US2773827A - Electrical precipitators - Google Patents

Description

Dec. 11, 1956 Filed Aug. 8. 1952 J. H. ROPER ELECTRICAL PRECIPITATORS 5 Sheets-Sheet l IN V EN TOR. Jal/Af /l HOP/5f? H A v-OA/f J. H. ROPER ELECTRICAL PRECIPITATORS Dec. 11, 1956 K 3 Sheets-Sheet 2 Filed Aug. a, 1952 INIENTOR.

' JOI/lv H. RoPER "f .l/ d if" Dec. 11, 1956 J. H. RoPER ELECTRICAL PRECIPITATORS 3 Sheets-Sheet 3 Filed Aug. 8, 1952 United States Patent O Claims. (Cl. 204-305) Pa., assignor to Roper Asso- Pa., a corporation of Dela- This invention relates to electrical precipitators and is particularly directed to new and useful improvements in electrical precipitators adapted for cleaning oil, particularly in connection with internal combustion engines.

It is generally well known in the art that oil can be cleaned to remove dispersed particles by passing it through the discharge eld of an electrical precipitator. It is also well known that water emulsified in `oil can be coagulated and removed therefrom by suitable electrical treatments, such as treatment of oil with an alternating current discharge. In my copending application, Serial Number 282,- 334, liled April 15, 1952, I have shown how oil used to lubricate internal combustion engines can be cleaned effectively of both dispersed particles and emulsied water by passing it through the discharge eld of an electrical precipitator energized by the ignition coil of the internal combustion engine.

It is an object of this invention to provide improved electrical precipitators suitable to purifying oil of an internal combustion engine which precipitator can be energized by the ignition coil of the internal cumbustion engine or any similar Ruhmkorf coil. A further object of this invention is to provide electrical precipitators of the class described which may be constructed cheaply and eciently. A further object is to provide electrical precipitators of such design and construction that they can be fabricated in can-forming machinery. Further objects will appear as the description proceeds.

It is standard practice in the can industry to form can-s suitable for withstanding relative high pressures by deep drawing sheet metal into bell-shaped elements or units having a main cylindrical body portion and a cup-shaped top or bottom. These standard elements are fabricated into suitable pressure vessels commonly used for dispensing insecticides, shampoos, lacquers, and the like. l now have found that these bell-shaped elements or units can also be successfully used in fabricating the shell or housing and the collecting and discharge electrodes of the electrical precipitators according to this invention. Thus by using deep-drawn, seamless can elements suitably arranged to provide concentric collecting and discharge electrodes in a pressure-tight housing, an ecient electrostatic precipitator is provided which can be fabricated by standard can-forming machinery. Units according to the invention are adapted to the mass production characteristic of the can industry and have the advantage of the economy also characteristic of that industry.

The various features of novelty which characterize my invention are pointed out with particularity in the claims annexed to and forming a part of this specilication. For a better understanding of the invention, however, its advantages, and specic objects attained with its use, reference should be had to the accompanying drawing and description in which I have illustrated and described preferred embodiments of the invention.

inthe drawing:

Figure 1 is a side elevation in section of a preferred modification of the invention;

Figure 2 is an isometric view of the apparatus shown in Figure 1 partly exploded and partly in section; and

Figures 3, 4, and 5 are side elevations in section of modield forms yof the invention.

In the several views like reference numerals are used to indicate like parts.

Referring now more particularly to Figures 1 and 2, but generally to the other forms of the invention shown, it will be seen that the electrical precipitators according to this invention are formed of a housing or shell 10 having a cylindrical main body portion 12 and cup-shaped top and bottom portions 14 and 16 respectively. The housing 10 is closed except for an axially disposed circular opening 18 in the top section 14, which is closed by an insulator 20.

The insulator 20 has a cylindrical portion 22 and an outwardly Haring enlarged bottom portion 24 shaped to conform with the shape of the top portion 14 of the shell or housing 10. The top portion 14 of the shell or housing 10 slopes inwardly at 26 to a cylindrical portion 28 and then inwardly at 30 to the cylindrical portion 22 of the insulator 20. The bottom portion 24 of the insulator 20 has a shoulder 32 sloping outwardly with the same slope as the inwardly sloping portion 30 of the top portion 14 of the yshell or housing 10 and has a cylindrical portion 34 of a diameter to tit snugly in the cylindrical portion 28 of the top portion 14 of the shell or housing 10.

A ring gasket 36 is disposed between the shoulder 32 and the inwardly sloping portion 30 of the top 14 and by means which will be described is under compression therebetween to provide an hermetic seal whereby the housing 1B is completely closed and pressure tight except for inlets and youtlets which will be described.

Arranged within said shell or housing 10 `is an inner member 38 supported by the insulator 20 having a cylindrical surface 40 concentric with the cylindrical portion 12 of the shell or housing 10 and spa-ced therefrom. From the top yof cylindrical surface 40, the inner member 38 slopes inwardly at 42 to cylindrical portion 44 which snugly fits into a circular, axially disposed depression 46 in the bottom of the insulator 20 and is secured therein by a bolt 4S which projects upwardly along the axis through said insulator 20 to a binding post 50.

The bottom portion 16 ofl the housing or shell 10 slopes inwardly at 52 to a cylindrical portion 54 to provide a shoulder, also designated by thereference numeral 52, and a well or sump 56 below said shoulder. Resting on said shoulder is a second insulator 58 having an axially disposed, circular depression 60 in the top thereof shaped to receive with a snug ft the bottom of the cylindrical surface 40 of the inner element 38. The bottom vof the depression 60 is cut away as shown at 62 to provide a central opening therein and to leave a ledge or shoulder 64 on which the bottom of the cylindrical surface 40 rests. It will be seen, therefore, that the insulator 58 is supported by the shoulders 52, that the inner member is supported by the insulator 58, and that the insulator 20 is supported by the inner member 38. Consequently when the elements of the housing 10 are united by a crimp or rolled seam as shown at 66, Fig. l, the top portion 14 is forced down onto the ring gasket 36 which is formed Y from neoprene rubber or other oil-resistant, compressable and resilient material, Vand compresses it into a permanently compressed con-dition thereby forming an hermetically sealed and pressure-tight unit.

The insulator 20 is provided with one or more diametrically disposed saw slots 68 across the bottom thereof, an axial bore 69 projecting upwardly from said saw slots into said cylindrical portion 22, and a radial bore 70 in said cylindrical portion 22 projecting into said axial bore 69, thus forming a passageway from the exterior through nlouldings..V Preferably they 'areeformqgfra 3. said'radial bore, down said axial bore to said saw slots and into the space between the cylindricalportion 512 of vthe shell or housing and the cylindrical surface 40 of the inner member 38.

'The passages 7 6 are formed by constructinggtheninsulator` 58 as ka square-shaped member having its corners cut 'on the curvature of the shell 1Q. The curvedorners thus rest on the shoulder 52 of Athe shell 10 and the sides areispa'ced therefrom'to form the passages 7.6.

Suitable iittings 7 S and Silare providedrespectively for the radial bore 7 0 and the axial opening 72 for connecting with-pipes 82 and 84 leadingrto and from the oil reservoir of an internal Ycombustion engine. In operation, the shell of housing 10 is grounded.v The bindingpost 50 is connected with the lead vto one of the spark plugs, and oil is pumped into andout of theunit through lines 82 by a. suitableoil -pump (not shown), such as, the oil pump used for circulating oil in the internal combustion engine to whichthe unit is attached. The oil as it passes through the precipitation zone, that is, the space between the cylindrical portion 12 of the shell of housing 10 and the cylindrical surface 40 of the inner member 3S, is cleaned of its dispersed particles and emulsiiiedV water. These collect in the Well or sump 56 and are periodically drained bynremoving the closureV 86 of the drain outlet 88.

In the form of the invention illustrated -in Figs. 1 and 2, the cylindrical portion 12 .and the bottom portion 16 of the housing 10 are integral parts of a deep-drawnseamlessl can element. The inner member 38 is a similar deepdrawnseamless can element of smaller diameter. These elements are stamped and/or drawn from iron or mild steel of deep-drawing quality or other ductile metal, such as, aluminum, copper, brass,y and the like. -These ele-V ments may be subjected to further can-forming operations as will be described in connection with the other modications, but in theV form of invention shown in Figs. 1

` and 2, are uniinished exceptas to provide for the starting of the rolled or crimped seam 66 and to provide a protectiVe coating as will be described later. The tops of thesestantpings or drawings are left intact as .shown at 90. and `92, exccptrtor the opening '72 inthe bottom .portion and atv-the same time, the vtop portion 14 is forced down`v with enough force to place the ring gasket 36 underrcompressionas already described.

In the modifications shown in Figs. 1 and 2, the tube 74 extends upwardly to a point adjacent the top of cylindrical surface 4Q of the inner member to provide'an exitfor the cleaned oil as far above thewell or sump 56 as practical, Thusas the4 oil ows through pipe 82 down through theprecipitation zone kand upwardly to the exit, or while the oil is standing in said unit, ample opportunity .is given to permit settlingout of any precipitated particles ory coalesced Water which might havebeen picked up by the Qil as could happen if the well or sump 56 were not dranedfrequently enough; There is thus provided a unit which c'anrbe formed, except. for the insulators and fittings,` by vstandard can forming operations. It is thus possible in' accordance with this invention ,to produce units with the economy and eficiency of can formingoperations.

Thev insulators shown are suitably formed as injection mouldings of any suitable plastic, and theforms` Yshowin and described are particularly Well adaptedV for..injectionyY t settingY resin, Yrsuch as a phenrl-'fornialV hyde resin.'

resins have the advantage of heat stability and economy. @ther materials can be used, such as ceramics and like standard insulating materials.

The unit which has thus been described is energized suitably by the ignition coil of the internal combustionr engine with which it is used. All that is necessary for this purpose is to connect the-housing 12 to ground as shown at 102Y and the binding post-50 to one of the leads 108 of the distributor head 110 leading to a sparkplug as exemplified bythe spark gap'104.v The spark plug and the unit are, therefore, .in parallel and are actuatedthrough the distributor head 110 by the ignition coil of the engine. Thus the connection 1616 leadsv toene of Vthe-.dist1ibuting points 108 of the distributor head shown diagrammatically in box 110. The rotary contact of the distributor head leads through conductor 112 to the secondary 114 of the ignition coil 116 and to ground through conductor 118. The secondary 114 is energized by battery 120 which has its positive pole connected to ground byy conductor 122: The negative pole 124 is connected to the makeFand-br'eak vcircuit 125 of the distributor head 110.v This make-andbreak circuit comprises a rotating cam 126, a contact arm' 128 pivoted at 130 and provided'with a cam rider 132 operative on rotation of the ca m 136 to make-and-break contacts 134. The contact arm 128 is connected by con- -ductor 136l to the primary 1380i the induction coil 116 which in turn is connected by connector 140 to ground. The condenser 142 is connected across the Contactpomts 134 to minimize arcing. When the contact is made byV contact points 1,34, the primary 138 is energized to the potential of the battery 120. When the contact 134 is broken,rthis potential goes rapidly to zero and inducesvin the secondary 114 the high potential necessary to eiect the spark discharge across the spark gap/of the spark plug 104.3.

The current thus created is an intermittent, ysemi-unidirectional current as hasbeen Vmore particularly .shownY oil of an internal `combustion engine of dispersed particlesl and emulsiiied Water, including corrosive' salts and acids which may be dissolved in the water.

In the deep-drawing operations necessary to form the bell-shaped seamless-units described above, severe stresses:- are set up inthe metal. VThese stresses coupled with the 1 thin gauge `of the` metal (in standard practice the units are about sixteen thousandths of an inch thick) lead to severe corrosion problems in contact with the corrosive salts and acids found in the emulsied Water inthe oils'of internal combustion engines. To eliminate this diiculty,

it has Vbeen found advantageous vto coat the units witha Y Thus the units in theirV stressed condition` without-anealingyor otherwise treatingV to relieve such-stresses are coated with a corrosion rel Y `sistant coatingto protect the iron or steel from which they are fabricated from being eatenaway Iby the corrosive corrosion `resistant coating.

salts and acids in the oil. I haveound that suitable coating compositionsare polyvinyl'lacquers and likeisynthetic lacquers compounded yof acidresistant, synetheticresinsfk These -coatingalthough non-conductorsdo not interfere with thegefciency, and operation of the units.V Other coatingswhichmaybe used arevcoatings of suitablyr resistant metals, suchr as tin, which may be applied'by-the hot-dipping process orbyelectrofplating;

The polyvinyl resin coatingszandllike. synthetic resin coatings have been found particularly suitable, however, andhave the advautagefof ieconomyaand4 ease ofA aPP13- tion.

. Suitable such polyvinyl resins are the .polymers lvof vinyl chloride, vinyl bromide, vinylidedne chloride, vinyl acetate', vinyl butyrate, styrene, mixtures thereof or copolymers of two or more of these monomers with each other or with methyl acrylate, methyl methacrylate, methyl ethylacrylate and ethyl acrylate. The resins may be compounded with a plasticizer such as tricresyl phosphate, dibutyl phthalate, dioctyl phthalate, undecyl tetrahydronaphthyl ketone or cyclohexyl o benzoyl benzoate. The coating compositions are prepared from these resins by dissolving them in solvents well known in the lacquer and varnish industry, such as acetone, alcohol, .and the usual spirit solvents. Suitable coating compositions may also be prepared by using the aqueous vemulsion vor dispersion which results from the emulsion polymerization of the monomers or monomer mixtures. When such :aqueous dispersions are used, the coating must be heated .above the softening temperature of the resin either during 'the drying or subsequent thereto to fuse the voids and to give a continuous and impervious film.

The rolled seams may be rolled with a thin layer of :neoprene or like gasket material to provide a pressuretight seam.

The distance between the discharge electrode and the collecting electrode is critical in establishing a discharge iield in the precipitation zone. If the distance is too great, no discharge eld is set up, if it is too small, arcing over is likely to occur especially if there are imperfections on the surface of the electrodes. This is minimized, however, because the spark plug is in parallel with the unit and rapidly discharges the induced potential. In general, the distance between the two electrodes may be greater if the electrodes are free of imperfections which tend to promote a point discharge and arcing over. The seamless, deep-drawn can elements are of particular advantage, therefore, because of their continuously uninterrupted, smooth, regular surface and because ofthe high ratio, at least 0.5, of the discharge surface to collecting surface. Thus in apparatus of the character illustrated, it has been found that a distance of 0.25 inch gives satisfactory results. This may be varied a few..hundieths inches either way. ln general, satisfactory operation is obtained with a distance between the two electrodes from about 0.2 to 0.3 inch.

Referring now more particularly to Fig. 3, there is illustrated a modication in which the parts are assembled in a different manner and in which further can forming operations have been performed on ysome of the parts. vlt will be observed lirst that the housing and top 14 :are formed of a single bell-shaped deep-drawn seamless fcan unit in which a neck has been drawn in the cup- :shaped top and rolled back to form the bead 144 which corresponds to bead 100 of Fig. l, and that the bottom 16 is formed of a deep-drawn seamless can element :similar to that already described in connection with the top 14 of Fig. 4. These two units are united by a rolled seam 146 which corresponds to rolled seam 66 of Fig. 1.

The inner member 3S has its neck 34 rolled back to provide a bead 148 which lits snugly into the axial depression 46 and is held therein by the cap-shaped washer 150 which is also a can element formed in a single stamping operation. A rolled edge 152 engages a shoulder 42 of the inner member 38 so that when nut 154 is tightened on bolt 156 the inner member 38 is secured firmly to the insulator 20. The bolt 156 is knurled or milled at 153 and ca-st as a unit with the insulator 20.

The pipe 74 in this modification does not extend upwardly as far as in the modification of Fig. l. The reason for this is that this modification is designed primarily for an upward flow of oil so that it is only necessary to extend pipe 74 up far enough to provide a lquiescent zone in the sump 56 for the accumulated sludge. Otherwise, the unit of Fig. 3 is constructed and operated as the unit of Fig. l.

Referring now more particularly to Fig. 4, it will be observed that the inner member 38 is constructed and attached to the insulator '20 in the same manner as in the unit of Fig. V 3. and that the housing 10, top 14, and bottom 16 are formed essentially as in Fig. 1. It will be observed, however, `that in bottom section 16 a further can operation has been performed to provide an opening like the opening through which the insulator 20 projects in Fig. 3 and the opening is sealed by a cap 156 by means of the rolled seam 158. While this requires an added step, it gives added strength and permits -the addition of a second collecting electrode as illustrated in Fig. 5 when desired.

ln Fig. 5, it will be observed that the cap 156 projects into the sump 56 and that a central, axially arranged tubular member 160 is positioned thereby with its beaded lower end 162 snugly fitting around the cap 156. The insulator 164, which is similar to the insulator 58 but smaller in diameter, rests on the shoulder 42 of the inner element 38 and positions the other end. 'I'he central, tubular member 160 is concentric with the inner member 38 and is spaced therefrom the same distance that the inner member 38 is spaced from the cylindrical portion 12 of the housing 10. There is thus provided a unit in which the oil flows in at 70 down through an outer precipitation zone between the cylindrical portion 12 of the housing 10 and the cylindrical portion 40 of the inner member 38 and then upwardly between the central, tubular member 160 and the cylindrical portion 40 of the inner member 38 and then downwardly and out through tube 74. The capacity of the unit is thus essentially doubled without materially increasing its cost and without increasing its size.

While I have described my invention with reference to particular embodiments, it will be understood that variation may be made therein without parting from the spirit and scope of the invention as set forth herein and in the appended claims.

l claim:

l. An electrical precipitator comprising, an insulator having a cylindrical top portion and an outwardly aring bottom portion; a metal cylinder having a top portion of smaller diameter than the main body portion of said cylinder with sloping sides connecting the two; means for fastening said top portion to the bottom of said insulator with the cylindrical portions of said insulator and said metal cylinder having a common axis; a metal shell surrounding said metal cylinder and having a cylindrical surface spaced from the cylindrical surface of said metal cylinder and arranged concentric therewith and projecting above the main body portion of said metal cylinder; said shell having walls tapering inwardly from the top of said cylindrical surface to the top portion of said insulator and conforming in shape substantially to the outwardly aring portion of said insulator; a ring gasket disposed between the said outwardly llaring portion of said insulator and the inwardly tapering portion of said shell and having a diameter substantially the same as that of the cylindrical portion of said insulator; said shell having a cup-shaped bottom having inwardly projecting shoulders; an annular insulator resting on said shoulders and having means for engaging the bottom of said metal cylinder; said shell having top and bottom portions united by a crimp seam crimped to place said gasket under compression; inlet and outlet means for introducing and withdrawing a iluid into and from said shell and passageways therebetween for directing fluid to llow between said concentric surfaces in its passage from said inlet means to said outlet means; and an electrical conductor passing upwardly from said metal cylinder along the axis of first-named insulator to the top thereof.

2. The apparatus which comprises a cylindrical metal shell comprising two parts united by a seam, one of which has an inwardly projecting portion and an axially disposed opening therein, a non-metallic closure member in said opening inside saidshell, a resilient gasket disposed between said closure member and said inwardly projecting portion, an inner cylidrical metal member in said shell 7 in* axial'gposition "andispaced'v from said. shellk ywitlLonel-end supportedfbyf antherrnommetllic member' whichv in' turn is supportedby said shell and the other 'end engaging said-fclosurefsaid'inner cylindrical member'being'of lsufcient length that'said gasket is undercompression.

'3. An electrical precipitator which comprisesan outer metallicshell having a cylindrical surfaceportion, said shell beingcomprised of two parts' united by-means of a'rolled seam,v saidl shell havingA an inwardlyprojecting portion terminating in an `axially disposed opening `of smaller diametenthanthe diameter of said cylindrical suitaceportion; an insulator disposed insaid shellhaving a'portionprojecting through saidaxially disposed opening and another;portion fitting `under saidA inwardly projecting portion "of'said shellfand another insulator which engages'the opposite end of said' shell, a resilient gasket betweenV said'otherportion of'said `irst named insulator andthe inwardly'projecting'portion of said shell, a' cylindrical metallic 'member axially 'disposed between said insulators in* spaced relation 'to 'the 'cylindrical surface of said'shellfsaidcylindrical member being of such' length thatsaidfgasket' is placed under compression as a result oftheu'olling of said seam.

4. Anelectrical precipitator comprising an inner cylindrical electrode Vand an outer'cylindrical electrode concentric'therewithysaidouter electrode comprising an imperforate housing completely vsurrounding said inner electrode, insulating' means arranged to maintain said electrodes 'in said concentric'relation, said insulating means having a portion Vprojecting through said imperforate housing along'the axis ofisaidconcentricity and having ajshoulderportion extending under said shell, a' ring gasket disposedfbe'tween said shoulder portion and said shell, and' means comprising said inner electrode acting against said insulating means maintaining said ring gasket under compression.

l'5. An electrostatic oil cleaner for motor vehicles poweredby an internal combustion engine having ajvpressure lubrication systemarranged to. circulate oil through an'oilcleanencomprising an imperforate outer Yhousing having a' top, a bottom' and right cylindrical `sidewalls; an inner'housing. having impe'rforate right cylindrical yside ofrsaid" housingssaidv passageway discharging outwardly and' radially fromsaid axis wherebythe oil entering into said Velectrostatic cleaner llows radially and outwardly between the' Atops of said housings and downwardly through the' annular; space between'said housings; an outlet :means projecting Athrough the bottom of said outer` housing and having4 an axially disposed passageway leading through the' bottom of said outer housing to al position within said innerhousing adjacent the top thereof; and an insulated conductor .passing through the top of said outer housing and making rcontact with the -top of said inner housingwhereby ajpotential can be impressed across the two housings; .said outer housing being small enough to occupy the space providedfor an oil cleaner in said motor vehicle `and being proportioned to said inner housing southat the outer cylindrical surface of said inner'housing isspaced from the inner cylindrical surface-.of the said outer housinga distance between about' 0.2 and about (X3/inches and has an area at least one half that 4of the apposite area of the outer housing.

AReferencesV Cited in the Vtile of this patent UNITED STATES PATENTS OTHER l REFERENCES t Donglasz. Transactions of the l-Electroehemical Society, vol.4I 74,'. 193 8,',pages` .83 to 189.

.vrPiersok VfElectricalCondenser Process for Demulsify-l ing-l0i1,';'Report,of Investigation'No. 29, Illinois VState Geological Surveyr1933, pagestlS to 18 pertinent.

Claims (1)

1. AN ELECTRICAL PRECIPITATOR COMPRISING AN INSULATOR HAVING A CYLINDRICAL TOP PORTION AND AN OUTWARDLY FLARING BOTTOM PORTION; A METAL CYLINDER HAVING A TOP PORTION OF SMALLER DIAMETER THAN THE MAIN BODY PORTION OF SAID CYLINDER WITH SLOPING SIDES CONNECTING THE TWO; MEANS FOR FASTENING SAID TOP PORTION TO THE BOTTOM OF SAID INSULATOR WITH THE CYLINDRICAL PORTONS OF SAID INSULATOR AND SAID METAL CYLINDER HAVING A COMMON AXIS; A METAL SHELL SURROUNDING SAID METAL CYLINDER AND HAVING A CYLINDER SURFACE SPACED FROM THE CYLINDRICAL SURFACE OF SAID METAL CYLINDER AND ARRANGED CONCENTRIC THEREWITH AND PROJECTING ABOVE THE MAIN BODY PORTION OF SAID METAL CYLINDER; SAID SHELL HAVING WALLS TAPERING INWARDLY FROM THE TOP OF SAID CYLINDRICAL SURFACE TO THE TOP PORTION OF SAID INSULATOR AND CONFORMING IN SHAPE SUBSTANTIALLY TO THE OUTWARDLY FLARING PORTION OF SAID INSULATOR; A RING GASKET DISPOSED BETWEEN THE SAID OUTWARDLY TAPERING PORTION OF SAID INSULATOR AND THE INWARDLY TAPERING PORTION OF SAID SHELL AND HAVING A DIAMETER SUBSTANTIALLY THE SAME AS THAT OF THE CYLINDRICAL PORTION OF SAID INSULATOR; SAID SHELL HAVING A CUP-SHAPED BOTTOM HAVING INWARDLY PROJECTING SHOULDERS; AN ANNULAR INSULATOR RESTING ON SAID SHOULDER AND HAVING MEANS FOR ENGAGING THE BOTTOM OF SAID METAL CYLINDER; SAID HAVING TOP AND BOTTOM PORTIONS UNITED BY A CRIMP SEAM CRIMPED TO PLACE SAID GASKET UNDER COMPRESSION; INLET AND OUTLET MEANS FOR INTRODUCING AND WITHDRAWING A FLUID INTO AND FROM SAID SHELL AND PASSAGEWAYS THEREBETWEEN FOR DIRECTING FLUID TO FLOW BETWEEN SAID CONCENTRIC SURFACES IN ITS PASSAGE FROM SAID INLET MEANS TO SAID OUTLET MEANS; AND AN ELECTRICAL CONDUCTOR PASSING UPWARDLY FROM SAID METAL CYLINDER ALONG THE AXIS OF FIRST-NAMED INSULATOR TO THE TOP THEREOF.

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