Looking at the back of a modern sprayer the pile of hoses and valves in a traditional plumbing system can seem complicated, and even more so when you start to look at recirculating sprayer booms.
Hoping to mitigate that confusion, Dr. Tom Wolf and Dr. Jason Deveau have “Everything you never wanted to know about spraying” on their non-profit website Sprayers 101, a font of knowledge for spray application and technology.
They were at Canada’s Outdoor Farm Show in Woodstock, Ontario last September where they were demonstrating with a new Rogator C Series sprayer equipped with a recirculating boom for Glacier FarmMedia’s AgDealerTV series.
“To show how conventional sprayers work, we used coloured pool noodles to demonstrate the flow and direction,” said Deveau.
“We took it from there and built it up to the recirculating sprayer boom.”
Jason gave me the same presentation he had just given to a group of about 20 farmers, before taking me to the new Rogator and demonstrating the concept on the real thing.
“On a recirculating boom, the pesticide line is fed all the way to the end of the boom,” Deveau explained. “This eliminates boom sections, the dead ends that historically hold product and create problems with cleaning and carry-over.
“The liquid then circulates through this smooth curve,” he added, pointing to a curved steel tube at the far end of the boom, “with very little to no pressure drop, back through the boom while being sprayed out the nozzles. The sprayer is now spraying until it stops, turns or maybe gets rained out, at which point we don’t want this line loaded with product, we want to push that product back into the tank for reuse.
“To do that we turn the nozzles off, the product circulates back into the sprayer. When this system stops spraying, the product is still moving through the lines,” Deveau said while pointing at the return valve bringing product back to the tank from the boom while the nozzles are off.
After demonstrating how the recirculating system works, Deveau and Wolf walked through some common questions and scenarios, starting with how to operate the section control on the recirculating system compared to traditional sprayers.
“In a traditional plumb system, all of the 10 to 15 nozzles in that section would be in use. On a recirculating boom, there are shut-off valves on each nozzle body. You now have control over the individual nozzles and that allows for higher resolution and therefore chemical savings,” Wolf explained.
Priming a recirculating boom
Scenario No. 1: You’ve just loaded your sprayer up for the day, and now you need to prime the lines and fill them with chemical. How does a recirculating system differ from a traditional boom?
In a traditional plumbed system, the sprayer operator would be parked near a ditch or on the outside edge of the crop to prime the boom and fill the lines with chemical.
“Priming a traditional boom usually takes about 30 gallons of product to fill all the lines, and that product ends up on the ground to make sure the water is replaced by chemical. It’s not a good idea, and it’s money out the window,” Tom Wolf explained. Wolf is the other half of Sprayers 101.
“In a recirculating system, you can close off all the e-stops and nozzles aren’t spraying. Chemical will flow through the boom back into the tank, and the boom is now primed without spilling a drop,” Wolf said.
Priming a recirculating boom can be done anywhere, avoiding wasting money just to fill lines and a reduced impact on your soil by avoiding constant dumping in certain spots year after year.
Scenario No. 2: You’re forced to quit because of high winds or rain. Now what?
“Similar to priming, in a traditional system the operator would again park off the field and draw clean water from the tank to pump out the chemical from the boom. That chemical has to go through the nozzles, there’s nowhere else to go,” Wolf said.
In a recirculating boom, the process is also similar to priming.
“For forced stops, the nozzles are turned off and you open the return valve. This draws clean water from the tank and pushes the product through the boom back into the tank,” he explained.
This can be done in the field and once again cuts down on unnecessary dumping and chemical waste. Cleaning and rinsing will also help to avoid any chemical absorption into the chemical lines. Wolf mentioned that a slight dilution can occur during this process, as some water will end up in the tank.
Saving money and the environment
Wolf and Deveau wrapped up their presentation by highlighting the main advantages of recirculating booms, centred on less waste and better resolution.
“Main advantages are that you never have to prime and spray (waste) and you can circulate clean water through the lines without spraying onto the ground,” Deveau said.
“Individual shut-offs at each nozzle improve on the section control, which saves you money,” Wolf added. “Our Saskatchewan customers are seeing three to five per cent savings compared to a traditional plumbed boom.”
Another major advantage and potential selling point is the fact that recirculating sprayers are easier on the environment by wasting less chemical. In conventional sprayers, priming and cleaning the sprayer requires chemical to exit the nozzles at some point, making it almost impossible to properly clean or prime without putting product on the ground.
“We need to make it easier for our customers to protect the environment,” Wolf said.
“With a conventional plumbed system it’s very hard to do because we have to prime and flush while stationary. With this (recirculating boom), it’s easy to do.”
Sprayers 101 is a non-profit resource dedicated to describing the best practices in safe, efficient and effective agricultural spraying. You can learn more at Sprayers101.com.