Effect of Filter Types and Sizes on Flow Characteristics of Standard Flat-fan Nozzles

The relation between flow rate (Q) and operational pressure (P) of standard flat-fan

nozzles can be explained by the power regression model 􁈾􀜳 􀵌 􀝇 ∙ 􀜲􀯡􁈿, where “k” is the orifice

coefficient, and “n” is the exponent of spray pressure. According to the model, the flow rate of a

nozzle is proportional to the square root of the spray pressure, the exponent (n) of which is 0.50.

This study examined standard flat-fan nozzles of different nominal sizes with slotted filters, cup

filters, and cylindrical strainers (40-mesh, 50-mesh, and 80-mesh). The “n” coefficient ranged

between 0.481 and 0.487. For nozzles with 50-mesh and 80-mesh ball-check strainers, the “n”

coefficients were 0.551 and 0.570, respectively. The “k” constants of the nozzles with ball-check

strainers were smaller than those of the other filters and strainers. The “k” constant of nozzles

ST11001, ST11002, ST11003, ST11004, and ST11006 could be estimated based on their nominal

flow rates (0.38, 0.76, 1.14, 1.51, and 2.27 L/min, at 2.8 bar) with the advanced power regression

models. The highest pressure fluctuation on the spray line was observed on the no-filter nozzles.

Nozzles with ball-check strainers showed the lowest pressure fluctuation. The strainer types shifted

the deviation rate from the nominal flow rate of the nozzle. The lowest deviation rate was observed

in the nozzles with no filters, slotted filters, or cup filters. The deviation rate from the nominal flow

rate of the nozzles with ball-check strainers was -11.4% for 50-mesh strainers and -12.3% for 80-

mesh strainers.