US3030892A - Diaphragm pump - Google Patents

Description

April 24, 1962 .1. E. PlccARDo 3,030,892

DIAPHRAGM PUMP Filed Feb. 25, 1960 United States Patent 3,030,892 DIAPHRAGM PUMP Jaclr E. Piccardo, Gilliland, Calif., assigner to Dorr- Oliver Incorporated, Stamford, Conn.,v a corporation of Delaware Filed Feb. 23, 1960, Ser. No. 10,391 9 Claims. (Cl. 10S-44) This invention relates to improvements in pressure-fluid actuated diaphragm pumps wherein a diaphragm is actuated bythe pressure of a controlled fluid pressure medium admitted to one side of the diaphragm.

The invention provides a fluid actuated diaphragm pump particularly adapted to handle coarse slurries or pulps, for example cement or concrete which had presented problems because of the relatively large solids and the resulting wear and tear on the parts and on the working diaphragm, and because of the possibility of overstretching of the pump diaphragm by the pressure of the operating fluid.

Diaphragm pumps employed for similar purposes suffer from a number of disadvantages, one of which is due to the fact that they are not readily capable of passing coarse particles and may become jammed when larger pieces of material pass therethrough.

Furthermore, since it is preferable to operate such pumps with rather high liuid operating pressures, such pressures may cause overstretching or rupture of the working diaphragm, unless a backing surface is provided dening the extreme outward position of the diaphragm. lf in the conventional pumps such a backing surface be presented by the associated wall portion of the pump housing itself, solids are likely to get trapped between the diaphragm and the wall as the slurry is being displaced through the discharge outlet in this wall, leading to damage of the diaphragm. Also, under such conditions, the pressure of the actuating fluid may cause undesirable distension of an unsupported portion of the diaphragm into the discharge opening, unless this is prevented by some perforated septum in the discharge opening. This may also be prevented by a perforated auxiliary backing wall across the pump housing and spaced from the pump wall and from `the discharge opening. Yet, under slurry pumping conditions such as herein contemplated, any such perforated backing element is liable t plugging by the slurry particles passing back and forth therethrough and thus offer undesirable flow resistance, also they are liable to excessive wear by the slurry particles passing back and forth therethrough. Plugging occurs when the perforations are too small, but when the perforations are too large the drawback is that the required amount of backing support is lost.

The present invention overcomes the aforementioned difficulties encountered with diaphragm pumps now commonly in use for this purpose. This is achieved by a double diaphragm arrangement wherein the actuating pressure from a fluid operating pressure medium such as water or air against an actuating diaphragm is transmitted to an associated working diaphragm through a pressure transfer liquid connedbetween the two diaphragme. Each one of these diaphragms has a pre-formed dished configuration which may assume bulging end conditions in opposite directions at the respective ends of the stroke of the pump, yet automatically so controlled thatvoverstretching of the working diaphragm is positively avoidable, irrespective of the amount of fluid operating pressure applied to the working diaphragm.

According to the invention, this eiect is achieved by providing in the pump housing between the two diaphragme a foraminous backing plate dish-shaped so as to conform to the predetermined pump stroke end position of the operating diaphragm. r[he working diaphragm through 3,039,892 Patented Apr. 24, 1962 ice the intervening confined body of transmission uid attains a correspondingly shaped bulging configuration that is without any stress on the diaphragm itself at the end of the pumping stroke. Thus the diaphragm is never overstressed since it never engages a backing face or the like but is in free contact at all times with the slurry being pumped. To ensure this, the confined body of transmission liquid must not exceed a predetermined maximum quantity.

According to a feature, the space between the diaphragm is in communication with manually adjustable means for varying the amount of iluid between the diaphragms.

Consequently, in the operation of the improved pump, regardless of the iiuid operating pressure (by either liquid or by air) applied to the actuating diaphragm, the pressure across the working diaphragm will always equalize itself to the prevailing pumping head. ln this way, the working diaphragm remains unrestrained and free-oating due to the equalized pressures on both sides thereof. Also, in case the suction valve should remain open on the pumping stroke while the outlet valve is normal, then the pressure on the working diaphragm itself will be more or less zero irrespective of what operating pressure is applied to the actuating diaphragm pressed against the foraminous backing plate. Furthermore, no plugging can occur in the foraminous backing plate since only clear liquid and not slurry passes back and forth through the perforations.

According to another feature, the discharge end of the housing is so shaped that the working diaphragm in its retracted or innermost position provides with the housing an ample space or relatively large area through which may pass relatively large particles freely that are being pumped through the apparatus. Also, in this way, the working diaphragm is always even in its outermost pumping strokeJ position, spaced from the adjacent walls of the housing, so that there is no possibility that solid material will be trapped between the working diaphragm and the housing walls that would tend to cause abrasion and excessive Wear of the working diaphragm, and the two diaphragms themselves are maintained in spaced relationship to each other due to the hydraulic pressure transmitting liquid contained between them. The actuating diaphragm is operated by suitable conventional iiuid pressure (water or air) operating mechanism, while the fluid disposed between the two diaphragms also serves as an effective means for conducting heat away from the working diaphragm in case hot slurries are pumped so that the diaphragm will not heat up excessively during operation.

An object of the present invention is the provision of a new and novel double diaphragm pump apparatus which is particularly adapted for use in pumping materials having relatively large objects therein such as concrete and the like.

Another object of the invention is to provide a double diaphragm pump apparatus wherein no special support means is required for the working diaphragm and which prevents excessive stretching of the working diaphragm.

A further object of the invention is the provision of a double diaphragm pump Iapparatus including means for l preventing excessive heating of the working diaphragm FIG. 1 illustrates a sectional view of an embodiment of the double diaphragm pump according to the present invention along with a diagrammatically illustrated operating mechanism for the pump apparatus;

FIG. 2 illustrates a modified form of the invention incorporating a different type of working diaphragm.

Referring now to the drawings wherein like reference characters designate corresponding parts throughout the views, there is shown in FIG. l a body means indicated generally by reference numeral and including three separate sections 11, 12 land 13 which are bolted to one another by nut and bolt assemblies 15. Section 11 of the body means includes an inlet portion 20 and an outlet portion 21. It should be noted that the outlet portion 21 is directed substantially horizontally while the inlet passage entering the pump from the inlet portion 20 is directed downwardly at substantially ya 45 angle to the horizontal such that it may be said that the inlet and outlet portions have an angular relationship to one another such that the inlet is directed at an angle of 45 to the outlet. This angular relationship is important in combination With the angular relationship of the longitudinal axis of the body means itself which is disposed at an angle of substantially with respect to the horizontal. This particular interrelationship as described hereinafter cooperates to assist in passing large objects through the pump.

Inlet portion is provided with suitable attaching flanges which are bolted to an attaching flange on a conduit 22. Conduit 22 is connected with a body portion of a check valve body indicated generally by reference numeral 23. A seat 24 is provided within the check valve body, and a ball 25 is adapted to rest upon seat 24 in sealing position therewith. Ball 25 is shown in sealing position in FIG. 1. An inlet conduit 26 is connected to the lower portion of the check valve body means, and the incoming slurry or pulp passes through inlet conduit 26 in the direction of the arrow during operation.

During the suction of the pump, ball 25 is lifted into the dotted line position shown in FIG. l thereby providing a large passage Iarea for coarse material through the check valve. It is evident that upon the pumping stroke of the pump, ball 25 will again be seated upon seat 24 of the valve to prevent reverse flow through the check valve. Outlet portion 21 is also provided with attaching flanges which are secured to suitable attaching flanges provided on a conduit 27. Conduit 27 is in turn connected with the lower portion of a second check valve body means indicated generally by reference numeral 28 which is similar to the check valve body means 23 previously described. Disposed within the check valve body 28 is a valve seat 29 and a check ball 30 is adapted to rest upon the valve seat in sealing relationship therewith.

'I'he outlet portion of valve body means 28 is connected with an outlet conduit 31. It is evident that during the suction stroke of the pump, ball 38 will be urged into sealing engagement with seat 29 to close off the connection of the pump with the outlet conduit. On the other hand, during the pumping stroke, ball 30 will be lifted off of the seat 29 into the dotted line position to provide a relatively large passage area to permit the coarse materials to freely pass through the check valve.

Clamped between body sections 11 and 12 is a flexible deformable working diaphragm 40 formed of gum rubber or other suitable material and being sealed with respect to the housing due to the clamping arrangement of sections 11 and 12. An actuating diaphragm 41 of similar construction to diaphragm 40 is clamped between body sections 12 and 13 whereby the working diaphragm and actuating diaphragm of the apparatus are normally disposed in spaced relationship to one another.

A support member 42 is preferably formed integral with body section 12 and comprises a rigid wall having la plurality of orifices 43 formed therethrough. Wall 42 is provided with such a configuration that when the actuating diaphragm is in its normal fully extended pumping pumping stroke position, it will conform to the configuration of supporting wall 42 and be firmly supported thereby.

It will be noted that as seen in FIG. 1, a space 45 is defined between the two diaphragms, or, stated another way, as seen in FIG. l, this space is defined between the working diaphragm and supporting wall 42. Disposed within this space is a suitable hydraulic fluid which is adapted to transmit movements of the actuating diaphragm 41 to the working diaphragm 40. It is apparent that the orifices 43 in wall 42 permit the hydraulic fluid in space 45 to pass freely through the wall portion whereby the working diaphragm will closely follow the movements of the actuating diaphragm.

It is evident that the hydraulic fluid between the two diaphragms will provide a good heat conductor such that heat Will be conducted away from the working diaphragm 40 and to further ensure that adequate cooling of the hydraulic fluid itself is obtained, a water cooling jacket space 46 is provided by a wall portion 47 spaced from the outer wall of body section 12. Any suitable means may be provided for circulating cooling water within the cooling jacket space.

A conduit 50 is disposed in communication with the space 45 between the actuating and working diaphragms, the opposite end of conduit 50 being in communication with the interior of a hollow closed cylindrical housing 51. A diaphragm 52 extends across` an intermediate portion of the housing 51, and hydraulic fluid is disposed within the space defined between flexible diaphragm 52 and the opposite end of the housing 51. A screw member 53 is threaded within the left end of the housing as seen in the drawing and is adapted to engage the flexible diaphragm 52. It is apparent that by adjusting the position of screw member 53, the position of flexible diaphragm 52 may be varied to control the amount of hydraulic fluid which is forced up into the space between the two diaphragms. In this manner, the amount of fluid between the two diaphragms may be altered to vary the stroke of the working diaphragm during operation of the pump. For example, if the screw 53 were being turned to move outwardly from the housing 51 thereby allowing for additional storage space therein, there would result a shortening of the effective pumping stroke of the working diaphragm 40 as indicated by the dot-and-dash end position D1 thereof, coordinated to the full line end position D2 of the actuating diaphragm 41 which latter is supported by the perforated wall 42. The correspondingly reduced effective volume of confined transmission uid is indicated by cross-hatching H1 in one direction between diaphragm position D1 and D2. The respective opposite end positions D3 and D4 respectively of the two diaphragms indicated in dot-and-dash lines represent the condition at the end of the pump suction stroke. The confined transmission fluid is indicated by hatched lines H2 in a different direction and the working diaphragm then in position D3 resting against and backed up by the central portion of the perforated wall 42 preferably supplemented by an auxiliary marginal wall 42 complementary to the central portion of wall 42 to constitute therewith a dish-shaped backing surface which may be substantially symmetrical to the dish-shaped wall 42. Consequently, the hatched areas H, and H2 overlap in the peripheral annular space H3 between the backing wall 42 and the auxiliary backing wall 42a. When the full stroke capacity of the pump is to be used, the device 51, 52, 53 may be manipulated so that overstressing of the working diaphragm at the end of the pumping stroke is partially avoided.

A clean-out openingis indicated at 55 in the side of the body means, and suitable plugs are indicated at 56 and 57. It is apparent that various drain plugs and the like may be provided as desired within the body means of the apparatus.

A threaded boss oil is formed in the central portion of body section 13 and a nipple 61 is threaded therein and communicates with a cross pipe fitting 62. A nipple 63 is threaded to one of the lateral sides of iitting 62 and a nipple o4 is threaded to the opposite lateral side of fitting 62. Nipples 63 and 64 are in turn in communication with solenoid operated valves 65 and 66 respectively which in turn communicate with conduits 67 and 68 respectively which are connected to sources (not shown) of fluid under different pressures. For example, conduit 67 may communicate with a source of subatmospheric pressure while conduit 68 may communicate with a source of atmospheric pressure or a source of subatmospheric pressure. Furthermore, gravity may be relied upon to either charge or discharge the pump. If gravity is utilized to charge the pump, then a positive pressure must be used to discharge the pump. If gravity is used to discharge the pump, then a subatmospheric pressure must be used to charge the pump.

Solenoid valves 65 and 66 are operated through a conventional electric circuit '70 from a timer or clock '71 of any suitable type. The fitting 62 is also connected through a valve 74 to a pressure or vacuum gauge 75. Clock mechanism 7l serves alternately to open and close solenoid valves 65 and 66 and to cause the actuating diaphragm 4l to oscillate between its suction position wherein it is drawn up against body section 13 to itsV pumping position shown in FIG. l wherein it is forced against the support wall.

It will be understood during operation that on the suction stroke of actuating diaphragm 41, working diaphragm llt will be drawn into the dotted line position indicated at D3 in FIG. -1. As this suction stroke occurs, the upper check valve will be open and the lower check valve will be closed. lt is apparent that as the material enters the body means, :it will be directed directly into the body means at an angle, and a relatively large area will be dened between the working diaphragm and portion 80 of body section 1l. This relatively large area is adapted to easily accommodate any large particles of material which may be drawn in with the pumped uid. Such large particles will tend to settle to the bottom of the pump body means whereupon the inclination of the pump body means itself with respect to the horizontal tends to move these large particles downwardly toward the outlet portion 2l of the pump.

Upon movement of the actuating diaphragm 41 in its pumping stroke, working diaphragm 4t) will be urged in a similar manner back toward the full line position shown in FlG. l through the intermediary of the hydraulic fluid disposed between the two diaphragms, and the iluid within the pump will be urged outwardly through the outlet portion 21 and the outlet conduit 3l. During this pumping stroke, the upper check valve will be closed and the lower check valve will be open. lf it is desired to vary the pump output as by shortening the stroke of the working diaphragm, the amount of liquid between the two diaphragms maybe altered by actuating screw member 53.

Referring now to FIG. 2 of the drawing, a modification is illustrated wherein the body means is indicated generally by reference numeral 8l, the body means including an inlet portion and an outlet portion, along with associated check valve mechanisms (not shown) in a manner similar to that described in connection with FIG. l.

An actuating diaphragm 86 is provided similar to diaphragm 4l of the device shown in FIG. 1 which is in communication with a similar operating mechanism through a threaded boss 87. The actuating diaphragm 86 coopcrates with a supporting wall portion 83 similar to wall portion 42 and being provided with a plurality of orilices S9. The primary distinction of the apparatus shown in FiG. 2 over that shown in FIG. l is the mode of construction of the working diaphragm 90. In the modification shown in FIG. 2, this working diaphragm is in the form of a bellows and includes a corrugatedside wall portion 91, this corrugated portion being preferably reinforced by a plurality of wires 92. With this type of construction, the diaphragm may be formed of Teon which is a very desirable material to employ in chemical pumping operations. Teon can not normally stand the exing encountered if it is fabricated as a diaphragm shown in FIG. l, but it is adapted to be formed as a bellows which is compressed by the actuating diaphragm during operation. It will be understood that the operation of the apparatus shown in FIG. 2 is substantially the same as that shown in FlG. l.

In order to provide an additional safety feature, a photoelectric cell (not shown) may be mounted in the body section -12 between the two diaphragms in Such a position that it is in communication with the space dened between the diaphragms and is adapted to sense changes in the fluid in such space. The photoelectric cell can be connected wtih a suitable alarm bell or the like such that if the working diaphragm should fail, the mixing of the pumped iluid with the hydraulic fluid would be sensed by the photoelectric cell thereby sounding the alarm bell. This safety feature may be important when hazardous liquids and slurries are being pumped and an immediate indication would be provided when replacement of theA working diaphragm is required.

It is apparent from the foregoing that there is provided a new and novel double diaphragm pump apparatus which is particularly adapted to pump materials having relatively large objects therein and which is adapted to operate under high pressures without damages to the diaphragms thereof. No special support is required for the working diaphragm in the apparatus, and in addition, the working diaphragm can not be excessively stretched during operation. This is insured by ythe provision of the support wall between the two diaphragms which positively limits pumping movement of the actuating diaphragm and accordingly thereby also limits the pumping movement of the working diaphragm. The hydraulic fluid also serves as an etlcient means for conducting heat away from the working diaphragm. The overall structural arrangement is such that the solid materials can not be trapped between the working diaphragm and the body means thereby reducing abrasion and wear of the working diaphragm to a minimum. In addition, pressures on opposite sides of the working diaphragm are equalized regardless of the discharge head conditions. The apparatus is also quite simple and inexpensive in construction and yet is sturdy and reliable in operation.

As this invention may be embodied in several forms Without departing from the spirit or essential characteristics thereof, the present embodiment is therefore illusltrative and not restrictive, and since lthe scope of the invention is dened by the appended claims, all changes that fall within the metes and bounds of the claims or that form their functional as Well as conjointly cooperative equivalents are therefore intended to be embraced by those claims.

I claim:

1. In a Huid-actuated double diaphragm pump wherein the pump housing is `divided by the diaphragms into an actuating chamber for the actuating iiuid, a pumping chamber, and an intermediate fluid pressure transmission chamber between said actuating chamber and said pumping chamber, the arrangement which comprises an intermediate substantially cylindrical housing section formed with a flange at each end and having transverse extending foraminous partition means integral and merging with one flanged end thereof, and shaped to conform to4 and said closure means and adapted to conformingly engage said foraminous partition means; a housing end section for closing the other end of said intermediate housing section and having intake means and discharge means, to constitute the pumping chamber; and working diaphragm means held between said intermediate housing section and said housing end section, and defining with said other diaphragm and with said intermediate housing section the intermediate fluid transmission chamber.

2. The arrangement according to claim l with the addition of a heat exchange jacket surrounding said intermediate housing section unitary therewith.

3. In a fluid-actuated double diaphragm pump wherein the pump housing is divided by the diaphragms into an actuating chamber for the operating fluid, a pumping chamber, and an intermediate fluid pressure transmission chamber between said actuating chamber and said pumping chamber, the arrangement which comprises an intermediate substantially cylindrical housing section formed with a flange at each end; a transverse extending foraminous partition means associated with one flanged end of said housing section, and shaped to conform to the actuating diaphragm means defined below, a flanged cover means for closing the one flanged end of said intermediate housing section; a dished actuating diaphragm means held between the associated flanges of said intermediate housing section and said cover means and adapted to conformingly engage said foraminous partition means; a

flanged housing end section for closing the other flanged end of said intermediate housing section and having in take means and discharge means for pumping, a working diaphragm means held between the associated flanges of said intermediate housing section and said housing end section, and defining with said other diaphragm and with said intermediate housing section the intermediate fluid transmission chamber; and a heat exchange chamber surrounding said intermediate housing section and defined by the cylindrical wall of said housing section, furthermore by the flanges thereof, and also by an outer Wall surrounding said cylindrical wall and having its ends connected to respective flanges of said housing section.

4. In a fluid-actuated double diaphragm pump for pumping slurry or the like, wherein the pump housing is divided by the diaphragms into an actuating chamber for the actuating fluid, a pumping chamber, and a fluid pressure transmission chamber intermediate said actuating chamber and said pumping chamber, the arrangement which comprises an intermediate substantially cylindrical housing section formed with a flange at each end, transverse foraminous partition means integral with said cylindrical housing section, comprising a pair of marginal annular portions each extending inwardly from a respective flanged end portion of said housing section integral therewith and merging with each other in a common central portion, said partition means presenting each in respective outward axial direction a surface contour substantially shaped to conform to the shape of respective diaphragm means defined below; a flanged closure means for the one flanged end of said intermediate housing section and with said foraminous partition means constituting said actuating chamber; a dished actuating diaphragm means held between the associated flanges of said intermediate housing section and `said closure means and adapted to conformingly engage said foraminous partition means; a flanged housing end section for closing the other flanged end of said intermediate housing section and having intake means and discharge means, to constitute the pumping chamber; and working diaphragm means held between the associated flanges of said intermediate housing section and said housing end section, and defining with said other diaphragm and with said intermediate housing section the intermediate fluid transmission chamber.

5. The arrangement according to claim 4, with the addition of a heat exchange chamber surrounding said intermediate housing section and defined by the cylindrical wall of said housing section, and by the flanges thereof,

as Well as by the outer wall surrounding said cylindrical wall and having its ends connected to respective flanges of said intermediate housing sections.

6. The arrangement according to claim 4, wherein the longitudinal axis of said intermediate housing section constitutes an acute angle with the horizontal, and wherein said intake means comprise an upwardly inclined intake neck portion, and said discharge means comprise a discharge neck portion located below said intake neck portion and directed at an angle with respect thereto, constituting a pump chamber shaped like a Y lying on its side adapted to facilitate gravitational passage of the slurry through said chamber.

7. In a fluid actuated double diaphragm pump for pumping slurry or the like, wherein the pump housing is divided by the diaphragms into an actuating chamber for the operating fluid, a pumping chamber, and a fluid pressure transmission chamber intermediate said actuating chamber and said pumping chamber, the arrangement which comprises an intermediate substantially cylindrical housing section formed with a flange at each end with the longitudinal axis thereof extending at an acute angle to the horizontal declining towards the pumping chamber; a transverse foraminous partition means provided in said housing section, shaped to conform to the actuating diaphragm means defined below; a flanged closure means for the one end of the intermediate housing section and with said foraminous partition means constituting said actuating chamber; a dished actuating diaphragm means held between the associated flanges of said intermediate housing section and said cover means and adapted to conformingly engage said foraminous partition means; a flanged housing end section for closing the other flanged end of said intermediate housing section, said section having an upwardly directed intake neck portion, and a discharge neck portion located below said intake neck portion and directed at an angle with respect thereto, constituting a pump chamber shaped like a Y lying on its side adapted to facilitate gravitational passage of the slurry through said chamber; and working diaphragm means held between the associated flanges of said intermediate housing section and said housing end section.

8. In a fluid-actuated double diaphragm pump, wherein the pump housing is divided by the diaphragms into an actuating chamber for the operating fluid, a pumping chamber, and a fluid pressure transmission chamber intermediate said actuating chamber and said pumping chamber, the arrangement which comprises an intermediate substantially cylindrical housing section formed with a flange at each end; a transverse foraminous partition means at one end of said housing section, shaped to conform to the actuating diaphragm means defined below; a flanged closure means for said one end of the intermediate housing section and with said foraminous partition means constituting -said actuating chamber; a dished actuating diaphragm means held between the associated flanges of said intermediate housing section and said closure means and adapted to conformingly engage said foraminous partition means; a flanged housing end section for closing the other end of said intermediate housing section and having intake means add discharge means, constituting a working diaphragm means held between the associated flanges of said intermediate housing section and said housing end section, and comprising an accordion-shaped body portion extending from said flanges towards said foraminous partition; and a heat exchanger chamber surrounding said intermediate housing portion and defined by the cylindrical wall of said housing portion, furthermore by the flanges thereof, as well as by an outer wall surrounding said cylindrical wall and having its ends connected to respective flanges of said housing portion.

9. In a fluid-actuated double diaphragm pump for pumping slurry or the like, wherein the pump housing is divided by the diaphragms into an actuating chamber for the operating uid, a pumping chamber, and a uid pressure transmission chamber intermediate said actuating chamber and said pumping chamber; the arrangement which comprises an intermediate substantially cylindrical housing section formed with a ange at each end, with the longitudinal axis thereof extending at an acute angle to the horizontal declining towards the pumping chamber; a transverse foraminous partition means at one end of said housing section, shaped to conform tothe actuating diaphragm means defined below; a anged closure means for closing said one end of the intermediate housing section and with said foraminous partition means constituting said actuating chamber; a dished actuating diaphragm means held between the associated ange of said cover means and adapted -to conformingly engage said Iforaminous partition means; a flanged housing end section for closing the other anged end of said intermediate housing section, said section having an upwardly directed intake neck portion and a discharge neck portion `located below said intake neck portion and directed at an angle with respect thereto, constituting a pump chamber shaped like a Y lying on its side adapted to facilitate gravitational passage of the slurry through said chamber; and a working diaphragm means held between the associated flanges of said intermediate housing section and said end housing section, and comprising an accordion-shaped body portion extending from said anges Itoward said foraminous partition.

References Cited in the tile of this patent UNITED STATES PATENTS 1,650,377 Nixon Nov. 22, 1927 2,311,229 Herbert Feb. 16, 1943 2,827,853 Bradley Mar. 25, 1958 2,950,396 Schneider Ang. 23, 1960 FOREIGN PATENTS 147,826 Sweden Nov. 23, 1954 376,842 Great Britain Apr. 14, 1932 673,850 France Oct. 14, 1929

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