Testing Knapsack Sprayers
Written by and Dr Andreas Herbst from Julius Kühn Institute (JKI, formerly BBA) Braunschweig, Germany and Dr Friedrich of FAO
How Are Side Lever Knapsack Sprayers Tested?
International Standard 19932 2006 describes what to test, how to test and the minimal test performance that is acceptable.
Testing must follow this order
The sprayers must have been worked before testing. Robots are used to mimic the operator pumping the sprayer. The sprayers are worked for 25 hours before testing to prove that the sprayers are robust enough for normal use and do not wear too quickly.
The shut-off valve is operated for 25 000 cycles; any spray liquid leakage from the valve is inspected and recorded.
Sprayer output is measured; the nozzle output must be +/- 15% of that stated in the sprayer’s instruction book
Carrying straps must be strong and at least 30 mm wide.
Loaded sprayers are dropped 10 times and restrained by their straps. Straps – or fixing points – must not be damaged.
Spray liquid must not be retained on the outside of the sprayer; spray liquid retained from over-filling the sprayer must be minimal.
External spray deposits are measured after the sprayer has been subjected to a simulated over-fill.
Residuals after spraying must be minimal; almost all spray liquid must be capable of being pumped out so that the residual volume is not a risk to humans, the next crop sprayed and the environment.
Sprayers must not fall over when placed on the ground. Sprayers must be stable on the ground when being filled or when loaded to avoid spills and damage
The tank contents scale must be accurate; the scales must be accurate if the required volume of spray solution is to be prepared and the prescribed dose applied safely.
Sprayers must be filled without spills; complete and safe filling must be possible in 60 seconds.
Sprayer manufacturers must state how to completely empty sprayers; sprayers must be completely emptied of any liquid before cleaning, storage or being maintained.
Accidentally dropped sprayers must not be damaged; loaded sprayers must be robust and not leak after being dropped.
Sprayers must not leak.
Leakage is measured after simulated use when sprayer is upright, inclined, at 45oor strap side down.
Manufacturers are continuing to make many advances to help meet the requirements of the International Standard. It is hoped that full compliance of their products will soon be a more commonly accepted achievement.