EQUIPMENT

Add A Wash System To Your Sprayer

When a spraying job is finished or when the spraying season ends,
several gallons of mixed spray may be left in the tank, hoses and
booms. The spray solution should not be flushed out and dumped on
the ground near a well when the sprayer is cleaned. When
pesticides are dumped in one place whether in a field or near a
well, it may pose an extreme hazard to the environment.

A practical solution is to rinse the sprayer in the field and
apply the  rinsate to an approved crop. Care must be used so that
the total amount of pesticide active ingredient does not exceed
label recommendations. This requires accuracy when the last
tankful is being measured and mixed.

A field wash system can easily be added to almost any field
sprayer. Equipment that will be needed is:

          30- to 50-gallon clean water tank
          2 tank wash nozzles (low pressure irrigation nozzles) 
          2 ball valves
          2 tank adapters
          Hose and fittings
          1 check valve
          1 optional drain valve

Many applicators use field nurse tanks to refill sprayers. This
method works well and eliminates the need for purchasing a 30-50
gallon water tank, tank saddle and one ball valve. 

The fresh water tank should be large enough to provide two to
three rinsings of the sprayer. It should be mounted above the
pump so gravity will prime the pump. This is especially
important with centrifugal pumps. Plumb the water line from the
tank into the intake side of the sprayer pump with a ball valve
installed in the line to control the flow. A check valve is
recommended to prevent any chance of pesticide entering the clean
water tank. The line should be 1 inch or larger to prevent
starvation or cavitation of the pump and to get the water
transferred in a short period of time.

Plumb another line into the outlet (pressure) side of the pump to
provide flush water to two tank wash nozzles (low pressure
irrigation nozzles) mounted in the top of the spray tank. These
nozzles are designed so that a stream of water is directed
through an orifice against a splash plate which deflects water
out in a spray to wash the sides of the tank. Two nozzles are
recommended to eliminate  dead spots  that might develop around
the fill opening. Low pressure irrigation nozzles are available
from various irrigation equipment manufacturers. 

Irrigation nozzles are available with various size orifices. It
is suggested to install nozzles with a flow rate of three to four 
gpm per nozzle. Various splash plates are available, but a
concave plate is best as it helps deflect more water up toward
the top of the tank. It is recommended to use a 5/8 inch hose or
larger to supply the two wash nozzle. A smaller hose will
restrict flow and may not provide sufficient flow to wash the
tank properly. 

(Submitted by Vern Hofman, Extension Agricultural Engineer)