Shurflo above and below

[Nemo5]

I currently have a shurflo 4008 at the end of my mainline. The mainline is about 800 feet of 1 inch. I was wondering if I were to add another pump at the top of my mainline would I be able to achieve even more vacuum? The pump would not pull any sap because the pump would be on the upside of the first saddle. I would just have a pail of water to recirc to keep the diaphragm wet. Did anyone ever try this?


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[wmick]

I was waiting for someone smarter than me to respond.... but nobody seems to be jumping on this one... I'm intrigued, and at the risk of sounding foolish, I will join in with some brainstorming...
I believe that you will be able to increase or maintain vac levels better, with a second pump on the system, however, I'm not certain you can expect that it wont draw out sap...
I'm making assumptions that you basically have a closed system... and plumbing your pump to draw from the end of a closed mainline...
This is not based on experience, so take it with a lot of salt... but, I'm pretty sure this will happen....
Your second pump will be evacuating air from the top of the mainline, from between it and the sap..... (and the sap will move towards the pump as air is removed). In order to prevent sap from getting to the pump, you would need enough air-leaks entering the system and mainline, rising to the pump, to equal or overcome what the pump is removing from the system. If you had that much air travelling against the flow of sap, are you gaining anything??

.....I think

[Nemo5]

My mainline has good slope from the top to the bottom.Right now I am pulling 11 inches of vacuum. Im thinking since there is slope on the mainline the sap should never want to flow uphill towards the upper pump. I could be wrong. I don’t know if it would conflict with the lower pump though. I’m thinking not because I think they would share the load of creating vacuum and the lower pump would still pull the sap. I’ll give it more thought before I purchase another pump. Might be good to have a spare pump though.


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[Nemo5]

Giving it more thought. Maybe it would be simpler to put a y in front of the lower pump and add the second pump there. Run two pumps parallel. Should have the same effect and everything would be in one location.


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[mol1jb]

Before you go to the trouble of something quite unorthodox I would focus on tracking down leaks.

[Nemo5]

Before you go to the trouble of something quite unorthodox I would focus on tracking down leaks.

That is my plan for Saturday.


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[hogisland42]

I don't have a shurflo system but was curious about this. Do you mean one on one end pulling and one on the other end pushing?

[Nemo5]

Both pulling. To create higher vacuum.


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[Mark B]

I don't know how you are set up but Im thinking you might be better off breaking your mainline into 2 sections and applying one pump to each. 800' of 1" main is a lot of volume to displace with a small shurflo. Ive got 550' 3/4"... a 250' run and 300' run to a low spot in the middle. with 2 pumps, pulling the individual sections Im upwards of 15-20". However one pump is down with a broken fitting, so I made a tee into just the one pump. Its only pulling 10 -14 on both. Close one side at a time and it is back up 18ish depending on flow. Just my thoughts.

[CampHamp]

I expect the limitation is more about the number of taps because that’s where you lose pressure (incoming air and liquid). I have the same number of taps that you do and I have a single pump (4048). You will need more time to build up vacuum in the lines with more line volume, but I expect you’d be drawing 15” in under 12 minutes if the diaphragm stays wet. It takes me about 3 minutes to get 15 vac with about 600’ of 1/2” tube (which is about 1/4 the volume). Also, if you keep drawing vacuum into the freeze before the pump shuts off (and you don’t have leaks), then you can keep pressure on the lines overnight so it will start quicker in the morning.

I don’t think putting diaphragm pumps in series makes any sense. If you suck on the outlet, do you think it will pump faster? Uphill maybe, but I don’t think it helps on a downhill line.

If you put a pump at the top and suck out, there may be days where the bottom is frozen and the top has thawed and you’d just suck your sap onto the ground! Also, when that top pump is dry (hopefully always) then it will only pull 12” - it needs to be wet to get 25”. So the best case is that you get your system up to 12” twice as fast, but then rely on the lower pump to crank the vac with a wet diaphragm.