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THE PRACTICE OF SAFETY IN THE CHEMICAL ENGINEERING LABORATORY R. I.HUNTINGTON University of Oklahoma, Norman, Oklahoma
THE
(*IIEUIC.L J~:NGIICI.LI~IS(:staff ar the t'ni~wsity oi Oklahoma has long n!comized rhr ilnlxxtnnce of nccident prevention in-the operation of its laboratories. All of its staff members to date have had previous training in those branches of industry where the principles of safety in operation and construction have been placed in the forefront. Before our students enter the knit operations laboratory or undertake research which calls for experimental work, they are given instruction in the basic principles of safety and are also informed of the common hazards which may be avoided in the lahoratory. The purpose of this paper is to point out some of the salient points which are covered in our safety lecture and in the laboratory rules which are distributed on mimeographed sheets. The staff realizes that a complete course in safety would require far more time than the short man of a few lectures: nevertheless, the results of these brief instruction periods show that our students have become conscious of the value of safe operating and construction techniques. Elements of Safety. Accidents are not a normal oressential part of engineering operations; therefore they can be prevented. By knowing the major causes of accidents, one can readily tackle and eliminate this unnecessary enemy which takes such a heavy toll of life and limb in this modern machine age. These major causes may be classified as follows: (1) Lack of elementary instruction in the proper methods of handling tools and operating machinery and plant equipment. (2) Physical unfitness for the job, such as poor eyesight, a weak back, or an injured member of the body. (3) Overzealous ambition to do more than a normal man should do, such as the lifting of excessive loads or climbing to heights without proper safety equipment. (4) Improper mental attitude of the employee or student toward the job a t hand as a result of such things as lack of sleep, sickness, or domestic troubles. (5) Natural awkwardness of the worker himself which marks him as a chronic accident repeater; however, causes 1 to 4 inclusive may contribute indirectly toward so-called awkwardness. (6) Lack of mechanical safeguards around machinery. This cause is one which can readily he eliminated by strictly following standard codes. Causes 1 to 5, inclusive, can result in accidents no matter how well all machinery and tools are maintained or protected by safeguards. The Student's Part. In the safety lecture, emphasis is placed on the value of safety practice, not so much for
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New Ensineerins Building a t the University of
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the benefit of the school as for the individual returns each student can expect through his cooperation in the program, such as freedom from suffering or loss of time which would result from accidents. Each student is requested to act as a committee of one to promote safety in the laboratory and to offer suggestions to the staff should he see how any present hazards may be eliminated. In this way the student becomes a part of the safety force. At the same time we make it clear to the student that no accident, however minor it may seem to be, should go unreported, as the staff is to be the judge of the treatment which is to be given. In case of any douht, or if the student expresses a desire for medical attention, the staff member always sends the student to the University hospital or infirmary. Importance of Proper Clothing. .Although machinery is supposed to have ample guards to protect its operators the students are required to wear work clothes which industry approves for its plant operators. Girls are requested to wear coveralls and the men to leave any loose apparel such as neckties in the dressing room. Moving parts of machincry are never to be touched nnless it is an essential part of the operation and then never with a loose rag. Handling of Tools. A lecture of one hour is given covering the topic. For example, this student is shown howto fit a pipe wrench onto a fitting so that the wrench will not slip. At the same time he is told never to depend upon a wrench to hold him secure when he is working on an elevated platform. Whenever the jaws
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of a wrench become worn they should be replaced by new ones. Each pipe size requires a wrench of a certain size, otherwise the fitting may bc ruined by too much power if the wrench is too large, or it will leak if too small. The use of a piece of pipe to augment the leverage of a small wrench is considered to be bad practice. Such techniques as the cutting of pipe by hack-saw or pipe cutter, the threading of pipe, the cleaning of pipe threads, the use of pipe and bolt taps, and the breaking apart of old fittings from pipe nipples are shown to the class as a group. Design of Pressure Vessels and Piping. The undergraduate student is seldom required to design or operate any equipment which calls for high pressure or high temperatures. He is given the advice to allow for an ample safety margin when he is faced with such a prohlem and if possible to obtain the counsel of an experienced engineer. Under all conditions the pressure vessel must first be tested hydrostatically with water up to a t least twice its normal working pressure, provided the operating temperature is substantially the same as the water test. All pressure vessels must be equipped with some kind of relief valve or safety head to take care of unexpectedly high pressures. All fittings such as valves, ells, unions, etc., must conform to the same pressure and temperature specifications as the vessel to which they are connected. Such references as the A.S.M.E. Boiler and Uniired Pressure Vessel Codes are given as guides for design work. Exwlosiue Mixtures. Smokine should be nrohibited in all chemical engineering laboratories. This rule may sound harsh for the inveterate smoker who will argue that welding is done in the laboratory and that flames are used for certain experiments. He forgets, however, that the staff has control over the use of welding torches and other flames but without a "No Smoking" rule a match may be struck by someone, such as a visitor, at the time an explosive mixture may be present. Strike-easy matches should not be taken into any laboratory, for they might accidentally fall on the floor. Before cutting into any vessel with a torch or chisel, it should be steamed out thoroughly. If any organic material is left in the vessel at the end of the steaming period, a small stream of steam should be passed through the vessel when it is pierced by flame or chisel. No matter what an empty vessel may have contained, steaming is always mandatory. For example, acid will cause hydrogen to be released in an iron drum. If it is necessary for one to enter a vessel, such as a boiler, it should be completely isolated and disconnected from the surroundings. Never enter a vessel unless someone is on the outside who can pull you out in case you are overcome by fumes or by heat. If air must be supplied from the outside, it is much better to use a blower than)to pull air into one's hmgs through tubing. Never strike a match in a room which has been closed for a long time unless it is checked by a Bureau of Mines Explosive Mixture Tester. Never depend upon one's senses to detect an explosive mixture, but should one smell any unusual odor
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all flames should be extinguished until the danger is over. Finely divided dust such as flour, aluminum dust, etc., can form a highly explosive mixture. Generalities. (1) Sight is probably man's most valuable sense. Goggles should be worn when any grinding, chipping, or welding is done. (2) If height causes dizziness one should not be required to work at an elevation. (3) Whenever a worker is located above you, try to keep on guard for all falling objects. (4) Never set off false alarms or be prankish while in the laboratory. Your fellow worker may not take you seriously when you really need help. (5) If working in a confined space make sure that available exits are marked and no obstructions are between you and the exits. (6) In fighting an electrical fire never use a liquid which conducts electricity. Carbon tetrachloride is a nonconductor of electricity but it generates phosgene when it comes into contact with a flame. The Use of Chemzcals. The Alpha Chi Sigma fraternity published a set of rules several years ago which cover very completely the safe operation of any chemical laboratory. They are included in this paper since the chemical engineer must necessarily he familiar with the "test tube" as well as the operation of the "pilot plant." LABORATORY SAFETY RULES
1. Use all chemical laboratory equipment and chemicals only according to laboratory procedure and instructions. 2. Keep all inflammable liquids or gases away from open flares, open electrical equipment and other sources of ignition. 3. Avoid breathing gases or vapors of all kinds, especially benzene, carbon tetrachloride, nitric acid, bromine, chlorine or hydrogen sulfide. Work under a hood. 4. Use goggles or a face shield when handling strong acids and bases where there is danger of splashing. If splashed use water freely and then rinse the skin with a ten per cent ammonium chloride solution. For the eyes a one per cent ammonium chloride solution should be used. If preferred use boric acid with alkalies and borax solution with acids. 5. Protect your hands with a towel or gloves when fitting glass tubing into rubber stoppers. 6. Always use a suction bulb or a safety pipette when pipetting a strong or poisonous substance. 7. Point the mouths of bottles, flasks, cylinders or test tubes and other vessels away from yourself and others when shaking or heating substances which might splash, spill, or explode. 8. All chemicals should be placed in clearly marked containers with the strength - of solutions designated. 9. Practice good housekeeping. Clean all spills a t
MARCH, 1948
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once but be careful when using inflammable solvents. Know the location and use of all emergency; protective, and fire fighting equipment. Examine all glass apparatus for cracks before using it. Do not use cracked or checked equipment. Fire-polish all chipped or newly cut glass tubing. Avoid direct blasts of air on the s k i from compressed air lines. Never play with air hoses. Never use a beaker for a drinking glass and avoid eating in the laboratory. Eat at some .designated place away from the laboratory. When pouring hot liquids place the receiver on a firm base; do not hold it in your hand.
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15. Avoid smelling deeply of any substances. Cup the hand and wave the gas or vapor toward the nose.
It is hoped that the small fraction of the semester which is devoted to safety in our chemical engineering laboratories will continue to produce worthwhile results in minimizing accidents, and in developing future engineers who will carry the thought of safe operation into industrial practice. In the construction of the new engineering building a t the University of Oklahoma, the chemical engineering staff has tried to incorporate as many features as possible for the promotion of safety in the well-equipped laboratories.
