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water trouble with rain barrels and drip irrigation need advice

T

thismembername

im slowly setting up my rain barrel drip irrigation setup but i have a pressure problem. Im not getting water at the end of my drip line 1/4. The barrels are currently three cinder blocks high and the spigot of the barrel is higher than the drip line entirely. I have one barrel setup for testing, 6 more to go.

Water is coming out of the barrel with no line attached.

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this is the drip line going down the fence, it was what appeared to be perfectly straight when i first started, its now all droopy and "un-setup" as i was trying to see where the water was getting stuck and trying to help it along the way. No luck.
 
I'm not a hydaulic engineer, but I'd say the swags in the run on the fence at not as much a problem as the large loops past the corner. That's where I bet you're losing pressure. If there are any rises in the pipe, even though it's all below the source, the source has to use pressure to push the water. It will siphon all day, but there is a loss of pressure.
 
yeah good eye @JJJessee

I undid that portion of the route of drip line when i was not getting any water at the other side of the yard. the looping was not present at first. sorry about that. the original setup down the fence was at a very slight slope. I have some emitters. still working on settting it all up at the end of the 1/4

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this line in these two pics are 1/2 coming off of the larger 1/4. I think i should of came down the fence with PVC instead of drip line 1/4. Maybe I need a pump, I was really wanting to avoid that.

do you think raising the barrels up another block or so would help?
 
I looked into gravity feeding my drip system when I set it up two years ago. I have an engineer friend take a look at the setup, he happened to know a lot about hydraulics. If I remember correctly, I needed something like a 10-12ft elevation drop from the water level to the end emitter in order to hold 6psi (which was the low threshold for my system). He told me you have to take into account the pressure drop as the water drains, so to maintain that pressure until the reservoir is empty, the BOTTOM of the reservoir has to be 10ft above the last emitter.

The reservoir I was looking into was 5 ft tall, so there was just no way I was about to engineer a structure to support 1600lbs of water 10ft overhead.

There was a lot of complicated math involved, and this was a while back, so don't hold me to accuracy in the numbers, this is just generally what I remember.
 
thanks for the info ghostpepperstore

http://www.dripirrigation.ca/HowTo_Gravity.asp

It takes 2.3 foot of height (head) to produce one pound per square inch (PSI) of water pressure. In other words, your water tank must be 23 feet above the field to produce 10 PSI or 12 feet up to produce 5 PSI. You can place the water tank on a hill or high in a barn or other building.
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crap.

is that an air traffic control tower in your yard??????

No, thats my rain barrel.

To get really good water distribution uniformity it is often necessary for the water source (barrel) to be 10,5 meters (yes, that's 35 feet) above the emitters.
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im going to work on it today, i don't really need perfect uniformity with water output. My main goal is to water between rains to keep the plants thriving, without spending 200 USD on my water bill in a month like last year.

luckily my back yard is on a slight slope downwards, so that should add to my height as the rain barrels are in the front yard under downspouts.
 
Those little 200GPH submersible pumps are $20.00 and are perfect for something like this. Just put it on a timer so it only runs 1 hour a day or whatever you need. The timer only costs a few dollars as well.

Also, your problem about not getting water out of the emitters might be because there is still air in the lines. Purge all the air from the lines and see if that helps.
 
you have to understand that each foot of your black poly pipe reduces the head you can deliver at a certain gph. each fitting will further add to the pressure loss, so will changes in elevation, so will kinks, and so will lowering the water levels in your tank. it quickly becomes untenable, however if you want to keep persueing this,i would recommend doing away with the black poly pipe and go with something like 1" pvc and lay it out as straight as possible. 1" in straight sections will have lower friction losses, additionally do not use 90's use 45's and separate the fittings by about a foot or so. you could also look at separating the system into small low volume zones. lowering the total flow drastically will mitigate the effects of pressure loss to a small extent. however this would entail adding solenoids that are very lossy.

to make something like this work very well you really need like 10-20 feet of elevation and a really good low end pressure regulator.
if it were me i would just build a 1 gallon accumulator setup with a simple diaphragm pump and power supply and regulator .
both can be had along with the necessary pvc and fittings for less than your 200$ water bill.

moreover with this setup you can switch to real pressure compensating emitters that will yield uniform flows at each emitter regardless of branch length and elevation.

a little 200gph pumps mentioned earlier are entirely un suited to drip irrigation as they are simply unable to develop any significant flows at reasonable pressures. diaphragm pumps are able to run at very nice psi's. i have a surflow smart sensor that gets up to around 60 psi at a few gpm. that's enough to run about 20 of my 3gph spray stakes. any more than that will require another zone to be added, or an accumulator and switch to be incorporated.


on an unrelated note, i dont understand how you spend 200 bucks on water? i can fill a 24k pool here + the regular home water usage for about 80 bucks.
 
Good, raising your reservoir helped with pressure. But, did you lower your mainline? Having your mainline off the ground negates some of the benefit of "head pressure". Going with larger mainline would also be a good idea.

I'm sure you already realize the more emitters you add, the worse your pressure issues will become.

Pressure compensating emitters have a diaphragm inside and usually requires a minimum of 10 PSI to operate effectively. A pump that operates "on demand" with a timer might be a little more costly initially but, it would absolutely solve your pressure issues.

I have run hundreds of irrigation systems with pressures at 55-60 PSI without using a regulator. Especially at the distances you have. As long as you use poly tubing and not the softer vinyl, you will be OK.
 
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