How to Place Sprinkler Heads in an Irrigation Design

okay we're going to walk through this assignment where we lay out sprinkler heads it's uh not the most easy thing to do if you've never done it before it involves a bit of trial and error and some critical thinking in order to think of multiple variables and the hardest part is there's no one right answer there are many acceptable good answers and sometimes there's no perfect answer and you're just looking for as good as can be so i'm going to walk you through what i do when i go through this assignment now yours may not look 100 like mine but i hope that by watching me go through the assignment you'll have a better understanding of how to think about it and then you could potentially try it again and you'll have much better head spacing as you lay out sprinkler heads here we go we are starting with an irregularly shaped area almost rectangular but not perfectly rectangular notice the scale 1 inch equals 20 feet and i have given you the actual dimensions of each side to assist if you did not have those dimensions you take a ruler 1 inch equals 20 feet so you try to convert that into a foot amount you can also have this fancy ruler which is an engineer scale and it has different scales on each side we see 20 feet here so here one inch equals 20 feet therefore if we measure this whole thing five one two three four fifty four is the feet so this is a handy little tool to have so we need to decide uh how we want to lay these out there are many acceptable ways to lay these out and i'll kind of go over the logic or the thought process behind how you would do that so let's look first at this straight line here on this side we know we're going to want a sprinkler head in this corner and in this corner i've given you the sprinkler heads we want to use we want to look at the hunter catalog and we want the pgp rotors with blue nozzles so this is our target here to use these rotors and to use the blue nozzles the rotors will all stay the same but each one could have a different blue nozzle to get us within the proper range now let's think about this logically 133 feet let's just do a little bit of calculations kind of trial and error to help us figure this out so we don't have any sprinklers that will throw 133 feet and if it did it would be going very wild but let's think about what it would take to add another one here remember our head-to-head coverage so a way to think of that is you're dividing the 133 into two spaces so with our calculator 133 divided by 2 equals 66.5 so i'm just going to take some notes if we divide this into two they're spaced 66.5 feet that's a pretty long distance as well let's see what happens if we divide it by three we get 44 and a third feet let's see what happens if we divide it by four we have 33 and a quarter feet and let's just see what happens if we divide it by five 26.6 feet do you see what i'm doing here is i'm dividing this into trying to figure out how many heads can go on this row and if i select these different numbers of heads then this is the distance apart they will need to be if we look at our catalog we look at the radius which is our distance and we can see we range from 31 to 44 feet of throw now remember we can reduce the throw we cannot boost the throw so we're somewhere between 31 and 44 as our radius so looking here on the side uh we've got uh 31 and 44 as our radius if we did three that's the upper end 44. that almost perfectly lines up if we did four then that's kind of toward our lower end so just by looking at the numbers and thinking about it it's going to probably be the most efficient if we divide this into either three sections or four sections so let's try one of each first we're going to divide this into three sections we'll take 1 33 divide it by 3 and we get 44.33 you could use a ruler but i'm going to use the engineers scale to be very accurate here i go up to 40 1 2 3 4 and i try to get right in there a third of the way down the line and if i multiply that two by two by two it's 88.66 8 85 86 87 88.66 and i can double check my math coming the other way 44 and a third now i'll draw in my sprinkler heads i have a handy little template here which helps to make things tidy we'll do quarters on either side and it's important that i remember the actual point when i draw the head it's not necessarily exactly at a point but it's helpful to visualize the sprinkler heads so here is the first component with three different sections four heads in a row let's do the same thing but with four sections 133 divided by four we're at 33 33.25 so we take the scale measure that out so now i'll draw in the sprinkler heads there we go so you can see when we compare the two here what it looks like if we choose three spaces four heads in a row or four spaces which would be five heads in a row both of these will get us to what's an acceptable range within our radii the radius of throw of the nozzles that we're trying to use so now let's take a look at the sprinkler heads if we're going to space them in three sections so this is uh the first option now there's several ways to do this remember here's the markings for the sprinkler head spacing based on the equal division of this length which is 133 feet so one of the ways to do this on pencil and paper is to use a compass we just want to before we decide and draw our spacing we want to just get a feel for what this is going to look like and i'm not using my final page here because i want to [Music] have a chance to just practice so i printed out a bunch of copies and i'm just going to see what this looks like to help me visualize so what i'm doing is i'm lining up the lead of this compass with the distance of the first sprinkler head remember when we lay these out we want head to head coverage so it becomes easy to use this compass to help us visualize where the water will be going on this plan we want to get the lines to line up as best as we can it's not a hundred percent accurate that's okay at this stage this is still for visualization purposes so there's what it looks like with three now i do the same with four spaces along the line so let's recap and compare if we have four heads three spaces in a line this is what our radius is going to look like if we put four spaces five heads in a line they'll be spaced closer together the throw will be a shorter distance and then we'll have more in the line and our big decision is going to be between these two so it's a little bit of a trial and error and we're going to decide whether we go between and just for clarity's sake we'll call this uh a we'll call this b option a option b okay so let's go with option a for now and we are going to use our compass and we're gonna try and pick up that same radius there we go and we're gonna just before we decide on anything we're gonna just see what goes on now we put a corner we put a quarter here and a quarter there and let's just assume we're going to put a quarter there as well if i take the same radius the same throw as our others we're gonna be about like that okay now just to kind of go down the line here remember this is not my final i haven't made any decisions yet but we're just sort of waiting to see what this looks like take a look at that you see how that fits almost perfectly right in this corner i like that i like the way that looks so we've gone all the way around the perimeter keeping the same radius the whole way head to head spacing and there's a little bit of an overlap right here whereas this one does not reach all the way back here this one does not reach all the way over here so well we may add a few more heads to get true head-to-head coverage but the fact that it lined up pretty good back at the beginning is a good sign let's see what happens if we do this for b okay so let's get our dimensions just right gonna go in this corner here that also lines up very well look at that that's nice okay so what we've done is method one where we go around the perimeter of an irregular shape and we're just trying to see okay how do these both line up they both line up pretty good and when we look here there's overlapping coverage it's not head to head but it overlaps slightly which means if we just left this as is we would have dry spots down the middle if we look at option b if we left this as is we'd have areas down the middle where it never got irrigated at all so um with these two different strategies it gives us a couple of different options let's again go with option a and we'll see how this works let's look down here at this first little dry spot in true head-to-head coverage this sprinkler would go all the way here and this one would go all the way here just how they go around the perimeter so this little area is our dry spot let's uh let's try to find what the true head-to-head coverage would look like so if we go from this head to that one so i've just drawn a few lines from our various known sprinkler heads and trust me the lines get confusing which is why on the final plan we erase these lines but if we find where the intersection is and we're going to try to put a full circle head here we're going to want to dial this back so that we don't have a whole bunch of overspray okay so just with a little bit of trial and error we're going to give this a shot so with a full head here we've been able to find a spot that improves our coverage i made that little cross just so i can remember where the sprinkler head goes now we've got head to head to head so we've got a row here we've got a crooked row on this side and we've covered our bases down in this corner everything's going more or less to the sprinkler head let's take a look up here if we're going to have a sprinkler head that throws to right here we might as well have another one that throws up here but if we kept the same radius did you notice we dialed this one down we're going to be potentially a little short on each side if we open this up just a little what impact does that have getting us to our desired head-to-head spacing pretty close another full head i'm a little bit shy of my head-to-head coverage right here but see how nicely it fits in there so i want to remember to keep track because i just used the compass to find that spot i want to keep track of where it actually is and to do that i just take the distance and get a few points all right so that's a lot of crazy lines but let's draw them out and let's see how this works oh before i forget we have a dry spot here it's easy to forget these things sometimes so we're going to need one last one up here so that way we have good head to head coverage because these did not go all the way across and these ones also don't go all the way across so we could probably benefit from another one now the only thing to consider here is if this is too small of a space we could maybe do without but remember our goal right now is just spacing get the best coverage possible so we're going to be having some slightly different dimensions here okay so again getting these dimensions we've got our layout now let's draw in the uh the spaces so here's how our a looks you can see we've got basically three rows and they bend a little bit and they're more or less in line so a bit a bit of a either a square or triangular spacing depending on how you look at it but for the most part uh that looks pretty clean let's do the same thing with our b phase now remember head to head coverage and what that will require if we just did a single line down the middle here we still have dry spots so it needs to be head to head with a little bit of overlapping now one thing i'm noticing is uh as we go up we've got nice little crosses here okay we're gonna put this side here it gets our total perimeter complete see the cross and see the cross and notice how they're like halfway in between it may be the case that this opens us up well for triangular spacing i still i'm not 100 sure that this is the way we want to do it remember there's a lot of possible outcomes here but you see how if we place one here it goes to there if we place one there we can end up with some nice head-to-head coverage patterns so i'm gonna make a little line there a little circle there and over here we're not head to head so we're going to need to do something similar so we'll put another full here and we can dial these back so notice i'm trying to just find wherever there is a throw and not a head so if there's a throw at a certain point and not ahead then we're not in good head-to-head coverage and in fact i think we're better off if we take these and bring them to this line i'm going to redo this which in the arc phase i can totally do with no problems i'm just going to shift it slightly so that we go there this is why trial and error is involved now we've got uh almost head-to-head coverage from here to here but not quite so let's see what it looks like to put another one right in this dry spot this will be pretty good okay so i'm scanning looking for head-to-head coverage i have it going down the middle i have it going on the sides and is there any other places where i've got gaps there's nothing hitting this and there's nothing hitting this from the center and you can see with this one it's also a little short and right here we've got our half going out here we've got this one going almost all the way with this full we're okay going to here we don't have anything hitting right in here there we go this here will work for us so if i do a full circle right about here that gets us to water back at this head and it gets water to these heads so we're looking good and we're going to need something similar up here we'll do another one just like so notice how it doesn't perfectly touch but it goes just past and just short of the rest so there we go quite a few more sprinklers okay so here we have the sprinkler heads laid out and it starts to become apparent that you've got some patterns so just to get it a little bit more clean we can actually go down here i'm gonna erase these i'm going to try to put them just right on the line triangular triangular so let's compare our two [Applause] we have our two options here's option a here's option b using different uh distances and just by looking at this you can probably see that this one appears to be the better answer fewer heads accomplishing the same amount of work these are in relatively good spacing the more we're outside of that perfect triangular or perfect square then we're going to be a little bit more inefficient we had to add two heads here to cover this wider section and here we only had to have two full heads in the middle so if i was going to be selecting which one to do i would go with this one but this one will still work it's not wrong and if we're going to use different size nozzles or if there was some different pressure on the side or all these different potential considerations may make this one the one worth going with but in general this will be the cheaper one the easier one to install and less chances for error in the future the cleaner the better so for that reason i'll go with option a and here's our sprinkler spacing

Channel: Prof. Mark Valen

Views: 5,199

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Id: aVFnJDP8eQ0

Length: 30min 50sec (1850 seconds)

Published: Thu Sep 30 2021