When certain hazardous chemicals are stored or mixed together, violent reactions may occur because the chemicals are unsuitable for mixing, or are incompatible. Classes of incompatible chemicals should be segregated from each other during storage, according to hazard class or other specifications.
However, no single method of determining chemical compatibility is perfect. This helpful Chemical Incompatibility Table and Storage Recommendations reference gives examples of the issues that arise when compatibility rules are based solely on hazard class:
- Many chemicals belong to more than one hazard class.
- The hazard class that is most important can change depending on factors such as quantity of material, and other chemicals in the storage area.
- Not all chemicals in a given class are compatible. For example, sodium dichloroisocyanurate and calcium hypochlorite are both oxidizers and belong to no other class of chemical, yet the mixing of these two materials can lead to the formation of nitrogen trichloride, a shock sensitive explosive.
- Rigid adherence to a classification scheme often leads to inefficient work practices. For example, chemical storing acids and bases together does not pose a problem if the solutions are dilute enough.
These examples illustrate why incompatibility management is best implemented as layers of rules. Yet the rules can number into the hundreds that should be checked every time a chemical is moved to be collocated with a new bunch of chemicals. This tedious and time-consuming but highly important verification process is a natural application for computers.
This critical safeguard functionality is featured in the Chemical Incompatibilities Management tools in Chemical Safety’s Environmental Management Systems (EMS) software. EMS iterates through all of the incompatibility rules (classification, hazard class, regulation, Uniform Fire Code, etc.) providing a complex layering of configurable safety checks. Chemical Safety’s Configuring Chemical Incompatibility Checks reference document describes the tools that are provided in EMS to enforce segregation of incompatible chemicals and promote a safe work environment.