Reactive Chemicals Screening

Experience has shown that reactive chemistry hazards are sometimes undetected during bench scale and pilot plant development of new products and processes. Reactive chemistry hazards must be identified so they can be addressed in the inherent safety review process. Chemists should be encouraged and trained to explore reactive chemistry of off-normal operations. Simple reactive chemicals screening tools, such as the interactions matrix described in Section 4.2, can be used by R D chemists. 

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Kohlbrand, H. T. (April, 1985). "Reactive Chemical Screening for Pilot Plant Safety." Chemical Engineering Progress, 52-56. 

Obtain and review reactive chemical screening data as a research project progresses. 

Reactive System Screening Tool (RSST) The RSST is a calorimeter that quickly and safely determines reactive chemical hazards. It approaches the ease of use of the DSC with the accuracy of the VSP. The apparatus measures sample temperature and pressure within a sample containment vessel. Tne RSST determines the potential for runaway reactions and measures the rate of temperature and pressure rise (for gassy reactions) to allow determinations of the energy and gas release rates. This information can be combined with simplified methods to assess reac tor safety system relief vent reqiiire-ments. It is especially useful when there is a need to screen a large number of different chemicals and processes. 

Use reactor calorimetry testing to determine thermodynamics and kinetics of process. See Appendix 2A (Chemical reactivity hazards screening). 

Up to this point, the chemical reactivity hazards of individual substances, either by themselves or in contact with common environmental materials, have been considered. This last question in the chemical reactivity hazards screening will address the potential for an unintended chemical reaction due to incompatible materials contacting each other. Compatibility, in this context, means the ability of materials to exist in contact without specified (usually hazardous) consequences under a defined scenario. A scenario, in this context, is a detailed physical description of the process whereby a potential inadvertent combination of materials may occur (ASTM E 2012-00). 

A review of material safety data and standard references for the ingredients may result in answering Questions 7 through 11 as shown in Table 5.5. Two of the ingredients, aluminum powder and sodium hydrosulfite, are known to be reactive chemicals, so a chemical reactivity hazard is obviously present. At this point, the Preliminary Screening Method would point the user to the information in Chapter 4, for identifying and managing chemical reactivity hazards. 

The Preliminary Screening Method is not intended to identify all conditions under which reactive chemicals and incompatibilities may lead to uncontrolled reactions. However, it should give an indication whether chemical reactivity hazards exist, as well as what to investigate more closely by analysis and testing. 

Mosley, D.W., A.I. Ness and D.C. Hendershot. 2000. "Screen Reactive Chemical Hazards Early in Process Development." Chemical Engineering Progress (96) 11 51-65. November. 

Materials that in the past were never considered to pose a viable threat have been successfully utilized in numerous attacks. If explosive screening technology hopes to match the growing threats, it will have to expand into the realm of reactive chemicals, which were previously discounted as nonviable for illicit use. 

Gerberick, G.F., Vassallo, J.D., Foertsch, L.M., Price, B.B., Chaney, J.G. and Lepoittevin, J.P. (2007) Quantification of chemical peptide reactivity for screening contact allergens a classification tree model approach. Toocicological Sciences, 97, 417 27. 

It is not possible to establish the exact point in a research project when the screening tests outlined in this guide should be used. (R D safety manuals often provide additional guidance on this issue.) The persons working directly on the project are the ones who can effectively evaluate and control this need. In general, no research project should be pilot planted unless a reactive chemicals review is held. The level and depth of review will be driven by the amount of reactive chemicals potential risk present in the project or process. Higher risk projects should be reviewed sooner in their development process, some-... 

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