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EQUIPMENT DECONTAMINATION PROCEDURES
All application equipment should be regularly washed, decontaminated and cleaned both internally and externally
whilst involved in routine operations, at least at the completion of each days work, and whenever a change of
agrichemical mix occurs. The easiest way to reduce the hazards of contaminated equipment is to dilute pesticides
with copious amounts of water, being careful to dispose of the rinsing in an approved manner. Decontamination
should preferably be carried out on a concrete loading pad, which is correctly drained and ensure proper disposal
of chemical wastes. If decontamination has to be carried out in the field, a safe area should be selected which will
not be grazed by stock and will not drain into waterways, other crop sites or residential areas.
Most agrichemicals are subject to degradation in the presence of an alkaline or acid medium. Decontamination
requirements vary with chemical types, however the following recommendations are presented as guidelines. If in
doubt or if further information is required, manufacturers should be consulted.
ORGANOPHOSPHATES
Clean with a solution of washing soda and sodium hypochlorite, followed by a double water rinse.
CARBAMATES
Use a solution of washing soda and detergent followed by a double water rinse.
PHENOXY HERBICIDES
Phenoxy herbicides present special cleaning problems. This class of chemicals cannot be removed from a spray
system using conventional methods and it is a group that is used widely in agriculture. If a fungicide or insecticide
application has to be carried out after use of 2, 4-D or MCPB etc the following methods are suggested for
decontaminating the spray system. Complete decontamination is generally considered impossible for this class of
chemicals and great care must be taken.
The following procedure is not a guarantee of obtaining a herbicide free spray system
SALTS (AMINE AND METAL) AND OTHER WATER SOLUBLE FORMULATIONS
Rubber hoses, nozzle diaphragms and seals may have to be renewed since they can retain chemical deposits.
Add 5g of washing soda to each 10 litres of water and discharge through the nozzles. Double rinse the system
with water.
ULV FORMULATIONS
Before using oil based formulations, it is important to remove any traces of water by flushing with diesel fuel.
Likewise when reverting to water based sprays, the system should be cleaned with diesel fuel followed by a water
based detergent rinse and water rinse.
SULPHONYLUREA HERBICIDES
It is generally possible to remove traces of these chemicals from a spray system provided the following method of
cleaning is used. The procedure is listed according to data supplied by Du Pont.
Procedure
1. Drain system and flush tank, boom and hoses with clean water for a minimum of 10 minutes.
2. Fill the tank with clean water and add 300ml of household chlorine bleach (containing 3 % sodium
hypochlorite) per 100L of water. Flush through the spay boom and nozzles and allow to sit for 15 minutes.
Drain system.
3. Repeat Step 2.
4. Nozzles and screens should be removed and cleaned separately. To remove traces of chlorine bleach rinse
the tank thoroughly with clean water and flush through hoses and boom.
NB:
For phenoxy herbicides, washing soda is the preferred cleaning agent since it helps to lift the offending
agent off the surfaces of the spray system. For Sulfonylurea herbicides, however, sodium hypochlorite is
the preferred cleaning agent because it reacts with the sulfonylurea, causing it to be broken down into
compounds with no herbicidal activity. The process occurs relatively quickly, (10
– 15 minutes) but is
done twice to ensure complete deactivation of the sulfonylurea.
WARNING
The products should be used as stated above. Under NO circumstances should washing soda be mixed with
chlorine bleach. Mixing releases a dangerous gas.
Refer to the Agrichemical Manual for additional information.
