Safe storage of dilute ethylene oxide mixtures in water

In the past industry has had to rely on a number of “rules of thumb” to provide a means of reasonable analysis for many design, operation, safety and similar issues. The lack of readily available computing facilities made the use of “rules of thumb” a necessary part of doing business in the hydrocarbon processing industry. And these “rules of thumb” have proven useful and allowed many tasks to be accomplished successfully. Today, however, availability of mainframe computers or desktop computing facilities has provided a tool that has decreased the need to rely on “rules of thumb.” And in many cases processing improvements can only be accomplished by replacing “rules of thumb” with more rigorous analysis. In the ethylene oxide producing/consuming industry a widely-used “rule of thumb” concerns the storage of ethylene oxide water solutions. A well-publicized “rule” stated that solutions in excess of 1-2 weight percent ethylene oxide in water should not be stored [1]. This “rule” is certainly valid in many situations. However, this guideline may be unnecessarily restrictive in other cases. The impact of several key process parameters impacts the amount of ethylene oxide in water than can be safely stored. This study will show that higher concentrations of ethylene oxide in water can be safely stored under the right circumstances. The study will also discuss the key variables that determine whether aqueous ethylene oxide solutions can be safely stored. Finally, a methodology used in determining how much ethylene oxide in water can be safely stored will be outlined.