I
K. D. ROETTGER’ E. 1. du Pont de Nemours & Co., Inc., Wilmington, Del.
A Laboratory Safety Program for Hazardous Catalysts and Catalyst Initiators A real contribution to safety in laboratories where large amounts of peroxides and hazardous chemicals are used in research
PEROXIDES
and other hazardous chemicals are being used in industrial and research applications in increasingly larger amounts. Despite their acknowledged usefulness as catalysts and catalyst initiators they carry with them in various degrees the dangers of fires and explosions. Explosions have occurred in the use of diethyl peroxide, peracetic acid, tertiary butyl peracetate, and many others. The literature records many calamitous events in the use of these chemicals. This peril was brought into sharp focus by the tragic explosion due to peroxides at Tonawanda, N. Y., in 1953, where 10 persons died and many more were injured (7). Because virtually all organic peroxides as well as many other organic catalysts-e.g., azonitriles, metalo-organics-are prone to dangerous activity, treatment of the entire field is made without possible exceptions. I t is beyond the scope of this article to give specific data on individual compounds for this information is given in previous publications (2-72). These materials were studied to consider all the issues concerned with lessening the hazards involved in employing them. An industrial program was applied to an industrial research laboratory for 4 years with success and with no accidents. As a result of this experience the program has been modified for efficient operation. I t consists of a specific plan for storage, ordering, distribution, disposal, intelligence, and testing. In its present form the initial bugs have been eliminated and its operation can be routine requiring a minimum of time to achieve a maximum of safety. This plan may be adapted to most laboratories, large or small, where handling hazardous chemicals is a problem. Organization The program was originally operated by a group who divided the tasks, so that each man devoted only a few hours a week to these activities. This committee consisted of a supervisor, who as chairman handled the administrative Present address, Worcester PoIytechnic Institute, Worcester, Mass.
duties; a second supervisor, who acted as advisor and handled liaison with other groups; a chemist, who actually handled the compounds and related work; and a trained technician, who assisted the chemist. The committee held quarterly meetings to discuss the previous three months’ experience and change operations as needed. I n addition, specific problems were discussed a t special meetings. Yearly reports were issued which tabulated the services and projects of the previous period. All of the committee worked an average of about 10 man-hours per week in the initial setting-up stage. However, it is possible to streamline operations and reduce this time expended. In a large laboratory, one supervisor can handle the administrative duties as well as liaison work. General meetings could be reduced to two times a year as most business can be settled on an informal basis. In a small laboratory, the committee could be reduced to two or even one man with a resulting reduction in time expended. Storage
The most basic and important need in a hazardous chemical program is to provide safe and convenient storage. Previous to a definite program, peroxides and similar compounds are usually kept in the laboratories where related work is done. This has a number of disadvantages. Many are not stored in refrigerators. Most of those chemicals that are kept cool are in ordinary refrigerators which are not spark protected and which have no alarm systems. Because of changes. many become orphans of the laboratory with no one assuming responsibility for their ownership. In addition, the tremendous duplication with its dangers of large stocks, the dangers of previous contamination, as well as the impossibility of a current inventory all make individual storage an impractical plan. T o improve this situation, four types of storage areas are established to meet all needs. The bulk storage area is specifically designated for the use by the committee only. Bulk supplies of
initiators and catalysts are kept here. The general areas are used by individual chemists. In these areas. small stocks of the most used compounds are kept in I-gram quantities plus any other stocks in current use and individual storage as needed. Permission must be obtained from the committee before a chemist can use space in this area. Besides these two areas, experimental storage space is arranged for storage of experimental hazardous materials and special storage space for specific situations. Peroxides or related compounds remain in a laboratory only during regular working hours or when being used. An initiator must be returned to the proper storage area when not actively being used. I n a small laboratory the areas may be reduced to two. The bulk area and general use area can be combined if the bulk storage is under 1 pound. The special and experimental areas may also be combined if sufficient space is available for the conditions outlined. Refrigerators were necessary for the bulk and general use storage areas. Unfortunately. no commercially available refrigerator satisfies the strict safety requirements, so special refrigerators must be ordered. The refrigerators originally ordered are made of stainless steel with a storage capacity of 5 cubic feet. They maintain a temperature of 5’ C. 1 2 ’ . Periodic temperature checks have indicated no variation greater than the stated 1 2 ’ in 3 years of operation. The coils are in the walls of the refrigerator to maintain this even temperature and also to isolate them from the storage compartments. The top storage compartment is completely isolated from the mechanical compartment. No wiring or parts are located in the storage area. This eliminates the possibility of an accidental spark. A drainage system from the storage compartment eliminates dangers from build-up of accidental spillage as well as creating a pressure vent. There is a positive latch on the front door of the storage compartment and a special “blow-out” back which would tend to vent an explosion to the rear. VOL. 49, NO. 10
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The cannister, detonator, peroxide, and cannister cover used in testing the cannister as a suitable peroxide carrier
The alarm system is as foolproof as possible. A thermostatic alarm goes off whenever the temperature rises above IOo C. within the storage compartment. Both audio (a horn which can be heard 1000 feet away) and visual (a blinking spotlight aimed at the refrigerator) alarms ensure adequate warning of any refrigerator trouble. Storage batteries eliminate power failure worries and a weekly check ensures against a defective alarm. Signs on the door of the refrigerator indicate what to do when the alarm goes off. The person who first is aware of the alarm calls a member of the committee who gives directions on what to do until he can get there and arrange other storage while the trouble is being rectified. Both business and home telephone numbers of committee members appear on the signs. If a 24-hour guard schedule is maintained at the plant or laboratory, someone will hear the alarm a t all times. In case no committee member can be reached, directions are given for “dry-icing” the refrigerator until the committee member arrives. The refrigerators are located in lightly traveled areas which are convenient to laboratories. Signs on them indicate the type of storage area. Bulk storage refrigerators contain large shelf space for the bulk supplies and are available only to the committee. General use refrigerators contain wire racks to hold 1-gram quantities of the currently used initiators as well as assigned storage shelves for specific projects. This type of refrigerator is open
to any qualified technical personnel to remove small amounts (1 to 3 grams) of the currently used initiators as needed or to store specific stocks. However, the storage must be approved by the committee. The third type of storage area available is for experimental materials which might be hazardous. Because of the possibility of extreme sensitivity, these materials are given individual attention. All experimental materials should be stored in a special barricaded and isolated area. Under no circumstances are unknown or experimental materials stored in the regular refrigerators. These areas should be well marked, fenced, and be not only away from other structures but also away from each other, Tests have indicated that a distance of 100 yards is adequate for storage of under 1 pound. If cold is needed, dry ice may be used. Ideal for this storage are small pits in the ground containing weatherproofed stainless steel storage boxes. The pits are larger than the box to permit dry-icing and a sunshade should be placed over the pit to provide weather protection. A fourth type of storage for special situations cannot be described as it would depend on the specific need. For example, a material requiring very cold storage would require a special dry-ice box. A material which has a high melting point and is very sensitive as a solid requires a higher constant temperature storage area than the refrigerators. Therefore, the committee should be prepared to cope with such situations. Inventories of these storage areas should be taken on a biweekly basis to eliminate unnecessary storage, aged or contaminated samples, and improper storage. This also enables the committee to keep the refrigerators properly stocked for future needs.
Ordering Closely allied to the problems of storage are those of ordering initiators. Unless this function is centralized, duplication, wasted effort, and aged samples usually result.
Results of peroxide carrier tests left.
Carrier was blown apart b y 15 grams o f tertiary butyl peracetate.
Fragments scattered aver
100 feet a w a y Right. Carrier was b a d l y fragmented b y 100 grams o f tertiary butyl peracetate. scattered over 300 feet away
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INDUSTRIAL AND ENGINEERING CHEMISTRY
Fragments were
The entire task of securing initiators is given to the chemist member of the committee. All requests are transmitted directly to him and if necessary he places the order with an appropriate vendor. Because he has a current inventory, needless duplication and subsequent hazards of large amounts can be prevented. Through previous contact and committee information, he knows most of the commercial and experimental sources of initiators. In addition, since he has ordered the stocks himself and has the orders on file he knows the age of all parts of his inventory and so can destroy samples which have become old and so are a potential danger. A special file is maintained to assist the chemist in ordering. All available catalogs, sales lists, trade literature, and references are kept here as well as an index of data cards with the source or reference for any initiator on which information is available. Another file contains carbons of all orders SO that figures on consumption and age can be conveniently calculated. A file of back inventories completes the necessary information for ordering. Distribution A necessary companion to storage and ordering is distribution. As the hazards in transporting large amounts of sensitive initiators are obvious this task has been restricted to the committee. Any initiator lots of over 10 grams are handled by the chemist or technician who observes these special safety precautions :
1. No vehicles are used 2. No elevators are used. 3. Jostling, running, or any bumpy motion is avoided. 4. Areas where flames, sparks, heat, vapors, vibrations, or other disturbances occur are by-parsed. 5. The sample is kept cold. 6. A special cloth carrier is employed---the result of the committee’s experimentation. At first, it was thought a heavy metal canister with perforations in one side would shield the transporter from the effects of any explosion when it was carried with the hole side away from the body. Carriers employing this design were fabricated from heavy aluminum and tested. I t was found that as little as 15 grams of some peroxides completely ruptured the carrier and 100 grams caused the carrier to break apart with many fragments traveling over 300 feet. Thus, the carriers proved to be makeshift grenades which would not only injure the person carrying it, but also an)-one within a radius of hundreds of feet. Other rigid containers tested gave the same results. At that point, cloth carriers were
SAFETY adopted. A double-walled construction permits the use of coolants such as dry ice and interior pockets hold bottles upright. A shoulder strap safeguards the bag against dropping. Three major types of transportation service are given by the committee. When an ordered shipment of initiator supplies arrives, a member of the committee immediately transports the shipment to the proper storage area. A second type of transportation supplied is from the storage area to the laboratory or semiworks where a large amount (over 10 grams) of initiator is desired. The third type is the most dangerous and therefore the most strict precautions are observed. This is the removal of aged or contaminated samples to the disposal area. By using the previously stated rules hundreds of pounds of initiators have been successfully transported without incident. Disposal After a few months of operation the committee observed that disposal of aged, contaminated, and surplus stocks was a major problem. Unlike most waste they could not be thrown directly into the incinerator, and the variety and amounts of compounds encountered prevented the use of a general chemical method such as a sodium hydroxide solution for most peroxides. The original method involved shooting at the samples with a rifle and igniting the resultant with a previously laid solvent trail. After some experimentation and consultation with explosive disposal experts it was found that remote control burning was the safest disposal method. An isolated revetment proved ideal for this method. The uncapped bottles are placed on a metal mesh resting on a heavy tray containing inflammable solvent. After the personnel have retired to a safe area, one hundred yards from the side of the revetment, the solvent is ignited by an electrical spark device. Testing has proved this method to be safe. Intelligence The actual handling of hazardous compounds as outlined can contribute much to a safety record but this information can be of equal value. The committee can serve as a clearing house for any matters relating to hazardous chemicals. A large file maintained by the committee chemist containing information on safety, handling, physical properties, chemical properties, syntheses, reactions, and references concerning hazardous chemicals is the tool. If a question cannot be answered by the data in the file, the chemist can
IN CHEMICAL I N D U S T R Y
refer the inquiries to an expert on the subject or call a meeting of the committee to solve the problem. I t is possible that serious accidents can be prevented by a 5-minute telephone conversation. The essential data for each compound are listed on file cards as it is available. The present data cards provide space for the name, structure, source, availability, cost, activity, useful temperature range, half-life, activators, form, melting point, boiling point, solubility, specific gravity, index of refraction, stability, shock sensitivity, safety notes, patent situation, and references. Classifications, other than data within the file system, include safety devices, testing procedure, accident reports, catalogs, orders, special projects, decomposition rate studies, and committee business. In addition, a 30-minute lecture and demonstration on safe handling of hazardous chemicals can be given by the committee before group safety meetings. This talk alerts the personnel to the potential hazards and the means to avoid them. Other intelligence services of the committee include the publication of general safety rules for handling initiators as follows:
1. Consult the committee before starting work. 2. Reactions involving hazardous materials should be attended at all times. 3. Handle all initiators in restricted quantities; the characteristics of the materials determining the actual amount. 4. Treat each new reaction involving an explosive material as a separate case. 5. Avoid friction. above all-no grinding. 6 . Avoid contamination of all kinds, Darticularlv organic materials such as imines a i d trinsition metals such as iron. 7 . Avoid unprotected glass containers and screw ca s (a pressure buildup can be dangerousy. 8. Keep all materials cool, but avoid freezing. 9. If possible, always handle in dilute solution. IO. Use a nonflammable liquid bath, preferably water, for the distillation of sensitive compounds. Avoid heating mantles. 11. Always place containers on a uniform support, preferably in a rack. 12. A very obvious and distinguishing label should be used. 13. Use safety devices such as shields, tongs, and glasses. 14. Distance means safety as the explosive power varies as the inverse third power of distance. Testing of Experimental Materials
Although the committee does no actual testing of experimental com-
pounds it can be prepared to advise and assist in such a program. The plan which is advocated is to make only that amount which is necessary for each step of the testing. The first test recommended is a temperature gradient bar test on very small amounts (a few milligrams) of the material From this test a rough classification of relatively safe, intermediate, potentially hazardous, or dangerous can be assigned. On the basis of this knowledge the more quantitative tests, thermostability, ballistic mortar, and impact, can be planned if the materials are not classed as dangerous. These advanced tests should only be undertaken by experienced personnel and their results should enable the chemist to classify properly the new compound. Until the material is completely classified it is not stored with other compounds but the rules given for experimental chemicals are followed. Acknowledgment
Appreciation for help in setting up and testing this program is given to Nolan Boyer, Carlton A. Sperati, Robert Wheatcroft, and Bruce F. Day of the Polychemicals Research Division, E. I. du Pont de Nemours & Co.. Inc. literature Cited
(1) Chem. Eng. News 31,4098 (1953). riegee, R Fortschr. chem. Forsch. 1, (2) 508 (1956)). (3) Criegee, R., “Herstellung und Umwanglung von Peroxyden,” in “Methoden der ornanischen Chemie.” (Houben-Weylyeditor), 4th ed., vol. VIII, Thieme, Stuttgart, 1952. (4) Eggersgluss, W., “Organische Peroxyde,” Verlag Chemie, Weinheim,
-,--.
1951
(5) Frank, C. E., Chem. Revs. 46, 155 (1950). ( 6 ) Hawkins, E. G. E., Quart. Revs. (London) 4, 251 (1950). ( 7 ) Leffler, J. E., Chem. Revs. 45, 385 (1 949 ’i. (8) Milas, N. A., in “Encyclopedia of Chemical Technology” (R. E.
(9)
(10) (11) (12)
Kirk and D. Othmer, editors) vol. X, Interscience, New YorkLondon, 1953. Rieche, A., “Alkyl Peroxyde und Ozonide,” Steinkopff, Dresden, 1931. Swern, D., Chem. Revs. 45, 1 (1949). Swern, D., Scanlon, J. T., Knight, H. B., J . Am. Oil Chemists’ Soc. 25, 193 (1948). Tobolsky, A. V., Mesrabian, R. B., “Organic Peroxides,” Interscience, New York, 1954. RECEIVED for review April 7, 1957 ACCEPTED July 9, 1957
Division of Industrial and Engineering Chemistry, Symposium on Safety in the Chemical Industry, 131st Meeting, ACS, Miami, Fla., April 1957. VOL. 49, NO. 10
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