Plumbing Restrictions

[ca1ore]

If anybody doubts the HUGE impact plumbing can have on net flow ......

I have been running a PanWorld 200 on my tank through 1" vinyl hose (including 2 flow-robbing barb fittings) and a 1" apex flow sensor, up 12 feet, with a net flow of 950 gph. As part of a tank upgrade I replaced that line with 1 1/2" flex PVC and a 2" apex flow sensor. Still pumping up 12 feet, but now getting 1,400 gph. Clearly there's some error in the sensors, but regardless it's an observably huge difference. More than I thought it would be frankly; had hoped to get to about 1,200.

 

[mcgyvr]

Not surprising at all to me..

 

[JTL]

Now you have me thinking. I want to maximize my return pump flow. Currently I have a 3/4" return line which is the best I can do. In order to isolate any pump vibrations I have a 3/4" barb from the pump to a short piece of vinyl tubing to another 3/4" barb from there it is hard plumbed. I guess I never looked at the inside diameter of a barb compared to the same size pvc before. I looks like 25% reduction or more. Anyway, it appears I have only a couple of options. (1) I can upsize the barbs to 1" which may be closer to the inside of a 3/4 pipe. or (2) I could hard plumb the pump to the return line and skip the vinyl tubing. I already have a union at the pump so that is not an issue. What do you think.

 

[ca1ore]

I'm not surprised it went up, just the magnitude of the increase - almost 50% more! I always knew 'barb fittings bad', just didn't realize quite how bad. The 1" apex sensor is clearly restrictive as well. I think if one is going to use them, go up a size.

 

[Ron Reefman]

John, rather than use barb fittings and vinyl, start with a short piece of pvc then use a rubber pipe splice (HD & Lowes) and the back to pvc. The rubber pipe splice is bigger than the pvc so you have no size restrictions, just some flow disturbance due to change in inside diameter which you already have with the barb fittings.

 

[JTL]

Ron, that is a thought. Don't those have metal clamps that will rust?

 

[der_wille_zur_macht]

I've had rubber pipe splices on external pumps for years with no signs of corrosion. They work great and function as a union as well, since they're so easy to remove. At one point I got in the habit of using them instead of unions. If you're worried about corrosion, you could spring for stainless clamps as replacement.

To be clear, these splices should be used dry, not submerged. If you have a submerged pump, run regular PVC from the pump up well above the water line, then do the splice.

Upsizing the hose barbs and hose works fine too, but ends up more complicated in terms of component count. You can hard plumb the whole run, then just slice it in a strategic spot, and use the splice right where you cut it. It's easier than any other method.

 

[JTL]

They would be under water occasionally when the sump fills from the drain down during feeding. I could then just eliminate my union. Good ideas, Willie and Ron!

 

[der_wille_zur_macht]

You can put them anywhere in the plumbing run you'd like. It doesn't have to be super close to the pump, but closer means less noise (shorter section of pipe is resonating).

 

[ca1ore]

Interestingly, when I up sized with new flex PVC, flow on the apex meter said 1,440, nominally. After about a month it has fallen to about 1,405. How does one account for the drop? It's a real drop too, not a measurement error as I've had to adjust the siphon on my bean drain. It's not a dirty pump, because I didn't clean it when changing the pipes, but I do think it may be buildup on the insides of the pipes increasing resistance just enough to steal 35 gph. Something to think about.

 

[Gorgok]

I'm not sure slime would steal that much actual flow, but maybe the slime coated the flow meter enough to slow it down. At least i assume its a standard paddle wheel design, which has some leakage and with some slime in the bearings/bushings would stick more than new (causing more leakage).

 

[ca1ore]

No because as a I noted it's a real flow reduction. Unless you meant the slime on the paddle is creating resistance to flow.

 

[Gorgok]

Ah missed that part entirely it seems.

 

[ca1ore]

Though ironically my flow sensor on that return has now flat-lined, so who knows!

 

[alemone]

I think going from 1" to 1.5" is by far the factor that increased your flow dramatically. The resistance increase going from 1.5" to 1" is 5-fold! The short flow-sensors and barb fittings are likely irrelevant in that scheme.

 

[ca1ore]

Agree that the up sized hose is likely the biggest contributor to the extra 450, I do think elimination of the barb fittings and larger flow sensor are material.