While pump selection on smaller sprayer may be limited to hand- or electric-style pumps, larger sprayer offer more options; for example, electric-, hydraulic- and PTO-powered pumps. Desired pressure and volume are important, but shouldn’t be the only deciding factors.
“We use Hypro roller pumps with our small 3-point-mounted sprayers,” says Ernie Zimmerman of CropCare Equipment. “They come in three different types—cast iron (economy); ni-resist, which is more resistant to wear; and their Silver Series that is harder and wears better than stainless steel. The Silver Series costs three times that of cast iron but lasts seven times longer. If you are going to be using it quite a bit, the more expensive pump is the cheapest in the long run.”
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Abrasive products, such as chemicals like glyphosate, can cause wear and lead to early replacement in cast-iron pumps. These same products can cause wear problems with nozzle tips.
Peter DeHaan, applications engineer for TeeJet Technologies, warns that acid content in spray products can also speed spray-tip deterioration. He says cheaper versions of glyphosate, which are commonly non-acidic, can on occasion have low pH values. Other non-glyphosate products on the market are traditionally acid based, which can lead to tip deterioration.
“If you are looking at plastic tips, acetal plastic wears well, but UHMPE [ultra-high molecular polyethylene] has potential to increase the nozzle’s wear life and is resistant to acids,” says DeHaan. “Stainless steel has a little longer wear than plastic, but not as much as people once thought. Ceramic tips have even better wear, but are very brittle. Drop them on the ground or bang them, and they can crack. Brass has great chemical compatibility but is susceptible to wear. You get better wear out of stainless, and plastic is more cost effective.”
Picking the right sprayer tip for the application is even tougher. Options include solid stream, flat fan, dual outlet, air induction and other variations. Your goal is to get maximum coverage and minimum drift or off-target contact. Large-droplet, low-pressure application was once recommended for minimal drift and small-droplet, high-pressure recommended for maximum coverage. Air induction nozzles mix air with the chemical, creating larger droplets and decreasing driftable fines. This allows applicators to spray in sensitive areas and windy conditions while maintaining comfortable operating pressures.
Regardless of the sprayer tip used, DeHaan recommends keeping an extra to check for wear on tips in use. “Fill the tank with water and run the boom,” he says. “By substituting the unused tip for a used tip, you can compare their flow rate. Measure the flow rate each tip delivers in a minute. If the variation from tip to tip is more than 10 percent, it’s time to replace tips.”