Diaphragm Pump Sizing and Limits

[SeanD]

I went a little overboard tapping a new area last year when I added a Shurflo to the line and ended up with 120 taps on a 4008. Probably explains why I had mediocre vac levels with plenty of sap in the line. I just reconfigured the mainline and it opens me up to more taps. I think I'll be near 150 taps now on a 3/4" line at about 300' with mix of 5/16" and 3/16" laterals. The 5/16" laterals have 3-5 taps each and the 3/16" have 16-20 taps and are much longer going 100' or so up to the top of the hill.

If I do get into the 150 tap range, will a Shurflo 4048 do the trick or should I think bigger? What's the next step up with a diaphragm pump, a Guzzler? Or is there something between a 4048 and a Guzzler?

Or if I get the 4048, could I run it in parallel with the 4008 already there by splitting the line between the two pumps?

[Biz]

A 4048 should work for you. I tested a 4048 on a 300' dry mainline without any laterals (or leaks) using a 4048 pump and found that with a recirculation line, it took over 20 minutes to get vacuum up to a good level (over 20"). It does take some time to draw down vacuum on the mainline due to the air volume. Leaks will limit max vacuum. It will take longer to achieve good vacuum if no recirculation line is used or if a smaller pump is used. I would say try the 4048 with recirculation line. Adding a couple ball valves to the mainline helps isolate leaks. If you can't pull good vacuum there is probably a leak or two.

There are 5 or 5.5 gpm diaphragm pumps out there and some larger ones. On my 100-tap system on 3/16 red maple lines, I pulled 24" of vacuum all last season with a 4008 3gpm pump. Interestingly when I put a 5gpm pump on this setup it could not maintain steady vacuum but it worked much better with the smaller pump. I didn't have time to diagnose why, but perhaps the larger pumps need a certain minimum flow to generate vacuum.

I'm not a fan of paralleled pumps but the topic came up during my talk on diaphragm pumps at Vernon yesterday. How can you ensure both get enough liquid flow to generate vacuum? If you use them let us know how they work out. A guzzler would definitely work better but is probably overkill and will mostly just overcome leaks in your particular setup.

Dave

[SeanD]

Was about to pull the trigger on a 4048 when I came across this Shurflo 5059. Seems like more bang for the buck than the 4048, but seeing your results with larger pumps has me wondering, Dave. Giving this a bump to see if anyone else has tried a larger Shurflo.

[Ultimatetreehugger]

I used the 5059 on 160 taps or so with great success. The trick is to avoid the backing up of sap in the line. A Circulation line helps but I found sloping the line gradually with no flat spot before the pump was just as affective. Good luck!

[SeanD]

Thanks for the feedback. I run into that same problem with my 4008s now. I'm constantly tweaking it. I'll think I have the sweet spot then come home and find it surging again. I'm wondering if I need to lower the temperature the pump comes on after a freeze. Maybe sap in the mainline is thawing and backing up before the pump gets going. I believe I have it at 33, but I'll check.

[Biz]

I tried a Delavan 5gpm pump in place of my Shurflo 4008 early last season, on 100 taps, four 3/16 runs feeding it. I found that during low to moderate sap flows there was apparently not enough flow to maintain steady vacuum, it would fluctuate. Replaced pump with a 4008 and instantly got a steady 23-24". I think the larger pump may have worked better later in the season with better sap flow, but the smaller one worked fine for me all season.

I have often seen vacuum coming up quickly in the AM as the pump draws thawed sap from the lines, then the vacuum drops since trees have not thawed out yet and flow stops. Eventually vacuum levels stabilize when trees are running. There can be a couple fluctuations, maybe that is what you are seeing. If a larger mainline has any droop or flat spot, you could see the same thing, but it might continue to fluctuate. In an experiment a few years ago with 5/16 lines that had droop, I saw fluctuations hard enough to cause the pump 10 amp fuse to blow when pump got a slug of sap. Very important to keep lines at a steady pitch if using something larger than 3/16.

Dave

[SeanD]

I've definitely improved the slope on all my mains. Ironically, the one with the least pitch has the least issues with surge.

On the two that surge, I do have a consistent slope on the wire and then a steeper drop from the wire down to the pump. Do you think it will help if I align those final 5-6 feet more in line with the slope of the wire? I knew droops weren't good, but is a change to a steeper pitch also not ideal?

I looked more closely at the 5059 and saw that it is almost 14" long. If that's accurate, it won't fit in my current box any which way. I'll go with the 4048 and it will swap right into my set up this year. It's only a little bigger than the 4008. If I notice an improvement, maybe I'll make a new box for the larger pump and move the 4048 to another spot.

[DMF]

Can someone explain the "recirculation line" to me please? What is it? What does it do? How is it tied into the system? Thanks!

[VTnewguy]

Can someone explain the "recirculation line" to me please? What is it? What does it do? How is it tied into the system? Thanks!

Because the diaphragm pumps are low CFM pumps that need liquid to generate good amounts of vacuum, you can force more liquid into the pump with a recirculation line to get consistent vacuum in the system. This is done by running a line from your collection tank to the front of the pump in a manifold. I typically build a manifold with my lines using a piece of mainline and saddles, some people build very intricate manifolds. One key on a recirculation line is it needs to have a valve to limit the flow of sap into the pump. You want just enough liquid to generate the vacuum but not so much you overcome what the pump can handle.

[DMF]

Because the diaphragm pumps are low CFM pumps that need liquid to generate good amounts of vacuum, you can force more liquid into the pump with a recirculation line to get consistent vacuum in the system. This is done by running a line from your collection tank to the front of the pump in a manifold. I typically build a manifold with my lines using a piece of mainline and saddles, some people build very intricate manifolds. One key on a recirculation line is it needs to have a valve to limit the flow of sap into the pump. You want just enough liquid to generate the vacuum but not so much you overcome what the pump can handle.

Thanks for the explanation. This kind of goes against the advice of not putting too many lines on one pump though no? It seems if you need to recirculate sap out of the tank to keep the pump pulling a vacuum, then wouldn't additional lines/taps serve the same purpose? I'm sure there's something I'm missing....