For many smaller growers, the use of towed pesticide sprayers is impractical. Two options are a garden sprayer or 2 in 1 knapsack sprayer. I will argue here that garden sprayers are not suitable for most commercial pesticides.
A typical garden sprayer that can be found in a garden store or hardware store usually has a capacity of 1 gallon or 2 gallons and a nozzle whose output can be manually adjusted from flow to spray. This sprayer uses air pressure generated by a hand pump. Some models are equipped with a valve that can quickly release air pressure. Although such sprayers may be useful for cleaning tasks, they are not suitable for commercial pesticide applications for the following reasons.
Let's start discussing the adjustable nozzle on the 2 in 1 knapsack sprayer. These nozzles may accidentally move to provide different streams or sprays. That is, the output can be changed from a full spray to a more stream-like output. We quantified the output of the garden sprayer in the flow and spray pattern. The output in the flow mode is more than twice the output in the spray mode. This means that if a person accidentally turns the nozzle, its volume output will change.
It is important to keep the output of the Spray machine manufacturer constant, because most commercial pesticide labels are based on the quantity per unit area, such as fl. Ounces per acre. If the yield changes, the amount of pesticide application will also change. If the amount of pesticide is less than the labeled amount, the application may not be effective. Too much pesticide wastes money and may cause damage to plants. Therefore, adjustable nozzles, which are very useful for domestic work, make garden sprayers unsuitable for commercial pesticide applications.
The second disadvantage of using garden sprayers for commercial pesticide application is that it is difficult to maintain a constant pressure. The method of generating pressure in a garden sprayer is through a hand pump. However, the pressure will begin to decrease with use. As the pressure decreases, the output also decreases. Therefore, in order to maintain constant pressure and output, a hand pump must be used continuously. For most users, it is impractical to constantly use the hand pump of a garden sprayer.
To demonstrate how the output of a garden sprayer changes with pressure, we collected the sprayer volume of 5 hand pumps and 15 pumps. The output of 15 pumps is almost twice that of 5 pumps. As mentioned above, most commercial pesticide labels are based on area. Therefore, sprayers with pressure/time-varying output are unacceptable.
On the contrary, most knapsack sprayers are very suitable for commercial pesticide use. An effective backpack sprayer will have:
Hollow conical or flat fan nozzles fixed on the boom. A sprayer with 3-4 nozzles on the arm is easier to use and calibrate than the stick sprayer shown in Figure 1.
Easy-to-read pressure gauge, so the same output can be maintained throughout the site. The sprayer can be powered by an electric motor, CO 2, or a hand pump.
For most applications, a capacity of 4-5 gallons should be sufficient.
Fixed or hollow cone nozzles are designed for pesticide application. Such nozzles are fixed and provide a constant output. The sprayer shown here has been changed from a single rod to a spray rod with three nozzles. The total price of the back-mounted sprayer and boom is about $100. The use of nozzles on the boom facilitates calibration and use. The knapsack sprayer in Figure 2 allows the user to hold the boom with one hand while pumping water continuously with the other hand to maintain proper pressure. Note that the pressure gauge on the handle allows you to monitor the pressure on a regular basis.
Another article will discuss the use and calibration of knapsack sprayers.