Metered Liquid Applicator

Operator uses a spray-wand to apply liquids to certain targets

Application of liquids is often performed manually with a spray-wand. Workers squeeze and hold the trigger of the spray-wand up to 25 times per minute. Workers also have to stoop repeatedly in order to reach further locations. Awkward wrist postures with occasionally extreme ulnar deviation are required for accurate control of the spray-wand.

A semi-automated, metered liquid applicator was developed for a precise dose-control to each plant and therefore reduced the need for repetitive hand squeezing. Repetitive squeezing is eliminated since the new applicator uses a valve instead of a trigger. A pistol grip wand was also introduced instead of a straight wand; this reduces the amount of ulnar deviation especially during far reaches.

$500 (material cost only)

Evaluation of Intervention

  • Pros
  • Reduces the frequency of hand squeezing
  • Reduces ulnar deviation and keeps wrist in a neutral posture
  • Reduces stooping
  • Less chemicals wasted
  • Productivity improved
  • Cons
  • Still required to grip in order to hold and control the wand
  • Additional control box and battery are required
  • Significant cost for materials and labor

Semi-Quantitative Evaluation of Intervention

  • Reduction of Identified Risk Factor
  • No New Risk Factors Introduced
  • Productivity not Reduced
  • Low Cost
  • Total
  • 4/5
  • 5/5
  • 5/5
  • 3/5
  • 17/20

Other Possible Interventions

  • Additional handle structure that allows two-hand operation
  • Wand with numerous spray heads to reduce repetitive squeezing

This project was funded by NIOSH and was carried out by the University of California Agricultural Ergonomics Research Center. Further information is available from the AERC website [] and in the CDC/NIOSH Publication, “Simple Solutions” [DHHS Publication No. 2001-111].