Hazard Screening Method for Mixing of Reactive Chemicals Using Small Scale Dewar Vessels

Unexpected chemical reactions triggered by mixing of reactive materials may occur in chemical processes industries or laboratories and lead accidents with gaseous release and equipment damages due to the rapid increase of pressure. Therefore, appropriate method of screening of mixing hazards is necessary to prevent the accidents [1]. Calorimetry such as reaction calorimeter (RC-1) and micro reaction calorimeter (Super CRC) has been used as a conventional screening tool for reactive chemical hazards [2]. However, operation of these apparatuses is rather complicated, measurement time is longer and these apparatuses are relatively expensive. In this study, a small-scale Dewar vessel test was developed as a new screening tool for mixing hazard analysis in terms of operability and cost effectiveness. To identify optimal measurement conditions for the screening method the neutralization reaction of hydrochloric acid and sodium hydroxide was carried out using Dewar vessels of 40 mL under several conditions such as the position of sample injection, the amount of sample, the stirring condition and the ambient temperature. It was found that the experimentally observed heat of reaction showed a good agreement with the theoretical value and the proposed test method was an effective tool for screening of mixing hazard analysis.

References

[1] A. Miyake, N. Yamada, T. Ogawa, Mixing hazard evaluation of organic peroxides with other chemicals, Journal of Loss Prevention in the Process Industries, 18, 380-383 (2005)

[2] Y. Fujimoto, Methods for evaluating reaction hazards, Specific Research Reports of the National Institute of Industrial Safety, 34, 5-10 (2006)