Safety Philosophy
In working with chemicals, certain best practices are overarching.
These are outlined in a number of texts, most notably the National Research Council's Prudent Practices in the Laboratory: Handling and Disposal of Chemicals (1995, ISBN-10: 0-309-05229-7). The book provides general guidance on good housekeeping, personnel protective equipment, pre-planning and documentation of operations, storage and disposal.
Common sense demands that MSDS (material safety data sheets) be available and reviewed for all materials handled and that personnel in the laboratory wear appropriate protective gear, e.g. safety glasses, face shields, or full-face masks. Established laboratory safety protocols should be followed or adapted as necessary with review. However, safety ultimately rests on the individual's attitude and knowledge. As new protocols become necessary, they should be added. Every researcher must be part of this process; it is essential for their safety and for the safety of everyone around them.
The ALERT Safety Program is not intended to replace or supersede protocols already in place; all the normal safety precautions applicable to chemicals apply. The additional hazard is uncontrolled release of energy. In handling a known energetic material, e.g. TNT, sufficient literature exists that the researcher should know the specific hazards faced. For unknown species or mixtures, some general guidelines can be followed until more specific information is obtained. A useful source for general hazard warnings is Bretherick's Handbook of Reactive Chemical Hazards, 7th ed, P Urben; 2006.
In general, the concern in the laboratory is synthesis and handling of bulk energetic materials - the issues are sensitivity and stability.
Sensitivity is the ease with which a material can be caused to react by relatively mild insult (something a human might inadvertently impart-impact, friction, electrostatic discharge) as opposed to the input of a shock wave (i.e. from a detonator). Sensitivity is generally determined experimentally at a small-scale. It is essential to get this information as soon as possible. Furthermore, although a scaled-up formulation is more hazardous, it is usually not more sensitive. (A possible exception is a change to more sensitive impurities with increase in batch size.)
Stability refers to the capacity of an energetic material to maintain its chemical composition for long periods at ambient temperature (such as during storage). A material that lacks stability may undergo catastrophic reaction on its own with no apparent additional input of energy. The temperature at which an energetic material maintains stability is a function of its chemistry, its quantity, and its degree of contamination. Generally, contaminated materials degrade more readily than pure ones; their degradation may be quiescent or violent. Large quantities of material undergo self-heating more readily than small quantities because their decomposition generates heat that raises the temperature that accelerates decomposition. Therefore, during scale-up of a synthetic process, stability tests are run at various stages.
In handling energetic material the rule is to minimize
and to maximize distance or introduce an adequate barrier commensurate with the amount of material.
- quantity of material
- time of exposure
- number of people exposed