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--/ Monsanto Chemicals-Plastics __________________ AN INDIRECT AROCLOR HEATER for UNIT CHEMICAL OPERATIONS Monsanto Technical Bulletin No. P*130 September, 1949 Monsanto Chemical Company St. Louis (4), Missouri Aroclor* 1248 (chlorinated biphenyl) is an ideal nonflammable liquid phase heat-transfer medium for temperatures up to 300C. This bulletin describes the physical properties of Aroclor 1248 and illustrates the design and operation of heaters that have been used successfully by Monsanto plants during the past seven years. The units described are gas fired and the capacities are in the range of 200,000 to 400,000 B.t.u. per hour. Other larger commercial installations using Aroclor 1248 have capac ities ranging up to 2,000,000 B.t.u. per hour. Also small electrically heated stationary and portable units with capac ities around 40,000 B.t.u. per hour,using Aroclor 1248 as the heattransfer medium,are in service. Several leading manufacturers of heating equipment are in position to build or offer Aroclor heating units to meet specific requirements. > z c z z o TO 0m 1n m n > > x o o o u r o m TO TO > X m H> O z </> x o X f v o 3 O 4ft o_ CD c_ <r z o "0 Reg. U. S. Pst. Office J1 The Information contained In thle bulletin It, to our beet knowledge, true end accurate, but all recomnendatlone or euggeetlona ere made wlinout guarantee, eince the conditions of uie are beyond our control. The Monearuo Chemical Company dlerlatme any liability Incurred In connection with the uee of there date or euggeeUone. furthermore, nothing contained herein ehell be conetrued ae a recommendation to ue any product In conflict with eelttlng patent* covering any materiel or He uee. '/r. 0558214 TOWOLDMON0036712 WATER_PCB-00021181 Reprinted from INDUSTRIAL AND ENGINEERING CHEMISTRY, Vol. 41, Page 1341, July 1949 Copyright 1949 by the American Chemical Society and reprinted by permission of the copyright owner An Indirect Aroclor Heater for Unit Chemical Operations MEADE McARDLE1, L. C. GARRETT, AND P. G. BENIGNUS' Monsanto Chemical Company, 4nn(tOR, ,4.1a. The characteristics of Aroclor 1248 indicate that it Sprat Flammability. When a tube ruptures in a liquid heat- is an ideal liquid phase heat-exchange medium for transfer system under high pressure, a spray or mist forms. temperature* up to 300 C. This orticle discusses its The possible fire hazard under these conditions requires considera properties and illustrates the design and operation of tions not covered by the foregoing discussions relative to the ma heaters that have been used successfully by Monsanto terial in the liquid form. In their comprehensive study of plants during the past seven years. flammability of the higher boiling liquids and their mists, Sulli van, Wolfe, and Zisman (9) 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 noneom- oxygen required for combustion. This value was then correlated bustiblc heat-transfer medium at pressures of 30 pounds per with the results of incendiary firing tests of the fluids conducted square inch or less and temperatuies up to 300 C. The following nt the Naval Proving Ground, Dahlgren, Va. The oxygen re general properties of a heat-exchange medium were required: quirement for Aroclor 1218 combustion in the spray flammability Freedom from fire hazards. Viscosities to permit pumping at room temperatures. Boiling point sufficiently above 300 C. to assure a liquid con dition at all times. Stability against, heat, with enough safety factor to accommo date accidental overheating. Controllable vaporization losses. Freedom from corrosive action against valves, piping, tank jackets, etc., made of cast iron and steels, bronze, and stainless steel. Freedom from toxicity hazard. limit studies was found to be 04%. Fluids requiring over 45 to 50% oxygen in the spray lest failed to cause a fire in the incendi ary test. These results establish the nonflammable and noncornbustible qualities of Aroclor 1248. VISCOSITY CONSIDERATIONS Cold Flow. For most inside installation centrifugal pumps will handle Aroclor at reduced rates without preheating. Experi ence confirms this. Outside installations have been started at Aroclor, chlorinated biphenyl (registered in U. S. Patent 0 C. by heating the pump and feed line until circulation through Office), was selected. The pertinent physical characteristics relnlivc to it' use ns n heat-transfer medium are given in Table I. Table I. Physical Properties of Aroclor 1248 FHEEItOM FROM FIRE HAZARDS Flash Point. Limitations of this test for the prediction of the fire hazard of relatively nonvolatile organic fluids have been recognized by the Aaierican Society' for Testing Materials com mittee (5, i). Fire Point is a more significant measurement. The Under writers' Laboratories (10) state that fire tests more truly reflect the (lack of) fire hazard of Aroclor. Spontaneous Ignition Temperature. The combustion- Appearance Absolute density, g./m). Absolute viscosity, centipc Practically colorless mobile liquid *C. {?.) 1.44 1 .37 1 27 1.17 30 (80) I (140> > (2121 t (302) > (.*>72) 112 17.5 4.2 0.99 0.47 30 {8ft > GO (140) 100 (212) 200 (392) 300 (572) resisting qualities of Aroclor 1248 are indicated by its high spon taneous ignition temperature of 704 C. (1299 F.) determined by Sullivan, Wolfe, and Zisman (9), using the convenient apparatus described by Sortmnn, Beatty, and Heron (F). Under conditions of industrial use the spontaneous ignition Thermal conductivity. B.t.u./hour/an. foot/ 0 F./foot Distillation range, A.S.T.M. D-20, C. Flash point, Cleveland open cup, A.S.T.M. D 02-45. 6 C, 0.0613 0.0698 0 0800 340-375 193-190 30 (801 60 (140) 100 (212) temperature will be determined by factors including the nature of the hot surface, the amount oT liquid impinging on it, the volume of enclosed space, and the ventilation. An accidental failure in a heating system demonstrated the nonflammability of Aroclor 1248 and its freedom from the hazard of fire propagntion An operator's failure to start the circulation of the heaUtransfer medium when the gas heater was on resulted in excessive coil temperatures and caused the lower coil to soften and sag into the fire chamber. A weld ruptured and Aroclor 1248 poured into the red-hot fire chamber in contact with the flame. Dense smoke arose from the heater but there was no external fire. After the gae flame was cut off, the smoking stopped. > Present address, Monsanto Chemical Company, Organic Chemicals Division, 8t. Louis, Mo. Present address, Monsanto Chemical Company, Phosphate Division, 8t. Louis, Mo. Fire point, Cleveland opm cup, A.S.T.M. D 02-45 Pour point, A.S.T.M. D-7, e C. Coefficient of expansion, ml./ml./ C (25 65 C.) Specific volume, mt./g. Specific beat, oal./g./ C. Vapor pressure, nun. Ilg 0 000702 0.696 0.709 0.728 0.787 0. SCO 30 (80) 60 (140J 100 212) 200 (392) 300 (572) 0.003 6.3*7 0.326 0.365 M) <133i 100 <2121 300 I303i 300 <6721 0.00037 0.16 2.9 18.0 3C0.0 37.8 100 150 200 300 (100) (212) 302) (302) (672) JZ 0558Z15 J TOWOLDMON0036713 WATER_PCB-00021182 1342 INDUSTRIAL AND ENGINEERING CHEMISTRY Vol. 41, No. 7 Table II, Stability of Aroclor 1248 Heated for 30 Hours Mg. of HCi per Grim of Aroclor 2B0 0.079 aoo 0180 310 0.199 320 0.222 830 0.248 Table III. Stability ok Aroclor 1248 Continuously Heated AT 280 0 AND 330n 0. Hours Mg. of HCI per Gram of Aioclor 280 C 330 C. 30 0 079 0.248 60 0 Ilf. 0.510 90 0.1 OH 0 923 120 0.194 1.141 150 0.201 1.302 Table IV. Gas Analysis of Aroclor 1248 Heated 4 Hours at 260 C. and 210 Pounds per Square Inch Pressure Carbon dioxide Carbon monoxide Oxygen (derived trom air) Methane Hydrogen chloride Cklorine Acidity {% by weight HCI) Pnoi to exposure After exposure 20O12 N.2 0 0075 0.0076 the heater had been effected so that the system could operate normally. BOILING POINT Operating experience has shown that the boiling point of Aro clor 1248 (340 C. at 760 mm.) is enough above the 300 C'. operating limit to prevent trouble from this cause. At the maxi mum operating temperature the vapor pressure is less than 0.5 atmosphere. HEAT STABILITY In order to establish a maximum practical operating tempera ture, the stability of the material when heated to elevated tem peratures in the presence of iron was noted. A slow, stream of nitrogen was passed over ihc hot- Aroclor to sweep the decom position products into a caustic trap. The amount, of acidic material was determined and calculated as hydrochloric acid. The results given in Table II indicate the Btid'ilitv of Aroclor 1248 when individual samples were heated for 30 hours at the given `"inpcraturev The decom position is very low at temperatures up lo 300 C. ' Tim stability of Aroclor j248 in contact with L iron continuously healed at 2S(|C and 330 C. is indicated bv Table Jll. Those test results indi cate that Aroclor 1218 in con tact with iron can be used satisfactorily at temperatures up to 300 "C. The Notional Board of Fire Underwriters (JO)reported that "decomposition of the product [Aroclor 124S] was not appreci able itt temperatures below 400D Cl., but became increas ingly apparent at higher tem peratures." Their workers analyzed the decomposition products of Aroclor 1248 heated in the pres ence of hot Iron at 469` C. and also heated in an iron cylinder at. 340 C. fitted with mi internal gas burner so that the gas flame impinged directly on the surface of the Aroclor. Analysis of the gases produced under these conditions included 0.6% carbon monoxide, 0.17%, oxygen (derived from the air). 0.99% hydrogen ohloride, 2.1% combustible gas calculated as methane, 0.002% chlorine, and no phosgene. The same workers studied the stability ol Aroclor when heated for 4 hours in an iron pipe at 260 C. under an internal pressure of 210 pounds per Bquare inch, resulting from the introduction of compressed air. Following tins treatment and cooling, the cases removed from the system were analyzed. The acidity of the Aroclor was determined prior to and after exposure to these con ditions. The results given in Table IV reflect an extremely small amount of decomposition under conditions similar to those selected for the practical use of Aroclor 1248 as n hem-transfer medium. In actual practice using the type of heating unit described below there has been no evidence of hydrochloric acid effect and no car bon deposits have been noted in the heater, pipes, or valves. The heaters have been operated successfully with combustion gase* at approximately' 600 C. in contact with the coils. At one time, a spiral coil type of heater was built and through faulty design a burner tunnel was located 1.5 inches from the 2inch steel pipe coil. The radiation from the white-hot refractory tunnel and the direct impingement of the- flame on t he pipe caused the pipe to glow a dark red for a space of about 2 inches. This unit was operated almost 3 months before a circulation stoppage occurred. When the line was opened lumps of carbon were found to have come loose and moved forward to lodge in the glebe valves. The lumps measured about 1 X 2.5 cm. and one face was formed to fit the pipe curvature. No hydrochloric acid effect was noted and the system was put back into operation after the burner location was changed. CONTROLLABLE VAPORIZATION LOSSES The heating systems in which Aroclor 1248 is used are seaied except for the expansion tank, which has n loose cover or a vent pipe. Because this tank is separated from the stream by a sub stantial length of pipe, the temperature in tlie lank remain? lew. In the light of the relatively low vapoi pressun- values for Aroelor 1248 (?), and us it is unlikely that the expansion tank will ever reach even the 1-mm. state (13UC C.), there should not be a measurable loss of Aroclor from the system. Actual experience bears out this contention. Other Losses. Although Aroclor darkens on use, its churur`.eristics remain the same and replacement has not been found necessary after 7 years of continuous use. Accidental leak? or spills constitute the only observed losses. asjo "apt srcTion 0558216 c TOWOLDMON0036714 WATER_PCB-00021183 uly 1949 INDUSTRIAL AND ENGINEERING CHEMISTRY 1343 RESISTANCE OF StRTCTTRAI. M ATEUUUS TO AltOCLOR 1248 Metal? Aluminum C Op|l(!l Nifltd Blivet Tio U I: KK. Licillejit rt'Msliiriee, less Ilian 1.0 X 10 cm. per dnv penctratiou or 0.00014 null j>er ycur. It, Good re*iMnnce. penetration between 1.0 X 10 * mid 10 X 10"* cm. per day or between 0.00014 and 0.0014 inch per year. D. 'Doubtful reeistuneo, penetration betui-m 10 X 10"* cm per day and 100 X 10" em. pet day or between 0.0014 und 0.0H tneli per year. e. Following letter indiratitiK reristtmee, signifies material mn> be b-tter tliuii inciiciiled if totall.v iiamerM-d, m> weight loss is btlieveJ <0 come lion) oxidation oi purl oi U-1 striji exfoM-d to air. ih>k;n ami construction IIeativ. Sx.'tir.M. The lie:.ting system required to utilize Arockir 1248ns the exchange medium includes a heater (Figure 1), cooler, pump, and expansion tank (Figure 2), and control and safety circuits (Figure 3 ). FltltFDOM FROM COHHOSIX F ACTION Tilt' resistance ol vi.lions metals (? j ai 2oeand 12oe`C. isgivtin Tahir V. 8imilur studio i.i:nli at d'i.V (o`j indicate hat the pene:i tion, in inches per voir, for mild .steel is l).Uhl's-; for velluv, tin Figure 3. (iontrol ami Circuit 0.01KM7; for copper, OdDl id Many years of practical operating experience wills Aroci as a hcat-trioisfei medium have shown that lire- material i tically iionentlosive to valves, piping, tank jackets, ole. of cast iron and steel?, bronze, and stabile's sleek FllKKIXl.M FIUI.M TOXICITY HAZARD Arndor 1248 is a veiy slahle, unrenrtive liquid. If the materia! is fpibeil tm Ihe skin, there are no noticeable ill effects; however, it ip well lo wash the skin with soap ai.d water after contact. A skin hurt) resulting fiom (incidental ronlaet with hot AroHor should he treated in the normal procedure um-J lor hot oil hums. Aroclot adhering to the hunted area need nm In- removed im mediately unless treatment of the burn demands it; m this cow Boaji and " (iter or rej>r: i id wadi mg.- wi'. li a vegetrd.de ill (linseed oil) should 1 >' ip i-d. The va|',|i,." ii.mied ly Armiui J2`S ncaied lo eievnmi tom- penuuivs air ii.iu:i"ii> to the liver on prolonged exposure and should ,rt he hieuthed. Drinker {o' indicated that On mg. of Aroclot 2D per t :; i i i ne! i r o! ai; - 1 le Maximum safe a mount pi Tlliissi I ,le Hi \\ . 'I' In eommere.al that the Aleck.r i ingly, I hi ie shrink .dim opportunity for Aeco.dne in eon- tact with vapors i S'tAM l------1 W*TFf< ' | Ili:.\TJ.!t Design-. The gcueaal requirement*! of the heater are compactness, ease of construction and service, and avoidance of direct flame impingement on the tula-. Direct flame impingement is prevented hv directing the gas flame through an enclosed channel with half-thickness lire brick pi electing the tubes above until the high temperature of the flame is reduced fry heat conducted through these bricks and radiated to the: two Tin si?AMif tin 1,eater is reduced to a minimum hv i t lie holiest arms n 'i io.-ln s of insulating fire brick in : J.agI" Xu (Hi insulation mi the Imc a niaxinmiu capacilv ,t.u. pi r IMVII n 1 igure 1. 'J'ltc larger lias 0,001 i |. 100,001) li t . T:i< insists o' 00 ie t of 1 -in.di standard weight steel pipe i - in-o three C'liks of six pipes i aeh and connected jr, a. lo-. i sj/,. coiijjstr,f pj.j feet of i.,'i-iuc!i standard < ) pipi :n iang- u in tin same lashimi. Results of teste iiall-.-i;:..- luati'i coveting ti mperalures from l,j()' in I.,w tenmi'-ature rises to 1(.|; to 20r' ii, tl,e Aruclur Wilh" H! ulatiiig a' a rale nf |j |n 20 gallons per miiuUe. The ollt h t IM temperaluie i s r, r l>i> le] 111 y Within 7:.' r. of tie- uulk-t At-idor i o.p11 at u:'1 k i- ` '1 .>.*i'v.,f3 that t iie h< 't t mu t wo cod' ] i-'i.iot paM <>: ihe heat. The small unit indicat's bo ir .1 - Am p n 1 n - up to 200.1)1)0 B t it. pm Icut w hen a c- m luoo [, 1. n. [hi cubic loot is hu t i; vl. A 8-urfne- a ( mnpmix- mgh pn -- uv inspirator .and tunnel . heal-t ' I , f! -it III' (/') 1 - t tie- flini.'nv jirr in ol I to b> Dt ,). | > 1 !,:.m pet s.piart 0 m 11 per uegree . I >\vr-:di ileal-, xemeig c .]!;-i.-n t s far \rclni J 2-1S n a tj'11:1.! pipe I r-m-.Aci.ang.a made fmm ].2a-md a 2-uieh pip-- jack" t ai'.- m ro- 12o In ]S.0 range. mo- ate cait'ijla: d bun- 1. -t ivsi; ts on lhi = AftOCuOfc FROM rttATtK^ I joc-tnco PIPC CCOlER 1 \y--------------------------------------------------- 4Kgh- YwATfR INtrr Hlrl OBJUH --{xj-- Ktocuyt JlS 5-^1;?Ostto Hcwrea BtLOT U&HT i-------------- txd---------- C'OOLKR. A very useful adjunct to tint sv.-teni is a double pipe cooler on 'he ouilet of the heater shown in 1 iguie 2. Hv i lrning water into the jn` k.'t. 1 ii(- Ati> lot run he fouled, arid '.lit- ' win] im in lie sy.-teM lowered 'I'le- is hdpiul when it is necessary Ui con] a luitch before removing it or whet, an exothermic reaction itarl# to get out of coniroi The pump for circulmin^ HEATER PIPING the Arociui 1248 may lie any ntie of a number of standard centrifugal units Figure 2. Cooler, Pump, and Expansion Tank designed fur hot liquid service. 0558217 TOWOLDMON0036715 WATER_PCB-00021184 1344 INDUSTRIAL AND ENGINEERING CHEMISTRY Vol. 41, No. 7 I-,,..' Construction ) reduces lunger lfllllK Unions VI.Table Piping Detail (Dimenniom is inches) t/4 */through 1 through (1 '/tw through 1 throne' fi Schedule 80. A.S.T.M. A53 or A106 Schedule 40, A.S.T.M. A53 or A106 Screwed Bentf in shop and field where pos sible. Must be l/aa through scale 1 urged steel screwed. Crane 300d J through 0 Welded fittings. Crane 300c ",' through V* Machine bolts A.S.A. ll-18.2 with hex agonal nuts for service Inlow 500' 1. Above use allow steel. Crime tri plex A.S.T.M. Ayr, ( rano 2.i2h forged step Gaskets Shut-off valves (<,,,!,-el VU|V"K >/,>/, throng!. 1 through 2 k a 1 IllOilgn V. < lii-cl; valves ''"hUiw" and glim `.'Mllll.-UgUV. 1 ('through r , ti.h.ugi, :t '/< irag. ..... ... compound Soft iron ring fiat or Crane SiiOGW, screwed, gate t lane 301MV, flange, gate Crane 33XR. flange, gate t rane Ho40 XR, screwed, globe ( tarn 8<;'i0 XK, flange. globe Ciane IM XR. flange, glob. Oitne X, screwed Crane 30Kh X. flanged Cui. l.va s. Unrig' -1 Cw.x.hdated H-70 I'-W, screwed C<m-., id.ite I 1012 W. Hanged ii.nn- a-401 oi l>m amctaliic H- Tyi- 100 PCl'K Marsh O-l 00 li'./Mi. ircli gig< siphon with Crime 2./1: bar stock valve. Icrguson Senes H20 Reflex type li ii.id level gape a.'.' Vf.rway flang-d Thi' Payli'ii Dowd Type C pump is an example of the type require-:!. li sljoukl lie jmtde of cast' steel and have a watercooled shifting I' >n and water-cooled bearings. The stufling box should have room for at least six rings of packing and a lantern ring. Dunne tallir No. D-UO or Omrlock No. 234 may be used for packing tDe pump. An open impeller is desirable, as it will handle i In cool, more viscous liejuid oi. starling the svstein better than will a closed impeller. Lnougb horsepower for the most visecum conditions is required Pii'iNfi i^vs'iitM andLxfansion Tank. The detail of the piping system for Arocloi 124N used up to temperatures of 300 C. (fnl'" 1'.) and 100 pounds per square inch pressure is given in Table VI, The valves and specialties given indicate the type re quired. All piping larger than 0.7n inch is flanged or welded; ex perience has shown that lmt Aroclor penetrates screwed joints of the larger size.-. Sled and cast sled arc used throughout. The system requires an expansion tank located at the highest level of the installation. The size of this tank is normally about 2bVr; of the capacity of the Aroclor system. Connections with valves, made on either side of the pump, enable the operator to connect a flexible hose and to pump in or out as required. 1 oi operation m location.- whore the Aroclor temperature may diop to where the attendant viscosities may make pumping imprnetind m the system us designed, it may bo desirable to steamjacket the Aioelor ehcuhuiiig lines to facilitate rapid starl-up. .Suitable safety provisions, such as safety pop-ofT valves, must be installed in tin steam picket system to prevent pressure ruptures which would develop if any condensate remained in a closed sys tem during high temperature operation. In order to establish opeiating conditions and to check the operation of the hosier itself, it is often desirable to measure the temperatures of the Aroclor in and out of the hpftter and cooler. Items It, 10, and 11 (Figure 2) provide for this. They may be dial thermometers or mercury bulb thermometers of any commercially available type recommended for the service. Table VII. Safety and Control Equipment Hipli preiturc alarm (detects stoppage of pipe) Low pressure alarm (detects stoppage of pump) Thermostat (detects excessive heating hence obstruction of flow) Float switch (detects leakage from aya- Fenwal 10002. Con increase Mereoid Figure 40. S.P. switch. Open at low Datne failure system (cuts off gas if pilot flame goes it) , Gas valvt >ntro! Corp. K-10-2. Closes ' current off lied light (alai Killark VA-1 <0 W, or Beniamin 7013-V Edwards 312 Type C-1104 UNO, 1-NC watertight (/) r-"ni '-xif, 1 -SC, watertight ((' J bulb thermometer Thermometer well (visual check of heater perform ance) Thermometer well (visual check of cooler perform- (1 300: . bulb thermometer 0-300 C. mercury bulb thermometer Soleiu.nl \1m For automatic temperat ure control a solenoid valve, item 12, is indicated in a by-pass arrangement with a manually operated needle valve. The needle valve is adjusted to give almost enough heat to meet the reauireinents and the actual control is carried on by the solenoid valve, which opens and closes as directed by a tem perature-control instrument connected to the equipment being heated. One unit was set up with temperature control using a Leeds & Northrop Model S all-electric control with droop corrector. Very close control over a wide range of heat demand resulted, when a throttling range adjustment of 4 was used on this control device. Safety Circuit. Figure 3 shows a safety circuit which auto matically protects the system by closing off the gas supply in the event of faulty operating conditions. Provision is made for shutting off the warning horn while the system is being put back into operation after a safety shuldowu. A detailed list of the safety and control equipment is given in Table VII. The equipment named indicates the type required. ACKNOWLEDGMENTS The authors ure 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 ()) Allen Bradley Co., Milwaukee, Wis., Bull. 700. (2) Ibid.. Bull. 800. (3) Am. fcoc. Testing Materials, Prac. Am. Soe. Titling MaUrialt, 34,53 (1934). . (4) Ain. Soc. Testing Materials, "Standards on Petroleum Prod ucts and Lubricants," 1945. (5) Drinker, C. K., J. Ind. Hyg. Toxicol., 21, 155 (1936). (G) Monsanto Chemical Co., Anniston, Ala., private communica tion. April 13, 1944. (7) Monsanto Chemical Co., St. Louis, Mo., MontarUo Tech. Bull. P-115 (August 1947). (S) Sortman, O., Beattv, H., and Heron. S., Ind. Eng. Cbem., 33. 357 (1941). (9) Sullivan. M. V., Wolfe, J. K., and Zisman, W. A., Ibid., 39, 1607 (1947). (10) Underwriters' Laboratories, Chicago, 111., "Miscellaneous Hazards," No. 2498,1934. Rkceivid August 27. 1948. Presented before the Meeting-io-Mioiaturc. Alabama Section. American Chimical Society. December 8. 1946. 0D5S218 A TOWOLDMON0036716 WATER_PCB-00021185  y---- ; Monsanto 1 Cl PiEMICALS ASTICS _________________________ 1 MONSANTO CHEMICAL COMPANY ST. LOUIS AKRON BIRMINGHAM BOSTON t CHARLOTTE CHICAGO CINCINNATI CLEVELAND . DETROIT . HOUSTON . LOS ANGELES NEW YORK . PHILADELPHIA . SAN FRANCISCO . SEATTLE MONSANTO (CANADA) LTD. MONSANTO (AUSTRALIA) PTY LTD. Montreole Toronto Voncouver Melbourne MONSANTO CHEMICALS LTD. London Representatives in the Principal Cities of the World PGB:UAQICDM>^49 Print'd in U.S.A. OS58219 I TOWOLDMON0036717 WATER_PCB-00021186