Class IV cosolvent processes

Class IV cosolvent processes are simple. Cleaning work is done with them as if only a single solvent were involved. And, the Class IV cleaning process may be conducted in a standard NESHAP-compliant open-top vapor degreaser ° . That s simple ... 

Actually, while the above statements are correct, they do not fully describe Class IV cosolvent processes. The additional needed information is that the integrity of the azeotropic composition can be lost over time of use. And when the integrity of an azeotropic blend is lost it becomes only a mixture of chemicals. 

As one uses the other classes of cosolvent processes to achieve a specific aim, so some use Class IV cosolvent processes to achieve one of two specific but different aims. However, only one of them is achievable the other is illusory. 

Whatever chemical contamination is encountered by the binary azeotrope can usually be removed witbin and around the distillation column associated with a Class IV cosolvent process. 

That in the Class IV cosolvent process operates continuously, and produces the same quality of overhead (OH) product throughout its use. 

But there is a third factor necessary to select binary azeotropes for Class IV cosolvent processes — it is their compatibility with water. One needs to know this to properly design and operate the continuous-type distillation column. It is unlikely this factor can be evaluated... 

Another perspeaive on the differences between a singlesolvent process and the Class IV cosolvent azeotropic process is that facilities and care are needed to manage an uncertainty that is certain to occur. 

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