MARCH 2017 –– PAGE B13 THE GROWER
FOCUS: CROP PROTECTION AND SPRAYING
Continuous rinsing achieves same results as triple rinsing in less time JASON DEVEAU (@spray_guy) At last year’s Outdoor Farm Show in Woodstock, Ontario, we did a show-and-tell demonstration of an innovative European approach to sprayer rinsing. I asked HJV Equipment to construct a demo unit and plumb a RoGator to see if “continuous rinsing” had benefits over “triple rinsing.” For our demo, we established the following scenario for the RoGator 700, which has a 50 US gallon clean water reservoir and a 700 US gallon tank. The boom had boom-end nozzles (i.e. no dead space at the end of each section) and the operator was able to “blow out” the boom with air from the cab. We scaled this down for the demo unit, and used salt to represent pesticide residue, as measured using a conductivity meter. Studies have shown continuous rinsing reduces residual pesticide to levels
achieved by triple rinsing, but in considerably less time and in some cases, using less water. Our results concurred: We showed that continuous rinsing achieves the same results in less than ten minutes compared to 30 minutes. Furthermore, the operator never had to leave the cab. That’s significant! Definitions vary, but in Ontario a full cleaning is a lengthy decontamination process performed at the end of a spray day or when switching between chemistries. It requires the operator to deal with any dead-end plumbing such as filters, boom section ends and filling circuits. Rinsing is a less-rigourous dilution process performed every few loads to prevent residue build-up and to dilute any liquid left in the sprayer during transport. Rinses are far more effective when performed with multiple, low volumes. Once the tank is empty, a volume is pumped from a clean water reservoir into the tank via wash-down nozzles.
Adam Ireland is pictured examining the test sprayer.
It is then circulated for five to 10 minutes through the bypass and agitation circuits before being sprayed out through the nozzles onto the field. This is performed three times and is commonly referred to as triple rinsing. Legislation in several European countries requires sprayers to have residue levels of 2% (or less) before they can
leave the field, and triple rinsing is too slow. In response, continuous rinsing was developed. Clean water is introduced through the tank rinse nozzles via a dedicated pump. This allows the operator to use the main pump to spray at the same time as the clean water is being added to the tank. So, rather than three serial dilutions of the remaining spray
mix, the clean water pushes the spray mix from behind. So, while it’s still early days, continuous rinsing has promise in North America. We have a lot to learn about which sprayers can be modified, and we want to establish how much residue remains in the dead-end plumbing. Research is continuing into 2017 – stay tuned to www.sprayers101.com.