Masters Theses

Date of Award

12-1992

Degree Type

Thesis

Degree Name

Master of Science

Major

Biosystems Engineering Technology

Major Professor

William E. Hart

Committee Members

Fred D. Tompkins, C. Roland Mote, James B. Wills

Abstract

An experimental apparatus was designed to quantify the effectiveness of commercially available tank rinse nozzles to adequately clean residues from inner surfaces of sprayer reservoirs. A laboratory scale test stand was constructed to perform two specific functions: 1) provide mounting and support for typical sprayer tank mounting brackets; and 2) house two independent fluid delivery systems.

A multi-position frame was designed to accept mounting brackets for four tank sizes. Design considerations included rapid and easy exchange of various tanks and still provide support for the mass of tank and fluid. Two fluid delivery systems were designed and assembled to facilitate the testing of sprayer tanks. One fluid delivery system was devoted to transferring concentrated trace solution (10000 parts per million ionic bromide) between a separate storage reservoir and test tanks. A 1136-L [300-gal.] polyethylene tank served as a storage vessel for the test solution. The ionic bromide tracer was used to contaminate interior surfaces of test tanks. The transfer system was used to move the concentrated chemical into test tanks. After filling a test tank, the solution was transferred back to the storage reservoir. A second fluid delivery system supplied clean rinse water to a tank rinsing nozzle centrally located inside a test tank. Clean water was stored in an auxiliary 114-L [30-gaI.] cone tank mounted on the test stand. Two separate fluid delivery systems were utilized to avoid potential rinse water contamination, which would ultimately alter rinsate sample concentration.

Two commercial tank rinsing nozzles (Spraying Systems Company model 27500-E %-18 TEF and Lechler, Inc. model 5E) were evaluated. Three operating parameters (pressure, rinse sequence, and rinse volume) were varied to evaluate performance of these two nozzles. Nozzle operating pressures were set according to manufacturers recommendations. The Spraying Systems nozzle was operated at 138, 207, 276, and 345 kPa [20, 30, 40, and 50 psi] for all tank sizes (190, 380, 760, 1136 L cylindrical and elliptical [50, 100, 200, and 300 gal.]). The Lechler nozzle was tested only on the 380-L [100-gal.] tank at pressure of 207, 276, and 345 kPa [30, 40, and 50 psi]. Two rinse volumes (5 and 10 percent of tank capacity) and three rinse procedures (single, double, and triple) were evaluated at each pressure. For the single rinse procedure, the tank was rinsed once with the total rinse volume. In the double (triple) rinse procedure, the tank was rinsed twice (thrice) with half (one-third) of the total rinse volume. All rinse tests were replicated a minimum of three times.

Rinsate samples were collected in disposable paraffin lined paper cups to prevent cross contamination between samples. Rinsates were drained between each rinse cycle. An Orion model 290A portable pH meter was used to measure rinsate sample concentrations. The meter, equipped with an ion specific bromide electrode and its corresponding double junction reference electrode, enabled direct concentration measurement ranging from 0.0000 to 199000 parts per million.

Rinse sequence was statistically significant (a=0.05) in reducing rinsate concentration for all tank sizes tested. Rinse volume and tank size were also shown to have an effect. Operating pressure had little impact on rinsate concentration. Tank geometry and nozzle type were not significant (α=0.05) factors in this study.

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