Optimizing CFC-113 Conservation in Batch Vapor Degreasers

Optimizing CFC-113 Conservation in Batch Vapor Degreasers 
Richard B. Flegel – Motorola, Inc. , Jonathon L. Andell – Motorola, Inc. (SSA Journal – September 1989 pp. 28 – 36 )

Statistically designed and analyzed experiments were used to optimize solvent conservation in vapor degreasers, while assuring that vapor concentrations in work place air remained will within safe levels. Simulated cleaning cycles were used to generate measurable solvent losses and vapor levels in the air. Fractional factorial experimentation was applied to evaluate and compare how four operational parameters contributed to emissions. The parameters were: air velocity over the top of the degreaser, cross-sectional area of the work load perpendicular to the surface of the solvent bath, speed at which work loads are inserted and withdrawn from the degreaser, and whether or not to have the work load pause in the vapor zone during insertion and withdrawal. Elimination of dedicated exhaust ventilation at the degreaser proved to be the primary means of effective conservation, resulting in savings between 66 and 89% without significant, adverse impact on safety. Data showed that further savings might be realized by contr0olling insertion/withdrawal velocity to a maximum of 11 ft/min (5.6 cm/s). Calculations based on the experimental data and others’work indicate the possibility of reducing solvent emissions by as much as 98%, while maintaining safety in the work place.