Doubling up a shurflo

[boondocker]

Has anybody tried to double up a shurflo pump on one main line? I guess I'm not sure if it would do anything or not I was just wondering if anyone has ever tried it. My mind wonders from time to time and I was thinking about it tonight on my way home. I'm all done for the season but going to connect the pumps back up this weekend to flush the lines and thought maybe I would try it to see what happens. :confused:

[Super Sapper]

If you connecting them separately to the main line you will double your gpm capacity which increases your cfm. 1 cubic foot equals 7.48 gallons so a 3.5 gpm pump would be about .5 cfm and 2 would be 1 cfm. I think these numbers would be with the pump wet so if dry it would be less. Putting them in series (one after the other) would have no benefit.

[Cedar Eater]

Has anybody tried to double up a shurflo pump on one main line? I guess I'm not sure if it would do anything or not I was just wondering if anyone has ever tried it. My mind wonders from time to time and I was thinking about it tonight on my way home. I'm all done for the season but going to connect the pumps back up this weekend to flush the lines and thought maybe I would try it to see what happens. :confused:

I haven't done the experiment, but I think two pumps in series could produce a higher vacuum than one if the up stream piping is just barely larger than one pump could pump down and the flow of sap is below the max flowrate of one. If the piping is larger than two pumps can pump down, and the flowrate of sap is close to the combined max flowrates of both pumps it would be better to connect them in parallel. If it's somewhere in between, there's probably a crossover point where additional vacuum becomes less important than pumping capacity and series loses to parallel.

[mellondome]

Diaphram pumps in series will not increase anything other than electrical consumption. Put them in parallel, you will increase your cfm...

[Super Sapper]

If you have two diaphragm pumps in series the most you can pump would be 3.5 gpm. If in parallel you could pump 7 gpm. With a centrifugal pump you could increase flow running in parallel but may burn the pump up. If your total flow does not exceed the capacity of the shurflo pump you will not gain anything by using 2. Keeping the checks wet with a recirculation loop would work much better but remember that the flow of the recirculation loop will decrease your net pumping rate.

[Cedar Eater]

Diaphram pumps in series will not increase anything other than electrical consumption.

You've conducted the experiment?

[mellondome]

You've conducted the experiment?

Don't need to. If you know how the pump works you will understand the difference. Also this is vacuum not pressure.

[Cedar Eater]

Don't need to. If you know how the pump works you will understand the difference. Also this is vacuum not pressure.

If it was a perfect positive displacement pump, I would believe you. Without the experiment, I am skeptical. Pumping into a downstream vacuum just seems like it would produce a better upstream vacuum than pumping into a downstream with no vacuum, at least with a dry line.

[Super Sapper]

With 2 pumps that delivered 3 gpm and were timed perfectly. While one is sucking and the other is discharging you could get 3 gpm flow rate because that is all the downstream pump can move. If they are not timed to be exactly opposite they would work against each other and slow your flow rate by fighting the checks of each pump. If both pumps are trying to suck at the same time the downstream pump will work against the upstream pumps discharge check and it won't seat properly which will not allow the upstream pump to suck up sap. When both are discharging you will be forcing the suction check on the downstream pump open and causing it to possibly back flow. With this, the best you could do would be to achieve the capacity of one pump only.

[Cedar Eater]

With 2 pumps that delivered 3 gpm and were timed perfectly. While one is sucking and the other is discharging you could get 3 gpm flow rate because that is all the downstream pump can move. If they are not timed to be exactly opposite they would work against each other and slow your flow rate by fighting the checks of each pump. If both pumps are trying to suck at the same time the downstream pump will work against the upstream pumps discharge check and it won't seat properly which will not allow the upstream pump to suck up sap. When both are discharging you will be forcing the suction check on the downstream pump open and causing it to possibly back flow. With this, the best you could do would be to achieve the capacity of one pump only.

Makes sense, but if you put enough tubing between them, that would buffer any effect one pump was having on the other 's checkvalves and the upstream pump would still be pumping into a vacuum. Your max flowrate would be the max flowrate of the weaker pump, but I think your maximum achievable dry vacuum would be higher than it would be with either pump alone and that could be useful.

[mellondome]

Only usefull if you put them in parallel to increase the cfm. Again, vacuum not pressure.

[Cedar Eater]

Only usefull if you put them in parallel to increase the cfm. Again, vacuum not pressure.

Again, I am skeptical that you can't get more vacuum with two pumps in series up to the point where you reach the max flowrate of the weaker pump. These pumps are not perfect positive displacement pumps. Their inefficiency provides room for doubt. I think the experiment could be worthwhile if an increase in dry vacuum is what you are seeking. Empirical data has its place. If you're trying to increase max flowrate and have plenty of taps feeding into it, then parallel is the way to go.

[mellondome]

Let us know the outcome.

[Mr. Red Maple]

This season i tried doubling up a shurflo 4008 with a 2088. I had it ran with 2 different pieces of tubing and one was pulling just air while the other was sucking the sap and air. The vacuum only went up about an inch and that's because of the increases cfm's to overcome leaks. I haven't had the best of luck with shurflos. The highest vacuum i was able to get this year was 7 inches.

[Cedar Eater]

This season i tried doubling up a shurflo 4008 with a 2088. I had it ran with 2 different pieces of tubing and one was pulling just air while the other was sucking the sap and air. The vacuum only went up about an inch and that's because of the increases cfm's to overcome leaks. I haven't had the best of luck with shurflos. The highest vacuum i was able to get this year was 7 inches.

It sounds like you had them connected in parallel. Did you try connecting the discharge of one pump to the suction of the other? If so, how much tubing was between them?