Pond Boss Forums GENERAL QUESTIONS Product sources Irrigation Pump Advice

I need some help selecting the pump for my temporary irrigation system. It will have two 300 foot loops of 1 1/4 inch diameter pipe that each circle half way around the pond. The pump will feed the two half-circles through a T-adapter. There will be 3/4 inch hose connectors every 100 feet. The individual Gilmour 5800 sprinklers work fine off my existing well water supply, which puts out 40 PSI at the end of a 300 foot 3/4 inch pipe with one sprinkler running. Now I need to find a pump to take water from the lake instead of my well and feed about ten sprinklers. I decided that none of the 120 volt 1 HP electrical pumps will run enough sprinklers simultaneously, so I am looking at gasoline pumps now. One pump I have found is a Pacer SE2UL E5HOC pump with a Honda engine for $370 from Tractor Supply at http://tinyurl.com/2e64lfq. I found a pressure-flow diagram for the Pacer pumps at http://www.pacerpumps.com/files/gc_pb.pdf It looks like that pump can pump up to 90 GPM at 40 PSI, which would supply up to 30 sprinklers. Since I plan to have only about 10 going at a time, it looks like that might work OK. Is my thinking roughly on track?

I found another pump for about the same price at Harbor Freight at http://tinyurl.com/248gac4. It has a slightly higher peak pressure and a maximum outflow of 108 GPM, but I haven't found a pressure-flow curve for that pump. I am inclined to go with the Pacer pump, because it has a Honda engine.

I would appreciate any advice on whether either of these pumps would be reasonable choices. This is a temporary irrigation system just to get my grass started, so I can't justify spending much more than this for the pump.

Thanks,

Charles

Bump....Esshup - any ideas?

The flow rate of the pump is of primary importance for your irrigation system. Either of those pumps should be more than adequate.

What are you planning to use for a foot valve and strainer?

How'd I miss it?

I'm going to do some thinking out loud.

Each sprinkler takes 4.9 gpm

10 sprinklers = 49 gpm

Pump can pump 90 gpm @ 40 psi.

I'm missing the length of 1 1/4" pipe for each semi-circle, and each length of 3/4" hose.

But, if each length of 1 1/4" pipe is over 200', my WAG is that you have too much friction loss in that size pipe for that length of run, feeding that many sprinklers of that size per run. My WAG is that you should bump the pipe size up to 2".

Go
here and plug in the numbers for 1 1/4" pipe, then run the same calculations for 2" pipe. You'll be amazed at the difference. I ran the #'s for each semi-circle being 400'. Your friction loss per 100' of run for that pressure and volume for the 1 1/4" pipe is 20.1 vs. only 2.8 for 2" pipe.
Friction loss

I have a three inch pipe for the intake with a shower drain at the end, which will sit inside a bucket to keep it out of the mud. I thought I would also cover the end with some window screen to reduce small particles getting in. If that does not give enough flow, then I will drill some holes in the side of the pipe.

Not sure yet about the valve. The Pacer pump is supposed to be self-priming, so I thought I would try it without a valve to start with. The pump will be sitting only about two feet above the water.

Each branch is three hundred feet, with seven valved outlets at the beginning of the two branches and every 100 feet; but the two branches end at each side of the dam, and I will only need about two sprinklers on each end to cover the dam. Most of the volume will come off the three T's at the beginning and at the end of the first 100 foot runs.

That's interesting; that is the same WEB page I used to figure the diameter of the
auxiliary filling pipe I put in back in October. I calculated we needed 8", so we used 10", and it works great.

My piping may be marginal. If it doesn't work OK, I guess I can replace the first two sections with 2" pipe.

I used to teach cardiovascular physiology, and I remember how hard it was to explain to my students that the flow resistance of blood through arteries varies with the 4th power of the radius. A little change in diameter does make a big difference.

Thanks for the input.

I have been thinking some more about the foot valve. The pump is very easy to prime, and I have a ready source of water for priming. I'm wondering if putting a foot valve in the 3" inlet pipe will cause enough resistance to reduce the pump output. I guess I could always add a foot valve later if I really need it.

The strainer is a 3" shower drain at the end of the 3" pipe. In addition, I drilled several 1/2 inch holes in the side of the pipe near the bottom and attached some window screen around the pipe. The end of the pipe also rests in a 5 gallon bucket to keep it out of the mud.

Opinions?

Charles

I think you'll need more screen area. One medium sized leaf will cut a LOT of flow. I have a semi-trash pump that has a 3" inlet hose. The screen is about 12" dia, and 8" high with 3/8 holes all over it, right next to one another. Grass, maple seeds and other various junk will clog it in a few hours and reduce the flow by 60% (I'm guessing). Since all the material was relatively soft, I removed the screen. But, the exit hole was a full 3" so I didn't worry about plugging anything with the junk that went thru the pump.

The engineer in me says measure the screen hole size, and calculate it compared to the 28 1/4 sq. in. that is the area of the 3" pipe. I'd vote for at least 4 times the open screen area vs. the area of the 3" pipe. In small screening you'd be amazed at how much area the wire takes up vs. the open area of the screen.

I took some pictures of the inlet section. This shows the 3" shower drain plus the 20 holes drilled in the side of the pipe

Here are links to the rest of the images:
End of the pipe covered with screen.
http://www5.vetmed.auburn.edu/~branch/images/pond/IrrigationSystem/IMG_3540_crop_500t.jpg
Bucket attached to end of inlet: http://www5.vetmed.auburn.edu/~branch/images/pond/IrrigationSystem/IMG_3541_crop_500t.jpg
Intake rotated to working position: http://www5.vetmed.auburn.edu/~branch/images/pond/IrrigationSystem/IMG_3545_800w.jpg

Do you think I need to increase the number of holes or get an actual pump inlet to replace the shower drain?

And would a foot valve add significantly to the flow resistance?

BTW: I followed your suggestion and replaced the first 100 foot sections on each loop with 2" pipe. I used schedule 40, because I could not find 2" poly pipe locally. I hope to get it hooked up today to give it a trial run.

We got most of the system in yesterday. The Pacer SE2UL E5HOC pump 2" discharge flows into a 2" PVC Tee which distributes the flow to two branches of 120 foot x 2" schedule 40 pipe. 3/4" outlets are every 60 feet apart, giving five outlets. At the ends of each section of 2" pipe it connects to two 100 foot sections of 1 1/4" poly pipe. Right now I have 7 Gilmour sprinklers running simultaneously off of the 2" section. As esshup predicted, the sections of 1 1/4 pipe cannot support more than two sprinklers simultaneously. That section does not need so many sprinklers running, so this may work out pretty well. One nice surprise is that each outlet can support two sprinklers in series, which I had never been able to do when running from my well. The picture shows five of the seven sprinklers.

It looks like you are on your way! With the bucket on the bottom, and the flat shower drain, is there anything in place to prevent the bucket from getting sucked up against the shower drain? If that were to happen, then a lot of your open area would be lost.

Keep an eye on the screen covering the pipe. It might plug up relatively quickly.

Thanks for the pics and the update!

I have the bucket handle attached to the inlet pipe so that there is about 2" clearance between the bottom of the bucket and the inlet drain.
I have been looking for a better system, but all the real inlets I have seen are pretty pricey. Also, I was surprised that the Pacer pump has 2" diameter for both the inlet and the outlet. I would have thought the inlet should be larger for efficiency. And when I was setting up the pump I found that it already has a flap valve at the inlet. So far it has held its prime, although I noticed that it does leak slowly out of the inlet when disconnected.

I was thinking about posting a project report like I did with the pier a while back. Something like that would have been helpful to me, and it would have saved me some money in false starts.

I wound up using 2" PVC pipe going in two directions through a tee. One section supports about 25 impact sprinklers with four to six sprinklers fed from each of 10 3/4" tees from the 2" main lines. One section has 26 sprinkler heads, and the other has 21. The two sections are controlled by 2" ball valves.

The Pacer SE2UL E5HOC pump is able to support either section, but it doesn't seem to hold its prime. The pump has a built-in flap valve. When I turn the pump off, I can hear a gurgling sound from the pump. And when I start the pump it may take a couple of minutes before the pump loads and starts pumping--whether or not I prime it. Does this indicate that the flap valve is leaking? If so, is that a defect in the pump? The inlet is about a 30 foot 2" PVC pipe, and the pump is about two feet above the waterline. I do not have a foot valve.

Thanks,

Charles

Good information on that pump supporting the sprinkler heads. I don't like to rely on flapper valves to create a perfect seal. I'd rather use a spring loaded anti-backflow seal like is used on submerged well pumps.

My guess is that it's slowly allowing the water to trickle back and even if the pump is primed, it still needs time to work all the air out of the supply pipe. All it would take is a grain of sand to disrupt the seal, and without any pressure on the flap to help it seal, it most likely won't seal 100%.

My 15,000gph 3" trash pump has the same set-up, and the same problem.

Any suggestions on a valve? The inflow is 3" diameter. I saw a foot valve for $30.00 at Northern Tool, but it's a ball valve, and it seems to me like it would interfere with the uptake and might not close tight with only about two feet of head.

With this situation, will it damage the pump to have it run until it primes itself? I timed it yesterday, and it took 3 1/2 minutes to suck the air out of the 30 foot inflow pipe. It takes about as long even if I prime it.
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The valves that I've seen were on the pressure side of the pump, not the suction side, so they would keep the pump primed unless you had an air leak somewhere on the suction side.

I haven't had any dealings with the company at the bottom, that is the first "store" that came up when I googled "well plumbing supplies check valve". (I'm not counting the www.wellowner2.org/2009 site) I'm just using them as a reference for the type of valve that I'm talking about. You should be able to find it locally, maybe talk to a local well driller and see if you can purchase the correct check valve from them. The one that is in my well is made from Brass, and is placed between the pressure tank and the submerged pump.

I can't tell for sure if yuor pump will be damaged if run for that long trying to get primed, but I hate to run them dry for any length of time. If you read the article that is first in line when you google, you'll see why they recommend a check valve even if there is a foot valve in place.

plumbing supplies - well

Those flap valves in irrigation pumps always leak. Most pumps have a place to add water into the pump from a container. We use a full-flow ball valve on the pressure side to keep the outlow pipe full. Open it up just befor starting and enough water drains back to get things flowing quickly.

Today I took off the inlet and outlet connectors to test the flap valve. I ran a garden hose to the outlet and filled it. Water came out the inlet at about 1 gallon/minute. At that rate it would not take long for all the water to leak out of the intake pipe. I guess that explains the loss of prime. One gallon/minute leakage seems like too much to me.

I already have such a ball valve at the outlet, but I have never used it. Tonight I closed the ball valve when I shutdown the pump. Can hardly wait until morning to see if your solution solves the problem.

That'd be the easiest fix yet. I hope it works.

This is an update on the irrigation system I installed last summer. It uses a Pacer SE2UL E5HOC gasoline pump. The pump feeds two sections of 2" PVC pipe that circle most of the pond. One section has about 21 sprinkler heads, and the other has 26. The pump can support either of the sections; I switch from one to the other with 2" ball valves. The only problem I have is loss of prime if I leave the pump off for a day or so. I did buy a foot valve, but never installed it. Here is the photo of the pond with the irrigation system overlaid. The pump with 2" control valves connects between branches #6 and #7.

And here is a picture looking across the pond from the dam. You can see part of the 2" PVC supply line at the edge of the pond plus a couple of the 3/4" branches with about six sprinkler heads on. I put a 1 foot border of centipede sod around the edge and seeded the remainder (about 2 acres) using centipede in the sunny areas and MaxQ fesque in the shady areas.

Last summer was one of the worst droughts we have had in years. If I had relied on Mother Nature, I am sure I would have just a bare eroded field. I won't know for sure until spring, but so far the centipede is looking pretty good. I'm not sure whether the fescue survived. Some of the areas do show some pretty good greening now, but I'm not sure whether that is the fescue or just annual rye grass that may have seeded itself before I cut it in June.

Nice! We had a really dry Fall here as well, my pond is down at least 6' (groundwater pond).

We're in the middle of another severe drought. After pumping the pond way down by irrigating last summer, I decided not to irrigate from the pond this year. So I removed most of the PVC pipe--leaving just two to three sprinklers on each of the 12 legs of the system nearest the main 2" feed pipe. My regular well pump can handle two sprinklers in series or three in parallel. I have been irrigating most days since spring--alternating each section for about 1.5 hours each. I also added sprinklers on hoses for some of the areas farther from the pond. Here is what it looks like now looking across the pond from the dam.

You can see that the pond is still down about three feet--showing both the pier and the large sweet gum root ball that is covered about a foot when the pond is full. The sections of white pipe hanging on the fence in the background are the ones I removed.

And here is a view from the far end of the field looking back to the south across the pond.

Considering the droughts for two years running, I guess the grass turned out about as well as I could have hoped for. And a lot of the credit goes to esshup for your advice on pipe sizes and lengths that turned out spot on.

The new river birch trees and wildflowers (on the left in the first image and the right in the second) are doing pretty well too; the birch and maples are getting about 100 gallons about every five days. One of the bald cypress died, and the second is looking pretty stressed.

All in all it has been a busy year. And the grand kids have had a ball catching the scrappy little yearling bass we stocked last July.

FarmerCharlie, I'm glad that it turned out as well as it did! The grass looks great. Thanks for the update.