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Checking your knapsack sprayer


This video will show you how to check your knapsack sprayer. Click the play button to view the video now or click on the script tab to view the storyboard. To view the video off-line, click the link from the 'download' tab.


You will need:

  • a clean work area
  • a clean knapsack sprayer
  • its instruction book
  • the nozzles supplied
  • clean water
  • detergent
  • cleaning cloths
  • a screwdriver,
  • a checklist and

your personal protective equipment (PPE). When checking your knapsack sprayer, wear your PPE so that you get used to wearing it and can adjust it so that you are comfortable.





This knapsack has already been cleaned – we show you how to do this in a separate video "Cleaning your knapsack sprayer. Check for any obvious damage. Check that the hoses and hose clips are secure and undamaged.






Check to see if the straps and fixing points are damaged in any way.






With the tank full of water, lift the knapsack sprayer and check to see if the straps and their fixing points are still secure.






Next check to see if the knapsack sprayer is stable when lifted and placed on a flat surface. With the knapsack sprayer upright, check thoroughly for any leakage.





Now place it on a slightly inclined surface - if the knapsack sprayer falls over easily then it must be replaced.





Now turn the knapsack sprayer onto its side and check for leaks. Then turn the knapsack sprayer upside down and check for major leaks






Check the pressure relief valve by pumping without spraying to create pressure. Is it opening and letting the water bypass the pump? If you are pumping very hard and the valve is not working then replace this valve.





Open and close the trigger or on/off valve. Does it start and stop spraying quickly? If it does not, then it will need to be replaced or repaired.





Next check the nozzle and if there is damage to the nozzle, replace it. To see how they are fitted just twist the nozzle cap off and the nozzle with its nozzle filter and a sealing ‘O’ ring can be seen. (See also "Fitting a nozzle"





The filter must be clean as it protects the nozzle from becoming completely or partly blocked. Sometimes the knapsack sprayer will be sold with just one nozzle of an adjustable type. Others may come with different types of nozzle





Using clean water, check that the nozzle that you are going to use emits the right amount of liquid and produces the correct spray pattern.





Remember to mark up your checklist - if you need one, you can download a check list from our website where you will also find more information about using pesticides and which PPE to use.