1 in the Chemical Laboratory I Edited by NORMAN V. STEERE, School of Public Health, University of Minnesota, Minneapolis, Minn., 55455
"
'
a
I I
feature
XXXVI. Fire and Explosion Problems in Laboratories and Pilot Plants* MATHEWM. BRAIDECH, Research Consultant, Dept. of Engineering ondSofety, American Insurance Associotion, 85 john St., New York, N. Y. 10038
When one considers the wide array of vsriuua types of institutional and industrial lnborabories snd the inweasing numbers in our growing technology, the fire and explosion experience in general has been most favorable. Despite the occasiounl instances of accident,^ involving loss of life and extensive property damage, the coutinrred maintenance of a goad record warrants a frequent review of the essential aspects of this phase of safety because of the poteot,ial of large-seek damage associated with fires and explosions. S d e t y information can bear a degree of repetition because most of our current attitudes and approaches to the problems have beeu born of past and toosoon-forgotten experiences. The experience must be carried over to college graduates and those entering the services of laboratories. This applies particularly to the growing chemical-consumer industries and other allied fields of laboratory and engineering service. We must also regard our research and laboratory talents as invaluable assets of our national well-being. I n this particular era, such human values are irreplaceable. The safeguarding steps that may be required to protect the equipment and records representing many costly hours of effort and heavy investments should be regarded as a normal part of any scientific activity. Because of the eommonnlaee nresence and usage of flammable liquids, compressed gases, combustible solids, unstable and energetic chemicals, fire and explosion hazards exist as persistent potentials in varying degrees in nearly all chemical and chemical engineering laboratories, and pilot plant,^. The severity of such hazards is governed by t,he scale of the experiment and the environmentd conditions of temperature, pressure, and catalysts, as well ns the physical construction of the equipment and the adjoining exposures. Records show that most of the fires involving the housing structure of laboratories usually result from ordinary hazards and t,hrongh common causes, while m i s haps with operations involving special hazards consistently rise from the misuse
* Presented a t the Fortieth National Safety Congress of the National Safety Council, Chicago, Ill. c Circle No. 121 01
R e l d ~ s 'Service Card
or improper combination of materials, incomplete cont,~mls,and ofterr faulty techniques. In the latter respect, the man factor is just as predominant in the more technical circles as it is in ordinary indastrial exposures. Deficiencies in training, skills, and background (emo~ional makeup) among laboratory workers and pilot plant operat,ors have, on occasions, contribnted their share of a& of h r ~ m a ~ ~ failure. These have generally appeared in the form of simple carelessness, incomplete information, lack of proper provision in design, process operation and control, inattentiveness and even inadequate instruction to subordinate technical aids. A prior consideration of such trouble sources is certainly in keeping wilh good technical practice and responsible Inboratory management. The prime object of any organized safety program is to stimulate an awareness for hazards and to oonvince the persons concerned that precautions are necessary and that they should he observed. A usual course of action involves the presentation of s. series of case histories which exemplify the various dangers that oan be encountered in different laboratory and pilot plant operrttions. The presentation of realistic ease histories should be followed with an outlined procedure for instituting organized safety effnrt and for promoting the formulation of a suitable and workahle safety code on a day-to-day basis. To aid in the first step, the following selected instances of laboratory fires and explosions are presented:
Shortly after 1945, a one-story university building (built as a barracks in about 1915) wss leveled to the ground in an hour after a. fire broke out; the building consisted of an excessively large undivided area subject to loss by one fire, housing chemical engineering and metallurgical laboratories. The valuable laboratory apparatus housed in this substandard structure accounted for most of the $500,000 loss. Lack of proper watchman senrice and insufficient water (low pressure due to high altitude location) were material fsetom in this unfortunate experience.
Mathew M. Braidech as 1.ererrtly appointrd I{e.;en~.rll ( h t s ~ d l s n tafter being ilirerlor of l'whnical Services in the I k p a r l m e ~ ~ui t , Engineering and Safety, American Insurance Associa, tion. He was formerly (194j-65) Resbwtrch Direcbor, Fire Prevention and Engineering Sbandards Depare ment of the Xnbiond Board of Fire Underwriters, New Vork. He is a native of Cleveland, Ohio, and a, gvsdnsie of The Ohio State University in chemical engineering with a B.Ch.E. ( ' 2 5 ) and Ch.E. ('31). He is a member of the society of Sigma XI, and a Fellow of the American Instit,ute uf Chemists. From 1936 to 194.5 he was Professor of Indmtrial and Sanitary Chemistry, Case Instit,nIe of Technology. He has been a special investigator in many fire and explosion disasters inch~ding the Cleveland Clinic Nitrocellulose Film Fire ('27), East Ohio Gas Disaster ('44), Texas Ciby D i s aster ('47), Holland Tunnel Chemical Fire ('49), the South Amboy Port Explosion ('49), General Motors (Livanis), Hydramatie Plant Fire ('531, and technical consultant on various safety boards and committees. JIe represents ACS on NFPA Committee on Chemical and Explosives and the AIChE on t,he Safety Standards Board of the new USA Standards Institute, and is Chairman of the Committee on Atomic Industry Facility Design and Operating Criteria of the USASI Nuclear Standards Board.
Following a latehonr experimental run, operators of a cyclotron unit failed to shut off a power switch of the magnet
Volume 44, Number 4, April 1967
/
A31 9
Safety
. ..
system, whirh ill turn caused the overheat,ing and "thermal rrackingnof the cooling oil, aud eventnally resulted in n canfined but smoky fi1.e. Lack of proper fire protectim equipmeut and emergency prefire planning with the local fire department resulted in a delay of several hours before the situatiou was brought r d e r control. The cyclc,lt.on was direcl,ly damaged by fire and the incidental smoke f m m the oil, and the electrical insulation extended additional damage t o other delicate electronic equipment and the general contents of the building-the mmetary loss was in excess of S:300,011(1. -111Approximately 200 K g of sudinm rlrlorate, stored in a hasement v s d t far more than 20 years, were being removed fa]. disposal when an explosion oerwred t h a t killed four employees. Furl,unxlely, this was beitlg done bet.ween aemestera wheu few student,^ were ~ r a n o dor the toll w\.ould have txen much higher. The ohemical was s t o d in 453 g one-poimd paper cert,ons, eighteen of which were packaged iu a larger outside metal container. I~loe to corrosion, a number of bhese met,al rom bainers were replaced by wooden boxes. From acarnmts available, the stored material had been located directly nnder water service pipes, suspended below n concrete ceiling, and i t was believed t.hnt condensation of atmospheric moist.nre dripped thel.efmm outo t,he rhlomte cartons. Preatmahly, the containers became impregnated n i t h the rhemiesl (no lids were fi1,ted ou n m ~ m b e rof these), causing n gritdual oxidat.ion of the cellulosic mat,erial t,o a chemically active slate d u r ing t,he prolonged conbact, requiring only a moderate degree of friction to initiale r m bustion and violent chemioal rearlion. The handling or dropping of the parkaees on the truck could have provided the necessary frictinu ellect. Chlorinaus odors not,ed around this stock of mater i d caused some concern in the past and led t o this safety cleanup and disposal program-fortnnatly, between semesters. About five polrnds of T N T were located a t the ather end of the basement in all "explosion-proof" storage room, but i t a n s not sKeeted by the low-order explosion.
-NAn explosion, due to escaping solvent vapors from piloksized reaction kettle, occurred when a fluorescent light above the equipment was accidentally broken ill a hurried at,tempt to close a valve. Unsuitable gasket materid was responsible for the leak and the use of unapproved electried fixt,ures in such hazardous locations was an equally serious violation. This near-serious incident disrupted another important project in the adjacent area, which was in t,he advance stages of commercial development.
-vA baffling explosion of a Pam calorim-
A320
/
Journal of Chemical Education
Safety
...
eter bomb was f o m d lo have resulted from erroneous proportiming of t,he react,ing components--coal sample, perchlorate accelerator, and sodium peroxide. The mixture called for 0.5 g of cod, 1.0 g of potassium chlomte, and 10 gm of the peroxide. The quantities of the chlorate and peroxide weve reversed by a strident, when he recalled "t,aking the hig quantity from the big coot,ainw" containing the perchlorate, when he had hrrrr,wed from the stock room whw the shelf bottle was fonnd empt,y. A somewhat similar nearmiss occurred when .r. student found t,hat, his bomb would not fit ahe nwembly vise became the bomh "expanded" in diameter after being fired. Investigation disclosed that the stndeut, used 5 g of sample inst,ead of 0.5 g, l ~ i n misled g by the lack of a zero figure in front of the decimal point, in the notes borrowed from his laboratory neighbor. These are typical examples of inattentiveness and xn i n d i c a h n of the importance of close supervision in even simple hut, hazardous experiments.
-VISafety co~tsiderations required a pilol, plant opeixikm to be condueled outdoors. On the day of the firs1 experiment a n explosion occurred, killing one of t,he engineers and injuring five others. A safety supenrisor and ihe plant fire chief were present. a t t,he t,ime. report,^ st.aied that, the charging of a mint,,tre containing sodium hydride into the equipment caused the formation of hydroge!l, due to ( h e unsuspected preselcce of mnistwe within the steel structure, later traced to a1,mospherir condensation believed to have occnrred during the previous night. period. Preliminary pnrging with CO9 (which was at, hand for fire protection) ns a preca~rt.ionnry m e w r e was overlooked.
-VIII n a sulfonatiou process involvin~fuming s~llfuricaeid and henad, 11nnotir:ed stoppnge of the agitator permitt,ed the compleie transfereuee of i,he charge ilcirl s water-jacketed reari.ion ket,tle withoult mixing. A not-t~,u-r~verly-ca~ltioll!s ope? ator hurriedly reset, the averload relay and proceeded to mix t,he t,wdayered charge. When the rapidly relensed heat of renctim exceeded the coolirrg capacity of the unit, it caused the um.eaet,ed herrsal to he quickly vaporized in vnlumes heyond the capacity of t,he pIast,ie vent tube. The tnhe ruptured and released the flammable vapors inlo the silrrmmding room p m viding a mixture which explcded on cont,act with x remote sonree of ignition. The original ttmble resulted from a "freehg" of the agit,ator drivo shaft,-eansed by the aeid ftlmes which atbacked and swelled the packing-gland material. The roof of the bniildiog wns blown; forlnnat,ely, no loss of life was enoountered.
-VIIILsck of regard for the spark hazard in drying ovens and refrigerators and the limitation of electrical controls in constant temperature baths have caused w i d e spread trouble in laboratories. The use
(Continxed on page A S B )
Safety
...
of conventional household eleet,rie refrigerators for storage of volatile and flammable liquids has resulted in a number of disastrous explosions. Thermostatic controls in unattended oil haths have been known to fail and cause the ail to be overheated and ignited, with the conseqnence of serious fires. These experiences have caused the Underwriters' Laboratories to prepare recommenda?ions that the control mechanism, light switch, and lamp holder he removed from the refrigerator interior intended for such use. Independent excesstemperature cutouts should be installed in connection with electrically heated hot-baths. Organo-siliron floids having remarkable heat stability a t t,heir boiling points (370440°C) have been developed in recent years, and shoold find preferred use in high-temperature baths. All electrical equipment should be explosion-proof, and adequate ventilation should he provided around such haths and refrigerators to assist in lessening any explosion hazard.
-1xFailure to recognize an important follow-up in a safety provision resulted in a most serious life lass and the dest.ruetion of a semi-scale works. A pressure reactor vessel was protected by a rupture disc or a pressure relief diaphragm. For some reason, the usual vent pipe connecting the ruptnre disc to the ouMoors was omitted. When the disc "blew" in an emergency, the flammahle vapor and contents v.ere discharged into the surrounding area. A source of ignition located a t a remote point some hundreds of feet away, red ported to he beyond a fire wall, c a ~ ~ s ethe explosion to take place. Had the venting been properly reeannecled, this sad experience would have been avoided.
-xThe oxygen-oil hazard warrants making reference to a laboratory explosion of some years ago, which resulted in two deaths and injured 11 persons. Experiments with ultra-low temperature conditions required a plentiful source of liquefied nitrogen. The leboratory was provided with an air-liquefaction unit, and to defray expenses of operation, the by-product oxygen was salvaged and sold to a number of consumer;. Although a carefd (but incomplete) check and inspection were made of the cylinder containers delivered for filling, failure to realize that an empty and completely purged cylinder, previously containing hydrogen, might have its interior surface oontaminnted with a film of oil, and through "pressure effects" (diesel heating), led to this mishap. I n practice, oxygen is compressed with water lubrication, while hydrogen compressors are oil lubriceted. Another more recent explcsion of a, somewhat similar nature killed twomenandinjured another, whena hydrcgen receiver accidentally contained a mixture of air and hydrogen, instead of pure hydrogen. The suspected cause of igni-
(Continued on page ASS44)
A322
/
Journal of Chemical Educofion
Safety
...
tion was the heat gewrat,ed in n pressure regdabor, pl.es,mnbly eont,arninnted with oil or another "ft~cl" material arcelel.at,ing the temperaburc risc. IIandling Rnmmahle gases or oxygnr linder pressure warrants exercise of considerahlo caution against chance cnntamilintion and iniriation of emnhnsbin~rh y presswe swges or "dieselisat,ion."
-XIT o rontnd "b~tmping" of boiling aulrrtians or violent ehdlitinn, a chemist e m ploycd small g?anules of carborondorn "to rip the heatinsulating film from the surface of the Hark," during a prolonged digestion period. After ~.epealed,we nf the flask on swr:essive bntrhes of nlrh preparations, the contniuer rlarked while being heated. The hot cnwtir-permangannte spilled over thc worker (warring him permanently) and rawed his assoeixte t,o bermme involved in a ierions secondary fire as the result of his vrerkinp a flammable solvent extraction apparatus. Use of glass heads, pumice, pulverized pore el nil^, or shredded s&estw for the control of "h~mping"n-ould have provided a safer practice nnd avoided this mishsp. -XIStatic .ipark pn,dtlccd hy the discharge of CO? thrmlgh n lm-r.o~d~lrt.ive (plastic) horn of n pol.t,ttblt. extinguisher was resprmsihle fat. a blml in an experimelital unit when t,he flamlllahk vapors ignited iu this adaptat,ion t,o purge and inert the system. All equipment shwdd have been p m p e ~ l y int,errouwctd m d groitnded for safety in such opn.nt,ions.
-mLack uf safety-mindelllws led n gl.nduate s b ~ ~ d r nworking t, in n uuiversity Inhoratory d w i t ~ gR late huw, 10 lose his life and swimlsly damape a rewjl.ch huildiltg. ITe exercised paor j\ldgnent i u Iuwiedly adding a renrtmt in n ret.t:iin wganie reaction (I)ieckmarin xynlherii). The experiment invdved 15 litew
