Source: Farmer's Business Network
If you’ve recently purchased a new on-farm sprayer, you may still be learning the ins and outs of the equipment. Or, if you are considering the purchase of a new or used tow-behind or self-propelled sprayer, then you may be thinking through the options, features and accessories you want and need.
But, even if you aren’t considering a purchase right now, it is important that the spraying equipment you do use is kept in prime working order to deliver your applications safely and accurately.
For farmers who want to learn what the pros know so they can do it themselves, let's take a look at the basics of owning and operating your own sprayer — that starts with equipment expertise.
The Basic Components of a Sprayer
Whether a pull-type or self-propelled sprayer, the most common type in production agriculture incorporates a boom dispensing system. Most boom sprayers are made with the following basic components: agitator, control valves and gauges, hoses, pump, strainer and tank. It’s a good idea to get familiar with these parts, as it will make troubleshooting spraying issues a whole lot easier.
Here's a typical agricultural tank system:
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Source: Hofman, V., & Solseng, E. (2004). Spray Equipment and Calibration, Agricultural and Biosystems Engineering North Dakota State University.
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Tank
Since many crop chemicals can be corrosive, it’s also important to select a tank with corrosion-resistant material, such as stainless steel, fiberglass or polyethylene plastic. Even when they aren’t in use, it’s important to keep tanks clean and free of dirt, rust and other contaminants which can damage the pump and nozzles.
Agitator
A tank agitator mixes materials in the tank homogeneously (i.e. with a uniform composition) and keeps chemicals in suspension instead of settling on the bottom of the tank. Different agitators are required for the various types of chemicals being applied. Wettable powders require intense agitation in suspension, so you should use a separate agitator – either a hydraulic or mechanical type.¹ An adjustable agitator can minimize foaming that occurs from certain chemicals as the volume in the tank decreases.
PRO TIP
If your spray tank includes a jet agitator, do not install it on the pressure bypass line. Low pressure and intermittent liquid flow will likely produce poor results because it will agitate the spray solution only when the spray boom is shut off.
Control valves and gauges
The relief valve on a sprayer should always be in the bypass position during start-up. Check your gauges at every start-up.
A pressure gauge should have a total range of twice the maximum expected reading.The gauge should indicate spray pressure accurately. If you’re is seeing spikes, then the gauge may always read high afterwards and should be replaced. Likewise, an opaque or leaking gauge should be replaced. Measure the discharge rate at a specific pressure on the gauge during calibration and install a gauge protector or damper to prevent damage to your gauges.
A pressure gauge can be used for more than measuring pressure. It also can be a helpful tool in diagnosing other problems — such as pump or plumbing issues — within the sprayer system. Keeping your gauges in good working order will make a big difference in sprayer performance and accuracy.¹
Pump
There are four general types of pumps: centrifugal pumps, roller or rotary pumps, piston pumps and diaphragm pumps. The nuances of different pump styles are primarily about how much water they displace and how they deliver the volume of material. More importantly than the style itself, your pumps should be resistant to corrosion from pesticides, and the materials used in pump housings and seals should be resistant to chemicals, including organic solvents. This shouldn’t be an issue for new equipment, but as your sprayer ages, or if you are considering buying used equipment, take a closer look at the pump.
Hoses
Undersized hoses and fittings can severely reduce the capacity of any pump. Suction hose diameter should be at least as large as the pump intake opening. Before spraying, all hoses and connections should be examined for cracks or leaks while under pressure. Avoid splices where possible — they offer another opportunity for leaks or failure in your system.
Strainers and screens
There are three types of strainers commonly used on sprayers: line strainers, tank-filler strainers and nozzle screens. Strainers (and nozzles) should be cleaned after every spray day. It’s best to use a bristle brush, because flushing will not completely clear them.