The following rules were adapted from:
Prudent Practices for Handling Hazardous Chemicals in Laboratories, National Academy Press, Washington, D.C., 1981.
Every laboratory worker should observe the following rules:
Think, act, and encourage safety until it becomes a habit.
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Laboratory workers should observe the following health practices:
Contamination of food, drink, and smoking materials is a potential route for exposure to toxic substances. Food should be stored, handled, and consumed in an area free of hazardous substances.
Well-defined areas should be established for storage and consumption of food and beverages. No food may be stored or consumed outside of this area.
Consumption of food or beverages and smoking is not permitted in areas where laboratory operations are being carried out.
Glassware or utensils that have been used for laboratory operations should never be used to prepare or consume food or beverages. Laboratory refrigerators, ice chests, cold rooms, and such may not be used for food storage; separate equipment should be dedicated to that use and prominently labeled.
There is a definite relationship between safe performance and orderliness in the laboratory. When housekeeping standards fall, safety performance inevitably deteriorates. The work area should be kept clean and chemicals and equipment should be properly labeled and stored.
Many laboratories require a large quantity of electrical power. This power need can the potential for electrically-related hazards. These hazards are both electrical shock hazard to the facility occupants and fire hazard potential. The following recommendations are basic to a sound electrical safety program in the laboratory.
The hazard of this operation is a break causing an implosion rather than an explosion since the higher pressure is on the outside, rather than the inside. The resulting hazards consist of flying glass, spattered chemicals, and possibly fire.
A moderate vacuum, such as 10 mm Hg, which can be achieved by a water aspirator, often seems safe compared with a high vacuum, such as 10-5 mm Hg. These numbers are deceptive, however, since the pressure differences between the outside and inside are comparable. Therefore any evacuated container must be regarded as an implosion hazard.
Apply vacuum only to glassware specifically designed for this purpose, i.e., heavy wall filter flasks, desiccators, etc. Never evacuate scratched, cracked, or etched glassware.
Vacuum glassware which has been cooled to liquid nitrogen temperature or below should be annealed prior to reuse under vacuum. Rotary evaporator condensers, receiving flasks, and traps should be taped or kept behind safety shields when under a vacuum. All condensers connected to rotary evaporators should at least be cooled with circulating ice water.
The use of a vacuum for the distillation of the more volatile solvents, e.g. ether, low boiling petroleum ether and components, methylene chloride, etc., should be avoided whenever possible. In situations requiring reduced pressure, two alternatives should be considered;
When a vacuum is supplied by a compressor or vacuum pump to distill volatile solvents, a cold trap should be used to contain solvent vapors. Cold traps should be of sufficient size and low enough temperature to collect all condensable vapors present in a vacuum system. If such a trap is not used, the pump or compression exhaust must be vented to the outside using explosion proof methods. After completion of an operation in which a cold trap has been used, the system should be vented. This venting is important because volatile substances that have been collected in the trap may vaporize when the coolant has evaporated and cause a pressure buildup that could blow the apparatus apart.
After vacuum distillations, the pot residue must be cooled to room temperature before air is admitted to the apparatus. All desiccators under vacuum should be completely enclosed in a shield or wrapped with friction tape in a grid pattern that leaves the contents visible and at the same time guards against flying glass should the vessel collapse. Various plastic (e.g., polycarbonate) desiccators now on the market reduce the implosion hazard and may be preferable.
Reactions should never be carried out in, nor heat applied to, an apparatus that is a closed system unless it is designed and tested to withstand pressure. Pressurized apparatus should have an appropriate relief device. If the reaction cannot be opened directly to the air, an inert gas purge and bubbler system should be used to avoid pressure buildup.
Last updated by Brian K. Dokter on
May 12, 1997. 
Personal Hygiene
Food Handling
Return to the Chemical Hygiene Plan Index.Handling Glassware
See Broken Glassware Disposal for safe disposal procedures.
Return to the Chemical Hygiene Plan Index.Housekeeping
Return to the Chemical Hygiene Plan Index.Electrical Safety
Return to the Chemical Hygiene Plan Index.Vacuum and Pressure Safety
Vacuum Operations
Water, solvents, or corrosive gases should not be allowed to be drawn into a building vacuum system. Pressure Operations
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