when the releaser dumps. I can still see some fluctuation in the laterals now that I am using 1.25" pipe to my releaser and it is alot smoother than when I was running a .75" pipe. My releaser is 900' away from my pump. Watch the sap flow in your laterals. If it is ebbing back and forth and you have no leaks it is because of the releaser.

[Thompson's Tree Farm]

Acer, About 1000 taps and there are 10 (I think, have to go back and count) sap ladders and lifts. Total distance from releaser to furthest tap 6000 feet. So 7400 from the pump. Pump runs 24 inches. Furthest taps 19 to 20 inches. Last year I ran a Bernard Single releaser on it. Will replace with a double this year. I'd like to get a couple more inches but I have other places I can make better gains at this point (more bush to tap).
Doug

[Acer]

theron got me thinking so tried to calculate head loss for vacuum

did this quick so it may be fudged up use it at your own peril

2000' long
3/4" 5cfm at 24" 1psi
1" 11cfm 1psi
1.25" 19cfm 1psi
1.5" 30cfm 1psi
2" 60cfm 1psi
3" 170cfm 1psi


used
friction coeff .023
2000' pipe
.016lb/ft^3 density of air at 24"
imperial units

http://www.engineeringtoolbox.com/darcy-weisbach-equation-d_646.html

[Haynes Forest Products]

Did I miss somthing? I didnt see the word VACUUM in the equation or on the page.

[PATheron]

Acer- Not sure I understand either. So If I have one inch pipe running 3000' I lose 3" but how does the cfm's work? Theron

[Amber Gold]

I'm pretty sure in terms of calculating flow and head loss, gases act the same as liquid so the formula's for liquids can be used for gases. The Darcy Weisbach equation is used for calculating head loss in pipes.

[Haynes Forest Products]

No they dont. Its all about pressure differantial and when you REMOVE a gas from a vessle other gas or liquid will move into that area! Now liquid and gases are effected buy friction that can slow its movment...BUT as vacuum increases the gases present decrease so there is less friction. PLUS head pressure causes the pump to work harder to push the liquid up the pipe/column and vacuum is achieved by removing Gases/liquid from the column that same is not true with gases. Its all about the pressure differential.

[Beweller]

Acer and I are at least within shouting distance. I calculated the loss for a 1 inch line flowing 11 cfm and got 0.74 psi for air or 1.12 psi for carbon dioxide, using Acer's friction factor, AND treating the flow as incompressible. One psi is equivalent to approximately two inches of mercury, so the flow should really be treated as compressible. I am don't know how Acer treated the compressibility factor.

Different people use different definitions for friction factors. I assumed the value was 0.023 velocity heads per diameter. Some people use a value that differs from mine by a factor of 4 and some by a factor of 2--still within shouting distance.

[Beweller]

Just to kep it simple, the pressure drop is proportional to the dynamic pressure and the line lenght divided by the diameter. The dynamic head varies as the square of the volumetric flow rate divided by the fourth power of the diameter, so we get the pressure drop proportional to the square of the volumetric flow rate divided by the fifth power of the diameter.

Taking the ratio of the flow in a two inch line to the flow in a one inch line of the same length and same pressure drop, the flow in the two inch line will be the square root of two to the fifth power, or a little less that six times.

Looking at Acer's results, the flow in a one inch line is 11 cfm and in the 2 inch line it is 60 cfm. Looks about right.

If you want the result for a smaller pressure drop, the flow will be proportional to the square root of the slected pressure drop.

All assuming incompressible flow and a constant friction factor.

We really should check the Reynolds number of the flow before taking these results as cast in concrete, and check that the effect of compressibility is not too large.

[Brent]

How would you ever know how many CFM you've got in a vacuum line ?

Like Haynes says, once you hit near 25" vac there's almost nothing left, and what little air is left has almost no 'head' loss if you want to call it that from friction. If there is no leakage, like said above, you could have 25" in a tube around the world and have 25" everywhere ( after a wee bit of time to suck the air out in the first place)

The real question is how many CFM your system leaks and how many CMF you've got to suck out when the releaser comes back on line at atmospheric pressure. I would think and average releaser might have 2 to 4 cubic feed.
As leakage and releaser cycling increases and the amount of air you have to move goes up, then the friction will start to become a factor.

Trying to measure it all ... good luck.

[Haynes Forest Products]

Beweller.......Not once did you mention VACUUM now that was cool but I think you need to rethink your calculations and quit watching Good will hunting:lol: :lol: :lol:

[Acer]

wanted it gone

[Brent]

what's an acfm ?

[Acer]

acfm=Actual cfm

you might suck 1cfm through a leak from the atmosphere, but at reduced pressure that expands to many cfm- the actual cfm that the pump must pump.

[Brent]

thanks for that Acer. Understanding that is THE key to a meaningful interpretation of the math.

[Beweller]

The capacity of vacuum pumps is normally quoted at the suction pressure. An ideal constant displacement mechanical vacuum pump rated at, say, 1 cfm will pump 1 cfm measured at its inlet at all pressures. If the inlet pressure is, say, 6 inches of Hg, it will be pumping 1/5 of a cfm measured at 30 inches Hg.

The required driving power increases as the inlet pressure increases. Most vacuum pumps are very lightly loaded when working at a good vacuum and may be severly overloaded pumping at 1 atmosphere pressure. Some pumps have an unloading device that reduces the displacement at high inlet pressures, avoiding overloading the pumps prime mover.

[Acer]

beweller check your pm's

[Beweller]

Brent,

If you have the characeristic curve for your vacuum pump, look at the vacuum you are running and read the volume flow rate. Correct this for the operating pressure and that is the amount of gas you are pumping

If you don't have the characteristic curve, you can make an estimate by assuming an ideal pump with a straight line characteristic. You assume the volumetric flow measured at the inlet is constant from zero to the maximum vacuum developable by the pump. Look at your operating vacuum, correct the flow for the actual pressure and that is the amount of gas you are pumping.

Considering the importance of the quantity of gas flowing to the operation of sap ladders, it is surprising that this quantity never seems to be mentioned or controlled.

[Brent]

Beweller

This year will see a new vac set up. Last year I ran a genset in the bush and a peristaltic pump the pumped directly into a holding tank. Got 21-22`from it so we were pretty pleased. But the wear and tear on the very expensive hose led us to run it less than we should have, along with re-fueling etc.

This year we`ve got a Gast dry vane 3/4 Hp that pulls 26 inches on the bench and plan to place it in the sugar shack and run about 850 ft to the releaser.
Last year we had 160 taps. This year we may hit 190 or so.
The big unresolved question is if we put vac on about 75 trees over the hill that will mean 2 or 3 ladders. That brought up my question in another thread about the Bernard air injector the opens to allow a breif blast of air into the system to raise sap. I figured it might be better than a ladder with a continuous bleed. I`m not convinced it will be better than the continuous bleed.

I`ve already got a lot of 1 inch tubing to run from the pump to the releaser and I`m trying to figure if that will be OK or if I should go up to 1 1/2 inch.
I have to buy some more in any case.

[caseyssugarshack93]

i think 1 1/2 is deffinly overkill for 160-200 taps id say 3/4 would work for like 500 taps, but if you already have 1 inch then just use that,

just my two cents

[PATheron]

Brent- Ive got two setups with one inch running releasers very far away. Ones around 3000' and the other is atleast 4000 maybe 5000. Ill be able to let you know exact numbers within two weeks of the vacuum drop without sap running into the releasers which shouldnt really effect it to the releaser anyway and I may very well be getting sap within a month. Ill post what I find on here as soon as I get my vac pump hooked up. I know Im going to lose some vac but for now Ill live with it becouse I dont want to run a remote pump and Im just not going to spend thousands more this year for bigger pipe. If I can stay around 20" Ill be real happy with that especially if I dont have to maintain another pump and put gas in it. If I have more money next year maybe Ill get the bigger pipe. Theron

[Brent]

Great Theeeeeeeeeeeeeeeeeeeeeeeeeeeeeron I'll watch for your results.

I think I'm going to add to the 1" line and do a dry run like you, and then start a little bleed to simulate a ladder and see what happens.

Temps going up from below 0 to about 28 here today. Get some outdoor stuff done.