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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.

Image of side lever knapsack sprayer (9 Kb JPEG)

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.

Image of robot pumping a side lever knapsack sprayer.  (26 Kb JPEG)

The shut-off valve is operated for 25 000 cycles; any spray liquid leakage from the valve is inspected and recorded.

Image of testing to establish if the shut-off valve opens and closes properly and for leakage after 25,000 cycles.  (15 Kb JPEG)

Sprayer output is measured; the nozzle output must be +/- 15% of that stated in the sprayer’s instruction book

Image showing testing of sprayer output (31Kb JPEG)

Carrying straps must be strong and at least 30 mm wide.

Image of testing of carrying straps; sprayer is filled with water to a total weight of 7 kg  and subjected to 10 drops from 200 mm height  (22 Kb JPEG)

Loaded sprayers are dropped 10 times and restrained by their straps. Straps – or fixing points – must not be damaged.

Image showing broken harness fixing point (14 Kb JPEG)

Spray liquid must not be retained on the outside of the sprayer; spray liquid retained from over-filling the sprayer must be minimal.

Image of sprayer likely to retain spray liquid on the top of the spray tank (17 Kb JPEG)

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.

Image of test to check the liquid remaining in the sprayer after emptying following instructions from the handbook (21 Kb JPEG)

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

Image of knapsack sprayer being tested on  a 10% incline, whilst full and empty in all  four different orientations  (12 Kb JPEG)

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.

During testing the knapsack sprayer is filled to each scale mark and up to the upper edge of the filling orifice.  Image showing filling scale.(12 Kb JPEG)

Sprayers must be filled without spills; complete and safe filling must be possible in 60 seconds.

Image of knapsack sprayer being filled at a constant flow (15 Kb JPEG)

Sprayer manufacturers must state how to completely empty sprayers; sprayers must be completely emptied of any liquid before cleaning, storage or being maintained.

Image of knapsack sprayer being emptied during testing (18 Kb JPEG)

Accidentally dropped sprayers must not be damaged; loaded sprayers must be robust and not leak after being dropped.

Image of knapsack sprayer being dropped whilst full from a height of 600 mm during testing  (17 Kb JPEG)

Sprayers must not leak.

Image showing sprayer leaking from cap (13 Kb JPEG)

Leakage is measured after simulated use when sprayer is upright, inclined, at 45oor strap side down.

Image showing sprayers being tested upright, at 45 degrees and with strap side down. (21 Kb JPEG)

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.