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Author: Subject: MIT Laboratory Safety Rules

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[*] posted on 29-7-2011 at 19:52
MIT Laboratory Safety Rules

I figure you can never have too many laboratory safety rules and these are some good ones. I’ll try to get the rest of the chapter posted, fire, explosions, caustic substances, etc.

Chapter 1


A. General Considerations

In the laboratory the chemist works with many potentially dangerous substances. Yet, with constant alertness, awareness of potential hazards, and a few common-sense precautions, laboratory operations can be carried out with a high degree of safety.

Most of the responsibility for the personal safety of the laboratory worker rests on the worker himself. In the event of an accident resulting from his neglect of appropriate precautions or disregard of laboratory regulations he is in a poor position to collect damages for his own injuries, and may even find himself the target of civil or criminal action if his negligence results in injury to others. Worse, injuries sustained in laboratory accidents can result in permanent disability, disfigurement, blindness, or death--a fact that far transcends legal considerations.

The basic rule of safety in the laboratory is : be alert--stay alert; the laboratory is no place for the "absent-minded professor". Beyond this, take the trouble to understand what you are doing and to know what the hazards are, take the appropriate precautions, and use the appropriate protective equipment.

We summarize here some of the more important specific laboratory rules and precautions.

(1) Never work in the laboratory alone. Before working in the laboratory outside regular hours be sure that this is permissible and be certain that someone else will be in the same room to provide assistance in case of need.

(2) At all times wear approved eye protection: "safety glasses" with impact-resistant lenses in approved frames, or protective goggles, or a face shield, or some combination of these. It should be borne in mind that this is required by Massachusetts state law. Safety glasses may be obtained either ground to prescription or non-refracting. Side shields of transparent plastic may be clipped on for additional protection. Ordinary prescription glasses provide about the same protection against spatter as do safety glasses but in the event of an explosion the lenses of ordinary glasses are much more easily shattered and the glass fragments may be driven into the eyeball; in such a case they can be worse than no glasses at all. Contact lenses (especially the corneal type) provide negligible protection, and indeed their use may seriously aggravate hazards from spatter since they will impede washing the cornea free of caustic liquids that creep or diffuse under them. It is inadvisable to wear them even under safety glasses, which (it must always be remembered) do not by themselves provide one hundred percent protection from spatter at top, sides, and bottom.

(3) Use the fume hood for all operations involving poisonous or offensive gases or fumes, as well as for operations involving highly inflammable or potentially explosive materials. A combination of a fume hood and a safety shield (see below) will provide the maximum readily available protection against minor laboratory explosions.

(4) Guard against injury from explosion, implosion, flash fires, and spatter of dangerous liquids by interposing a "safety shield" or other effective barrier between all personnel and any setup presenting such hazards. Vacuum distillations of more than small (about 100 ml) quantities should be shielded, as should gas scrubbing trains containing significant amounts of corrosive solutions and all evacuated equipment of any significant size such as vacuum desiccators.

(5) Use a metal safety pail with a well-fitting cover to transport any dangerous liquid, or more than a small quantity (a pint) of any solvent. Several years ago the writer was a witness to a fatal accident in which a sealed bottle of ethyl chlorocarbonate, C2H5OCOCl, blew up (from internal CO2 pressure) in the face of a technician who was carrying it in one hand from the dangerous chemicals vault. A safety pail would probably have saved her life.

(6) Never heat an organic solvent in an open vessel over an open flame; keep a respectable distance between open vessels containing organic solvents and any open flames or sources of sparks. Except under special circumstances, an open flame should not be used to heat a reaction apparatus containing inflammable materials.

(7) Never place beakers or unstoppered flasks containing chemicals in a refrigerator, even if it is of the "explosive proof" type, or in any other unventilated enclosure. Never store volatile toxic materials in a refrigerator or other unventilated enclosure even in a "stoppered" vessel. The first breath a person takes after opening the refrigerator door could be his last.

(8) Do not work with large quantities of reactants (i.e. more than about 100g) unless you have received special instruction regarding large-scale reactions.

(9) Always be careful to avoid pointing the mouth of a vessel being heated toward any person, including yourself.

(10) Except for certain operations for which special instruction should be obtained beforehand (reduced-pressure distillations, reactions in bombs or sealed tubes, etc.) never heat reactants of any kind in a fully closed system; be sure the system is open to the air at some point to prevent pressure buildup from boiling or gas evolution. Never add anything TO a concentrated acid, caustic, or strong oxidant; instead add the acid, caustic, or oxident slowly and cautiously to the other ingredients, preferably no faster than it is consumed by reaction.

(12) Never add solids (boiling chips, charcoal, etc.) to a hot liquid as this may result in violent boiling if the liquid happens to be superheated. Perform such additions (or put in an appropriate ebullator) when the liquid is still at room temperature.

(13) Never pipette by mouth any toxic or corrosive substance or (preferably) anything else. Use an automatic pipette or fill a conventional pipette with a rubber bulb. (Exceptions to this can be made for certain dilute non- toxic or slightly toxic solutions used in analytical work: HC1, NaOH, NaCl, NaHCO3, Na2S2O3, etc. If some of any such solution gets into the mouth it will be sufficient to spit it out and wash the mouth out well with water.) Assume any unfamiliar substance to be toxic unless you know definitely to the contrary.

(14) Be sure all chemical containers are correctly and clearly labelled. Labels for your preparations should contain, besides the name or formula of the contents: your name, the date, and a sample number by which it can be identified in your notebook.

(15) Never pour anything back into a reagent bottle.

(16) Protect your clothing with a laboratory apron or a laboratory coat.

(17) Protect your hands: with rubber or polyethylene gloves when handling caustic liquids, with canvas or asbestos gloves when handling hot objects. Remember that some highly toxic substances can penetrate rubber or polyethylene gloves; do not hesitate to discard gloves (or aprons, or coats, even shoes) that become dangerously contaminated.

(18) Dangling .neckties, unrestrained long hair, and fluffy or floppy clothing (including over-large or ragged laboratory coat sleeves) can easily catch fire, dip into chemicals on the laboratory bench, get ensnarled in apparatus and moving machinery, etc. Remove or restrain your long necktie; put up long hair or at least restrain it with a rubber band.

(19) Know and observe the approved procedures for disposal of the chemicals and laboratory refuse associated with your experiment. In particular, never throw chemical wastes into a waste crock, or water- insoluble solids into the sink; flush down soluble substances with a great excess of water; never dispose of cyanides or mercury or alkali metals in the sink or crock; package hazardous chemical wastes in suitable containers appropriately labelled, and call the Safety Office to take them away.

(20) Know the location of exits, fire extinguishers, fire blankets, safety showers, gooseneck faucets for douching eyes, and other safety devices; familiarize yourself with the purposes of these devices and with the procedures for their use.

(21) Before beginning any procedure with which you have not had adequate previous experience and thorough knowledge of the hazards, find out what the hazards and appropriate precautions are by reading the literature and/or conferring with someone having such knowledge and experience.

This list of twenty-one safety rules and precautions has been chosen somewhat arbitrarily and is by no means complete. However, it represents in our view a selection that contains the most important precautions. It should be reread periodically until observance of these precautions has become second nature. These same precautions and some additional ones will be treated in specific contexts in the following sections, which should be read in advance of performing the corresponding laboratory operations and reviewed from time to time. Since observance of the precautions here presented can be of crucial importance, we do not apologize for being occasionally repetitious.

Laboratory Techniques Manual, Volume I: Undergraduate Chemistry Laboratory, pp. 1-1 to 1-3. Copyright 1974, Department of Chemistry, Massachusetts Institute of Technology. Revised 1979.
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[*] posted on 30-7-2011 at 07:45

I would like to add one more.

(22) Before using vacuum, inspect the flask to be evacuated for chips or cracks. If there is a deformity, refrain from evacuating the vessel. Also, place a shield or barrier in between yourself and the vacuum, in case of an implosion.

My quite small but growing Youtube Channel:

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The difference between chemists and chemical engineers: Chemists use test tubes, chemical engineers use buckets.
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[*] posted on 30-7-2011 at 12:32

So smoking while filtering solvents was a no no?
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[*] posted on 30-7-2011 at 14:53

Thanks for posting this! For some reason I love this type of material, the older the better! Its interesting to see how the rules change over the years as the federal restrictions change on waste disposal. In the very old textbooks some of them advise one to dispose of mercuric salts directly down the drain! Along with other non advisable practices such as pipetting by mouth and the such.
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[*] posted on 31-7-2011 at 11:39

Quote: Originally posted by bwpatton1  
Thanks for posting this! For some reason I love this type of material, the older the better! Its interesting to see how the rules change over the years as the federal restrictions change on waste disposal. In the very old textbooks some of them advise one to dispose of mercuric salts directly down the drain! Along with other non advisable practices such as pipetting by mouth and the such.

i dont know if youve seen this from vogels
The operations of practical organic chemistry are attended by certain
dangers, the chief of which is that from fire since many of the liquid
chemicals and the solvents are highly inflammable substances. Highly
volatile liquids, such as diethyl ether, carbon disulphide, acetone and
benzene, should never be handled in the vicinity of a free flame (compare
full discussion in Section 11,14) ; the vapours can " flow " along the top
of a bench (particularly if assisted by a draught of air), become ignited
by a flame at some distance and strike back to ignite the parent liquid.
A common mistake by beginners is to heat an inflammable liquid in an
open vessel over a free flame. The correct, and the only permissible,
procedure is to heat the liquid in a vessel provided with a reflux condenser
on a water or steam bath or upon an approved electric hot plate or by
i C
immersion in a bath of hot water with the burner extinguished. Volatile
solvents must be removed by distillation and not by evaporation.
Recovered solvents should be poured into the special bottles provided
for them in the laboratory ; they should not be poured down the sink
nor into the waste boxes.
If a fire should occur, all flames in the vicinity should be extinguished
and all inflammable materials removed. A small fire may be smothered
with a wet towel or by throwing sand upon it. For a large fire, the
laboratory fire extinguisher (C02, etc.) should be used. The well-known
" Pyrene " fire extinguisher, containing carbon tetrachloride, should not
be employed in the confined space of the laboratory since the highly
poisonous phosgene may be formed ; furthermore, an explosion may
occur if it comes into contact with sodium. If the clothing of a fellow
student should catch fire, he (she) should be wrapped in the special fireproof
blanket or, if this is not available, in a heavy coat; he (she) should
not be allowed to run about and fan the flames.
Other sources of hazard arise from the handling of such chemicals as
concentrated acids, alkalis, metallic sodium and bromine, and in working
with such extremely poisonous substances as sodium and potassium
cyanides. The special precautions to be observed will be indicated, where
necessary, in the experiments in which the substances are employed, and
will also be supplied by the demonstrator. The exercise of obvious
precautions and cautious handling will in most cases reduce the danger
to almost negligible proportions. Thus, if concentrated sulphuric acid
should be accidentally spilled, it should be immediately washed with a
liberal quantity of water or of a solution of a mild alkali.
Finally, the student should familiarise himself with the contents of
the Section in the Appendix upon Laboratory Accidents, with the position
of the fire extinguisher, buckets of sand, first aid cabinet, and the fireproof blancket

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