Spray Alcohol: Specific Issues

Isopropyl alcohol was chosen as the material to replace CFC 113 for precision cleaning operations. An enclosed booth is used to pressure spray the alcohol onto and through the hardware being cleaned. Alcohol best met the required criteria and Martin Marietta has over twenty years of experience designing alcohol systems and using low pressure alcohol spray for cleaning components.

Alcohol has a number of concerns which were addressed in design of the system. These concerns were addressed during the demonstration program. The specific concerns addressed were as follows:

1. Flammability: Isopropyl alcohol has a low flashpoint. Flammability is addressed in the system by keeping the chamber atmosphere below the lower explosive limit (LEL). This is accomplished by the high turnover of air in the chamber and the use of a blower in the exhaust stack to evacuate the chamber atmosphere.

2. Alcohol vapors are considered volatile organic compounds (VOC's) and must be captured and not released into the atmosphere. VOC's will be recovered/ treated in an as yet undefined manner. Several systems currently under consideration include activated carbon recovery, incineration, or barrier membrane technology. Final selection is planned by November 1992 and will be sized and designed in the same timeframe. Incorporation of the recovery/treatment unit with the alcohol spray chambers will occur in the first quarter of 1993.

3. Uses for the spent alcohol must be found to reduce or eliminate disposal as a hazardous waste. Alcohol will be reused in the cleaning system through a distillation process. The distillation system is currently being sized and designed for installation in the first quarter of 1993.

4. Alcohol loss through the air exhaust system must be addressed since significant airflow through the chamber occurs during cleaning cycles. This is being addressed as described in item 2 above.

5. Life of the alcohol bath before disposal from the cleaning system for exceeding water and/or NVR limits must be assessed.