Reactivity instabilities

Reactivity (instability) information Acceleration rate calorimetry Differential thermal analysis (DTA) Impact test Thermal stability Lead block test Explosion propagation with detonation Drop weight test Thermal decomposition test Influence test Self-acceleration temperature Card gap test (under confinement) JANAE Critical diameter Pyrophoricity... 

HAZARD The inherent property of a substance capable of causing harm (e.g. toxicity, radioactivity, flammability, explosivity, reactivity, instability). In a broader context anything that can cause harm, e.g. electricity, oxygen-deficiency, machinery, extreme temperature. 

Because of the reactivity, instability and hazardous nature of O3 it is always generated on... 

To summarise the information aiready presented and to enabie an opinion on the possibiiities of forecasting instabiiity risk to be formed, it is interesting to make a comparison of the different reactivity/instability risk classifications. The table below sums up these different approaches. The substances are classified in descending order according to the NFPA coding and are taken from Stull s publication already mentioned (note, p.120) ... 

Reactivity (instability) information Acceleration rate calorimetry Differential thermal analysis (DTA) Impact test Thermal stability Lead block test... 

In a broad sense, any substance or mixture of substances having properties capable of producing adverse effects on health, safety or the environment. These dangers may arise from but are not limited to [flammability, explosibility,] toxicity, reactivity, instability or corrosivity. 

The reactives program emphasizes both self-reactivity (instability) and binary reactivity. 

The program focuses on binary and higher levels of reactivity in addition to self-reactivity (instability). 

This section also includes a review of the NFPA Identification System. This color-keyed system is in use within the chemical industry for in-plant identification— blue for health, red for flammability, and yellow for reactivity (instability). A fourth square is reserved for special or unusual hazards, as for example, radioactivity or an especially violent reaction with water. These four squares are arranged to form a larger square on point. The top (red) is always flammability, the right (yellow) is always reactivity (instability), the left (blue) is always Health, and the bottom special hazards. 

These dangers may arise from but are not limited to [flammability, explosibility,] toxicity, reactivity, instability or corrosivity. 

Material factor This factor, denoted by MF (vid. Table 9.2), is a measure of the intrinsic rate of potential energy release from fire or explosion produced by combustion or chemical reaction. It describes the flammability and reactivity (instability) of a material and is obtained from tables given in [9]. Its value lies between 1 and 40 and refers to ambient temperature. It is modified if materials are present at higher temperature in order to cater for the resulting increase in hazard potential. 

The dicarbonate configuration in dimethyl dicarbonate (DMDC, Section 7.7) is responsible not only for the electrophilic character of the chemical but also for its distinguished reactivity (instability), which does not allow use of DMDC as a preservative, but as a powerful cold sterilizing agent. 

Modest stability of the diketone. Cycloheptane-1,3-dione is a colorless oil. We foimd that crude san5>les of this material tended to discolor upon storage above 0 °C. This color could be removed by distillation or filtration through silica gel, but with associated loss of material (distillation was particularly inefficient, 60-65% recoveries were typical). This is in marked contrast to cyclohexane-1,3-dione, which is a stable, crystalline, white solid. Interestingly, the NMR spectra of these two materials in CDCI3 are also quite different the 6-meiribered diketone is completely enolized, whereas the 7-membered diketone exists exclusively in the diketo form. Transannular interactions or some other form of ring strain are presumably responsible for this difference in enolization propensity, and this correlates with the greater reactivity/instability of the 7-... 

YELLOW (right corner) background for reactivity (instability) hazard... 

On occasion, NFPA hazards are written horizontally, left to right, as NPFA 0—4 (health) 0-4 (flammability) 0-4 (reactivity/instability) Special Hazards. ... 

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