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Bob’s Big Guns

February 20, 2014

Bob Rupar, Vice President and Key Player of Nelson Irrigation for over 40 years tells his story.  He knows these products just about as well as anyone, and he’d like to share his current thinking. Click here for the Mobile Big Gun video

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I am not sure how we ended up with so many small, cut-up pieces of ground with creeks and power lines and roads running through our farm. We do have some nice big open fields, and of course, those are irrigated with center pivots, just like they ought to be. We are fortunate to own this property, but it is not easy to irrigate. I suspect that many other landowners have this problem, and this story is being written to help those people understand that there are some good, new solutions for tough ground to irrigate.Our crops are primarily a rotation of alfalfa and wheat with some beans and seed corn in the mix. Oh yes, and some cattle pasture also. Our soils are deep, well-drained silt loam, and we are blessed with an abundance of water from both wells and creeks.

It seems like I grew up with the Big Guns, both because of my work at Nelson Irrigation Corp (known world-wide for pioneering the Big Gun sprinklers), and on our family farm and ranch. I hated hand lines, so the Guns were a natural solution. In the early days, we moved guns around on tripods with aluminum pipe. The Guns worked just fine, but were hard work at inconvenient times of the day. One consolation was that they did keep me in good shape during the summer months.

In the early 1980’s Nelson perfected what we call the Quick Coupling Valve system (QCV) that allowed you to connect and disconnect a gun from the valve while it was still under pressure. It is the only product of its kind in the entire world and it works flawlessly in my opinion (actually all of this is just my opinion). When the QCV came on the market, I started to bury PVC pipe to feed the QC’s so we could get rid of the aluminum pipe. Life got a lot easier, but we still were plagued by the task of having to move the guns every few hours (about once every 4 hours) and I can remember the many times I had to get up and move guns in the middle of the night, as crazy as it seems in retrospect.

I spent many years trying every way imaginable to automate the guns with the idea of sequencing through a series of guns and then moving them to new locations once a day. I tried several battery operated systems; all of the wireless systems that proved to be lacking; and finally I took one 15 acre field and hard wired in automated solid set guns. One gun and solenoid valve on every riser. It was very expensive, but very nice, until I started having gophers eating the wires, lightning taking out the solenoids and lots of problems keeping the wire connections water tight. To say nothing about me ripping up the wire where it was not buried as deep as I was told it was buried. Finally, in frustration, I abandoned the system, but did not abandon my desire to end up with a system that made sense.

Then, along about 5 years ago, Nelson got the idea to enter into a development program on a new wireless control system to operate our line of control valves. Naturally, I was to become one of the Beta testers of this system with the first automated, wireless guns going at my place in 2011. From previous experience, I was leery of radio controls and the problems I had always heard about. Right out of the gate, we did have some problems, but we have a great engineering team at Nelson and they simply solved all of the early on problems. In 2012 we had a great season for the first time ever, and in 2013, the system has been flawless except for a couple of plugged solenoids from dirty water. Wow! I cannot tell you what a pleasure it has been to operate this system. I will tell you more about it, but first I want to share some experiences that will assure successful use of Big Guns.

Big Gun Systems. I will be upfront and tell you that these systems are not for everybody, nor for every situation. I already have stated that if you have ground and crops that can utilize a center pivot, you should do so and look to the Big Guns as an alternative where the pivots do not fit. Here are some things to watch out for:
• Wind. Wind is the enemy of all sprinklers, but it is especially tough on Guns. If you are in a windy area where you would have to irrigate all the time in windy conditions, the guns may not be the right solution.
• Acreage. You don’t have to have a large acreage for the gun system, but once you are much below 10 acres or so, you probably do not have adequate water to run Guns, and it is tough to get any economy of scale. The minimum is around 80 gpm. Maybe a little less. But they really start making sense when you have over 100 gpm available. (gpm is gallons per minute).
• Pressure. Gun systems are high pressure systems. It is the pressure that gives the guns the performance they are so famous for. I tell people all the time that if you are not willing to make sure you have plenty of pressure, you should not even consider a gun type system. I am talking here about having 70 to 80 psi at the nozzle of the gun. (“psi” is pounds per square inch of pressure).
• Sprinkler spacings. Guns throw water a long way. They are amazing! It temps most people who are not knowledgeable about guns try to stretch the spacing’s between guns resulting in very poor coverage. Do not violate the spacing rules that we are going to show you. If you do, you will not be happy with your gun system.
• Get professional help. I always recommend this. There are some very good irrigation dealers and irrigation engineers, and if they need help we are there to give them our suggestions. We do not want any unhappy Nelson Big Gun users. Period!
OK, back to my story. I now have two kinds of automated, wireless Big Gun systems on my property and they are both worthy of consideration. One of them is very expensive but extremely nice. The other is much more economical, but requires a little bit of labor to operate it.

AUTOMATED SOLID SET BIG GUNS. In this system, there is a gun with its own valve and radio receiver at each gun location in the system. This is the Cadillac of systems. It is the envy of any land owner. These systems are in operation all over the globe, literally. And what we have now brought to the party is the wireless technology to operate them. This system virtually eliminates labor and operates by push button control. For the more advanced amongst us, the system is now web accessible for monitoring and control. Remember, I am speaking from the experience of hand move pipe and guns from the old days. I could not be happier with the 40 some acres that I have in automated solid set guns.

MOBILE GUNS. A NEW CONCEPT MADE POSSIBLE BY WIRELESS TECHNOLOGY. I am in that group of land owners that have a tough time justifying the cost of the solid set guns, so I have worked diligently as a tester for our team as they came up with a system that is still automated, still takes advantage of the gun system, but is much more affordable. We call it the “Mobile Gun System”.

At each gun station, a Quick Coupler Valve is permanently mounted, either on a post or in a valve box. For about every 5 or 6 QC valves, you have a Gun and Key that is equipped with the wireless control device. In one of my systems, I have 60 QC valves and 12 automated guns with keys. What we do is set out the 12 guns and sequence through them. I have enough water to run two guns at a time, so there are six sets. In 24 hours, each gun will have run for 4 hours, applying about 2” of water (.5” per hour application rate). The ratio of guns/keys to the QC valves varies a lot depending upon the design that works for your operation.

Once a day, our irrigator (sometimes me…maybe once or twice, my wife) hops on the ATV, collects the guns and moves them to 12 new locations to begin another sequence. We have gotten good at this, and it only takes about 40 minutes on average to move the 12 guns to new locations. Then, it only takes us 5 days to cover all 60 valves and get 2” of water on about 50 acres. This is quick, easy, painless and very effective…. As well as cost effective because you are spreading the cost of 12 guns, keys and wireless devices over 50 acres as opposed to having 60 guns/valves and wireless devices on the solid set system. Yep… fun, easy and very affordable.

ATV racks. We move our guns with an ATV. We already had the ATV’s and we have adapted some gun racks to the ATV to make the moves easier on the guns. It is not like they are fragile, but there is no sense in beating them around and having expensive repairs. We have also moved the guns in our modified golf cart and also the back of the pickups. Whatever works for you.

Mobile gun mountings. First with the QC on a post. I started my gun career by mounting the QC valve on a galvanized riser supported by a wood post, way back in 1985. The original risers I installed way back then are still in operation today…. We like to build products that last a long, long time. But back to the riser story. These work great, but the riser is in the way when you work the field, and is especially vulnerable when livestock are being grazed. But it is simple and cheap and we have just learned to farm around them. Some people just build a crib around the gun to keep the guns from animal damage.

QCs in a valve box. Later on, we got the idea to mount the QC valve in a valve box, flush with the ground and out of the way of equipment and livestock. They are more costly than a mounting on a post, and take a couple more minutes of time when you are moving guns. They have to have concrete support underground, and you have to provide a type of swing joint riser so that the QC can be plumbed as near vertical as possible. We have been doing this for several years now.  Even before we were automated. It is really nice to be able to mow, fertilize, spray, etc without having to contend with any risers in the field.

Although I like mountings on risers and buried in valve boxes, I continue to work on ways to mount the guns that are easy to install and are very cost effective. The latest riser mount that we installed this spring was staked to a six foot long 6” X 6” treated post as shown in the photo.

GUN SIZE AND SPACINGS. Nelson makes guns in four different sizes from the 75 series up to the 200 series. The size relates to the gallonage and the radius of throw. I have always (25 years at least) been partial to the 100 Series guns as I think they deliver great value for solid set systems. I like the .7” nozzle operated at 70 to 75psi, with spacing’s between guns around 165’. There is about one gun for every ¾ of an acre. I have some windy areas where I have closed up the spacing to 120’ X 140’, but I also have some very low wind areas where I have the guns spaced at 160’ X 180’ which is very economical. Each gun requires about 135 gpm, including a spreader nozzle that is required to pick up the in-close water. Please do not let anyone talk you out of a spreader nozzle. This is a good flow range to work with as it generally requires 3” and 4” PVC laterals which are easy to work with and are economical. I use class 160 PVC pipe without any issues. Back in the days when I was putting my kids through college, I skimped a little with class 125, but that is not a very good way to save money.
We have a lot of Big Gun customers around the globe that prefer the larger guns, especially the 150 series where you can get the spacing’s out to 200’ and more, but that requires higher flows and higher pressures. When you get up into this range, you really need an experienced pro to work with to get everything right. The bigger guns are really magnificent to watch and enjoy.

THE REAL BEAUTY OF BIG GUN AUTOMATION
It should be fairly obvious to you by now that the main thing you accomplish with the automated gun system is the savings of labor and the convenience of operation. Automation changes irrigation to an enjoyable task instead of hard and inconvenient labor. But there is a lot more to this than meets the eye.

Each gun location needs to run around 4 hours per week in our climate. On my system that puts on 2” of water which is about right for my soil, crop and climatic conditions. If you are running the guns manually, that means they have to be moved every 4 hours which is extremely inconvenient. With automation, you can go to shorter sets, like one hour sets, 4 times a day. That way you run some sets during the night, some during the day and even during different times of the day so that you catch the wind at different speeds and different directions which really makes a big difference in the uniformity of coverage of the guns.

In the industry, we refer to these short, frequent run times as a “cycle and soak” concept. Run for a while then let the water soak in. This eliminates run-off and helps get the water into the ground even with heavier soils and sloping ground conditions. You probably wouldn’t think of this unless you heard it from someone with a lot of experience with gun systems, but automation gives you the tool to put down exactly the amount of water that the crop needs. No more, no less. You can be as exact as you wish to be and you are not at the mercy of the irrigator who “tells” you he put on 4 hours of water but accidently gave you 6 hours because he slept in. That also means he had to give you one 2 hour set to get back on schedule.

Efficiency of the gun system. If you are concerned about the gun system because it requires higher pressure to operate, it is just something that you have to get over. Besides, high pressure does not necessarily equate to low efficiency of operation. Look at hand lines that you can run at much lower pressure, yet they are horribly inefficient.

If you think that an automated gun system might work on your farm or ranch, here are some things that you must be serious about that will make or break your system (so please pay attention):
• Trapped air. As with any irrigation system, trapped air is a big problem and must be dealt with. Use good air relief valves at all the high points in the system. Trapped air at the base of the guns can cause violent pressure surges, sometimes referred to as “water hammer”. Use the Nelson ACV 200 as an air management tool. Overkill in this area!!
• Pressure relief. When you automate, you must equip your system to anticipate the failure of a valve to either fail to open, or fail to close. These events are very infrequent, and in my case I have had 2 or 3 solenoids go bad causing a failure to turn the gun on. So that this does not become a problem, just be sure you have adequate relief valves in the system to handle excessive pressures, and low pressure cut-offs in case something like a mainline were to break. This is simple, every day stuff for an irrigation dealer as they deal with it on a daily basis.
• Use a VFD pump. VFD stands for variable frequency drive. They are a great invention as they hold the pressure constant while the flow demand fluctuates. As this stage in my career, I would never own a system without one or more VFD pumps in the system.
• Winterization. In freezing climates, good winterization is essential. You must either provide very good drains, or blow out your system with compressed air. I do both and we really take our time and do it right so that we do not face freeze damage the following spring.

That’s my story folks.  I am hooked on the gun systems and they have served me very well. Like I said earlier, they are not for everyone nor for every situation, but where they fit, they are absolutely unbeatable.

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