# Ask a Question forum: Drip Algebra Question

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 Name: Philip BeckerFresno California (Zone 8a)PhilipwonelNov 20, 2016 11:27 AM CST I have 40 psi. at my main faucet of house. Im running drip off of auto sprinkler valve. Putting 1 gph. Dripers every foot. How many drippers can i put on one line ??? And how long to run them to get 1inch acre foot a week ? Thank you !πππAnything i say, could be misrepresented, or wrong. [Last edited by Philipwonel - Nov 20, 2016 11:30 AM (+)] | Quote | Post #1321545 (1)
 Name: Sallycentral MarylandSeriously addicted to kettle chips. sallygNov 20, 2016 2:44 PM CST great question!! would take me a while. Somebody somewhere must have guidelines for this..come into the peace of wild things..-Wendell Berry Life is a buffet (anon)
 Name: greeneSavannah, GA (Sunset 28) (Zone 8b)My dogs love me; some people don't. greeneNov 20, 2016 5:52 PM CST I understand the question but my brain cannot handle the details. I remember that for each foot away from the source you lose pressure...that's all I remember. Here are a few links that may help. Good luck and maybe you can write an article to help the rest of us. http://www.harmonyfarm.com/dri... https://www.rainbird.com/docum... http://www.sprinklerwarehouse....Sunset Zone 28, AHS Heat Zone 9, USDA zone 8b~"Leaf of Faith"
 Name: Daisy IReno, Nv (Zone 6b)Not all who wander are lost DaisyINov 20, 2016 10:25 PM CST It sounds more like physics than algebra. I don't know the answer - too many variables. Even though the drippers are rated to gallons per hour, they do their own thing, depending upon water pressure. But don't add in those pressure regulators - a total waste of money. The pressure in the line depends upon terrain: up, down, flat, and the length of the line. If you are going off sprinkler heads, all the sprinkler heads in any one set need to be converted to drip or capped. The other sets can remain sprinklers or converted. You can use a combination of drippers and micro-sprinklers on each line though. If you use micro-sprinklers, be prepared to clean them out. Just a speck of sand will clog them. My favorite cleaning tool is a thin piece of florist wire. Ants love drip lines. You turn them off for the winter and come spring, they will be full of ant nests. Take the end caps off and run water through the line once in awhile. That helps with keeping them clean. Raccoons and squirrels also love them (they eat the lines). Keep spare parts on hand. You will get more water pressure if you use all the sprinkler heads in a set. Using one and capping the rest reduces the water pressure. So instead of one 100 foot line off one sprinkler, use two 50 foot lines off two sprinklers. Take the end caps off for the winter. That will drain the lines and keep them from freezing and breaking your drippers. You will know when you have reached capacity on a line when no water comes out the end. Make a map of your set up. Life is not a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather to skid in broadside, thoroughly used up, totally worn out, and proclaiming...."WOW What a Ride!!" -Mark Frost Webmaster: osnnv.org
 Name: ElaineSarasota, FlThe one constant in life is change dyzzypyxxyNov 21, 2016 10:20 AM CST To then calculate how long to run your system to get an inch of water, do it the simple way - just set out a tuna can, leave the sprinklers on for 15 minutes (set your timer) and then measure how much water accumulated in the can. Multiply by 4 to get the rate per hour. Do this at several different spots along the supply line so you can get a feeling about the different rates on the emitters. The ones farthest from the faucet will give the least. I'm a Math major, and wouldn't even try to hazard a try at calculating your pressure drop along that line. I've also done at least 4 yards, converting form traditional sprinklers to micro-irrigation. I'd recommend you start with maybe 6 drippers, and add on one at a time until you see the pressure drop (the basic kit comes with 'goof plugs' so you can take one out if you put in too many.Elaine "Success is stumbling from failure to failure with no loss of enthusiasm." βWinston Churchill [Last edited by dyzzypyxxy - Nov 21, 2016 11:10 AM (+)] (4) | Quote | Post #1322005 (5)
 Name: Philip BeckerFresno California (Zone 8a)PhilipwonelNov 21, 2016 10:53 AM CST @daisyl. Daisy i lmbo when you said physics ! So should i edit my question to : physics algerbra question ? Or algebra physics question ? πAre thoses oxy morons ?πlol ? Good to know pres.regs.are junk ! Someone asked if i had them on my present system.so i was thinkin i should.but i have no prob without.so why πππ Anything i say, could be misrepresented, or wrong.
 Name: Philip BeckerFresno California (Zone 8a)PhilipwonelNov 21, 2016 11:22 AM CST The drip system im putting in is in my front yard is a good 1100 sq ft. I have 3 auto valves.Anything i say, could be misrepresented, or wrong.
 Name: Daisy IReno, Nv (Zone 6b)Not all who wander are lost DaisyINov 21, 2016 2:25 PM CST Its become a calculus problem because of recursive function for the water pressure. Every time you add a dripper, the whole problem changes. Maybe Elaine will write a formula for you. Elaine, remember that the drippers themselves have variable output. Life is not a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather to skid in broadside, thoroughly used up, totally worn out, and proclaiming...."WOW What a Ride!!" -Mark Frost Webmaster: osnnv.org
 Name: Rick CoreyEverett WA 98204 (Zone 8a)Sunset Zone 5. Koppen Csb. Eco 2f RickCoreyNov 21, 2016 5:58 PM CST Philipwonel said:I have 40 psi. at my main faucet of house. Im running drip off of auto sprinkler valve. Putting 1 gph. Dripers every foot. How many drippers can i put on one line ??? And how long to run them to get 1inch acre foot a week ? Thank you !πππ It's not so much the PSI at the faucet. It's the diameter of the mainline, or actually the diameter of the narrowest restriction in the mainline. (Whatever the most restrictive point is, it gets turbulent at some water speed in feet per second. The diameter of the narrowest point, times that turbulent flow rate, is the max flow rate you can get. Increasing pressure after turbulent flow is reached doesn't increase GPH very much, it just makes the turbulence more turbulent.) Say you have NO restrictions: say the valves and couplers are as wide-open as your mainline. Say the inside of the mainline is perfectly smooth, with no "barbs" or fixtures causing extra turbulence. What diameter is your mainline? 1/2 inch (0.6" ID) or 3/4"? Typically you can push UP TO 240 GPH = 4 GPM through "1/2 inch mainline". Start with 40 PSI and get some pressure drop every foot. Typically you can push UP TO 480 GPH = 8 GPM through "3/4 inch mainline". So 1/2 inch mainline can support UP TO 240 drippers, at 1 GPH each. But expect substantial pressure drop and varying flow rates! 3/4 inch mainline can support UP TO 480 drippers, if you don't mind pressure drop and very little flow at the ends of the lines. But really, any kink or fixture reduces the max possible flow rate. So you might "round down" by a factor of two. That would reduce the "feet per second" speed of water, and reduce the turbulence at your most restrictive point by a LOT. If the shutoff valve impedes flow at all even when "wide open", that limits the maximum GPH that can pass through. The above qassumes things like using "compressions fixtures" whose inner surfaces are bigger than the inner surface of mainline. "Screw-on" fittings REDUCE the inner diameter and greatly reduce the max possible flow rate.Just because it ISN'T complicated doesn't mean I can't MAKE it complicated! Weather Links ~ Sunset Zones ~ Degree Days ~~ National Gardening Association Kitazawa Seeds ~ Tainong Seeds ~~ ATP Member Map ~~ My Blogs ~~ Coop Extension Finder Seriously Hot Peppers ~~ Seed Library Resources ~~ Piggy Swap Chat #11
 Name: Philip BeckerFresno California (Zone 8a)PhilipwonelNov 22, 2016 11:46 AM CST @rickcorey BINGO Rick #!!! Thats the numbers that i was looking for π. Some guidelines on gph. I know about all that loss of pressure stuff. After reading what you wrote. I thought now i can put line together with no drippers.and meas.the pressure at end of furthest line. And make ed. guess. ??? πππhahaha!!! Thank You ! πππAnything i say, could be misrepresented, or wrong.
 Name: Philip BeckerFresno California (Zone 8a)PhilipwonelNov 22, 2016 1:01 PM CST We're thinking the same way Rick ! Adding shut-off valves for rows. Thanks for your ideal π.havent been to store to see. I have to get my design layed out and implimented. You know how plantin time sneekes up real fast. Can't keep saying. Oh ! I got time. That nips me in the wagon. Just about ever year ###. πππAnything i say, could be misrepresented, or wrong.
 Name: Rick CoreyEverett WA 98204 (Zone 8a)Sunset Zone 5. Koppen Csb. Eco 2f RickCoreyNov 22, 2016 2:56 PM CST Running out of time every year - me too. In fact, almost every week. The opportunities are insurmountable. Just because it ISN'T complicated doesn't mean I can't MAKE it complicated! Weather Links ~ Sunset Zones ~ Degree Days ~~ National Gardening Association Kitazawa Seeds ~ Tainong Seeds ~~ ATP Member Map ~~ My Blogs ~~ Coop Extension Finder Seriously Hot Peppers ~~ Seed Library Resources ~~ Piggy Swap Chat #11
 Name: Philip BeckerFresno California (Zone 8a)PhilipwonelNov 22, 2016 7:54 PM CST I hear yea ! LOUD AND CLEAR πππ Ho ho ! πππAnything i say, could be misrepresented, or wrong.
 Name: CarolSanta Ana, ca Sunset zone 22, USDA zone 10 A. ctcarolNov 22, 2016 8:52 PM CST Rick, I very much enjoy your detailed instructions...very informative. I do have to point out that there are a lot of varieables, however. (1) who has the time to turn on/off all of these valves? (2) do all of these valves work properly? (3) level really does make a difference. (4) If you're on city water, the pressure can change between night and day, or in my case in a mobile home park, during heavy use hours. (5) those pressure regulators aren't so useless if you have to go a distance to turn on the water, and blow off a couple of heads. You can always shut off all lines until the main line is full, then turn each zone on separately, but that can be very time consuming.
 Name: KarenNM (Zone 7b) plantmanagerNov 22, 2016 8:57 PM CST Carol, we have a huge drip line system in our front and back yards. It's all turned on and off automatically by a fancy timer system. We've never had any problems except a few cases of the dripper heads coming off and having huge geysers, rabbits nibbling through the lines, and some drippers have plugged up with sand or silt. Once a system is set up it works pretty well. You just have to keep watch for any problems.Handcrafted Coastal Inspired Art SeaMosaics!
 Name: CarolSanta Ana, ca Sunset zone 22, USDA zone 10 A. ctcarolNov 22, 2016 9:19 PM CST I was referring to all the small valves Rick showed. Those can't be turned on and off automatically. I worked in freeway landscape for years, and am very well trained on those automated systems. Unfortunately, not all homes have, or really need automated systems, though it sure would be handy since we're supposed to do out watering before 6 AM or after 6 PM. Not going to happen here.
 Name: Daisy IReno, Nv (Zone 6b)Not all who wander are lost DaisyINov 22, 2016 9:24 PM CST My current drip system is all converted sprinkler heads on built in irrigation lines, originally designed to water a lot of lawn in the desert (the lawn is gone). And my yard is very small. So much easier than my system in California. That system covered 2 acres. I had 5 lines for the entire property. It was complicated by the fact that it was all on a hill. So 2 lines on top, 1 line in the middle and 2 lines at the bottom - that was it. I ran it on battery powered irrigation timers, each going off at different times during the night (better water pressure) and for different lengths of time, depending upon what I was watering. I also run my greenhouse watering system on drip irrigation and battery powered timers. Makes watering SO much easier. Except for all the critters who seem to think that drip lines are tasty or would make great homes, never a hitch. Except when a battery dies (they last a couple years though).Life is not a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather to skid in broadside, thoroughly used up, totally worn out, and proclaiming...."WOW What a Ride!!" -Mark Frost Webmaster: osnnv.org
 Name: CarolSanta Ana, ca Sunset zone 22, USDA zone 10 A. ctcarolNov 22, 2016 9:43 PM CST I've thought of doing that here, but then there are those hundred or so pots and hanging baskets that have to be moved to chase the sun. I have soaker hoses in the beds, with separate hose bibs for each, but still have to drag that 100' hose around the house for the pots. The orchid shack, requires hand watering with rain water or RO because our water is bad.
 Name: Rick CoreyEverett WA 98204 (Zone 8a)Sunset Zone 5. Koppen Csb. Eco 2f RickCoreyNov 23, 2016 11:06 AM CST Carol, I agree that having multiple zones and manual valves requires spending time, keeping track of time, and "walking the line" repeatedly. The idea of multiple battery-powered timers spread out over the yard, (like one for each zone), really appeals to me, though fortunately my yard is small enough that I don't need them. I defer to the experience of people who irrigate large areas! I've also seen diverter valves that "toggle" each time the water pressure goes to zero and then back up. They water each zone every-other-time, and perhaps they can be stacked to water each zone every-fourth-time. Those are more expensive than I need, so I don't have any and don't know how often they break down. But if you need to water more area than the main supply line to that area can handle all at once, I think zones are necessary, whether the valves are manual or automatic. Maybe one answer would be "water slower and longer", but that means fewer emitters per square yard and I'm not sure they go any lower than 1/2 GPH. Just because it ISN'T complicated doesn't mean I can't MAKE it complicated! Weather Links ~ Sunset Zones ~ Degree Days ~~ National Gardening Association Kitazawa Seeds ~ Tainong Seeds ~~ ATP Member Map ~~ My Blogs ~~ Coop Extension Finder Seriously Hot Peppers ~~ Seed Library Resources ~~ Piggy Swap Chat #11

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