Addressing gumming in pulse width modulation sprayers


While pulse width modulation (PWM) offers much to pesticide application – variable rates, individual nozzle control – it’s not without its challenges, namely “gumming up.”

“It has a moving part – it’s called a poppet,” explains Tom Wolf of Sprayers 101, on RealAg Radio. “It looks like a little piston moving inside a cylinder. So the tolerances are reasonably close.”

According to Wolf, some formulations of chemical seem to cause the creation of an oily layer that slows the poppet down, throwing an error signal. The only way to fix it? Clean the poppet (which may mean taking it apart).

“The common ingredient in this are oily adjuvants such as Amigo, that’s usually applied with Centurion.”

In talking to customers, Wolf says anecdotes are pointing to cold water, and possibly hard water, as somehow related to Amigo causing the gumming in the sprayer.

Wolf suggests operators with PWM sprayers try moving to surface water, and that there is a possibility adding conditioner may help as well. As for switching Amigo for another alternative, Wolf says he doesn’t have the go-ahead to make that recommendation from any manufacturer, but he knows it’s happening.

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