PRECAUTIONS IN HANDLING EXPLOSIVES IN LABORATORY

How to handle explosives in laboratory?

Storage
The quantities of potentially explosive materials in store and in use should be strictly limited. Stores should be specially designed, constructed of non-combustible material, and located away from other hazards (e.g. brick ‘coal bunkers’ are suitable for small samples, but purpose-built constructions with explosion-proof lights etc. are required for larger quantities).

They should be designated ‘No Smoking’ areas and be well labelled. Stores should be used exclusively for these materials. Other combustible material such as fabric, paper, organic solvents should not be stored there.

Generally the substances in this class are unstable when heated or exposed to light; they should be stored cool and in the dark. However, for liquids with added stabilizer cooling may cause separation of the material from the stabilizer.

Similarly, precipitation of a potentially explosive compound from a diluent may occur on cooling. In both cases this can represent a hazardous situation.

Stores should be ventilated and sound, e.g. no cracks in floors, no rusty window frames, no water seepages, etc.

Stores should be clean, tidy and locked. Contamination must be avoided and a high standard of housekeeping maintained.

Heat sources should not be permitted nearby.

Material should be purchased in several small containers rather than one large container and always stored in original containers. Integrity of the labels should be checked.

Use
Use must be restricted to experienced workers, aware of the hazards and the necessary precautions. Records of usage should be kept and stock rotated. Old material should be disposed of.

Work should be on a scale of <0.5 g for novel but potentially explosive material until the hazards have been fully evaluated and <5 g for established, commercially available, substances such as peroxide free-radical initiators.

For the above scales, eye protection should be worn and work should be undertaken in a standard fume cupboard behind a well-anchored polycarbonate screen. It is advisable to wear a protective apron and hand protection; whether leather gauntlets or tongs should be used will be dictated by circumstances.

Such measures are recommended but it should be ensured that they do not precipitate a hazard as a result of loss of tactile sensitivity (e.g. dropping a flask, overtightening clamps, exerting excessive pressure when assembling apparatus). The material of gloves needs consideration. (PVC but not rubber is suitable for tert-butyl peroxide.)

For large-scale work, armour-plated fume cupboards are likely to be required. Skin contact, inhalation and ingestion must be avoided. Splashes in eyes or on skin should be washed away immediately with copious quantities of water. Medical attention should be sought. If material is swallowed, medical aid is required immediately.

Glass apparatus should be pickled (e.g. in nitric acid) and thoroughly rinsed after use. Sources of ignition such as hot surfaces, naked flames etc. must be avoided and smoking prohibited where explosives are used.

Accidental application of mechanical energy should be avoided (e.g. material should not be trapped in ground-glass joints): seized stoppers, taps etc. must not be freed by the application of force. To minimize risk of static electricity, laboratory coats of natural fibre rather than synthetic fabrics are preferred.

It is important to neutralize any spillage on the coat immediately, since delay could result in the impregnated garment becoming a fire hazard.

To prevent glass fragments from flying in the event of an explosion, use should be made of metal gauzes to screen reaction flasks etc., or cages, e.g. for desiccators. Vessels of awkward size/shape may be covered with cling film.

Whenever possible a stabilizer or diluent should be used and separation of the pure material should be avoided. Any waste material (and contaminated cloths, tissues, clothing etc.) must be rendered safe by chemical means or by controlled incineration of dilute solution where practical prior to disposal.

In the event of fire, the area should be evacuated, the alarm raised and the fire brigade summoned. Only if it is clearly safe to do so should the fire be tackled with an appropriate extinguisher.