Less time spent filling means more time spent spraying

Cutting sprayer fill times in half would significantly improve farmers’ bottom lines, says a spraying systems engineer.

Syngenta researcher Doug Baumann has developed and proofed a mathematical model showing how a producer can fill a 1,200 gallon sprayer in six to eight minutes.

He said optimizing fill time is the easiest way for farmers to get a better return on their sprayer investment. In many real life scenarios, saving five minutes on a fill can turn into 20 more acres sprayed per hour.

“The gut feeling of most growers is that it would be a significant economic benefit if they could save time on their fills,” Baumann said.

“A number of years ago, (Saskatchewan sprayer expert) Tom (Wolf) worked out some numbers on the back of an envelope showing that fill time is a very significant component in your overall cost of production. So two years ago, we (Syngenta) started working on that assumption to make it more powerful. First, we did a survey of farmers just to get a better idea of how they were running their spraying operations right now. We can’t assume that everybody has a brand new sprayer with a 120 foot boom because we know that’s not the situation. We wanted to make sure the model deals with those real world factors.”

Baumann said he quickly realized too many factors were at work to make a simple assessment, but the five major considerations are:

  • forward speed
  • carrier volume in gallon/acre
  • boom width
  • water fill time
  • chemical fill time

“Once you’ve bought the sprayer, you’ve established one basic factor. You’ve set your boom width and you’re going to have it at that width (for a) few years.”

He said the first tier is getting the water into the sprayer quickly. The second tier is getting chemical into the tank just as quickly.

It’s the classic case of always finding the weakest link in a chain. Once you’ve found it and fixed it, then you find the new weakest link and fix that one. It goes on and on, and as it does, you keep improving your spray operation.

“The common assumption is that water fill time is greater than chemical fill time, but it turns out that’s not the case. With the latest pumps, you can put the water into a 1,200 gallon sprayer in three minutes,” he said. “But if you have a three or four product tank mix, there’s no way you get those products into the tank in three minutes. So now the chemical product has become the bottleneck, the next weak link in the chain.”

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Baumann said producers in the Syngenta survey intuitively knew a quality impact is associated with that extra two m.p.h. if they drove 16 instead of 14 m.p.h.

“All the operators we talked to are already driving as fast as they can without impacting spray quality. On a nice flat field, guys are up to 18 m.p.h. I don’t know how much faster they can go without having a serious problem with the quality of the application.”

Some operators spray faster than 20 m.p.h. and wonder if the product is faulty. The hidden danger inherent with every speed increase isn’t just the rate of travel but also boom height. The faster you drive, the higher your boom must be, which is a major detriment to spray deposition.

“High speed and a high boom not only results in a bad spray job and a waste of your money — it also exposes you to environmental factors such as spray drift. Spray drift can become a big financial liability when it damages adjacent crops,” Baumann said.

“High speed causes eddies and air currents. A high boom makes droplets just fall by force of gravity. They don’t strike the target at the angle you intended as they exited the nozzle. It all becomes very squirrely. There are smarter ways to increase your productivity without high speeds and high booms.

“If you can fill five minutes quicker than your neighbour, you might get 20 extra acres sprayed before he’s back in the cab. Think how that adds up over a season. And if he’s driving too fast thinking he’ll keep up with you, think how much better the quality of your application is.”

Baumann said investing in fast fill equipment is the smartest way to maximize the number of acres sprayed per hour. His mathematical model allows him to juggle all five of the major elements involved in a fill.

He said the model shows how to reduce fill times to six or eight minutes on a 1,200 gallon sprayer. There’s no special equipment, he added. It’s all off-the-shelf components.

“Most sprayers today feed water from one end or the other and chemical comes in at the side. You park parallel to the truck on the side of the road and you have two operations happening at the same time, two lines going into the sprayer. The pumps are generally 50 gallons per minute to 75 g.p.m.,” he said.

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“But there are companies out there offering chemical handling equipment that fill chemical and water through a single line, so you only have to be in that one location. You only have one operation happening.”

Baumann said the key is to invest in pumps that move 200 g.p.m. or higher. The venturi effect created by these big pumps forms a vacuum that sucks product out of the tote into the single fill line. The pump that was previously used to draw from the tote is eliminated from the setup.

Banjo and other companies have digital flow meters that are installed between the tote and the venturi on the main line. The flow meter connects to a valve that shuts off the tote once a programmed volume of active product has been drawn.

“I was talking to a farmer two weeks ago. He has a flow meter between the tote and venturi. He runs (the) water pump full bore and sets (the) flow meter. If he needs 30 litres active product, he sets the flow meter to shut off at 27 litres. Once it hits 27 litres, there’s still three litres in the hose, so that all gets flushed into the sprayer. It’s totally automated,” Baumann said.

“Another option is the large-volume hot-load chemical-ready tank. This technology originated with aerial applicators where fill time is even more crucial because of their higher cost per minute. They spray an acre every seven seconds, so that’s where time really is money.

“Their hot-load concept is perfectly suited to ground sprayers. The tank mix is already blended. It’s sitting, waiting for the sprayer to arrive, agitating in a 200 gallon water tank. It’s pumped into the sprayer at the same time as the main volume of water. This also re-duces the amount of time required for the water fill.”

Baumann said some equipment companies now have manifolds for multiple chemical addition ports. These manifolds let farmers load pre-determined volumes of different chemicals simultaneously.

“For example, while pumping 200 g.p.m. of water, I could simultaneously add a high volume product from a tote and a couple specialty products from jugs,” he said.

“With multiple ports, I could add all those chemicals and the water all at the same time. I would call that the final key.”

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Baumann said he still calls the project a mathematical model rather than an app. He is continuing to test it to ensure that it will be relevant in all combinations of the five main factors before he releases it to farmers.