Document xz0nY7GqXD3bVwRLN1mKd9Vb6

---- s Monsanto Chemicai-sTM Plastics Ks4____ AN INDIRECT AROCLOR HEATER for UNIT CHEMICAL OPERATIONS Mwiwto Technical Bulletin No. 0-130 Octobar, lffl Chomknl Company, Organic ChamMi Btvkton, SI. LmIi 1, Ma. Aroclor* 1248 (chlorinated biphenyl) it an ideal nonflammable liquid phase beattransfer medium for temperatures up to 600 F. This bulletin contains a magaaine reprint which describes the physical properties of Aroclor 1248 and illustrates the design and operation of beaters that have been used successfully by Monsanto plants for many years. The units described an gas fired and the capacities are in the range of 200,000 to 400,000 B.t.u. per hour. Larger commercial installations using Aroclor 1248 have capacities ranging up to 2.000,000 B.t.u. per hour. Also small electrically heated stationary and portable units with capacities around 40,000 B.t.u. per hour are in service. Although the magaaine reprint contained first appeared in 1949, the basic information is still valid. Since that time Monsanto has developed a considerable amount of en gineering data on heat transfer applications of Aroclor 1248. Those interested in such information are invited to correspond with the Organic Chemicals Division of Mon santo. Monsanto does not manufacture heat-transfer equipment using Aroclor fluids. It supplies only the Aroclor 1248 needed. Several leading manufacturers of kg equipment are In a position to build or offer Aroclor heating units to meet specific requirements. |h. mltinMI** cW.lnJ in ni. BullaMn * <> <--*<< -f' ur.i. l> r.r.ii*ifi*njallion* ur *w|(**IIBn* * mnda -- IIHout fuarant**. .me. (mditlnl ol Jn H-yonri out rnntrot. I h. Stnn.nnln l h.m.c.4 Cn-aanr dialala Hafcillly inawrad l tocmaetiaf* -lh <h u.a ot tb. data at >u|..<<0n. ratatln PM.MI rnv.nnt any mataMal o> il. un. MGNS 076335 Reprinted from INDUSTRIAL AND ENGINEERING CHEMISTRY, Vol. 41, Page 1341, July 1049 Copyright 1049 by t.)te American Chemical Society and reprinted by permmion of the copyright owner An Indirect Aroclor Heater for Unit Chemical Operations MEADE McARDLE\ L. C. GARRETT, AND P. G. BENIGNUS* dMonaanto Chemical Company, Jnnbton, Ala. '|'hc charaeteriatlc* of Aroclor 1248 indicate that it Sprat Flammability. Whoa a tubs ruptures in s liquid heat- ia an ideal liquid phaae heat-exchange medium for temperature* up to 300* O. Thia article dlaeuaaca ita properties and illuatratea the design and operation of healer* that have been ueed successfully by Monsanto transfer system under high preemire, a spray or miet forme. The possible Are hazard under these oondittona requires eoniden^ tions not covered by the foregoing dieetusioDS relative to the m* terial in the liquid form. Id tbeir comprehensive study o( plant* during the pa*t aeven year*. flammability of tbe higher boiling liquids snd tbeir mists, Sulli van, Wolfe, and Zisman (3) determined the spray flammability IN CERTAIN manufacturing processes of the Monsanto limit of numerous materials in accordance with the percentage of Chemical Company, it was necessary to employ a noncoin* oxygen required for combustion. This value was then correlated liustible host-transfer medium at pressures of 30 pounds per with the results of incondiary firing testa of the fluids conducted Hquare inch or less and temperature* up to 300 * C. The following at the Naval Proving Ground, Dahlgren, Vs. The oxygen re general projwrtics of a hcat-oxchange medium were required: quirement for Aroclor 1248 combustion in the spray flammability Fremhun from fire hazards Viscosities to permit pumping at room temperatures. Roiling noint sufficiently above 300* C. to assure a liquid con dition at all limes. Htability against Iteat, with enough safety factor to ncoomino- limit studies was found to be 94%. Fluids requiring over 45 to 50% oxygen in the spray tost failed to cause a Are in the ineeodi- ary test. These results establish the nonflammable and nnocom- biistiblc qualities of Aroclor 1248. ' late accidental overheating. Controllable vaporization losses. Freedom from corrosive action against valves, piping, tank jsekuts, etc., made of cast iron and steels, bronze, and stainless steel. Freedom from toxicity hazard. VISCOSITY CONSIDERATIONS Cold Flow. For most inside installations centrifugal pumps will handle Aroclor at reduced rates without preheating. Experi ence confirms this. Outside installations have been started at Aroelvr, chlorinated biphenyl (registered in U. 9. Patent 0 C. by heating the pump and feed fine until circulation through Office), was selected, The pertinent physical characteristics rclnlivn lo its use as a lu-rU-tmuefcr medium arc given in Table I. Tarls I. Physical Propsktibb op Aroclob 1248 FRKRINIM FROM FIRR HAZARDS Flash Point. Limitations of this test for the prediction of the lire hazard of relatively nonvolatile orgaoio fluids have been recognized by the American Society for Testing Materials com* tntuce(3,4). Fta* Point is a moro significant measurement. The Under* writers' Laboratories (10) state that fire tests more truly reflect the (lack of) fire hazard of Aroclor. Ki'ontanboos Ionition Tbmfebatviuc. The combustion* resisting quslities of Arook* 1248 ore indicated by its high spon* earaoco Absolute deiwily, a./ml. Absolute vixeonty, eantiiioiae* Pro*Orally aolorlcw raobti* liquid c. c r. <!> (i3n1n3) <S7J> (SI) (140) (313) <3M) (873) Humous ignition temperature of 704 * C. (1299* F.) determined by Hullivan, Wolfe, and Zisman (3), using the oonvenient apparatus described by bortman, Beatty, and Heron (8). Distillation raoge. A.S.T.M. D-20. * C. Undor rnnditiouz of industrial uss the spontaneous ignition lemperaturo will )>e determined by factor* including the nature of the hot surface, the amount oT liquid impinging on it, the volume of anolosed space, and the ventilation. Pour point. A.S.T.M. D-7. ' An accidental failure in a heating system demonstrated the nonflammability of Aroclor 1248 ana ite freedom from the haisrd of fire propagation. An operator's failure to start the circulation of the heat*transfer medium when the gas beater was on resulted in excessive coil temperatures and caused the lower coil to eofton and sag into the Are chamber. A weld ruptured and Aroclor 1248 poured into the red-hot tire chamber in contact with the flame. Denee smoke arose from the hester but there was no external Are. After the gas flame waa cut off, the smoking stopped. 1 I'rMsst kddrnM, Monsanto ChamisaJ Company, Orzaaio Chtmieala btriiioB, 8L Louia. Mo. < Vrmst address. Mooaanto Chemical Company. Phosphate Dlvwio*, Ht. Lewie. Mo. SpooiSo voluma. ml./*. Spoelfle heat, eal./g./* C. Vapor prMauro. mro. Kg 0.70S 0 721 0 717 o.m 3M S.3IS o.oouer o.ie ii 19.0 300.0 MONS 076336 1342 INDUSTRIAL AND ENGINEERING CHEMISTRY Vel. 41, No. 7 T*atA II. Stability op Aroclor 1248 Hbatbd por 30 Hours UCl 2IS3#3 0 24E Table HI. Stability op Aroclor 1248Continuously Heated AT 280 AND 330 C. Hour* M , of 11Cl if Orm of Aroclor iltFc 330* C. 30 0 070 0 548 HO 0 lilt 0 510 HO 0 KIM 0 023 130 tl 104 I 141 150 U 201 1302 Tablb IV. Qas Analysis op Akoclor 1248 Heated 4 Horns at 280* C. and 210 Pounds per Square Inch Pressure Cm % dioxide ('rhn moaoude Oxygen (rtnvni Iron tirl Muim Mydrogta eWorld* Chlorin* Aeidtty (% by wnght HCI) Prior M rtixmira After npMura* 1 None 20 2 0 Oil? "i 0 (1073 Uis healer had been effected so (hat (lie system rould operate normally. BOILING POINT Operating experience has shown that the boiling |joint of Aro clor 1248 (340* C. al 760 mm.) is enough above the 300* C. opsretiag limit to prevent trouble from this cause. At tho maxi mum operating temperature die vnpor pressure is leas limit 0.3 atmosphere. IIEAT STABILITY III order to establish a maximum practical operating tempera ture, the stability of the materia) when heated lo elevated tom- peralurei in the pretence of iron was noted. A slow stream of nitrogen was passed over the hot Aroclor to sweep the decom position products into a ciuisUc trap. The amount of ucidic mnlorinl was determined nod calculated as hydrochloric acid. The results given in Table II indicate the sud'dity of Aroclor 1248 when individual samples were heated for 30 hours at Die given ` *mpemi ures. Tho dccom- position it wry low at temperatures op to 300* C. The stability of Arodor-1248 in contact with L iron continuously heated at 280* and 330* C. is indicated by Table IIL These test results indi cate that Aroclor 1218 in oon- taot with iron can be used satisfactorily at temperatures up to 300* C. The National Board of Fire Underwriters(10) reported that 'decomposition of the product 1Aroclor 1248 J was not appreci able at U'in|n*rnturiM Inflow MW* C., hut became incretw- iugly apparent at higher tem peratures.'' Their workers analyzed dm decomposition products <>f Aroclor 1248 heated In the pres* enea of hot Iron at 469* C. sod aim heated In an iron cylinder at 340 C. fitted with n internal gas burner so that tbs gaa flame impinged directly on the surface of the Aroctor. Analysis of the gases produced under them: conditions iodurind 0.6% carbon monoxide, 0.17% oxygen (derived (rom the air), 0 90% hydrogen chloride, 2 I % combustible gas calculated SE methane, 0.002% chlorine, and no pitnsgene The same workers studied the stability "I Aroclor when heated for 4 hours in an iron pipe ut `2U() >' under hii iuhriml pressure of 210 pounds per snuarc inch, resulting fmm the introduction of compressed air. Following tins treatment :uoi cooling, the cases removed from the system were analyzed The acidity oi tbt Aroclor was determined prior t* and after exposure lo these cobditions. The results given in Table IV reflect an extreinelv snmll amount of decomposition under conditions similar in those selected for tbB practical use of Aroclor 1218 as a heat-iransfcr medium. In actual practice using the type of he:u jug mm diMirdicd Mow there has been no evidence of hydrochloric acid effect and no ear* bon dejiouits have been noted in the healer, pipe*, nr vnivre. Tlis heaters have Irccn operated successfully with combustion gtwex at approximately 000a C. in contact with the mils At one lime, a spiral coil type of heater was built ami through faulty design a burner tunnel was located 15 inches from the 2* inch steel pipe coil. The radiation from the white-hot refractory tunnel and the direct impingement of llte flame on i he pipe t-sused the pipe to glow a dark red for a space of about 2 inches. Tbit unit was operated almost 3 months before a circulation stoppage occurred. When the line w as opened lumps of carbon were luuad to have come loose and moved forward to lodge in the glchs valves. The tumps measured about I X 2.5 cm. and one face was formed to fit the pipe curvature. No hydrochloric and effect was noted and the system was put back into operation after tbs burner location was changed. CONTROLLABLE vaporisation lorhk* The heating systems io which Aroclor I24H is u.vd are scaled except for the expansion lank, which low n loose cover or a vent pi|>c. Because this ( oik is separated from die stream by a sub stantial length of pipe, the temperature io the lank remains low. In the light of the relatively low v.ijioi prc*itrc values for Aroclor 1248 (7), and ns it is unlikely (fiat the expansion tank will ever reach even the 1-mtn. state (130* C.), there should not lot a measurable loss of Aroclor from the system. Actual experience hears out tills content ion. Other Losses. Although Aroclor darken* >>m use, its eimroctnblics i t-main the same and lepkiietuent ha* not been fouod necessary after 7 years of continuous use Accidental leaks or spill* eonsuiiuv die only oliaetved Ii>*h*>*. PLAN ANO PART SECTON 9 9 Figure 1. Ileulrr HONS 076337 air INI INDUSTRIAL AND ENGINEERING CHEMISTRY 1343 Taeui V. Resistance op Structural Materials to Arocloe 1249 CMoupi#n* I Nlsisl Zlrte Mild sle*t I'hodpliof lironi* KHioadinblfammatari Yellow bran HR. Kseirfleal rrdsUnes. lew thee 10 X 10`*m. per dsy ptMtrstiooor QU0014 ImIi p* mr. H. Oeed rsetstoner, i>enrtraUofi betwrse 1.0 X KM and 10 X KM cm. per day or betwne 0.00014 end 0.0014 ineb per year. D. Doubtful rftdstaiws. psnetretioa between 10 X ID-* cm. per day end 100 X !*. per day or between 0.0014 and 0.0>4 loch prr y#r, . Fellewlni letter Indicetine retletenea. sieniftee material may be b-tler tkan indirnted if totally immersed. a weiff.l Ion is brHered le come (tom esldelion of part of teat atrip espoeed to air. DESIGN AND CONSTRUCTION Heating System. The heating system required to utilise Aroclor 1248 as the exchange medium includes a heater (Figure 1), cooler, pump, end expensioo tenk (Figure 2), end control eod safety circuits (Figure 3). FIIKKINIM FHOM COKROHIVK ACTION The resistance t>l various metals (7) :i( 25* nnd 125s C. in given ill Table V. Similar studies made at 325* C. (0) indicate that the penetra tion, in incline per ytstr, for mild steel is 0.0028; for yellow braes, 0.00047; for coppor, 0,00145. Many yews of practical operating experience with Aroclor 1248 as a heat-transfur medium have sliuwn that the material is prac tically tHMionrrtmive to valves, piping, Lank jackets, etc., made of caul iron him! steels, hronxe, nnd alaiulf^a steel. FREEDOM FROM TOXICITY IU7ARD Aror.kw 1218 in wry stubie, uttrvnelive liquid. U lit* material la spilled on the skin, there tire no noticeable ill effects; however, It ii well to wash Utu skin with soap :uid water after contact. A skin burn (milling from accidental contact with hot Aroclor shnuhl be trusted in the normal procedure used for hot oil bums. Aroclor adhering to the burned urea need not lie removed im mediately unions treatment of tlie burn demands it; in this case oop end water or repented washings witli u vegetable oil (linseed oil) should Ihi used. Tim viqmrs emitted by Aroclor 1218 heated to elevated temprraturrw are injurimix to the liver on prolonged exposure and should not In* breathed. Drinker (J) indicated that 0.5 mg. of Aroclor 1218 |mt cubic meter of nir is the maximum safe amount permissible in workrooms. Ill eoninierriul hcal-truiisfer installations, the presumption is that the Aroclor is in a rloml system free from leaks. Accnrdingly, there slioulti Ih-. no opimrtimily for workers to come in con tact with vapors from tlie hot heat-transfer metliuni. Heater Demon. The general requirements of the heater are compactness, ease of construction aod service, and avoidance of direct flame impingement on the tubes. Direct flame impingement is prevented by directing the gas flame through an enclosed channel with helf-thieknerefir* brick protecting the tubes abovo until the high temperature of the name is reduced bv heal conducted through there brisks ted radiated to the two bottom coils. The sire ofthe healer iereduead tio a minimum boy using only 4.5 inches of insulating lfire brick ia the hottest arre--a-s---a-n-1d*2` inc1 hes o'f .R..a..g.l.e....N..o.....6..8...insu^lation on the cioooolleer spots. Two siscs of units arc used: One has a maximum capacity of 200,000 D.t.u. per hour, as shown in Figure I. The larger has a ranee of 200,000 to 400,000 D.t.u. The small tin consists of 00 feet of I-inch standard weightsteel pipe made into three coils of six pipes each and connected ia series. The larger sixe consists of 114 feet of 1.5-ineh l` *- * weight steel pipe arranged in the some fashion. Results of Um on the small-sixe heater covering temperatures from 150* to 300* C. show temperature Hues to 10s to 20* C. in the Aroclor while circulating at a rato of 15 tn 20 gallons per minute. The outlet gas temperature is consistently within 75* C. of the outlet Aroclor temperature. |t is observed that the bottom two code ab sorb the major part of the heat. The small unit indicates 50 to (50rceHicietieie for capacities up to 200.000 D.t.u. per hour when a natural gas of 1000 D.t.u. per cubic foot is burned. A Surface Combustion Company high pressure inspirator and tunnel burner set is used in thin instaiialion. Over-all heat-exchange riwrtieients (C) for the furnace arc ia the range of 7 to 10 D.t.u. jut hour per square foot per degree Fahrenheit. Over-Ail heat-vvchnngi* coefficients for Aroclor 1248 to water in a double pipe lient-cxchaugcr made from 1.25-mtb jhpe with a 2-inch pi|ie jarkei are in tin- 120 to 180 range. n` ` " are caleulatid from tent results on this HEATER PIPING Figure 2. Cooler, Pump, and Expansion Tank Cooler. A very useful adjunct to the system is a double pipe cooler oa the outlet of the heater shown ia Figure 2. By turning water into tbs jacket, the Aroclor can bo cooled and the temperature of the system lowered. This is helpful when it ia neeereary to cool a batch before removing it or when an exothermic reaction starts to get out of control. Push*. The pump for circulating the Aroclor 1248 may be any one of a number of standard centrifugal unite designed for bot liquid service. HONS 076338 1344 INDUSTRIAL AND ENGINEERING CHEMISTRY Vd. 41, No. 7 TABLE VI. ('wUntlti /, through /. 1 through <1 V* through */ I throng (I Hmt-nff valve# '/, tlinmgh V 1 through 2 2V1 through It Vi lUroiign '/ > through 2 it'/, through ft rirlNO Detail is lashes) Schedule 80. A.S-T.M. A53 or A100 Schedule 40. A.S.T.M. A48 nr AIM Screwed Hanged Urnu to shop tod 0ld where poewble. Muil be clMined to remove arete Forged iteel Mrewed. Crane 300d teriee 'Willed Otlingg. Crone 300e flertee 30 (to match valve*) Marliine hoila A.S.A. IM8.2 with he*ngonel nute for w?rvee below 400* K. Above tie* alloy le*l. Crane tnl>le A.S.T..M. AIM Crane 2421, forged lne < 'rane 424 high tem perature thread compound floll iron ring flat or nnrmgatvd Crane 3K0QW, *prwi>fl. gate (.'rane .1l)|5VV, Range, gale ( rune 33XK. flange. gate ( rune 3040 XII. Mrowed, glelve ('rune 3(1541 XR. flango. irtolw Cinne l.ll XR. flango. ginlw Crane 3tt?4 X, earowed < raiir 3fl8* X. flanged Crane I3H X. Ranged f.xmoli.latod 11.70 I'-'A. vrrvwrrl ( nlitlaiPil (t.12 U. ilamc-H <401.1 or DuruiiiPtallir UI Ml . o-itm . ... . Iptnm with i rane 22211 bar nock valve. h-rgtiMon Si-riea H20 K. llv* trim li.iiml levH gage Ml V.rway H.t^ndi-J* l Tint Dayton Dowd Tyjnt C puiti|> in nti t-xampk* of (ho ivpp required. ll should Ik; matte of cant atccl and have a walcrrtMitetl stuffing box and tvalur-cooleil bearings. Thn stuffing lw>x nlittuki have room for at least six rings of imckioc and a lantern rin*. IhirameUUlie No. D-II0 or (larlnck Xo, 234 may lw used for imekinn the pump. An uiiuii imiwlter in donrable. as it will handle th oool, more viacoua liquid on slurting the system better Ilian will a eteevd impeller. Enough horaepower for the mi*t vieeoue condition* is required. 1'ipinq Ststkm and ExrANiiiON Tank. Tlie detail of the piping gyatem for Aroclor 12-18 used up to temperatures of 300* C. (472* F.) ami 100 jmund* per square inch pressure is given in Titltia VI. 'Hie valves and epoeinltiee given indicate the type re quired. All piping larger than 0.75 ineh is flanged or welded; ex perience hoe shown that hot Aroclor penetrates screwed joints of lhe larger vises. Steel and cast steel are used throughout. The system requires an expansion tank located at the highest Invoi of the inatallotion. The site of this tank it normally about 25% of the capacity of"the Arooior syntem. Connections with valvee, mode on cither tide of the pump, enable the operator to conneeta flexible hose and to pump in nr out ns required. For operation in location* where the Aroclor temperature may drop to where thr attendant viscosities may make pumping im practical in the system an designed, it may lie dwirabln tu stenmjsoket Uie Aroclor circulating limn to facilitate rapid siart-up. Huitobla safety provisions, such as safety pop-off valves, must be installed in the steam jacket system to prevent pressure ruptures which would develop if nny comlrnxnlc remained in a closed sys tem during high temperature operation. Iu order tu establish operating conditions and to check the operation of Ibo heater ilseir, it is often desirable to measure the temporalurca of tbc .Aroclor in and out of the heater and cooler. Items ft, 1ft, and 11 (Figure 2) provide for this. They may be dial Utonsoraotcr* or mercury bulb thermometer* of any commercially available type recommended for the service. Tail* VII. Safbtt and Control Eqoipuont High proMurr *ltrm Mereeid PA-31. own eireuit sa Mali preaurs. idrirct* itoppsge Actual reuing* detrend oa individual layout .rf pipe) Low prvMiirc alarm Meicoid OA-31-3, ones wreutt low pnoiiw. (detect* topimgv Actual eettlng* depend oa individual layout of pump) Tlxrnuwtnt (ilotcrt* Fcnw*l >6003. Contact* opea oa temperature citeeMive lirsting increase cli>e( nfleoew)ubttruetion Final ftwilch (detect* M.-reoi'l Firm? 40. S. P. witoh. Opes at low leakage from sys level tem) 5. ( lame failure *vstem < omhiiftiion Control Corp. Firoya FFfl. Flama (cut* off (.* >f lailurc control far manual IfoiUon goa buraer pitn, Din* gor* n. Cae valve (cut* nfl (n-neral Cnnlrnl Corp. K I0-2. C1oM wftb rn caae nrnreiliu* i-urrunl oft [(evlee* nvtl Hr-.l lialit (uUrin) KHlnrl. VA-i no w, or Urnjamin rni3-v Horn (m,n<l alarmi l-Mn-ar.la 112 Alarm rainy sio|. imrn relay Tv,-e C-IUI4 lA'O. l-NC watertight (1) T. I.r C.) )0 l-No, I VC, watertight U> Stop horn button 1-HA 4 r*i * Thermometer .ll ii .l'.i>" C. ui.'reiirv bulb thermometer (vImimI chevh tieatrr perform- (0. Thermometer well 0 1'-"' ' m.-n ury l> ill ihermameter <viuai check uf heater perform- aneo) Thermometer well 0 3f>0* C. mereurv bulb fbarmameter (vi*unl eheek of ermler )M-rform. anee) Snli-nmtl vnlve Cenernl Control K-10-2. Omtroll A rodor ti->i>|iernture tu meet .lemaiula uf lyatem* 1 2 3 4 5 * 7 * 9 10 For automatic toni|N*r:Uun; control a solenoid valve, item 12, is indicated in abv-naas arrangement with a manuftUyoperatadnesdk vnlvu. Thu nuedlu valve is luljuatud to give almost enough heat to meet tin* requirements and the actual control ia carrtea on by tin.* olenoiil valve, which opens and closes as directed by a tetriiN-raluri'-Rmttrol instrument ennuected to tlMr equipment biung nuatetl. One unit "as set. up with temperature control uaing a Isunis A Xnrtlirop Model 9 all-electric control with droop corrector. Very close control river a wide range of heat demand resulted, when a throttling range adjustment of 4 was used on this control device. Saphtt Circuit. Figure 3 shows a safety circuit which auto matically protect* the system by closing off the gas supply in tha event of faulty operating conditions. Provision is mod* for shutting off the warning horn while the system is being put back into operation after a safety shutdown. A detailed list of the safety and control equipment is given in Table VII. l'lm equipment named indicates the type required. ACKIVOWLKDCMKNT9 The authors arc grateful to A. M. Ellenburg of Monsanto's Re search Laboratory at Anniston, Ala., for furnishing many of the technical data about Aroclor 1248 and for assistance in preparing the manuscript. LITERATURE CITED (1) Alien Bradley Co., Milwaukee. Wi., Bull, 700. (2) Ibid., Bull. 900. (3) Am. Soe. Testing Materials. Proe. Am. See. Tutinf tfsfenisfi 34.53(1934). . (4) Am. See. Testing Materials, "Standards on Petroleum Prod ucts and Lubricants," 1945. (5) Drinker, C. R.. J. Ind. Hyg. Toxicol.. 21. 1M (1989). (0) Monsanto Chemical Co., Anniston, Ala., private eommunte^ (inn, April 13. 1044. (7) Monsanto Chemical C . St. Louis, Mo.. Monmmt* 7*#cA. Bull. P-115 (August 1047). (9) Sortman, C., Boaltv. H.. and Heron. S., Ind. Emo- Casas.. 33. 357(1941). 'hi Sullivan. M. V., Wolfe. J K.. and Zismsn. W. A.. Ibid.. 30, 1007 (1047). (10) Underwriters' Laboratories, Chicago. III., "Misetlianeous Hasarda." No. 2498,1934. Rkckivso Augnit 27. 1048. Preaaated before tbe Meetiag-ia-Miafatare, Alabama flection, Ambrican Crshicai, Socidtt, Deeamber 8. IC4*. Frintcd in U. fl. A. HCNS 076339 CHEMICAL OPERATIONS V---- Monsanto Chemicals-Plastics ___ KA. O M > . I MB MONSANTO CHEMICAL COMPANY ST. LOUIS AKRON ATLANTA BOSTON CHICAGO CINCINNATI CLEVELAND DETROIT HOUSTON LOS ANGELES MINNEAPOLIS NEW YORK SAN FRANCISCO SEATTLE WILMINGTON MONSANTO CHEMICALS LTD. London MONSANTO CHEMICALS (AUSTRALIA! LTD. Motboomo MONSANTO (CANADA) LTD. Monlrool . Toronto Voncoovor Roproiontativoo in tho Principal Citioi of tlio World HONS C76340