Incidents fire, solvent

Zirconium Fire and Explosion Incidents, TID-5365, Washington, USAEC, 1956 Calcium disilicide exploded when milled in the solvent. 

Two violent pressure-explosions occurred during preparations of dimethylsulfinyl anion on 3—4 g mol scale by reaction of sodium hydride with excess solvent. In each case, the explosion occurred soon after separation of a solid. The first reaction involved addition of 4.5 g mol of hydride to 18.4 g mol of sulfoxide, heated to 70°C [1], and the second 3.27 and 19.5 g mol respectively, heated to 50°C [2]. A smaller scale reaction at the original lower hydride concentration [3], did not explode, but methylation was incomplete. Explosions and fire occurred when the reaction mixture was overheated (above 70°C) [4]. Reaction of 1 g mol of hydride with 0.5 1 of sulfoxide at 80°C led to an exotherm to 90°C with explosive decomposition [5]. These and similar incidents are explicable in terms of exothermic polymerisation of formaldehyde produced from sulfoxide by reaction with the hydride base [6]. The heat of reaction was calculated and determined experimentally. Thermal decomposition of the solution of hydride is not very violent, but begins at low temperatures, with gas evolution [7]. 

A major fire erupted in a nonflammable solvents manufacturing unit in a U.S. Gulf Coast chemical complex. A furnace tube in a natural-gas-fired heater ruptured due to overheating. At least 1,800 gallons (6,800 liters) of a combustible heat transfer fluid spilled and burned intensely. Within about 25 minutes, the intense hot fire damaged four levels of structure and associated process equipment. The plant on-site emergency squad quickly and properly responded. However, the price tag for short-lived incident was over 1.5 million in direct property damage and over 4 million in business interruption (U.S. 1979). Fortunately, there were no injuries. [2]... 

Materials incompatibility is one of the most frequent causes of process incidents. Degradation of seals and gaskets that have become softened by solvent effects can lead to minor leaks or major loss of containment, and hence to fires, explosions, or more serious accidents. If seal or gasket leakage is identified in a process, then the plant engineer should consult with the manufacturer to confirm the material is suitable for the service. If necessary, all the seals or gaskets of that material should be replaced with something more resilient to the process conditions. 

Downside reports a yes score has been awarded. Two fires and eight releases concerning four German plants are reported on in the CER under the section titled Environmental Incidents , and there is an article describing the work being carried out on land remediation at Berghausen, where over 1200 tonnes of chlorinated solvents have been extracted from the soil. 

Chemical-resistant suits — Protection is frequently needed in chemistry incidents for protection against corrosive liquids and vapors. In standardized situations, materials for protective suits can be custom selected for maximum protection for the specific chemicals of concern. Where a variety of chemicals such as acids, bases, and frequently used solvents are involved, a butyl rubber suit is often a reasonable choice. Combination units of chemical and fire resistant entry suits are available. 

Solvents are widely used in organic reactions. These liquids are often flammable and have varying degrees of toxicity. As illustrated in Incident 1.2.2.1 there is always the possibility of fires when handling flammable solvents, especially if there are unrecognized ignition sources in the vicinity. While we really don t know speciflcally what the researcher was doing or why the particular 10% ethyl acetate/90% petroleum ether solvent was chosen for her work, one can speculate that perhaps a less hazardous substitute or a smaller scaled experiment could have been considered for her experiments. 

Risk Management Safety Department, University of Arizona. Incident Solvent Fire available at http //risk.ariziona.edii/ healthandsafety/chemicalsafetybulletins/solventfire.shtml (accessed August 27, 2009). 

The debate about "containing" vs. "intrinsically safe" design is for safety engineers, and outside the scope of the book. This author has successfully used both approaches. Fires in vapor degreasers using flammable solvents are nonexistent, or occur with an extremely low incidence, or are well-concealed. 

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