Page Banner

United States Department of Agriculture

Agricultural Research Service

 Search for This

# Related Topics

Title: A MATHEMATICAL MODEL TO PREDICT THE WEAR RATE OF NOZZLES WITH ELLIPTICAL ORIFICES

Author
 Zhu H Reichard, Donald Ozkan H E Brazee, Ross Fox, Robert

 Submitted to: Transactions of the ASAE Publication Type: Peer Reviewed Journal Publication Acceptance Date: 4/12/1995 Publication Date: N/A Citation: N/A Interpretive Summary: To achieve satisfactory pest control at minimum cost, pesticides must be distributed over the target at the proper rate. Due to wear, nozzle flow rates increase with usage time and the amount of increase depends on several factors. It is desirable to be able to predict wear rates of nozzles for different conditions without conducting long expensive tests. A mathematical model has been developed to predict nozzle wear rates from experimental wear rate values obtained from tests conducted over short periods. The model agreed very well with experimental values obtained over long periods with orifices of various sizes and materials, and different spray mixtures. The model could aid both manufacturers and users of nozzles in selection of the optimum orifices for various needs. Technical Abstract: A mathematical model was developed to predict orifice wear rate for fan-pattern, spray nozzles. Variables affecting nozzle wear rate in the model are usage time, spray pressure, initial orifice size, effective coefficient of friction between orifice wall and fluid, orifice material and the fluid. Spray-pattern measurements for new and worn orifices verified that wear mainly increased minor-axis length of the elliptical orifice with very little wear at the ends of the major axis. There was good agreement between predicted and measured flow rate increases for worn orifices with various materials and nominal capacities for up to about 38% increase in flow rate relative to new orifices. Both the model and experiments indicated nozzle wear rate increased with usage time, spray pressure, effective coefficient of friction between nozzle orifice wall and fluid, and ratio of major to minor axis of the elliptical orifice.