Vacuum Pump Station Critique

[HondoLane]

Fellas.

This is my second year on tubing and a diaphragm pump. Last year I was t happy with thawing lines so I decided to revamp my pumping station.

Today is the first day tubing the new setup and I’m only pulling 10-15 in vacuum. At times it seems it locks up with sap. Could it be my discharge? The discharge is 1/2” pvc and it rises about 6 feet right after exiting the box then out to my sap tank. I have a 3/16 recirculating line with needle valve. The needle valve is barely cracked open. No leaks from what I can tell. I did pull some goop through the lines and had to clean my screen several times.

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Let me know what you think?

[VTnewguy]

I'd check for leaks and make sure the reciric line is open enough for a good amount of liquid.

[tombaisley]

I'm running a Shurflo 4008, I have 53 taps divided into three 3/16" lines, I also have a 3/16" recirc line with needle valve. The first line runs down hill to the pump, The second line line is level or maybe 10' below the pump, And the third line is aprox 15' below the pump. I'm making 23" Hg with the recic line aprox 25%

After running all night I had 26" Hg with the recirc line aprox 25%

[HondoLane]

Had some more time to monitor it today. It hovers around 12” and the clear tube starts to fill. I “burb” it before the intake of the pump and it’ll run remove the sap then sap flows. After a couple of minutes it will stop moving again and “stalls”

Sap sits in line after pump and doesn’t move. Could it be my diaphragm? The pump is a 3.0 gpm pump. Would I be better off upgrading to a shurflo?

[wmick]

Sounds to me like you're maybe just running the pump a little dry... I know mine sort of pulsates up and down.... When the trees are flowing really good, the pump stays wet and vacuum stays high... but when the trees slow down, the pump will pulsate when it gets gulps of liquid and then dries out.... back and forth...
What happens when you open up the recirc line? I'd pinch off your incoming sap lines to rule out leaks, and see what vacuum you can achieve, while just playing around with the recirc.

It would be nice to have a system that adjusted the amount of recirc, automatically to account for the volume of incoming sap... but I haven't figured that one out yet.

[HondoLane]

I’ve tried recirc open and closed and it seems as if It makes little difference. I noticed that when it’s “stalled” some air bubbles flow in reverse. Then the pump seems to bare down and the sap shoots back in and vacuum rises swiftly. I’ll try to post a video shortly.

[VTnewguy]

Add more liquid via the recirc line to rule out the pump. Last year when my pump started acting up for no reason it took searching every bit of line for a small squirrel chew that made the whole system not work.

[HondoLane]

Ok. No video tonight. Now I just checked it via Blink (yes.. I have a blink camera on it!) and I’m up to 20” of vacuum and slow flow.

Now I’m wondering if my trees aren’t flowing quite yet like they should.

I will work with the recirc though to see.

[wmick]

Ok. No video tonight. Now I just checked it via Blink (yes.. I have a blink camera on it!) and I’m up to 20” of vacuum and slow flow.

Now I’m wondering if my trees aren’t flowing quite yet like they should.

I will work with the recirc though to see.

your symptoms are exactly the same as mine... and I'm fairly certain, its the pump getting dry and losing its seal. When that happens, all the air pockets throughout the system under vacuum instantly expand back to atmospheric pressure, and suck back from your pump. until it seals up again and starts the cycle over... Not certain, but this is my theory.

Just throwing out ideas, because I really haven't solved it myself either... but what about re-plumbing the recirc in "immediately" before the pump... to ensure that a steady stream from the recirc goes directly into the pump seals, rather than spending time out in the piping..

Or maybe create a bit of a vertical rise in the pipe immediately after the pump... to hold liquid... air bubbles would rise up through it immediately and leave a supply of liquid against the pump... If the seal thinks about leaking, it would only have liquid to draw back and keep the seals wet ???

Just brainstorming.

[Biz]

I had a very similar situation yesterday. 100 taps on 3/16, 5gpm pump. No recirculation line. The vacuum would sit around 12", flow would start to come in, up to 22", sap coming in good. Then eventually there was not enough flow to sustain the vacuum and it would drop back to 12". Sap would flow backwards in the lines. Cycle repeated every 10 minutes. I swapped the 5gpm pump for a 3gpm Shurflo 4008, reasoning that the smaller pump would be better at holding a steady vacuum. Bingo, after that it held 22" steady for the rest of the day. I am thinking that my trees were not flowing well yet so the larger pump did not work well with the low flow. I want to try it again later in the season when sap is running hard to see if it makes a difference.

Dave

[wmick]

I had a very similar situation yesterday. 100 taps on 3/16, 5gpm pump. No recirculation line. The vacuum would sit around 12", flow would start to come in, up to 22", sap coming in good. Then eventually there was not enough flow to sustain the vacuum and it would drop back to 12". Sap would flow backwards in the lines. Cycle repeated every 10 minutes. I swapped the 5gpm pump for a 3gpm Shurflo 4008, reasoning that the smaller pump would be better at holding a steady vacuum. Bingo, after that it held 22" steady for the rest of the day. I am thinking that my trees were not flowing well yet so the larger pump did not work well with the low flow. I want to try it again later in the season when sap is running hard to see if it makes a difference.

Dave

Thats interesting.... Thanks for the update... If you didn't have the smaller pump handy, I wonder if putting a valve on the output of the pump might work as well? Im guessing not, because air would flow through the valve much faster than liquid... Might not be able to maintain any consistency either...

Or another thought.... Rheostat speed control on the pump motor... DC motors are easy to speed control, by simply lowering the voltage... but I don't know if these pumps would take to it?

[HondoLane]

Here is a video of it today. Sap seems to be flowing better. I opened the needle valve all the way and it seems to run the best as in “pulls hard” but then it stalls, then pulls etc. I appreciate the help. I do t have any close maple friends that I can personally view setups etc so I rely a lot on the trader to help!!


https://youtu.be/j08Xny0afWk

[mainebackswoodssyrup]

That looks like it’s working OK to me.

[HondoLane]

Well... needless to say it is working. No leaks. It was just a case of sap not flowing from trees. In fact it’s working so well... last night everything froze outside but inside box and insulated recirculating lines, etc didn’t freeze. Today when pump kicked on... vacuum has shot up to and pegged my gauge trying to suck frozen exterior sap lines!!

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