US2416571A - Sealed apparatus for degreasing and drying articles - Google Patents

Description

R. cosw'AY 2, 1 SEALED APPARATUS FOR DEGRBASING AND DRYING ARTICLES Feb. 25, 1947.

and Sept. 10, 1942 3 Sheets-Sheet 1 u v m n a 6 w\ l w a H I m y m 1 L T l am fiq X /1 a P a m w FIGURE I ATTORNEY Feb 25, 1941,

5mm Arum-ms FOR nmnmsme AND mums An'r cms 3 Sheets-Sheet 2 Filed Sept. 10, 1942 FIGURE 2 INVENTOR RICHARD coswA'Y A'ITORNEY iCLES Feb. 25, 1941. R. 505w SEALED AIPARA'IUS FOR DEGREASIIIG AND DRYING ART Filed Sept. 10, 1942 a Sheets-Shoot s AiTQRNEY 1'. 5' r a FIGURE 3 luvs mon' mcump coswAY av PatentedFeb. 25,

mm'rns ran naonnasma name ARTICLES seamen Richard Cosway, Penketh, England, assignor Imperial Chemical Industries Limited, a corpo-v ration of Great Britain Application mesa, 10,1942. Serial No. 45mm in Great Britain mms, 1941 This invention relates to improvements in apparatus for degreasing metal and like non-absorbent articles.

It is knownto treat' metal and like non-absorbent articles with a volatile solvent such as trichlorcethylene either in liquid or in .vapour form, or both, so as to remove adherent greasy or oily material. The operation is frequently conducted in an open-topped vessel adapted to,

contain the solvent and having in the lower part means for heating the solvent, and in the upper part means for limiting upwardly the solvent vapour level. The goods so treated are subsequently dried by lifting them into the upper part of the vessel above the vapour level, when ad- ,herent solvent evaporates by reason'of the heat content of the goods and the heavy vapour falls back into the solvent zone. The ability of the goods to dry in this way is limited by their heat content and in some cases, as for example when they have hollows which retain solvent, this mode of drying may not be satisfactory. In British Patent No. 466,443 an apparatus for treating articles, particularlymetallic articles, with a liquid volatile organic solvent such as trichloroethylene is described in which the cleansing vessel is di-' rectly below a drying vessel provided in its lower part. with means for withdrawing solvent vapour generated by the drying, and which has a floor I ?caused'to open by the action of introducing the articles to be treated. into the lower vessel, and to close again. automatically when the articles are raised ,into the drying vessel. The means for withdrawing solvent vapour could be a pump in communication with a vessel containing an ad- .sorbent, and, though primarily designed for, use

stated to be with cold solvent, the apparatus was capable of use with a heated liquid solvent.

According to the present invention, an apparatus for degreasing metal and like non-absorbent articles with a volatile solvent and subsequently drying them comprises a lowersection adapted to act as a solvent degreasing compartj ment and an upper section adapted to act as a drying compartment, means for introducing articles into either section, means for isolating the upper section from the atmosphere and from the remainder of the apparatus'when thearticles are in the upper section, and means forestablishing,

when the articles are in the drying compartment, 50

a closed air circulation system,-whereby air can be passed through the drying compartment and thence through a solvent recoveryunit; In .a.

- preferred form of our invention the closed air circulation system, comprises a heater, a 'con'-= scams. (or. zoz-i'zoii heater.- 1 s In such' an. apparatus using a forced, hot air circulation system, rapid drying of the articles can be achieved irrespective of their heat capacity, and this withoutentailing'losses of sol-- vent to the atmosphere, and while keeping the i0 degreasing apparatus proper ready for immediate use when the dried articles are removed. The apparatus is particularly suitable for use in .degreasing with a solvent whose vapour is heavier than air, e. g. trichloroethyiene.

comprises an open-topped or tank-shaped vessel having around the walls at an intermediate height means for condensing solvent vapour, the vessel being thus divided into an upper and lower part 20 each adapted to contain means for'heating solvent in the lower part, a

closed air circulation system whereby hot aircan be circulated through the upperpart, a lid for isolating the vessel from the atmosphere, and means to isolate the upper part of the vessel from the lower part. Preferably the last said means comprises a platform adapted to carry the articles, which platform is capable of beingraised or lowered so that when in the lowered position the articles are in the lower part of the vessel and when in the raised position they are in the upper part, the platform then forming a closure be? tween the two parts of the vessel.

In use a charge of solvent is put into the lower part of the vessel so that articles therein are immersed in the solvent, the condensing means, e. g. condensing coils'to which cold water can be supplied, are put into operation, and the solvent is heated to boiling point. The condensing coils cause" vapour rising from the solvent to condense and fall back into the body of solvent so part of the-vessel forming the degreasing zone. Articles are then loaded on to the platform, and

the platform is then lowered into the solvent and left there until degreasing is completed. Preferably during this operation the lid of the vessel is closed to prevent escape from the apparatus of any solvent laden air which may rise in spite of the condensing coils, and this possibility is also minimized by having the upper part of the vessel forming. as it were, an antechamber between the degreasing none and the atmosphere. After the articles have been degreased, the platiorm is raisedso. that. when the articles are transferred In one form of. my invention" the apparatus I the articles to be treated,-

that the solvent vapour is confined to the lower I 'lid still being closed, the fan is put into operation so as to-circulate hot air through the upper part of the apparatus. containing the articles. thus drying them by causing solvent still adhering to evaporate and to be carried away in the hot air stream; the vapours are removed from the air stream in the solvent recovery unit, and the air is reheated and returned to the'drying compartment. When all the solvent has thus been removed the fan is stopped, the lid'opened. and the articles removed. In such an apparatus, instead of using the platform for the goods as the means for separating the two compartments the goods may be supported in a basket or the like, and a flexible sLutter or swinging doors may be used to cut off the drying compartment from the degreasing compartment,

In a further formv of my invention particularly suitable for continuous operation, the apparatus comprises a vessel having a closable opening and having around the walls at an intermediate height means for condensing solvent vapour, that part below the condensing means constituting a zone adapted for carrying out the degreasing process, and that part above the condensing means includingboth an {antechamber for load- .ing-and unloading the articles and a drying compartment, .an endless oonveyor for carrying the articles in turn through the antechamber, the

the motion of the conveyor is intermittent, the

conveyor being at rest for a short time while the articles are in the various sections of the apparatus. In using this apparatus articles are loaded on to the conveyor and are then moved down into the degreasing zone where they are freed from adherent grease and the like in the customary manner. The articles then rise from the degreasing zone on the opposite side of the partition and pass into the drying compartment. The doors to the drying compartment automatically open for this to happen and when the articles are inside they shut again, completely isolating the compartment from the atmosphere .and from the rest 'of the apparatus. The closedhot air circulation system is then putinto operation, and the articles are thus freed from adherent solvent carried up from the degreasing zone; The circulation of air is then stopped, and

degreasing zone and the j drying compartment, means for isolating the drying compartment from the degreasing ,zone and from the antechamber when thearticles are in the drying compartment, and a closed air circulation system whereby hot air can be passed throughthe drying compartment and thence through a solvent recovery system.

Thus the apparatus may comprise a closed vessel having condensing coils around the walls at an intermediate height and heating means in the lower part of the vessel for heating solvent placed therein so as to set up a solvent or a solvent vapourdegreasing zone. A centrally disposed vertical partition is arranged in the upper part of the vessel extending onthe one hand to somewhat below the level of the condensing coils and on the other hand almostto the top of the vessel, leaving only room for the passage of articles from one side of it to .the other. The upper section of the vessel isthus divided into two parts,

each capable of'containing the articles, and each of which is in communication with the solvent degreasing zone beneath.- One section is fitted with a closable opening for charging and discharging articles, and thus constitutes the antechamber, while the other section is in communication with the hot air circulation system and constitutes the drying compartment. An endless conveyor is arranged to carryarticles from theantechamber down into the degreasing zone, under the partition, and up into the drying compartment; thence the articles pass over the top of the partition. and back to the antechamber.- Moveable doors are provided for shutting oil the drying compartment from the degreasing zone and also fro m'the antechamber and thus from the atmosphere; Suitably these doors are autopassage throughthe condenser, it is frequently the conveyor then carries the articles over the top of the partition as the doors automatically open for this to be possible, and so into the antechamber. There they are unloaded and more are loaded in their place. The conveyor may be arranged to carry, e. g.th ree loads of articles so that one load is in the degreasing compartment while another is in the drying compartment, and the third i n the antechamber for unloading and replacement. I g

This continuous apparatusjis capable of various modifications. Thus the degreasing zone may include two or more degreasing compartments, for example, several liquor compartments together with a hot spray or vapour treating compartments. Again instead of dividing the upper part of the vessel into two by a permanent partition located within' the antechamber or between the antechamber and the degreasing zone,

' the drying compartment may be formed of-a pair of box-like members rotatable about perforated hollow axes to. approach one another and thus enclose the articles on the conveyor 'as they emerge from the degreasing zone. The hot air is supplied to and removed fr0m.the compart ment formed by the closed members through the hollow perforated axes. When drying is' complete the air circulation is cut oil and the boxlike member'sare moved apart to allow the articles to progress to the position for loading and unloading.

, The hot air circulation system suitable for use in any of theabove forms of the invention, may comprise a water-cooled condenser, a condensate trap, a blower and a heater, conduits being provided so that solvent-laden air from the drying compartment passes through the water-cooled condenser to condense out solvent vapour, and the'condensate is separated in the trap and returned to the degreasing compartment through a liquid seal formed, e. g., by a U bend in the return pipe. The air conduit from the condensate compartment. Suitably the air is "delivered to andremoved from a number of separate points of the drying compartment 50 that all parts of it may be swept by the air stream. In order to-free the articles of the least odour which might arise. from traces of solvent vapour remaining after desirable to complete the drying with fresh air, and for this purpose the air circulation system may be provided with an inlet for atmospheric condenser and condensate trap. If desired the' discharge to atmosphere may be through a charcoal adsorption system, or outside of the building housing the plant. The invention will now be described with reference to the accompanying diagrams in which Fig. I represents an elevation oi one form of apparatus according to' my invention,

Fig. II represents a sectional elevation of the same apparatus taken on a line 2-- 2 ofFlg. I,

trap 21 built on to the condenser II, and

a blower it operated by motor 29. Condenser II and blower I! are mounted on staging 3|. Condensate from trap 21 can be returned to sump 3 throughpipe 2s, and the air outlet from trap 2L to enable the passage of condensate through pipe closed and vice-versa. dicated generally at H air can be causedto cir- Fig. III represents a further form of my invenculate by blower .IS in turn through air heater tion adapted for continuous operation.

In Fig. I and Fig. II only, like numerals rep resent like parts, and for simplicity the condenser and like external parts of the air circulation system have been omitted from Fig. 11 and Fig. III.

Referring now to Figs. I and II, the apparatus comprises a deep open-topped vessel I. of sheet metal having at the bottom a sump 3 for solvent which can be heated by gas bumers 2. A flue ll for hot waste gases is provided extending vertically at the side of vessel I, and the sump 3 has a removable door fitted with a drain cock for emptying and cleaning purposes. At an intermediate height around the inside perimeter of the vessel I are condensing coils 4. through which cold water can be circulated by means not shown,

and which thus set an upper limit to the solvent degreasing zone I constituting the. lower part of vessel I. The upper part 8 of vessel I constituting the drying compartment, has a lid I which can be slid to one side on to supports 3 when articles have to be introduced and removed; both lid I and the parts of walls of vessel I bounding the compartment 8' are la ged with insulating material 32 to minimize loss of heat during the drying operations; an insulating course 33 is also built into the walls of vessel I at the level of the bottom of compartment 6. A cold-line" channe1.3l'to which cold water can be supplied is disposed somewhat below insulating course 33, so that the temperature gradient in the parts of the walls immediately above coils 4 can be minimized in the raised position. At the bottom of its travel the platform and any articles on it will be sublect to the action of the solvent in the lower 28 to be observed. An inlet 20 for atmospheric air controlled by valve 221s provided between valve l8 and blower I8, and between valve I8 and trap 21 is a discharge I9 to atmosphere controlled by valve v2I. Valves I8, 2I and 22 are interconnected by'linkwork 23 operated by lever 24 so that when valve I8 isopen valves 2| and 22 are By means of ducting indrying compartment 6, condenser I5 and trap 21 and thence either out through valve 2-I and outlet It or back to blower it according to the position of the valves I8; 2|, and 22. The ducting II has a number of inlets into compartment I tofacilitate the distribution of hot air. Several outlets are similarly provided. y In using this apparatus part 5 is filled with sol- 1 vent e. g. trichloroethylene, almost up to the level of coils, cooling water' is supplied to coils l and to channel, and the burners 2 are lit so as to heat solvent in the lower part I of vessel I to boiling,-vapour formed being condensed on coils ,4. Articles to be degreased are put on to the platform which is then lowered into the solvent, preferably after lid I has been moved into position over the top of vessel I. During this time the air circulation system is out or operation. When position in which valve I8 is open and valves 2| and are closed, and blower I6 is then put into operation, lid 1 being closed. Air'is thus circulated through heater I3, and after being heated passes into the drying compartment 6 causing sol; vent adhering to the articles on. platform! to evaporate and the vapour to be carried away in the air stream. Such vapours will be condensed out in condenser 25 and the condensate trapped v in trap I and returned via pipe 28 to sump 3, while pour, will'return to blower III through valve I8 to valve I8 is clpsed and valves 2| and 22 open. Air

the. air, freed from substantially all of the vabe re-circulated. When no more condensate is seen to flow past the sight glass and the articles are thus deemed dry, lever 24 is moved so that is thus sucked in through inlet 20 by the blower part 5 heated in sump 3. At the top or its travel the platform II co-acts with a ledge I2 inside the vessel at the level of insulating course 33 to form a seal between the part 6 of the vessel above the insulating course and the part 5 below coils 4. When the platform isin this raised position and lid I is in position, the drying compartment 8 is closed both from the atmosphere and from the.

' sisting of a Jacket around a part of due pipe I4,

- degreasing vessel, and the articles on the platform arewithin it.

a water-cooled condenser II fltted with. an inlet 7 2! and an outlet 26 for-cooling water, 'a con and circulated through the system and out through outlet I9.

A short time with this position of the valves snfllces to remove any odour of solvent which might otherwise remain, and blower I6 can then be stopped, lid 8 opened, the articles removed, and more articles requiring treatment introduced.

. The apparatus is immediately ready for. treating needed.

A further form of my invention will now be de- In t diagram the degreasi-ng apparatus is closed except for an opening 2' in the upper part of one side. Somewhat below the bottom of opening 2' are condensing coils 3' around the meme trough It walls, which coils can be supplied with cooling water by means notshown. Below coils3' the apparatus is .divided by a partition 9 into two degreasing-compartments ,5 and 6', and solvent'in these compartments can be heated by steam coils I and 8' respectively. A trough 10" is arranged to collect condensate from coils 3 and deliver it to compartment normally compartments 5.

will be full of solvent while compartment 8 will contain only suflicient to keep coils- 1 covered when in operation, and the supply of steam to that coil will be sufiiciont to keep the apparatus full of vapor up to coils3; condensate from falling into compartment 5 wi1l thus cause solvent to overflow partition 9' into compartment 6 to maintain the supply of solvent for vaporisation. A conveyor ll formed of two chains (one of which is shown) spaced apart at intervals along their path by spacer bars l2 (of apparatus the basket comes again adjacent to' opening 2' ready for unloading. Across the major portion ofgthe apparatus extends a partition 20', space being left to permit .the movement of the largest of pulleys l3. Opening 2is provided with a door I 9 so hinged at the lower edge of opening 2' that'when'open part of the door projects inwards and meets the edge of partition 20'; when closed the inside portion lies adjacent to the wall of the a paratus out of the path of the baskets of articles.

. v Q 8 I of the members 14, I 4', a1so form a surface substantially continuous with partition 20' and the inside portion of door 19 when it is open, thus cutting oi the lower degreasing compartments of the apparatus from'the upper part -4' of the ap aratus which thus constitutes an antechamber On the side of partition 20' remote from opening 2' are two box-like members I4. l4 rotatable about hollow axles l6, IB','of which the portions IT to the? air heater of the closed' hot air cir-" culationsystemand the other is connected by conduit l8 to the solvent recovery unit (con-'- 1 denser) thereof. 1 the drawing, but is equivalent to that of Figure I in all relevant respects, except that a steam This system is not shown in operated air heater is provided and the condensate from the condensate trap is delivered to degre'asing compartment 5". The two members l4, l4 can be rotated each about one of the axles l6, l6, so that in one position the bottom faces I 5, l5 thereof project verticallyupwards leaving room for the passage of articles on the conveyor upwards from the lower degreas'ing section to the top of 'thesectiori 4' of the apparatus above the members l4, 14'. In the position'shown, how ever, the two members co-act to enclose a basket of articles shortly afterit'has left the degreasing sectionof the apparatus, thus forming a drying compartment 2|, in which the basket of articles is isolated from the atmosphere and from the remainder of the apparatus." The members are provided with the necessary recesses to accommodate the suspension members of. the basket, and if desired the members I4 may be edged with some resilient material substantially inert to the ment is formed." One basket is shown in position in the drying compartment 2|. In the position shown, the sloping lower faces [5, I5,

to the decreasing compartments in which loading and unloading can proceed. Normally mem I bers l4, I4 are-in the position shown in the diagram and are only moved aside when it is depropriate for loading and unloading'a basket of articles. The lengthof the conveyor is such also that when any one spacer bar is in position for loading'and unloading, a basket of articles hanging from another bar is in one 'of the sol vent degreasing compartments and another hanging from a third bar is in the drying compartment. p

In using this apparatus compartment 5 is filled with a solvent, e. g. trichloroethylene, and sufficient is also put into compartment 6' to cover coils 8'. Condensing water is then supplied to coils 3' and steam to coils 1' and 8' so that the solvent circulation is set up; the apparatus is then ready for carrying out the degreasing process. .The door- I9 being open and the conveyor ll' being at rest in an appropriate position, a

basket ofarticles to be degreased is hung on'ap proprlate spacer bar H. The door I9 is then closed leaving a clearpassage for the basket, and

the conveyor 'ls put into operation so that the basket is carried-down into degreasing compart- I ment 5'." The conveyor II will then automatl cally stop, and door [9" can be opened for an other basketto be inserted and-so on. When a basket rises rrom the degreasin'g compartment 6' and approaches compartment -2l" members I 4',- H are separated to permit'it to enter and are then brought together again to enclose it, the conveyor ll automatically stopping when the basketis in the appropriate position in the compartment. While a basket of articles adjacent to opening 2' is being unloaded and another solvent so that a substantially air-tight compartloaded in its place the hot air circulation system is put into operation to dry articles in that basket within compartment 2| in th manner described in connection with the apparatus 'illus-- trated by Figures I and II. When this operation and the loading operation are complete the air stream is out ofi, door I9 is closed, members I4, I 4' separated, and the conveyor caused to move on by an appropriate amount. This cycle of operations will then be continued in this manner as desired, the articles being carried from theantechamber 4' in turn through solvent compartment 5', where they receive a hot liquor treat ment, and through compartment 6', where they receive a solvent vapour treatment, to drying comlpartment- 2| and thence back to the antechamer v I claim:

1. An apparatus for degreasing metal and like non-absorbent articles with a volatile solvent and subsequently drying them, comprising in combi- The shape of partition 20' nation an open-topped vessel having around its walls at an'intermediate height and within a; lower degreasing compartment means for condensing solvent vapour, a solvent recovery system an upper drying and-a lower degreasingarticles under treatment are in said drying compartment, comprising an upwardly projecting ledge member disposed on the internal walls of said vessel, and a movable partition member provided -with meansvfor coacting with said ledge member, means for introducing the articles into either compartment, and a closed hot air circulating system associated with said "drying compartment, whereby air can be passed in turn through the drying compartment and through I said solvent recovery system.

.2. An apparatus for degreasing metal and like non-absorbent articles with a volatile solvent and subsequently drying them, comprising in combination an open-topped vessel having around.

1o h l. 4. An app atus for degreasing metal and like non-absorbent articles with a volatile solvent and subsequently drying them, comprising in, combination an'open-topped vessel having around its walls at an intermediate height and within a lower degreasing compartment means for condens'ing solvent vapour, a solvent recovery system, an upper drying and a lower degreasing compartment in said vessel each adapted to con- 'tain the articles to be treated,-means for heating solvent in the lower compartment, means for sealing oil and isolating the upper compartment from said lower compartment and the atmosphere when articles under treatment are in. said drying compartment, comprising a movable platform adapted to carry the articles and to be raised or lowered so that when in the lowered position the articles are in the lower compartment of the vessel and-when it is in the raised position they are in the upper compartment, a ledge member inwardly projecting from and secured to the internal wallslo'f said vessel, means its walls at an intermediate height and'within a lower degreasing compartment means for condensing solvent vapour, a solvent recovery system, an upper drying and a lower degreasing compartment in said apparatus each adapted to contain the articles to be treated, means for heating solvent in the lower compartment, means for sealing oil! and completely isolating the upper compartment from said lower compartment and the atmosphere when articles under treatment are in said drying compartment, comprising a ledge member projectingv inwardly from and secured to the internal walls of said vessel, a movable partition member provided with means adapted to coact with said ledge member, means for introducing the articles into either compartment and a closed hot air -circulating system communicating with said,drying compartment, comprising a heater, a water-cooled condenser,

- a condensate trap and a blower whereby air may be caused to circulate in turn through the'heater,

the drying compartment, and the water-cooled condenser.

3. An apparatus for degreasing metal and like non-absorbent articles with a volatile solvent and carried by said platform adapted to coact with said ledge, whereby said compartments are sealed on. from each other when said platform is in its completely raised position. and a closed hot air circulation system in communicationlwith said drying compartment comprising a heater, a water-cooled condenser, a condensate "trap and a blower whereby air may be caused to-circulate in turn through the heater, the drying ,compartment, and the water-cooled condenser.

5. An apparatus for degreasing metal and like non-absorbent articles with a volatile solvent and subsequently drying them, comprising, in combination, a lower section adapted to act 'as a solvent degreasing compartment, an upper section adapted to act as a drying compartment, means for introducing articles into said compartments atmosphere and from said lower section after introducing articles under treatment into said drying compartment, a solvent recovery system,

and means in communication with said drying compartment for establishing a closed hot air I circulation system, comprising a heater, a conmerit, a platform provided with means for seal- Y ing of! and isolating the upper compartment from said lower compartment and the. atmosphere when articles under treatment are in said drying compartment, said platform being adapted to carry the articles under treatment, and capable of being raised or lowered so that when in thelowered position the articles are in the lower compartment of'the vessel and when it is in the raised position they are in the upper compartment, and a closed hot air circulation system in communication with said drying compartment. whereby air can be passed in turn through the drying compartment andpsaid solvent recovery unit. 3

denser.- I 6. Anapparatus for degreasing metal and like denser, and a blower, and further means for selectively controlling the circulation of air through the system and in turn through said heater, said drying non-absorbent articles with a volatile solvent and subsequently drying them, comprising, in combination, a lower section adapted to act as a solvent degreasing compartment and an upper sectiori adapted toact as a drying compartment means for introducing articles into 'said compartments for treatment, means for sealing oif ,and'completely isolating said upper section from the atmosphere and from said lower section after turn through said heater, said drying compartment and said water-cooled condenser. 1 -'1.- An apparatus according toclaim 6 in which the said hot air circulation system includes an compartment, and said conthe condenser.

through the said inlet and discharged again 5 through the said outlet after passing in turn through the heater, the drying-compartment and 8. An: apparatus according to claim 2 in which the said hot air circulation system includes an inlet for air, a dischargeto atmosphere, and a system 01' valves interconnected so thatinone positionthe air circulates repeatedly through the system and in another'position air is drawn in L through thesaid inlet and discharged again through the said outlet after passing in turn a through the heater, the drying compartment and the condenser.

9. An apparatus according to claim 4 in which the said hot air circulation system includes an inlet for air, a discharge to atmosphere, and a system of valves interconnected so that in-0ne position the'air circulates repeatedly through the system and in another position air is drawn in through the said inlet anddischarged again through the said outlet after passing in turn through the heater, the drying compartment and the condenser. I

e RICHARD COSWAY.

v 12 REFERENCES crrnn.

The'following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,234,593. Ferm Mar. 11, 1941 2,240,989 Hood May 6, 1941 2,273,939 Dammers Feb. 24, 1942 1,873,167 Weber Aug,23, 1932 1,851,856 Loesch Mar. 29, 1932 1,631,036 Ironside" May 31, 1937 2,090,192 Edhofer Aug. 17, 1937 2,280,811 Edhofer Apr. '28, 1942 FOREIGN PATENTS Number Country Date 528,040 British Oct. 22, 1940 216,423 Swiss Dec. 1, 1941 87,314 Sweden Sept. 8, 1936 528,080 British Oct. 22, 1940 466,443 British Mayt28, 1937' 400,613 British Oct; 23, 1933 OTHER. REFERENCES Imperial Chemical Ind., British 475, 814, C. A); Nov. 25,1937. 1 r

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