Document Ne5Z3mgmzXeeNRa94X3ymxdyD

BULLETIN NO. IC/FF-38R-2 AskarelTRANSFORMER(RevisadAugust,1976) Inspection & Maintenance Monsanto 706961 SECTION A TRANSFORMER A S K A R E L S ........................................1 I. In tro d u c tio n ........................................................ 1 II. History of Trade Name T y p e s .............................1 Table I - The Composition of Transformer Askarels .........................................2 III. Interchangeability . . . ......................................2 IV. Table II - Official Transformer Askarel Shipping Specifications . . . ; ................... .3 V. Ordering Instructions ........................................ 2 VI. S ta b ility ............................................................... 2 V II. Precautions When Handling Drums, Tank Cars and When Opening Transformers....................... 2 A. Keep Dry During Handling .......................... 2 Table III - Handling and Pumping Temperatures................................. 4 B. Use Ordinary Personal Precautions ............. 4 C. Precautions on Opening an Askarel Transform er...................................... 5 V III. Avoid Environmental P o llu tio n ......................... 5 1. Labeling Askarel Transformers.....................6 2. Disposal of Liquid and Solid Wastes ...........6 3. Conditioning of New or Recycled Askarel .6 4. Teardown of Transformers for Repair or Scrap ...................................... 7 5. Transformer D isp o sa l....................................7 IX. Expected Service L i f e .........................................7 X. General Characteristics of Transformer Askarel F lu id ........................................................7 XI. Sampling Transformer Askarel Fluid ............... 8 X II. Evaluation o f Askarel Received in New E q u ip m e n t..............................................8 X III. Dielectric Breakdown Voltage - Moisture R elationship.........................................9 Table IV - Relation of Dielectric Breakdown Voltage to Amount of Dissolved Water in Askarel and Mineral O i l ...................................... 9 Table V - Approximate Solubility of Water in Transformer Askarel and Mineral Oil . . . . 10 XIV. Turbidity ...........................................................10 XV. Check Points for Maintaining A *a re l Insulation ............................................10 A. General Considerations................................10 B. Modern Sealing Procedures .......................11 C. The Older Sealing Arrangements................ 12 XVI. Periodic Fluid Inspection and What Checkpoints Mean ..................................12 A. Visual Inspection..........................................13 B. Dielectric Breakdown Voltage ................... 13 X V II. Inspection Checklist ......... 13 X V III. Contamination in Transformers........................ 14 Table VI - Effect of Common Insulation Materials on Power Factor and Dielectric S tre n g th ............................................14 Table V II - Effect of Common Insulation Materials on Volume Resistivity of A skarel...........................................................14 X IX . ASTM Method for Investigating the Compatibility of Transformer Insulation and Construction Materials in A skarels........... 15 XX. Refining Askarel for R e-Use.............................15 A. F iltering Through Dry Blotter Paper to Remove Moisture and Extraneous Particles.................................... 15 XX. X X II. Table VMI - Water Removal by Filtering Askarel Through a Paper Press B. Disposal of Solid Wastes C. Solid Insulation Requiring Drying D. Earth Treatment for Maximum Improvement of Power Factor and Volume Resistivity Table IX - Effect of Power Factor and Volume Resistivity Cleaning Arced Transformers Sampling A s k a re l............................... 16 16 16 16 17 17 17 SECTION B ASKAREL FILLED SWITCHES AND TERMINAL CHAMBERS ............................. 19 I. In tro d u c tio n .................................. ^ II. Sources of Contamination ................... 19 III. Sealing Switches and Terminal Chambers 20 IV. Askarel Used Under Mild Arcing Conditions 20 V. Maintenance for Askarel Filled Switches . . . . 20 VI. Askarel Under Excessive Temperature or Fault Conditions ........................ 71 SECTION C TOXICITY AND SAFE H A N D L IN G .......................... 21 I. In h a la tio n ........................................................ 21 II. Skin C o n ta c t................................................... 21 SECTION D ANALYTICAL SERVICES ON TRANSFORMER ASKAREL AVAILABLE FROM MONSANTO ..............................22 Types of Analyses Available: ........................................22 1) Routine Maintenance C heck................................... 22 2) Complete A n a ly s is ..................................................22 3) Analysis After Earth Refinement ......................... 2? SECTION E A P P E N D IC E S ........................... 23 Appendix A - Askarel Stability and Composition of Arc Formed G a s .................................23 Appendix B - Solubility of Gas in Transformer Askarels .................................... 23 Appendix C - Effect of Tempcratuie on Dielectric Breakdown Voltage of Askarel .................. 23 Appendix D - Comparison of the Approximate Viscosity in Sayboit Universal Seconds of Transformer Askarels and Mineral O i l ..........................24 Appendix E - The Density of Inerteen 54201 KA 7336-9 and Transformer Pyranol A 1 3 B 3 B -3 ........................................................24 Appendix F --Thermal Conductivity Values of Transformer Pyranol A13B3B-3...............................24 Appendix G - Heat C a p a c ity .........................................24 Appendix H - Coefficient of Expansion....................... 24 Appendix I --Fire Resistance.........................................24 Appendix J - Seals, Properties and Procurement .......................................................... 25 Appendix K - Caution L a b e l.........................................25 NOTICE: "Nothing contained herein is to be construed as a recommendation to use any product in conflict with any patent. MONSANTO MAKES NO WARRANTIES AS TO THE FITNESS FOR A PARTICULAR PURPOSE OR MERCHANTABILITY OF ANY PRODUCT REFERRED TO, no guarantee of satisfactory results from reliance up on contained information or recommendations, and dis claims all liability for any resulting loss or damage." NEV 007710 706962 W 'K ><"' v-**1-- :' " " 'v--,*?".( . " i ^ T / - P> -. > : **r $ Ni \ TrSan@AsfsDok(rDammreAerl I. Introduction The term "askarel" as defined by IEEE, ASTM and the National Electrical Code generally describes a broad class of fire-resistant* synthetic chlorinated hydrocarbon insulating liquids widely used in transformers, reactors and accessory equipment operated at power frequencies. Askarels of various compositional types are in use. (For the general properties and types see ASTM D-2283.1 Under arcing conditions the gases produced, while consisting of predominantly non-combustible hydrogen chloride, can contain varying amounts of combustible gases depending upon the askarel type. This manual describes the operating characteristics of transformer askarel liquid insulation as manufactured by Monsanto and how it differs from mineral oil. Appropriate handling and disposal procedures for both scrap askarel liquid and impregnated solid materials are given in accordance with the guidelines recommended by the American National Standards Institute. The information Is based on facts gathered by Monsanto over 40 years as a producer of askarel, plus knowledge gained from the experience of transformer manufacturers and users. This guide outlines the maintenance required for askarel fluid in "modern** transformers and offers suggestions for sealing and maintaining askarel in old units. By following this guide, believe users w ill obtain maximum service from askarel insulation with a reasonable minimum of maintenance, if questions arise relating to the designing and building of transformers, these should be referred'to regular transformer suppliers. Monsanto gratefully acknowledges the assistance, guidance and the contributions of certain data by the following: Edward L Raab - General Electric Dr. T. K. Sloat - Westinghouse Electric II. History of Trade Name Types "Askarel** is the generic name for the fire-resistant liquid insulation and coolant first used by General Electric Company in 1932 for their Pyranol1 brand name fire-resistant transformers, Westinghouse Electric Corporation uses their brand name, Inerteen.* Whatever the trademarked brand, the askarel contains chlorinated biphenyl - one of the best liquid insulations developed by science. This inert material is chemically stable, fire-resistant, heat stable, non-corrosive, and has high dielectric strength under the operating conditions encountered in transformers. In addition to manufacturing Aroclor chlorinated biphenyl . Monsanto also mixes this dielectric fluid w ith chlorobenzenes to produce the presently used Inerteen and Pyranol blends described in Table I. "N O T E : Materials designated 'fire resistant' generally are more difficult to ignite, or once ignited, burn at a slower rate than corresponding conventional materials. This term does not mean that fire resistant materials will not burn. However; when properly used. Monsanto's firt resistant ASKAREL FLU ID S are useful in helping customers meet their fire safety requirements." trad em a rk of General Electric Company tra d e m a rk of Westinghouse Electric Corporation Registered trademark of Monsanto NEV 007711 i 706963 ;\ * V- i% h'r v . L>- -A A -i- ' Table l , Th# Compoiltion of Typical Transformer Askartii Method ASTM D2283 -, Type D Type E Tvoe G Trade Names Inerteen 70-30 Inerteen 100-42 Pyranol A13B3B3 Ingredients (% by wt.) Aroclor 1254, chlorinated biphenyl (54% chlorine by weight) 70 Aroclor 1242, chlorinated biphenyl (42% chlorine by weight) Trichlorobenzene 30 Phenoxypropene oxide scavenger 0.18 to 0.22 Diepoxide scavenger - 100 - 0.18 to 0.22 - 60 40 o o *- ID d ASTM Method 0*2283, titled "Chlorinated Aromatic Hydrocarbons (Askareis) For Transformers", also lists the composition of all transformer askareis used at various times since 1932. Monsanto manufactures similar transformer askarei fluids in England where the trade name Pyroclor is used. III. Interchangeability In general all transformer askareis are interchangeable. However, it is suggested that the transformer manufacturer be consulted prior to mixing in significant proportions or total substitution. IV . Transformer Askarei Specifications Specifications for the three modern transformer askarei fluids are shown in Table II. V . Ordering Instructions Monsanto's current policy is to sell askarei transformer fluids only to transformer manufacturers. Others interested in these fluids should contact the manufacturers of askarei transformers and not Monsanto. The transformer name plate indicates the transformer maker and usually gives sufficient data to identify the specific askarei fluids used. V I. Contamination Askarei insulation must never be mixed with mineral oil. Over two percent of mineral oil by volume in askarei begins to lower its fire resistance. In modern transformers, the principal "enemy " of askarei is contamination by water. Keeping askarei water-free will insure long-time service. Askarei is heavier than water. If water gets into askarei insulation, only a tiny amount (approximately 125 ppm) dissolves - the rest floats on top. Askarei is very Insoluble in water, only about 200 parts per billion of askarei dissolve in water, at normal temperatures. V II. Precautions When Handling Drums, Tank Cars, and When Opening Transformers The following are significant precautions: A Keep Dry During Handling: In handling, storing, sampling and inspecting askarei - and in . * j. ' . ' ' NE V 0 0 7 7 1 2 706964 I X. . Tabla II Transformar Askarel Specifications (New Fluid) /'V . V Spuif icitkw Properties1 C o lo r/A P H A .-/'C o n d itio n > Water content. ppm (ASTM 01533*60) .Acidity, mg KOH/g (ASTM 0974-55) ;. v * '-StDielectric Strength. 25*0.0.1 m. gap ' 1 * `< 5 "W S TM D877 4 9 ) ^ Y '^ i e l e c t r i c Constant, 100*0.60 Hz ` IASTM 0924-49) < '? /.^.V o lu m e Resistivity. 100*0, 500 volts DC 0.1 inch gap. 109 ohm-cm (ASTM 01169) ' Inorganic chlorides, ppm (ASTM 01821 and G.E. Method E4C41B) Refractive index. 25C (ASTM 01807) . Viscosity at 37.8C {ASTM D88-56) Saybolt Universal Seconds Pour Point *C (ASTM D-97-57) Specific gravity 2 5/15.5*C (ASTM D 1810) Burn point (ASTM 092) Distillation range (ASTM 020-56) corrected for stem and barometric pressure General Electric Co. Transformer Pyranol A13B38-3 ASTM D2283 Type G 150 max. Clear 30 max. 0.014 max. 35 KV. min. 4.2 to 4.6 100 0.10 max. 1.6110to 1.6120 44 to 48 38 or lower 1.495 to 1.510 None to boiling 1st drop 200C min. 40% max. below 270eC 90% 379 to 394 Westinghouse Transformer Inerteen 70-30* ASTM D2283 Type D 150 max. Clear 30 max. 0.014 max. 35 KV, min. 4.2 to 4.5 100 0.10 max. 1.6153 to 1.6173 56 to 61 -30 or lower 1.518 to 1.528 None to boiling 1st drop 2O0*C min. 35% below 270*C 90% 379 to 394 Westinghouse Transformer Inerteen 100-42* ASTM 02283 Type E 60 max. Clear 35-max. ^ 0.01 max/* 35 KV, min. 4.710 4.9 - lo o 0.05 max. 1.6240to 1.6260* 82 to 92 -17 or lower 1.381 to 1.392 None to boiling 10% 325-C m in .. 90% 360 max. Fixed chlorine 56.4 + 0.5% 55.6% min. 43 0.5% Corrosion test Color, APHA A cidity, mg KOH/g Inorganic chlorides ppm Condition Scavenger content Typical Properties2 A fte r heating w ith aluminum for 6 hr$. at 200 to 220*C, the aluminum must not be corroded on either visual or weight inspection and the askarel should meet the follow ing specifications: 200 max. 200 max. 200 max. 0.014 max. 0.014 max. 0.01 max. 0.15 max. 2.0 max. 0.15 max. Clear Clear Clear 0.1151O 0 135% 0.18 to 0.22% 0.18 to 0.22% Diepoxide phenoxypropene oxide phenoxypropene oxide CoeHicient of Thermal Expansion IASTM 01903). cm2/cm2/C Arc formed gases Westirrghous uses their private number Inerteen 5^201 KA #or Inerteen 70-30 and their private number Inerteen 54201 CM for Inerteen 100-42. 0.0007 0.0007 0.00068 Askarels of various compositional tvoes are used. Under arcmg conditions the gases produced, while consisting predominantly of non combustible hydrogen chloride, can include varying amounts of combustible gases depending upon the askarel type ln$udUO'> . .'*'*> incorporating these askarels and cellulose or other organic materials may. when arced, produce gaseous nrv.- which ae moderately flammable. As a precaution, such gases should be lemoved from the askaie* by bub;.-! g a*v ntrooen through the askarel and flushing the gas space with dry nitrogen before any work is oeifoimed on the apparatus 1These quantities are final sales specifications only to the extent that they coincide with Monsanto's published specifications. 2 This data <s based upon samples tested in the laboratory and is not guaranteed lor all samples. Write us for complete sales s>ecifications for Askarel fluids. NEV O 7 7 13 9 706965 operating,tkiifr ^ranifornndfi take' very. i**cautfon to gueita the kiirri insulation from exposure-to high humidity end moisture contamination, Keep 8 or 56 gallon drums of askarel dry; lay stored drums on their sides with the bung at tha highest point from floor to keep water off the drum head (which can be sucked Into the askafy by the drum "breathing"). This precaution is not necessary when drums are stored Indoors, which is the preferred place for storage. To avoid leakage the drums used for askarel are of heavy construction. Sixteen gauge metal is used, with special rim seal and bung construction. The drums should be drained as completely as possible and then flushed twice with kerosene type solvent to remove all of the askarel. Accumulated liquids and washings should be collected and should be incinerated at high temperatures, e.g., about 2000*F,to destroy the polychlorinated biphenyls (PCBs). See Section A, V III. Tank cars used to transport askarels are in exclusive service and not used interchangeably for other products. A ll cars must be unloaded through the top (dome fitting) either by pumping or with controlled pressure using dry air or dry nitrogen. If nitrogen has been used for unloading it is necessary to advise the shipper so that when the car returns the nitrogen can be replaced with dry air before any one may enter the car. If the car is to be unloaded by pumping it w ill be necessary to use a dryer on the air intake line to remove moisture. A ll tank cars are fitted w ith steam coils, which are available for unloading under extreme low temperature conditions. Convenient handling and pumping temperatures are given in Table III. B. Use Ordinary Personal Precautions: Transformer askarel has been made, handled, and used for over 40 years. It can be handled safely w ith recommended precautions. If accidentally spilled on hands, no serious skin irritation w ill occur. However, liquid askarel has a solvent action (similar to paint Table III Handling and Pumping Temperatures Product Unloading, Handling and Pumping Temperature *C Pyranol A13B3B-3 Inerteen 70-30 inerteen 100-42 20 56 20-65 35-75 thinner) on the fats and oils of the skin and prolonged contact may lead to drying and chapping of the skin. In case of contact, wash tha skin with soap and water; remove and destroy saturated clothing. Clean up spills with rags, sawdust and absorbent clay. Segregate these items fo r proper disposal. (See page 6, " Disposal of Liquid and Solid Wastes" .) Eye contact may result In painful Irritation but no permanent damage to tissues. If askarel get! In the eyes, flush with large amounts of water. As with ail eye first aid, refer to a physician. To relieve irritation, physi cians have used an opthaimic anesthetic solution as well as opthalmlc cortisone acetate solution. Infrequent exposure to pskarel vapors will not cause ill effects. However, prolonged Mpbiure to high vapor concentrations should be avoided If hit* Hkarpl must be handled in a closed or confined area, provlck th e a re e w fth m ^ a n ic a l exhaust ventilation - or. 4 NEV 0 0 7 7 1 4 706966 * *. wear an organic cartridge respirator approved by the U.S. Bureau of Mines. C. Precautions On Opening an Askarel Transformer: Askareis of various compositional types are used. Under arcing conditions the gases produced, while consisting of predominantly non-combustible hydrogen chloride, can yield varying amounts of combustible gases depending upon the askarel type. Insulation systems incorporating these askareis and cellulosic or other organic materials may, when arced, produce gaseous mixtures which are moderately flammable. As a precaution, such gases should be removed from the askarel by bubbling dry nitrogen through the askarel and flushing the gas space with dry nitrogen before any work is performed on the apparatus. The American Institute of Electrical and Electronic Engineers Guide IEEE Std. 76-1974 gives more detailed instructions and guidance " For Acceptance and Maintenance o f Transformer Askarel in Equip m e n t This guide is published by the Institute of Electrical & Elec tronics Engineers, Inc., 345 East 47th Street, New York, New York 10017. We recommend that users of askarel transformers refer to this IEEE document. V I I I . Avoid Environmental Pollution Transformer askareis contain polychlorinated biphenyls (PCBs) which have been used in the United States and elsewhere over the past 40 years for many industrial and consumer applications. During the past several years evidence has accumulated to indicate that PCBs are widely dispersed throughout the environment and that they can have adverse ecological and toxicological effects. The United States Government's Interdepartmental Task Force on PCBs, Com-72-10419, in their March 20, 1972 report titled, "Polychlorinated Biphenyls and the Environment", recommended restricting PCBs to use in capacitors and transformers. This report is distributed by the National Technical Information Service, U.S. Department of Commerce, Springfield, Virginia 22151. A document titled, "Guidelines for Handling and Disposal o f Capacitor and Transformer Grade Askareis, Containing Polychlorinated Biphenyls"t has been prepared and is available from the American National Standards Institute, Committee C107, 1430 Broadway, New York, New York 10018. Document number is ANSI C107.1-1974. (This guideline is being revised during 1976. The new edition should be available 1976/77). The scope, objectives and the composition of this committee are: ANSI Committee C l07 Scope: Procedures and guides for safe use, maintenance and disposal of askarel and askarel-soaked materials used in electrical equipment. Objectives: 1. Source of technical information and advice for Federal, State, local authorities and ail others concerned. 2. Encourage development of suitable disposal facilities and kocp all concerned informed. 3. Serve as the advisory group for United States participation in international organizations: CEE, IEC, CIGRE. Composition: Organizations active in or represented by this ANSI committee include: National Electrical Manufacturers Association, Electronic Industries Association, Institute of Electrical and Electronic Engineers. American Society for Testing and Materials; Electric Light and Power Association; Certified Ballast Manufacturers Association; Environmental Protection Agency; Office of Environmental Affairs; General Services Administration; National NEV 007715 706967 /fx * cO, j E lectrifica tio n Administration; Division of Environmental : Research, TVA ; American Public Power Association, Water I Pollution Control Federation; Food and Drug Administration; National Fire Protection Association; Underwriters Laboratories; and several sections of the U.S. Department of Interior. The following are pertinent excerpts taken from the ANSI Guidelines for askarcl transformers: 1. LABELING ASKAREL TRANSFORMERS (Pg. 16) 4.2.2.1 New Transformers. A/f new transformers that contain PCBs shall have a label of adequate durability, permanently and prominently attached to the tank by the manufacturer, given adequate warning and instructions. A suggested label includes the following: CAUTION: TI)C insulating liquid in this transformer contains polychlorinated biphenyls fPCBs). Care should be taken to prevent entry into the environment. In case o f malfunction or leaks, consult the instruction manual or the manufacturer. 4.2.2.2 In-Service Transformers. The transformer manu facturer should make available suitable labels with a simitar warning as shown in 4.22.1 for use on existing transformers. ?. DISPOSAL OF LIOUID AND SOLID WASTES (Pg. 15) 4.1.6.5.1 General. Disposal o f askarels andaskare!-soaked materials should be accomplished by means in which there is no significant release o f askareI to the environment. A t present, disposal is accomplished by carefully controlled incineration o f liquids and soaked software, and by con trolled landfill burial o f apparatus and other hardware from wf)ich askare! has been previously drained and washed. Present knowledge indicates that proper incineration must involve a suitable balance between dwell time and temperature in the incineration plus oxygen availability and, finally, suitable scrubbers to remove the HCI that w ill be formed; for example, 2-second dwell time at 200CT'F and 3% excess oxygen in stack gas, or 1.5-second dwell time at 270CPF and 2% oxygen in stack gas. These facilities sltould meet the applicable requirements o f the state in which they are located and should control effluents within the lim its set forth in this standard. Controlled landfill or deep-wetI disposal can be used where permitted by federal, state, and local regulations. The ANSI Guide lists the locations of facilities that conform with the above requirements. Monsanto has such an incin erator at the W. G. Krummrich Plant, Department 831, Saugct, Illinois 62201, where arrangements can be made for scrap askarel liquid disposal for a modest fee. For disposal of solid scrap a controlled dry land-fill can be used where permitted by Federal, State and local regulations. 3. CONDITIONING OF NEW OR RECYCLED ASKAREL (Pg. 16) 4.2.1.3.1. Askarel Conditioning Equipment. The condi tioning u n it should be located either in the storage tank area or in the main transformer manufacturing area for filling with askarel. 4.2.1.3.2 Fuller's Earth. Conditioning o f new askarel or recycled askarel requires fuller's earth treatment. The spent fuller's earth in cartridges or bags, when replaced, should be allowed to drain thoroughly over drip pans to remove as much liquid askarel as possible. The cartridge units o f steel mesh construction should be placed in the "STEEL CON TAMINATED WITH A S K A R E L" container for disposition. Cloth bags filled with fuller's earth should be placed in the "SCRAP BURNABLE ASKAREL WASTE" container for disposition. NEV 0 0 7 7 1 6 706968 r- 4. TEARDOWN OF TRANSFORMERS FOR REPAIR OR SCRAP (Pg. 16) 4.2.1.4.1 Drain all askaraf from the unit either into a holding tank or reuse or into the drum labeled "SCRAP A S K A R S L" for disposition, and then allow sufficient time fo r all o f the askare! to drain from the core and coils. 4.21.4.2 Remove the core and coil assembly from the transformer. Sufficient absorbent material should be pieced on the floor to absorb any askareI fluid that still drips from the transformer. 4.2.1.4.3 Place all materials in the appropriate salvage containers during the dismantling for later disposition. 4.2.1.4.4 AH used materials, including rags, sawdust, tape, etc, regardless o f quantity, shall be put into the appropriate containers for disposition. 5. TRANSFORMER DISPOSAL (Pg. 17) 4.2.3.6 The ultimate disposal o f an askare/ filled trans former may be accomplished in either o f two ways: (11 Complete drainage and dismantling with the proper disposal o f the askareI and askarel-soaked components as described in 4.1.6. (2) Disposition o f askareI transformers by means o f junk or scrap dealers. This should be avoided unless a transformer is first drained, followed by soaking the interior with a suitable solvent. Accumulated liquids and waslnngs are to be disposed o f as described in 4.1.6. I X . Expected Service L ife Manufacturers indicate that properly designed and installed askarel transformers are expected to give trouble-free service t ji at least 30 years. Since their introduction in 1932r the manufacturers report finding the overall failure rate to be less than 0.5% fur ail units under test and service conditions. The Edison Electric Institute's report (1956-1958) on their member utilities publishes the failure rate for askarel transformers as 0.13 per hundred banks per year. Mr. Frank M. Clark, who invented transformer askarels at the General Electric Company in the early 1930s, made the highly pertinent comment based on his many years of experience with G.E. Pyranol (askarel type) transformers that -- "The important thing is to keep them dry - otherwise leave them alone". These words of wisdom became especially applicable in more recent years when welding shut rather than gasketing became the main method of sealing askarel transformers. These units are sold with the understanding that the liquid is in a normally hermetically closed system. X . General Characteristics of Transformer Askarel Fluid Appreciation of the following characteristics, as given in the IEEE Guide, leads to understanding the reasons for selecting dielectric breakdown voltage and moisture as the prime practical tests to judge the quality of transformer askarel fluid. Also, due to these characteristics the power factor of transformer askarel will be normally much higher than the corresponding values for mineral oil. In comparison to mineral insulating oil, askarel is a relatively polar material; i.e., its molecules are dipoles, free to rotate around their axes and responsive to orientation by electrical forces. Askarel also exhibits a much higher dielectric constant and capacitance than insulating oil, and these differences must be kept in mind when interpreting electrical test data. 8ecause it is relatively polar, and possesses high solvency power, askarel is much more electrically sensitive than mineral oil to traces of extraneous soluble polar materials, and consequently the choice of r NEV 0 0 7 7 1 7 i 706969 constructional materials destined for use in askarel is very critical. This sensitivity is reflected in the power factor and resistivity (specific resistance) of the askarel. It is important to note that, w ith the exception of water, the dielectric breakdown voltage of askarel is not generally adversely affected by many of the soluble polar materials to which its power factor and resistivity (specific resistance) are so sensitive. In fact, the dielectric breakdown voltage of askarel is somewhat greater than that of insulating oil. Therefore, the values assigned these dielectric fluids in newly supplied transformers are 30 KV min. and 26 KV min., respectively. As with insulating oil, askarel must be kept dry. 11 can pick up moisture from exposure to humid atmosphere. Under similar conditions of exposure, askarel can pick up nearly twice as much moisture when measured on a parts per million weight basis. X I . Sampling Transformer Askarel Fluid The following precautions about sampling are quoted from the IEEE Guide. "Representative samples, whether of the complete contents or only parts thereof, are extremely important from the standpoint of evaluation of the quality of the product sampled. Obviously careless sampling procedure or contamination in the sampling equipment will result in a sample that is not truly representative. This generally leads to erroneous conclusions concerning quality and incurs loss of time, effort, and expense involved in securing, transporting, and testing the sample. It is strongly recommended that all of the procedures and precautions outlined in the latest revision of ASTM D 923 (Sampling Electrical Insulating Liquids) be followed. "Because of the high specific gravity (relative density) of askarel (greater than 1), water and some other impurities are most likely to be found at or near the surface. The top sample, therefore, is considered to represent the worst condition." X I I . Evaluation o f Askarel Received in New Equipm ent Some users of askarel equipment find it desirable to make "as received tests" on all equipment. It is quite common to use the dielectric breakdown voltage test and visual appearance as the most significant tests. If suitable equipment and trained personnel are available additional information may be obtained from the power factor, color, and moisture content tests. In sampling askarel contained in apparatus extreme care must be exercised in order to obtain a representative sample. ASTM Method D 923 should be followed. New equipment with askarel exhibiting the following characteristics is considered acceptable: Dielectric Breakdown Voltage Color Condition Visual Water Content Power Factor at 25* C 30 KV min. 300 max. (Straw color) Clear 3 5 ppm max. ASTM Methods D 877 D 2129 D 1702 D 1533 D 9 2 4 ,D 150 "The power factor of askarel taken from new transformers, reactors and accessory equipment can reflect the presence of moisture, dissolved polar compounds, or other contaminants and may vary w ith the type of equipment from which the sample was taken due to the different ratios of liquid*to-solid insulation and to the high solvency power of the askarel. Given an acceptable water content and dielectric breakdown voltage of the askarel as indicated above, a high power factor seldom impairs the serviceability of the askarel w ithin rather broad limits and is fo> rh i ) NEV 007716 vv indicative of the degree of extraneous soluble polar materials present. Recognizing the possibility of a wide range of power factors being recorded for askarel in new equipment, it is d ifficult to establish a single lim it which would be acceptable to both suppliers and users for all applications. However, as a broad guide, power factors up to about 10% at 25#Cand 60 cycles per second (hertz) do not in general indicate any abnormal contamination providing that the other criteria (water content, dielectric breakdown voltage, etc.) are met. Much higher power factors may indicate excessive contamination or the misapplication of the solid materials used in manufacture in contact with the askarel and should be investigated. X I I I . Dielectric Breakdown Voltage - Moisture Relationship The dielectric breakdown voltage of askarel is highly sensitive to excess moisture; not-sensitive to ordinary dissolved polar materials. While the dielectric breakdown voltage can also be towered by severe arcing, askarel turns noticeably black or has particles of sooty carbon floating in it if arcing has occurred. Then the transformer should be repaired and the askarel replaced. If the dielectric breakdown voltage is checked periodically and decreases significantly -- this indicates moisture pick up, arcing, or both. When the dielectric breakdown voltage has dropped to 26 KV or less, an analysis for water is necessary. If water is found in excess of 40 ppm at room temperature, its source should be located and corrections made. When the moisture content approaches 125 ppm (saturation level at room temperature), the dielectric breakdown voltage of askarel drops below the value required for efficient insulating. The moisture content should not be allowed to rise over 70 ppm, sampled at operating temperature. If the moisture content is found to be in a satisfactory range and the dielectric breakdown voltage is low, the transformer manufacturer should be consulted. Table IV shows the relationship of dielectric breakdown voltage vs. moisture and Table V indicates the approximate water solubility limits in askarel and mineral oil. Table IV Relation of Dielectric Breakdown Voltage to Amount of Dissolved Water in Askarel and Mineral Oil Water Content (PPM) Breakdown^/oltage (ASTM D877) Askarel Mineral Oil 0 20 40 60 80 e 110 70 KV 55 47 40 38 10 50 KV 39 30 26 22 5 NEV 0 0 7 7 1 9 \ 706971 Tabi V Approximate Solubility of Watar In Transformer Atkaral and Minorai Oil Amount of Water (PPM) Dissolved Askarel Mineral -30 -22 -20 4 10 14 0 32 10 50 20 68 30 86 40 104 8 16 28 41 65 94 128 170 8 10 13 20 33 58 85 130 X IV . Turbidity .. . may be the visual sign of undissolved water, or may indicate dirt. Cloudiness may also result from cold precipitation of tin tetraphenyl "scavenger" that was used in the earlier Pyranol transformers. This scavenger begins to come out of solution around 15F above zero. To redissolvc it requires heating to 150-200*F and agitation. High dielectric breakdown voltage w ill quickly indicate that any turbidity present is not moisture; that the insulating efficiency of the askarel is still excellent. However, if the dielectric strength is below 26 KV, moisture should be determined, using the Karl Fischer method (ASTM D 1533-60). The dielectric breakdown voltage test for askarel serves prim arily as an indicator for moisture. It is by far the most important maintenance test for transformer askarel. X V . Check Points for Maintaining Askarel Insulation A. General Considerations: Modern askarel transformers w ith welded construction or silicone or Viton* gaskets {hand hole-cover, switch and terminal compartment covers) and w ith properly constructed bushings require little maintenance. With properly constructed trans formers, annual or semi-annual visual inspection and dielectric breakdown voltage test of the askarel fluid should suffice for routine maintenance checking over many years of service. However, many askarel units were installed in the early 1930s before the development of some of the better modern gasketing materials and before improved designs were developed for sealing out moisture. Such early units should be, and can be, modernized. Leaky or deteriorated gaskets should be replaced. If the askarel has become contaminated, it should be reconditioned. A t the same time, a general clean-up of the unit and possible refinishing may be desirable. If it Is not convenient to take an old transformer out of service for general repairs, leaky gaskets can be sealed temporarily by painting over the leaky area w ith epoxy cement. A survey of users indicates a good number of early-built askarel transformers (over 20 years old) are kept in continuous service in critical installations by the following steps (instead of modernization). The operating units are equipped w ith compound pressure gauges for reading pressure above and below atmospheric. Positive Ti/m'Trademark of E. I. DuPont DaNemours & Company. Inc. pressure is maintained on the shell by introducing nitrogen at 2 to 3 pounds above atmospheric. Regular workmen in the area daily record the temperature and pressure. If a sudden pressure drop is noted more nitrogen is introduced and the gaskets are checked for leaks with soap solution. Leaks are sealed by applying epoxy cement. Modern Sealing Procedures: Transformer purchasers should specify the following modern techniques for sealing: 1. Welding Construction: Covers, radiator connections, switch and terminal housings, instrument connections, etc. should be welded. 2. Bushing Connections: A number of bushings h.ive been developed to obtain a proper seal for the electrical connection through the tank wall. They are classified as follows: 1) Welded T yp e (Bushing flange welded to tank wall) a. Cast resin bushing with a molded seal to the bushing stud and external stainless steel or copier flanges. b. Rolled flange bushing with the metal to porcelain seal at the cap and flange made by being rolled into grooves in the porcelain over silicone rubbi-r rings. The seal between the cap and stud .s nm)* t>y welding. c. Porcelain or glass bushings with m : :iav; nr metal to porcelain seals. 2) Bolted Type (Bolted to tank wall) a. Cast resin bushings w ith either cast 1 ti.ingcs containing recessed gasket groove... b. Porcelain or glass bushings with ft ii.nning recessed grooves or gasket stop. The gaskets may be cither of rectangular or circular ti >. . f r> >n. usually % inch thick. Bushings with recessed grooves nr* smbibie to use with cork, cork nitrile rubber combinations or nrtrtit rubber as well as gasket materials such as silicone or Viton 3. Small Size Connections: When not possible to weld, small size connection seals should be made with Flexitailic* stainless steel rings. The surfaces must be machined and parallel. The filler between the steel laminations of the FlexitaHic ring should be either silicone or Viton. 4. Gaskets for Hand-Hole Covers: Modern design specified silicone gaskets. Such gaskets must be retained m a groove The groove preferably is machined into the flange or cover However, it can also be formed by welding concentric steel strips to the flange or the cover. Generally the gaskets should be 5/16 to 1/2 in. thick for covers, depending on the depth of the groove or stop. A rectangular cross section $ usually used. The silicone material should be Dow Corning No. 50 Silastic** or equivalent. This is a low compression set m a te ria l. For best scaling 20-25% compression >s recommended, with ample clearance in the groove or stop to allow for this compression. No cement is required. With reasonable care thL* gasket -> removable without damage and is reuscable. Silastic 50 is slightly swelled by askarel which conti bo: , i-> the tightness of the seal. It is not deteriorated by a*.kjf.-. I '. j.-i or vapors. It resists weathering and it is thermally stahi*- h. i Trademark of flexitaltic Gasket Company Trademark of Oow Corning NEV 007721 706973 flexible at all operating temperatures. It is an excellent moisture barrier. NOTE: Dow Corning, Midland, Michigan w ill supply a list of Silastic 60 gasket fabricators to all transformer manufacturers or users. They w ill also furnish technical data. See Appendix J: Seals, Properties and Procurements. C. The Older Scaling Arrangements: The older type gaskets consist of either cork or cork-nitrile rubber combinations or straight nitrile rubber. 1. Cork-Nitrile Combinations: Covers for the main tank, hand holes, switch and terminal chambers, relief diaphrams, etc., are held in place by studs welded to the flange or by bolts. The gaskets are cut with openings and placed over the bolts. Often Shellac (Westinghouse Style No. 1150419, or General ' Electric Company's Glyptal* 1276) is used to cement the cork to the flanges. The following is recommended for sealing with the cork - nitrile rubber combinations: l Use Armstrong NC-757 cork-nitrile material or equivalent. The gasket can be cut from a single sheet or by scarfing strips of the material. A convenient method for joining strips is to make a Keystone Type joint. For this purpose, Westinghouse, Sharon, Pennsylvania, offers their gasket cutter Style No. 328 B614G01, (about $15). The joints - and also the gasket - should be cemented to the flange, using one of the above cements. Excess cement should not be allowed to reach the interior of the transformer. After installation and bolting, the outside edge of the gasket should be coated thoroughly with epoxy cement to increase weather resistance. This epoxy cement is a paste to which a curing catalyst is added immediately before use. Typical are: a. Epoxy Patch K it #1-C Hysol Corporation, Olean, New York b. Scotchcast** Resin #4 Minnesota Mining & Manufacturing Company St. Paul, Minnesota c. Adhesive A -1 and Activator Type 8 Armstrong Products Company Argonne Road, Warsaw, Indiana d. Adhesive 9860-1, Synthetics Organic Company, Cleveland, Ohio, used w ith activator diethylene triamine (Carbide and Carbon Chemical Company) 2. Straight Nitrile Rubber: When straight nitrile rubber was originally used, Invariably the gasket was recessed in a groove. This was to prevent gasket flow and to protect the material against excessive compression. Although this type seal was not cemented, the nitrile rubber gasket is not reuseable. Since grooves or stops have already been provided for the nitrile rubber seal, Silastic 50 can be easily substituted and is recommended. This conforms with modern practice. X V I. Periodic Fluid Inspection and What Checkpoints Mean On a regular schedule - at six, nine, or twelve-month intervals - make a simple visual inspection of your askarel insulation and run a dielectric breakdown voltage check. trademark of Ganaral Electric Company 9*Trademark of Minnesota Mining & Manufacturing Company : t ir V p A A. Visual Inspection: Askarel is a clear, faint-yellow liquid. A fter long term use this color may gradually intensify to light brown. The fluid should remain clear and free from turbidity or cloudiness. Any color change - such as to a green, red or blue cast - indicates extraction of impurities (color materials) from the solid insulation. If a distinct foreign color pick-up is noted, check the complete range of electrical characteristics and notify the transformer maker. Blackening of the askarel may indicate an arcing condition. Other color changes alone are not danger signals since the dielectric breakdown voltage is not likely to be impaired. B. Dielectric Breakdown Voltage If the dielectric breakdown voltage has decreased significantly from the last inspection, or if it has gradually decreased below 26 KV range (at 25*C) - RUN A CHECK FOR MOISTURE. Use ASTM D1533 (Karl Fischer Method). The dielectric breakdown voltage of askarel is the major indicator to the operating efficiency of your liquid insulation. Besides the visual inspection tests, dielectric breakdown voltage is the only test necessary to run on a routine basis. Well-sealed askarel transformers have service records of 25 to 30 years on the original askarel. X V II. Inspection Checklist 1. If askarel is clear - even though darkened to light brown, has no sediment or turbidity, has dielectric breakdown voltage over 26 KV - give it the inspection "O K ". 2. If askarel is clear, but has foreign color of blue, green, red . . . it is "extracting color" from internal materials. This is not, of itself, an operating hazard when the dielectric breakdown voltage stays over 26 KV and moisture remains low. However, this rare occurrence calls for checking into the condition of the interior construction and consulting the transformer maker. However, when sampling the fluid care should be taken to avoid getting color into the askarel from paint that may be inside or outside of the sampie valve. 3. If the moisture content is found to be above 70 ppm at operating temperature, then sampling should be done at more frequent intervals to establish a possible trend, particularly on outdoor installations. 4. If askarel is clear, but dielectric breakdown voltage drops to 22 or lower KV, and moisture rises over 80 ppm when sampled at operating temperature . . . the askarel is ready for simple "refining". If the moisture is near the saturation level (about 125 ppm at room temperature) a thorough inspection should be made for water droplets in the transformer tank, and even for "globules" of water floating on the askarel surface. If found, the transformer manufacturer should be consulted for reconditioning both the transformer and the fluid. 5. If askarel is dark brown to black, if black particles of carbon are seen, and dielectric strength is low . . . the askarel has been broken down by arcing. It cannot be refined and should be removed and Incinerated under proper conditions. (See ANSI C107.1 -1074, Section 4.1.6). If any of these five simple inspection tests appear out of the ordinary or the relationship between appearance and test values is abnormal, contact your transformer supplier for a complete analysis. Whenever a sample is to be shipped to Monsanto, please follow the directions shown under: "SAMPLING ASKAREL". N6V 0 0 7 7 2 3 ^ C \ * i JA I i 706975 ! ; X V III. Contamination in Transformers Moisture, particulate matter and arced decomposition products are known to be serious contaminating influences on transformer askare). The power factor test normally used for the detection of contamination in minerai o il filled transformers is of little use for this purpose in askarel filled transformers, due to the extreme effect of extraneous soluble polar materials. This increase in power factor as illustrated in Table VI has no adverse effect on dielectric breakdown voltage. Table VI Effect of Common Insulation Materials on Power Factor and Dielectric Strength ! (Heat Aged 96 Hours in Askarel at 100C.) I I Material Immersed None (control) Black varnished cloth i Copper Pressboard Manila paper Phenol formaldehyde resins Shellac Iron Synthetic rubber __ Askarel After Exposure^ Power Factor, Percent at 60 j :yc., 100*C_ Dielectric Strength _ 25*C._ 1.0 85.0 1.5 2.0 1.5 1.6 6.0 5.0 70.0 35 KV 42 40 37 39 41 36 39 39 Similarly, trace contaminants from commonly used construction materials can lower the volume-resistivity of askarel, without affecting its dielectric breakdown voltage. This is shown in Table V II. Table V II Effect o f Common Insulation Materials on Volume Resistivity of Askarel Sample Volume Resistivity x 10 ohm-cm (at lOO'C., 500 Volts DC., 0.1" gap)__ 1. New askarel before heat aging 2. New askarel after heat aging 96 hours at 100*C 3. After heat aging w ith 1 sq. inch specimens of: a. Phenolic resin tap changer material b. Paper c. Grade A pressboard (tan) d. Grade A pressboard (gray) e. Grade A pressboard, laminated strip f . Cotton wrapping g. Glyptal 1276 cement, cured 48 hrs. at 110"C 2,000 1,900 1,200 750 500 500 400 300 100 While trace contamination easily lowers volume resistivity from high levels, it is important to note that heavy contamination (as when arced) does not lower the resistivity below the order of 10$ ohm-cm. at 100*C. The different behavior of askarel vs. mineral oil in these respects can be summarized as follows: High power factor and low volume resistivity in transformer mineral oils are commonly regarded as "danger signals" that the oil has deteriorated and broken down chemically or excessive moisture is present. This is NOT TRUE of askarel liquid insulation unless the dielectric breakdown voltage is low or the moisture content is high. U NEV 00772<* 706976 Manufacturers of askarel type transformers point out that it is quite well known that askarel transformers w ith initial power factor of the askarel fluid in excess of 50% at room temperature and 60 Hz are giving satisfactory service life. However, there needs to be assurance that both dielectric breakdown voltage and moisture are at satisfactory levels and do not show adverse trends. X I X . A STM D 3 2 5 5 Method For Investigating The Compat . I ib ility of Transformer Insulation and Construction Materials in Askarels This method uses the change of electrical and/or chemical characteristics of transformer askarel resulting from its coniioilcd J exposure to insulation and construction materials, to order to evaluate their immediate major "contamination" effect on the askarel fluid. Delayed or long time contamination effects may not be detected. The method also utilizes various physical tests on the insulation and construction materials after controlled exposure to the askarel to determine the compatibility of these materials with transformer askarel. Properly proportioned specimens of the insulation or structural materials are immersed in refined askarel for 168 hours at 100 t 1C in a forced draft oven. Changes in electrical and chemical prop' tu.-s of the transformer askarel are compared against a control s.impic of ti e askarel treated in the same manner, in absence of the tr.t sot-nmi-ns. Dissipation factor (ASTM D 924) change is one of the <: : . i -sed 1 he askarel fluid is refined by absorptive treatment to a ciis. . mon far tor level of 0.05 max. at 100C and 60 Hz and 0.01 m,x C and GO Hz. Corresponding values of the askarel fluid after heat <hours at 100*C in absence of a test specimen are 0.075 ami v lively. The maximum dissipation factor levels suggested for tm* u>kaei alter heating in presence of the test specimen are 0.20 at 100'C and GO Hz and 0.04 at 25C and 60 Hz. X X . Refining Askarel for Reuse A. Filtering Through Dry Blotter Paper to Remove Moisture and Extraneous Particles: Most operators prefer portable refining apparatus, such as a plate press fitted w ith a dolly, available from Sparkler, Mundelein, Illinois or General Electric Company, Pittsfield, Massachusetts; or the earthen cartridge filter type available from Industrial Filter Corporation, Lebanon, Indiana. Filter paper iineis for the plate press are available from Carl Schleicher and Schuell Company, Keane, New Hampshire and manufacturers of filter presses listed above. The filter paper must be dried immediately before use. For best results, spread the paper for maximum surface exposure in a hot air circulating oven and heat it for 4 to 6 hours at 110C. Circulate the askarel hot (but not over 4 0 *0 through the filter fitted w ith the dry paper liners. After filtration the diefecliic breakdown voltage of the askarel should be 35 KV minimum. PRECAUTIONS: 1. Filtering should not be done when the relative h u m i d i t y exceeds 75%. 2. Any flexible hoses and gaskets on the refining e q u ip m e n t should be lined with or made of materials that will not ! be softened by contact with askarel fluid. (Materials linod with Silicone, Viton or Teflon* or flexible n u tjl materials are suitable.) Trademark of E. I. DuPont DeNemours fi Company, Inc. n1 NEV 007725 706977 TABLE VIII Guide to Rate of Diuolved Water Removal By Filtering Aikarel Through a Paper Praia Passes Through _ Paper Press Water in Askarel PPM 0 115 21 3252 3 18 4 12 5 10 6 10 6. Disposal of Solid Wastes: The ANSI guide C107.1-1974, Section 4.1.6 gives detailed recommendations. C. Solid Insulation Requiring Drying: If the solid insulation of the transformer requires drying, consult the transformer manufacturer or an apparatus service shop, as in such case oven drying is preferred. D. Earth Treatment for Maximum Improvement of Power Factor and Volume Resistivity: We question whether pumping and filtering the fluid solely to achieve a change in power factor or volume resistivity alone is justified in today's ecological climate regarding PCBs. We recom mend that in these situations the original transformer manufac turer be contacted. 1. Procedure: The askarel liquid should be relatively dry p jio r to the following earth filtration. As a coating on the filte r paper surface use finely divided Attapulgus* clay or Fuller's earth dried and activated by heating for 12 hours at 300350F immediately prior to use. i The amount of earth used should be 0.1 to 0.2 percent by weight on the weight of the askarel to be treated. Askarel i weighs about 12.5 pounds per gallon. To deposit the earth evenly, stir one-third of the earth with a small portion of askarel in a clean container. Pump the mixture through the filte r and follow with two more one-third portions. Then circulate askarel taken from near the top of the transformer, pass it warm (not over 55C) through the earth-coated filte r and feed back through the bottom transformer outlet. Continue circulation until the fluid is clear and test shows that the electrical properties are fu lly restored. 2. Effect of Earth on Removal of Scavengers Only slight and insignificant loss by selective absorption of tin tetraphenyl and epoxides occurs when askarel is refined by treatment with 0.1 to 0.2 percent by weight of earth. To remove significant amounts of the scavengers requires repe titious treatment with much larger amounts of earth. trademark of Engelhard Minerals and Chemicals Corp. NEV 0 0 7 7 2 6 706978 Ttblt IX Approximate Relationship Showing the Insignificant Effect of Power Factor and Volume-Resistivity on Dielectric Breakdown Voltage of Transformer Adcarel Power Factor (60 eye.) TS'C 2ETC Volume Resistivity x 109 ohm-cm (at 100-C, 500 Volts DC. O . r gap) Breakdown Voltage 25*C, 0.1" gap 2% 55% 15% 2025% 40-50% 0.05% 0.1% 0.7% 2.0% - 1500 500 100 60 70 25 35 KV 35 35 35 35 X X I . Cleaning Arced Transformers if a unit has arced so that the askarel is no longer fit for use. a thorough cleaning of the unit is necessary before refilling w ith new askarel insulation and returning it to service*. Follow this procedure insuring care is taken to prevent any loss of liquid askarel to effluent streams. A. Drain out all dark, carbon-contaminated askarel. Arrange to have the scrap fluid incinerated under proper conditions. (See ANSI Committee C107 report.) B. Carefully brush carbon deposits from internal parts and insulation, using a soft bristle brush making sure that insulation is not damaged. C. Flush thoroughly using new askarel - not an oil, not a cleaning solvent. D. Flush a second time w ith fresh askarel; drain; then fill to the proper level with new askarel. E. Energize transformer to warm the fluid for 24 to 48 hours; then circulate the askarel through a filter, returning it to the unit filtered and ready for use. X X II. Sampling Askarel Take a sample as close to the top of the liquid surface as possible. Many large askarel transformers have a built-in sampling tube near the surface for convenient sampling. Then, to make sure that your sample truly represents your askarel insulation, take another sample from the bottom. If additional sampling tube connections are contrived on the valves for easier sampling, make the tubes of clean glass, stainless steel, aluminum or tin for rigid types; and silicone, or Viton or Teflon tubing for flexible types. Use NEW containers for the askarel sample. A new and thoroughly pre-dried, small-mouth quart glass bottle fitted with a Bakelite*" screw cap w ith aluminum or tin cap liner is recommended for quick, on site testing. (If complete analysis is to be made, a 5-pint size sample is required.) Be sure that the new bottle does not stand open to collect dust or moisture. Rinse the sample bottle and cap lining two or three times w ith askarel from the transformer, then fill it. If the sample w ill be tested promptly, a clear glass bottle can be used. If sample is to be stored indefinitely, use an amber glass bottle or wrap clear glass with aluminum foil. A. Select a dry day. Do not sample insulation on a warm, moist day when humidity exceeds 75%, and . . . This assumes that the causa of arcing has been established and corrections made. When severe arcing occurs, major repairs are usually nacassary and the unit rebuilt. This procedure can be applied for flushing out tha repaired units. 4* Trademark of Union Carbide Corporation NEV 007 727 706979 When sampling iskarel from transformers, it is best to take the sample when the unit it warm and operating at average or maximum load, especially for a check on moisture as reflected by a dielectric breakdown voltage test. Sampling the warm askarel more truly represents Its condition during opration, Experience shows that water w ill migrate from a transformer's solid insulation to the askarel liquid and vice versa, depending on temperature. Therefore, when the transformer is hot, the moisture is most likely to be found in the liquid. This accounts largely for periodic variations in dielectric breakdown voltage. For example, a relatively high dielectric breakdown voltage may be found during winter months and a relatively low dielectric breakdown voltage during the summer months on samples taken from the same unit. When testing has been completed, the remainder of the fluid sample should be destroyed by high temperature incineration described in Section V III. FialnleddCST)ShAewarmsimnktcbaimhnereraeIBssll I. Introduction High voltage leads are usually connected to askarel or mineral oil-filled network transformers and power centers through terminal chambers and switches. In some cases terminal chambers are not used, and the high voltage leads are connected directly to the switch terminals. They may be filled with either askarel or mineral oil. Switches are usually rotary or drum type fitted with a revolving block and porcelain u n it as the principal element arranged for three-phase service. Askarel transformers with attached switches have been in use for about 30 years. When they were first introduced, the availability of insulating and gasketing materials was rather limited and even the best materials at the time had no service history. As a result, inadequate gasketing materials such as cork, nitrile rubber, and nitrile rubber-and cork particles were used. While satisfactory for a limited period of lime, these materials cannot be depended upon for the expected long life of the equipment. The terminal chamber is usually above or below the switch compartment and separated by a steel wall through which the bushings are inserted. When bushings are properly selected and correctly installed, there is no leakage from one compartment to the other. With poor bushing seals, and the terminal chamber above the ..vitr.h, potting compounds or cable oil can seep into the askarel. When the terminal chamber is below the switch, askarel can drain into the terminal chamber. II. Sources of Contam ination There are three possible sources of contamination for askarel in switches and terminal chambers; they rank in this order of frequency: ID water entering through poor gaskets; (2) decomposition products from arcing when switch is used to break magnetizing current; (3) entrance of pothead or cable compounds through leaky bushing seals. Unlike an askarel transformer where the amount of contaminant is likely to be very small (probably only trace amounts) in relation to the volume of askarel fluid - in switches or terminal chambers with faulty seals, the amount of contamination can be relatively large. Experience has shown that, based on the number of installed askarel-switch units, the percentage of failures is extremely small. When investigated, it has been found that most failures originate in the switch chamber. Water is the chief source of contamination. However, heavy contamination of askarel with petrolatum and asphalt material, due to leakage, have caused a few failures. Petrolatum is used frequently for filling terminal chambers. When either cable oil or petrolatum seeps into askarel, no great harm results. The fire resistance w ill be somewhat decreased and power factor of the askarel w ill increase w ith an accompanying drop in resistivity. While highly undesirable, it is doubtful that failure of the unit results. Where asphaltic compounds are used in place of petrolatum, the danger is increased somewhat because asphaltic contamination may cause excessively high dielectric losses in the askarel. When the terminal chamber is below the switch chamber, the potting compound can be contaminated by askarel if the bushing seals are leaky. This is undesirable because the askarel will increase the power factor and conductivity of the potting compound or cable oil and develop heat from dielectric loss. If this mixture is drawn into the cable NV 0 0 7 7 2 9 706981 Insulation, c cable failure is likely. This again emphasizes the importance of tight bushing assemblies. III. Sealing Switches and Terminal Chambers Proper bushing construction, use of Silastic seals and welding wherever possible is highly desirable (as covered in Section A). Where an elastomeric seal is to be used in contact with both askarel and petroleum oil, DuPont's Vlton is suggested. For new equipment the user should specify these modern sealing arrangements to keep out contaminants and minimize maintenance. IV . Askarel Used Under Mild Arcing Conditions The IEEE Guide for Transformer Askarel calls attention to the following: "Askarel is used, to some extent, in apparatus where it is subjected to light intermittent arcing, such as in self-contained induction regulators, where operating switches are continually producing slight arcs, in transformer de-energizing switches, etc., Under normal conditions, deterioration of the askarel is very slight. However, improperly adjusted or defective switches in this type of apparatus can produce excessive and prolonged arcing and accelerated deterioration of the askarel. It is recommended that whon askarel is used under these conditions, checks of the liquid, especially for moisture and dielectric breakdown voltage made more frequently than when it is used only as a cooling and insulating fluid. Deterioration of this type is indicated by a blackening of the liquid. It can usually be reconditioned as previously described. Special attention should be given to maintaining the scavenger at the appropriate concentration." V . Maintenance for Askarel Filled Switches A. Switches used for grounding after power source has been de-energized will not undergo arcing. B. Switches interrupting magnetizing current will be subject to arcing; the amount of decomposition will depend on power interrupted, time and frequency of operation. As a general rule, tho liquid should be checked after 5 to 10 operations. 1. On newly installed switches, check the askarel at 3, 6 and 12 month intervals; if found satisfactory, check once annually thereafter. With proper attention to the gasketing of covers and bushings, experience will probably indicate that less frequent inspection is warranted. 2. Check askarel for: a. Dielectric breakdown voltage (ASTM D877): It should be 26 KV minimum. If dielectric breakdown voltage is low, confirm presence of water by Karl Fischer method ASTM D-1533, Filter to remove moisture. Dielectric strength should then be 30 KV minimum. b. Presence of carbon from arcing; Fluid should be relatively free of carbon. If badly arced and very black, replace fluid. If only minute amounts of carbon are present, filtration is recommended. Check power factor of liquid (should not be over 5% at 25*C and 60 cycles). Flush out switch chamber with several gallons of fresh askarel before refilling. 3. If there is discoloration, high power factor, detectable change in specific gravity or refractive index, or if fluid flashes below 26<7F, there is a possibility of seepage of potting compound into the switch compartment. In this case, correct any leaky bushing seals with proper replacements and fill with new askarel, 4. If terminal chamber is below switch, check potting oompound for presence of askarel (can usually be detected by odor or by en increase in specific gravity). If askarel is present, correct any leaky bushing seels with proper replacements, and renew compounds. 5. Examine cover gaskets visually. Deterioration can be detected by swelling and cracking of the exposed edge. In cases of severe deterioration, liquid seepage is usually present. 6. Check for leakage at packing gland of switching shaft. If leaking, repack with a Silastic ring type gasket. V I . Askarel Under Excessive Temperature or Fault Conditions The IEEE Guide also points out that, " Chlorobenzenes used in transformer askarels begin to boil at c temperatures of about 205*C, under atmospheric conditions. If the material is heated to such high temperature in a sealed system, pressure develops. Pressure w ill also develop in the system if the s? askarel is arced sufficiently to generate copious hydrogen chloride gas. 'Therefore, it is recommended that wherever possible, sealed askarel-filled equipment be provided with pressure relief devices. These devices must be large enough to provide immediate relief at a definite pressure, and to prevent further build up of pressure if decomposition continues. It must be remembered that the presence of devices of this sort does not necessarily preclude the rupturing of containing vessels, since pressure build up can be extremely rapid under violent arcing conditions." I r Safe HToaxgxntfifdiccDiltmiyn&g i. f I. Inhalation At ordinary temperatures the chlorinated biphenyls in Askarel have not presented industrial toxicological problems. The hazard of potential toxic exposure varies with their volatility: the lower-chlorinated, morevolatile ones present more of a potential problem from the standpoint of both inhalation and skin contact. When Askarel fluids are used at elevated temperatures, engineering controls must be applied, either by the use of closed systems or by effective local-exhaust ventilation together with general workroom exhaust. Vapors of Askarel at room temperature should not be breathed in a confined space, and no vapor of any fluid evolved at elevated temperatures should be allowed to be dispersed into the general workroom. Inhalation tests on animals indicate that the maximum safe concentra tion of vapor is in the range of from 0.5 to 1.0 milligram per cubic meter of air. The threshold limit value (maximum allowable concen tration of an 8-hour working day) set by the American Conference of Government Hygienists are 1.0 milligram of the lower chlorinated biphenyl compounds per cubic meter of air and 0.5 milligram of the. more-highly-chlorinated compounds, per cubic meter of air. II. Skin Contact Prolonged or repeated skin contact with the Askarel fluids must be avoided by the use of gloves and protective garments, because of the possible occurrence of a condition called chloracne. Although reports of this condition caused by Askarel are rare, it can be produced by excessive skin contact. If the fluid Is spilled on the skin the skin should be washed in the usual manner with a soap solution. A burn caused by contact with hot Askarel should be treated like any ordinary burn. For disposal Instructions of Askarel fluids, see Section A - V III. page 6 NEV 0 0 7 7 3 1 706983 tw -..v, iy i" s- I " * T .r- i(g(Dmin) AoAnvnaTailrlyaatbniclseafolFrrSmoemrevriMAcesosknasraenlto Transformer users not wishing to make their own fluid analyses can obtain the service from Monsanto. Simply contact Monsanto f and specify what analyses are wanted. You will be sent the proper-sized, clean sample container, fitted with a proper label. When Ij you receive this, carefully take your sample (following the procedure for sampling in this guide). Send the container to Monsanto's laboratory. Charges listed include sample container and laboratory costs. The charges are those in effect August 6, 1976, and are subject to change. Types of Analyses Available Analysis!) ROUTINE MAINTENANCE CHECK Total Charge: $35.00 Per Sample To dotermine the general condition of the fluid and find whether further analysis is necessary, (one-quart sample required) Properties Tested Dielectric Breakdown Voltage Color and Condition Moisture You will bo notified of the results of this test. If further testing is indicated, and you want a complete analysis, you will be sent a five-pint sample container. This sample w ill be used for the following series of tests: Analysis 2) COMPLETE ANALYSIS Total Charge: $165.00 Per Sample (1 ) To determine the extent of fluid contamination, (2) earth refinement to determine what degree of restoration of electrical and insulating properties is possible, (3) check test to see how the fluid responded to earth treatment. a) Complete Analysis: to determine the extent of contamination Properties Tested Free Chlorides Color and Condition Acidity Specific Gravity Dielectric BreakdownVoltage Refractive Index Power Factor, Dielectric Constant, and Resistivity Water b) Earth Refinement Response: Consists of treatment for 2.5 hours at 50-6CTC. w ith 0.1 to 0.2 percent by weight of properly conditioned Atlapulgus clay and then filtration through dry filter paper. c) Analysis After Laboratory Earth Refinement: Properties Tested Acidity Refractive Index Dielectric Breakdown Voltage Water Power Factor, Dielectric Constant, and Resistivity Free Chlorides You will be notified of the results of this test series on your sample. Then after refining your entire transformer fluid fill you can check on the results by requesting the following analysis: Analysis 3) ANALYSIS AFTER EARTH REFINEMENT Total Charge: $70.00 Per Sample (This charge w ill not apply when analyses 1 and 2 have already been made.) To dotermine whether the entire lo t of the askarel fill responded to the same extent as the laboratory sample, (five pint sample required) Properties Tested Free Chlorides Color and Condition Refractive Index A c id ity Dielectric BreakdownVoltage Water Power Factor, Dielectric Constant, and Resistivity To arrange fo r the tests described above write to the following address: David Wood Monsanto Industrial Chemicals Company 600 North Lindbergh Blvd. St. Louis, Missouri 63166 Semples to be test'd should b i dearly marked for identification and sent directly to: Monsanto Company W. G, Krummrloh Laboratory Sauget, Illinois 62201 Attention J. A. Gloeckner . 007732 * \ i % I* III '' 1J t i t 706984 Appendices a p p e n d ix A ___________________________________________________ _________________________ Askarel Stability and Composition of Arc Formed Gas: Askarel insulation is one of the most inert, chemically-stable heat resistant, non-corrosive liquids known. It w ill not break down, oxidize or sludge when exposed to air and high temperatures, 160*C. or oven somewhat higher. Arcing, however, w ill break down the compound to liberate some hydrogen chloride and small amounts of carbon. APPROXIMATE COMPOSITION ARC-FORMED GAS FROM TRANSFORMER ASKAREL BLENDS ASTM TYPES D AND G (INERTEEN 70-30 AND PYRANOL A13B3B-3. RESPECTIVELY) Gas carbon monoxide carbon dioxide oxygen inert gases hydrogen chloride (note the absence of phosgene) Amount 0.3% 0.3% 0.6% 1.5% 97.3% This arc-formed gas from ASTM Type D and Type F transformer askarcls is non-flammable and non-combushbio. For all practical purposes, the amount of gas liberated from askarel under a given set of arcing conditions is about 100 cubic centimeters per kilowatt-second. A PPEN DIX fl_________________________________________________________ SOLUBILITY OF GAS IN TRANSFORMER ASKARELS ASTM TYPES D AND G Carbon dioxide Air Nitrogen Hydrogen chloride1 1In absence of scavenger Percent of Gas By Volume Corrected to: 25*C 760 mm Q*C. 760 mm 25*C 10CTC 2S*C 100*C 71% 5.7 6.0 37.8 47% 4.9 4.8 60.9 ... _ 5.8 5.0 5.5 4.4 '" A PPEN DIX C______________________________________________ __________________________ EFFECT OF TEMPERATURE ON DIELECTRIC BREAKDOWN VOLTAGE OF ASKAREL Temperature *C -6 0 --40 -2 0 0 20 40 60 80 Dielectric Breakdown Voltage ASTM D877 67 KV 63 57 55 50 50 48 45 NEV 0 0 7 7 3 3 ------------------- 706985 APPENDIX D COMPARISON OP THE APPROXIMATE VISCOSITY IN SAYBOLT UNIVERSAL SECONDS OF TRANSFORMER ASKARELS AND MINERAL OIL Temp. *C -2 0 a 20 40 60 80 100 Pyranol A13B36-3 1,000 100 70 45 39 34 30 10-C Mineral Oil 1,000 160 85 49 40 34 30 Inerteen 70-30 2,800 195 85 50 40 36 33 A PPENDIX E THE DENSITY OF INERTEEN 70-30 AND TRANSFORMER PYRANOL A13B38-3 Approx. Density gm/cc. Temp. *C 0 20 40 60 80 Inerteen 70-30 1.574 1.552 1.529 1.507 1.485 Pyranol A1383B-3 1.577 1.555 1.532 1.510 1.488 A PPEN DIX F __________________________________________________________________________________ The thermal conductivity values of transformer Pyranol A13B3B3 at 27*C and 58*C are 26.2 and 25.8 x 10*5 calories centimeters**, degrees centigrade*!, second*!, respectively. Or, approximately 0.06 BTU per (hr.) (sq. ft.) CF.) per foot. This same approximation applies to Inerteen 70*30. A PPEN DIX G__________________________________ _______________________________________________ __ Heat Capacity Over the temperature range of 25* to 125*C the specific heat of transformer askarel is close to 0.30 calories per gram per degree. A PPEN D IX H____________________ _______________________________________________________________ Coefficient of Expansion The average coefficient of expansion of transformer askarel over the temperature range 20 to 100*C is0.0007 cc/cc/*C. One gallon would increase to 1.056 gallons on heating from 20 to 100"C. APPENDIX I Fire Resistance Askarels of various compositional types are used. Under arcing conditions the gases produced, while consisting of predominantly non-combustible hydrogen chloride can yield varying amounts of combustible gases depending upon the askarel type. Insulation systems incorporating these askarels and cellulosic or other organic materials may, when arced, produce gaseous mixtures which are moderately flammable. As a precaution, such gases should be removed from the askarel by bubbling dry nitrogen through the askarel and flushing the gas space with dry nitrogen before any work is performed on the apparatus. NEV 0 0 7 7 3 4 706986 a p p e n d ix j ______________________ ____________________________________ ______________________ Seals, Propertiesin^iPCurcment Dow Corning Corporation, Midland, Michigan w ith Districts at Atlanta, Boston, Chicago, Cleveland, Dallas, Los Angeles New York City. Washington, D C. and Toronto has available Bulletin 09 019, August 1962 entitled "Silastic Design Data" This lists the gasket fabricators throughout the country from whom the "Silastic 50" gasketing can be purchased in sheet, extrusions or molded shapes. Generally, Silastic 50 sheet.goods are stocked by local die cutters, hence, could be generally purchased locally. Usually small Quantities of gaskets are die cut. If larger quantities are needed, tools are made of the same type used to cut other elastomers. Where the gasket is extruded for fitting into a machined groove or between gasket stops, Dow Corning advises use of a scaivcd joint. This joint is then cemented using Dow Coming's Silastic 140 (clear) or their RTV 731 (white) materials, which air cure. Dow Coming points out that the local "rubber" fabricators purchase the Silastic 50 in billet form. This is worked on a roll mill in preparation for sheeting or extrusion. Then to obtain the desired physical properties the fabricator must oven cure the Silastic 50 for 24 hours at 480F. SPECIFICATIONS* ASTM D676 ASTMD412 ASTM D 412 ASTM D395 Color Specific Gravity at 77*F Hardness, Shore A. Scale Tensile Strength, psi, min Elongation, percent, min Compression Set after 22 hrs at 300*F, percent, max White 1.20,10.02 45 to 60 800 250 30 All physical properties measured on 0.075 inch thick samples molded 5 minutes at 240*F, and oven cured 24 hours at 480-F. a p p e n d ix k Caution Label Yhc following or equivalent caution statements should be fixed on all containers of transformer askarels and ti.e transformers themselves: This product contains Polychlorinated Biphenyls (PCBs). Care should be taken to prevent entry into the environment through spills, leakage, use, vaporization, or disposal of liquid or containers. Avoid prolonged breathing of vapors or mists. Avoid contact with eyes or prolonged contact with skin. If skin contact occurs, remove by washing with soap and water. Following eye contact, flush with water. In case of spillage onto clothing, the clothing should be removed as soon as practical and the skin washed. Dispose of any contaminated materials as suggested in the American National Standards Institute document C107.1, "Guidelines for Handling and Disposal of Capacitor and Transformer Grade Askarels. Containing Polychlorinated Biphenyls". MONSANTO INDUSTRIAL CHEMICALS COMPANY FUNCTIONAL PRODUCTS GROUP 800 N. LINDBERGH BLVD. ST. LOUIS, MISSOURI 63166 The information herein regarding obtaining optimum results from askarel fluids in your transformer has been accumulated by Monsanto for ovor 40 years from the experience of makers and users of askarel transformers and it is believed will be helpful. Nothing herein shall be construed as applying to other than askarel insulation. Data and maintenance suggestions herein do not apply to the other components of the transformer. All operating and maintenance suggestions recommended by the manufac turer of the transformer should also be carefully followed. Because these maintenance directions apply only to the askarel insulation, Monsanto disclaims any liability for damage to property or injury to persons arising from transformer operation. NEV 0 0 7 7 3 5 706987 U S CUSTOMER SERVICE CENTERS AKRON. OHIO 44313 260 Springeide Drive Box 5444 Monfrom Development Perk Tel. 2161 6664111 ATLANTA. GEORGIA 30339 320 Interstate North Parkway Suie 600 Tel. (4041 434 4949 HOUSTON. TEXAS 77066 1300 Pott Oak Towar 6061 Westteinter Road Tei. 713) 621-9650 LOS ANGELES, CALIFORNIA 1401 Dove Street Suite 350 Newport Beech. Calitornie 92660 Tel. 714) 833-9150 NEW YORK. NEW YORK 10036 1114 Avenue of the Americas Tel. (212) 764 5000 ST. LOWS. MISSOURI 63166 800 N. Lindbergh Bird. Tel. 314)694 1000 IN I L U N A IIO N A l Of F ICES ARGENTINA - Momenta Argentine S.A./.C. Avde Medero 1020. Floors 17th & 18th Buenos Aires. Argentine AUSTRALIA Monsento Australia Limited Eest Tower, Princes Gete Bldg. 151 Flinders Street Melbourne, Victoria 3001 Austrelie Monsento Austrelie Limited 36 Terry Street Ro/elle. Sydney, NSW Australia 2039 Monsento Austrelie Limited Post Ofiice Bom 111 IK, Adoleide South Austrelie 6031 Monsento Austrelie Limited Brisbane P. 0. Bom 63, Hamilton Central Queensland, Austrelie 4007 Monsento Australia Limited Perth P. O. Bom 77 Doubleview West Austrelie 6018 AUSTRIA Monsanto GmbH Austria Am Stedtperk (Hilton Center) A 1030 Wien, Austria BELGIUM Monsento Europe SA. Avenue de Tervuren 270272 B-1150 Bruuels. Belgium Moneento Europe NV/SA 163 Mechelsesteenweg 2000Antwerp, Belgium BRAZIL Industries Monsanto Ltde. $81 Coneufeceo, First through Fifth Floors Seo Paulo, Brasil 01220 CANADA Monsento Canada Ltd. 176 Rexdete Blvd. Rexdeie, Ontario, Canada Monsento Canada Ltd. 100 Perk Royale. Suite 701 West Vancouver, B.C.. Cenede CHILE Monsanto Chile Comerciel a Industrial Limitede Edificio Esperte Olitine 602 Celle Estedo 337 Sentiego de Chile COLOMBIA Monsento Colombiens Inc. Cerrete 14. No 77 - $9 Bogota, Colombie DENMARK Momento A /S 6 Rysentteensgede O K 1664 Copenhagen Denmark EL SALVADOR Monsento Centroemence IE I Salvador) S.A. Edificio Plaie 67 Avenida Sur y Celle e Sente Tecla Sen Salvador, El Salvador FEDERAL REPUBLIC OF GERMANY Monsanto (Deutschland) GmbH Immermannstrasse 3 D -4 0 0 0 Dusseldorf, Federe! Republic of Germany FIN LA N D Monsento (Scandinavie) AB Arkedienketu 8 C 20 00100 Helsinki 10. Finland FRANCE Socit Monsento SA. 9 rue d'Argenson 76 Peris (8) France GUA TEMALA Monsento Guetemete Inc. Edifcio Cam 7e Avenida 7-t1 Zone 9 Guatemale City. Guatemale HONG KONG Monsento Far Best Ltd. Management House, 2nd Floor 26 Cene/ Rood West Hong Kong INDIA Mindle Chemicals Ltd. Wakefield House I f Sprott Rd.. Ballard Estate Bombay 400 001, Indie Mindie Chemicals Ltd. 19 Reiendreneth Mukherjee Rd. Calcutta 700 001, Indie Mindie Chemicals Ltd. 310-311 Linghi Chatty Street Madras 600 001, Indie Mindie Chemicals Ltd. 3/8 Asaf Ali Road New Delhi 110 001, Indie INDONESIA P. T. Monsanto Pen Electronics 191 Dj. Dr Seherdjo Jakarta, Indonesia ITALY Monsento Italiane Sp.A. Vie Melchiorre Gioie B Milano 20124, Italy JAPAN Monsento Japan Ltd. Room 217, Shin Kokuse! Bldg. 4 1, Merunouchi 3<home Chiyode-ku, Tokyo. Japan MALA YSIA Monsento Far Eest Ltd. Malaysia Branch) 116, Jelen Semenget Pete/ing Jeye. Selangor. Malaysia M EXICO Monsento Comerciel S.A. de C. V. Thiers No. 248 Mexico 5. D.F., Mexico NETHERLANDS Monsento B. V. Jen van Nassaustreet 63 56 Den Heeg Holland. The Netherlands NEW ZEALAND Monsen to New Zealand L id. 19 Greet South Roed Remuera Auckland 5, New Zeeland NICARAGUA Monsento (Nicaragua) S.A. P. 0. Box 288 Managua. Nicaragua NORWAY Monsanto Norge A.S. Fred Olsensgate 11 Oslo f. Norway PHILIPPINES Monsanto Philippines Inc. Suite 1101 Security Bank 6 Trust 6788 Ayate Ave. Meketi Risei 0-708. Philippines PUERTO RICO Monsanto Puerto Rico Company Munoz Rivere Ave. Borniquen St. Rio Piedras, Puerto Rico SINGAPORE Monsento Singapore Company fPte ) Ltd. Suite 706 Cathey Bldg.. 7th Floor Mount Sophie, Singapore 9 SOUTH AFRICA Monsanto South Africa (Pty.) L td. 11th Floor. Sandton City Bldg. Sandton, Transvaal, South Africa SPAIN Monsanto Iberice SA. Lepanto 3605 Barcelone 13. Spain SWEDEN Monsanto (Scandinavia) AB XxhemmersQBten 27 Bores, Sweden SWITZERLAND Monsanto (SuitoeI S.A. Postfach CH 5600. Lemburg, Swittertend TAIWAN Monsento Far Best Ltd. - fTaiwan Branch) 3 6 Cheng An Eest Road. 6th Floor Section I, Taipei Taiwan THAILAND Monsento Thailand Ltd. 6th Floor, Kamrnkfj Bldg. 120 SHom Road Bangkok, Thailand UNITED KINGDOM Monsanto Ltd. I 0 1$ Victoria Street Monsento House London SW1H ONQ England VENEZUELA Monsento (Venezuele) CA Torre Phelps Pisn 24 Plate Venezuele Caracas 101. Venezuela N6V 0 0 7 7 3 6 Monsanto Monsanto Industrial Chemicals Co. / A Unit of Monsanto Company / 800 N. Lindbergh Blvd., St. Louis. Mo. 63166 7 - l i me Mv < * 706988