Parts of a simple compression weed sprayer include a pressurized tank, a hand-operated plunger pump, a pressure gauge, a decompression control valve and a spray lance with nozzle. This type of compression sprayer is typically used to apply herbicides to lawns and bushes. Advantages of the device include that pumping is not required during application and that it is simple to use and maintain.
For a simple compression weed sprayer to function effectively, approximately one-third of the tank should be left for air space when filling it with liquid. Too much liquid causes the pressure in the tank to drop quickly once spraying begins, creating a very uneven flow to the nozzle. To pressurize the tank, pump the plunger until the pressure gauge indicates a pressure within the optimal range. After spraying weeds, the decompression control valve is used to relieve the pressure in the tank so it can be opened safely.
Other types of weed sprayers are the portable power sprayer, the motorized mist blower and the controlled droplet atomized sprayer. These sprayers offer a number of advantages. They use motors to pressurize tanks, so operators do not need to pump by hand, they can typically hold more liquid than a simple compression sprayer and they can spray a farther distance. However, these sprayers are noisier, they have more moving parts to break, and the higher operating pressures may pose a greater risk to users.