Less Than 40 Percent By Weight Clay Patents (Class 501/131)
  • Patent number: 11078583
    Abstract: There are provided processes for preparing lithium hydroxide that comprise submitting an aqueous composition comprising a lithium compound to an electrolysis or an electrodialysis under conditions suitable for converting at least a portion of the lithium compound into lithium hydroxide. For example, the lithium compound can be lithium sulphate and the aqueous composition can be at least substantially maintained at a pH having a value of about 1 to about 4.
    Type: Grant
    Filed: September 23, 2019
    Date of Patent: August 3, 2021
    Assignee: NEMASKA LITHIUM INC.
    Inventors: Jean-François Magnan, Guy Bourassa, Gary Pearse, Peter Symons, J. David Genders
  • Patent number: 8388990
    Abstract: A two-part disinfecting system, as well as disinfecting compositions and methods for making and using the same. The two-part disinfecting system contains a first part and a second part adapted to be mixed to yield an aqueous acidic disinfecting composition, wherein the first part comprises a chlorite and the second part comprises an acid, and wherein the first part, the second part, or both the first and second parts further comprise a nitrogenous stabilizer having a nitrogen group substituted with at least one hydrogen.
    Type: Grant
    Filed: October 7, 2003
    Date of Patent: March 5, 2013
    Assignee: Ecolab USA Inc.
    Inventors: Joseph Morelli, Kelly Walker, C Cayce Warf, Jr.
  • Publication number: 20120255327
    Abstract: A disk roll base material includes 20 to 38 wt % of alumina silicate wool that include 40 to 60 wt % of alumina and 40 to 60 wt % of silica, and have a content of shots having a dimension of 45 ?m or more of 5 wt % or less, 10 to 30 wt % of kibushi clay, 2 to 20 wt % of bentonite, and 20 to 40 wt % of mica.
    Type: Application
    Filed: April 5, 2011
    Publication date: October 11, 2012
    Applicant: Nichias Corporation
    Inventors: Kazuhisa Watanabe, Masaaki Nakayama, Osamu Horiuchi
  • Patent number: 7825053
    Abstract: Sintered, spherical composite pellets or particles comprising alumina fines, at least one of clay and bauxite and optionally a sintering aid, are described, along with a process for their manufacture. The use of such pellets in hydraulic fracturing of subterranean formations and in grinding is also described.
    Type: Grant
    Filed: January 25, 2010
    Date of Patent: November 2, 2010
    Assignee: Carbo Ceramics Inc.
    Inventors: Robert Duenckel, Mark Edmunds, Steve Canova, Benjamin Eldred, Brett Allen Wilson
  • Patent number: 7678723
    Abstract: Sintered, spherical composite pellets or particles comprising alumina fines, at least one of clay and bauxite and optionally a sintering aid, are described, along with a process for their manufacture. The use of such pellets in hydraulic fracturing of subterranean formations and in grinding is also described.
    Type: Grant
    Filed: May 19, 2008
    Date of Patent: March 16, 2010
    Assignee: Carbo Ceramics, Inc.
    Inventors: Robert Duenckel, Mark Edmunds, Steve Canova, Benjamin Eldred, Brett Allen Wilson
  • Publication number: 20090280975
    Abstract: The present invention relates to a method of producing a ceramic material comprising the steps of: a) mixing a first clay composition comprising silica and a silicate mineral with a second clay composition; and b) firing the mixed clay composition from step a) to form a ceramic product. The present invention also relates to an engobe clay composition, sanitary ware and methods of productions thereof.
    Type: Application
    Filed: July 17, 2009
    Publication date: November 12, 2009
    Applicant: Caroma Industries Limited
    Inventor: Emile SALEH
  • Patent number: 7101821
    Abstract: This invention provides a silicon composition comprising at least 15 wt % of hydrolysed silicon compounds and at least 3 wt % of a binder material. The silicon composition is used in the manufacture of ceramics. The hydrolysed silicon compounds can for example be the gel produced by hydrolysing higher boiling point organohalosilanes produced in the manufacture of organohalosilanes or halosilanes by the direct process.
    Type: Grant
    Filed: May 27, 2003
    Date of Patent: September 5, 2006
    Assignee: Dow Corning Corporation
    Inventors: Hagen Demes, Helmut Fackler
  • Publication number: 20040204305
    Abstract: A batch, in particular for the production of refractory shaped bodies, includes a mixture of a refractory, metal oxide main component containing 40 to 60% by weight of Al2O3, a phosphate bond and finely particulate SiC having a grain size of <0.2 mm, and a process using the mixture for forming the batch to produce the refractory shaped bodies.
    Type: Application
    Filed: April 28, 2004
    Publication date: October 14, 2004
    Applicant: Refratechnik Holding GmbH
    Inventors: Heinrich Liever, Hans-Jurgen Klischat, Holger Wirsing
  • Patent number: 6753299
    Abstract: An improved lightweight and highly permeable proppant composition for use in increasing the productivity of a gas or oil well. The proppant composition includes equal amounts by weight of uncalcined bauxite, uncalcined shale and quartz, held together with a binder formed of wollastonite and talc in an amount of less than 10% by weight of the composition. The proppant composition has an alumina content of less than 25% by weight of the composition and a silica content of over 45% by weight of the composition.
    Type: Grant
    Filed: November 9, 2001
    Date of Patent: June 22, 2004
    Assignee: Badger Mining Corporation
    Inventors: Eugene P. Lunghofer, Larry A. Wolfe
  • Patent number: 6387319
    Abstract: A method of making a product which is generally impervious to water including the steps of making a generally homogenous mixture of slate particles and clay, setting the mixture as necessary to produce a formable composition, forming the wet mixture to a desired configuration, at least partially drying the formed mixture and subjecting the dried formed mixture to a temperature of at least 1145° C. for a time sufficient for at least some of the clay to convert into a binder to bind together the slate particles.
    Type: Grant
    Filed: January 5, 2001
    Date of Patent: May 14, 2002
    Assignee: Digive Limited of York House
    Inventor: John Dutton
  • Patent number: 6281266
    Abstract: Disclosed is a taphole plugging composition for metal melting apparatus, the composition comprising (a) a refractory aggregate having a maximum particle size of 5 mm or less, (b) graphite and silicon nitride each having a maximum particle size of 0.2 mm or less, (c) a refractory clay, (d) a compatibilized binder mixture comprising a phenolic resin, a ketone compound and a pitch, and (e) an organic fine fiber.
    Type: Grant
    Filed: June 16, 2000
    Date of Patent: August 28, 2001
    Assignee: Nippon Crucible Co., Ltd.
    Inventors: Kenzo Takeda, Kunihiko Shiraishi, Fumiyuki Inoue, Norio Honda
  • Patent number: 6245701
    Abstract: The invention relates to a porous ceramic used for producing alkali ion water. The ceramic of the invention includes finely particulate zeolite having an average particle size of 0.1 to 40 &mgr;m and an alkali ion producing material as components. Besides the above components, the invention preferably comprises a fibrous mineral and/or a clay mineral. To produce the ceramic of the invention, a slurry obtained by grinding zeolite by a wet process, a slurry obtained by grinding the alkali ion producing material and the clay mineral by a wet process and a slurry obtained by grinding the fibrous mineral are first mixed and stirred to prepare a mixed slurry. This mixed slurry is then dried and fired to obtain a sintered body.
    Type: Grant
    Filed: January 28, 1999
    Date of Patent: June 12, 2001
    Assignee: Japan Zeolite, Inc.
    Inventor: Takashi Sato
  • Patent number: 6176769
    Abstract: A ceramics dress substrate of the present invention capable of both performances of cutting a cut material with a high accuracy and dressing a diamond cutting grindstone with an excellent cutting property and an reduced wearing amount of the grindstone. This ceramics dress substrate comprises sintering a mixture of ceramics grinding particles and a silicate mineral, The ceramics grinding particles are preferably uniformed and have a scratch hardness ranging from 6 to 10. Alumina grinding particles, silicon carbide and mullite are preferably used as the ceramics grinding particles, and a kaolin mineral, pyrophyllite, montmorillonite, sericite, talc and chlorite are preferably used as the silicate mineral. The ceramics dress substrate is preferably coated with glass.
    Type: Grant
    Filed: December 22, 1998
    Date of Patent: January 23, 2001
    Assignees: Narumi China Corporation, Sumitomo Special Metals Co., Ltd.
    Inventors: Masato Suzuki, Shirohito Matsuyama, Katsushi Sugita, Kazutoyo Shimizu, Naoyuki Okamoto
  • Patent number: 6103651
    Abstract: This invention is directed to ceramic metal composite useful as a refractory and having improved abrasion, corrosion, and oxidation resistance. The ceramic metal composite of the present invention is comprised of ceramic refractory aggregate, metal particulate, and a nonaqueous binder wherein the ceramic refractory aggregate, metal particulate, and binder residuals react to form a three-dimensional ceramic-metal matrix. The ceramic-metal matrix is further stabilized by bonds between the metal particulate, reaction products of the metal particulate, and the ceramic refractory aggregate.
    Type: Grant
    Filed: February 7, 1996
    Date of Patent: August 15, 2000
    Assignee: North American Refractories Company
    Inventor: Timothy A. Leitzel
  • Patent number: 5898010
    Abstract: A red brick comprising waste foundry sand of 30.about.50 wt %, dusts of 5.about.10 wt %, and a remainder of clay. The waste foundry sand and dusts can be efficiently recycled, and the quantity of the sand used, the supply of which sand which is nearly exhausted, can be reduced. The heating temperature in the red brick manufacturing process is remarkably lowered, and the economical efficiency of the manufacturing process is improved greatly by using iron oxide included in dusts, instead of a chemical compound to obtain desired color.
    Type: Grant
    Filed: January 3, 1997
    Date of Patent: April 27, 1999
    Inventor: Chang-woo Kang
  • Patent number: 5880048
    Abstract: A ceramic and method of producing the same are disclosed, the ceramic having as principal ingredients natural zeolite and shells, wherein silver nitrate, magnesium oxide, potassium oxide, sodium oxide selenium oxide and ferric oxide are added thereto, and the resultant mixture fired to produce a granular ceramic. The granular ceramic enables the production of deoxidized water having an appropriately low oxidation reduction potential, for use as drinking water and the like.
    Type: Grant
    Filed: September 22, 1997
    Date of Patent: March 9, 1999
    Assignee: Tohoku Bankin Toso Kogyo Kabushiki Kaisha
    Inventors: Kazuo Sato, Kazutomo Kikuchi
  • Patent number: 5880047
    Abstract: A granular ceramic is prepared by firing a powder of a natural zeolite mineral, a pre-fired powder composed of shell fragments, a pre-fired powder of a silica-alumina mineral, and a copper oxide powder. When used as a fuel additive, the ceramic makes it possible to improve the combustion efficiency of hydrocarbon oils, especially of petroleum products such as gasoline, gas oil kerosene, and heavy oil, as well as to reduce CO.sub.2 and NO.sub.x emissions in exhaust gases discharged during combustion.
    Type: Grant
    Filed: August 13, 1997
    Date of Patent: March 9, 1999
    Assignee: Tohoku Bankin Toso Kogyo Kabushiki Kaisha
    Inventor: Kazuo Sato
  • Patent number: 5858900
    Abstract: A composition suitable for admixture with refractory grains to make a refractory monolithic formulation, consisting essentially of:2 to 10 parts by weight of activated alumina;0.25 to 1.0 parts by weight of an additive material which comprises at least one of an alumino-silicate-phosphate compound; a resin derived from an aldehyde and either an amine or an aromatic hydroxy compound; cellulose; polyethylene glycol(s); and methoxy polyethylene glycols;0 to 50 parts by weight of fine alumina;0 to 10 parts by weight of fine silica;0 to 1 parts by weight of a dispersant; and0 to 1 part by weight calcium aluminate cement.
    Type: Grant
    Filed: November 28, 1997
    Date of Patent: January 12, 1999
    Assignee: Alcan International Limited
    Inventors: Farid Azizian, Kevin John Wills
  • Patent number: 5814572
    Abstract: An object of the present invention is to provide a glassy sintered body and to effectively reuse scrapped glass.The glassy sintered body of the present invention is made by preparing a raw material of the body by adding ceramic clay to glass as a main element so as to adjust the amount of water and kneading the glass and the clay, forming the raw material into a prescribed form, and sintering the formed material.
    Type: Grant
    Filed: October 10, 1997
    Date of Patent: September 29, 1998
    Assignee: Crystal Clay Corporation
    Inventors: Kazuo Saiki, Masami Kato, Kokichi Hanaoka
  • Patent number: 5763345
    Abstract: A synthetic clay for ceramics is formed of 30-65 wt % of amorphous silica, 30-65 wt % of alumina trihydrate, and 2-20 wt % of at least one element selected from a group consisting of sepiolite, palygorskite, and bentonite. The clay may have a slurry form, partially dehydrated form, or mass or dry powder. The synthetic clay is comparable or even superior to natural clay in plasticity, water retentivity and capability of forming water film. The synthetic lay is useful for ceramic industry or pottery.
    Type: Grant
    Filed: May 2, 1997
    Date of Patent: June 9, 1998
    Assignee: Cosmo Clay & Ceramics Co., Ltd.
    Inventors: Iemitsu Ohshima, Akira Kikuhata
  • Patent number: 5583079
    Abstract: A ceramic kiln-fired product which comprises glass, fly ash, and a clay binder. Further provided is a method for preparing raw material suitable for forming a shaped, kiln-fired, ceramic product. The method comprises mixing glass, fly ash, and a clay binder with from about 10 wt. % to about 15 wt. % water, on a dry weight basis, to form an aqueous mixture, separating the aqueous mixture using a mesh of from about 10 to about 12 screen into first and second portions, the first portion comprising the aqueous mixture which does not pass through the mesh and the second portion comprising the aqueous mixture which passes through the mesh, and drying the second portion until the moisture content of the second portion is less than about 0.5 wt. % to form the raw material. The present invention also provides a tile glazing formulation which may be used with the ceramic product of the present invention, as well as a method of using the formulation. The glazing formulation comprises, on a dry weight basis, about 70 wt.
    Type: Grant
    Filed: July 19, 1994
    Date of Patent: December 10, 1996
    Inventors: John T. Golitz, John F. Mainieri, Bruce H. Bennett, Richard D. Moore, Angela M. Paxton
  • Patent number: 5565245
    Abstract: Mg.sub.x Al.sub.2-2x Ti.sub.1+x O.sub.5 (x.ltoreq.0.2) protective coatings have been developed for both dense and porous substrates, such as SiC and Si.sub.3 N.sub.4, using a chemical solution processing method involving the hydrolysis and condensation of magnesium, aluminum and titanium precursors. The solution viscosities, pH values, H.sub.2 O/alkoxide molar ratios, and dip coating withdrawal rates which are optimum for crack-free Mg.sub.x Al.sub.2-2x Ti.sub.1+x O.sub.5 (x.ltoreq.0.2) are 1.0 to 6.2 cP, pH 1-4.5, molar ratio 1.5-10, and withdrawal rate of 2.2-8.0 cm/min, respectively. Conversion of the amorphous coating to crystalline Mg.sub.x Al.sub.2-2x Ti.sub.1+x O.sub.5 (x.ltoreq.0.2) is achieved by a succession of calcination below 450.degree. C. and a final heat treatment above 1000.degree. C. for ten hours with controlled heating and cooling rates.
    Type: Grant
    Filed: March 1, 1995
    Date of Patent: October 15, 1996
    Assignee: Virginia Tech Intellectual Properties, Inc.
    Inventors: Tawei Sun, Nancy R. Brown, Jesse J. Brown, Jr., Min Kang
  • Patent number: 5307046
    Abstract: It is disclosed that the properties of a ceramic mullite-kaolinite based passivating coating composition applied as a collar to metal oxide varistor valve block cylindrical surfaces are improved by including in the coating composition from 0.03 to 15% by weight of the coating composition one or more of the following additive compounds: TiO.sub.2 ; Y.sub.2 O.sub.3 ; ZrO.sub.2 ; ZnO; Boroflux (2ZNO.sup.. 3B.sub.2 O.sub.3.sup.. 7H.sub.2 O; or 3ZnO.sup.. 2B.sub.2 O.sub.3.sup.. 5H.sub.2 O); or Si.sub.3 N.sub.4. The coating composition comprises by dry weight a mixture of 55-85% mullite and 15-45% kaolinite, one or a mixture of the above additive compounds, and sufficient water to form a sprayable slurry. The inclusion of the additive compound results in enhanced contact adhesion between the collar and the metal oxide varistor peripheral surface.
    Type: Grant
    Filed: November 6, 1992
    Date of Patent: April 26, 1994
    Assignee: Hubbell Incorporated
    Inventor: Mohammad A. Alim
  • Patent number: 5284712
    Abstract: The occurrence of efflorescence has been reduced or eliminated in ceramic articles formed from a novel vitreously bonded cement-containing composition. The articles also exhibit improved strength, reduced firing shrinkage and increased frost resistance. The articles are produced by combining hydraulic cement containing calcium silicate and/or calcium aluminate components, vitrifiable inorganic powders forming molten liquid-flowing substances, and reactive or sinterable mineral powders selected from the group consisting of magnesium silicates, aluminum silicates and mixtures thereof; combining the ingredients with water to form a mixture; molding the mixture into an article; hardening the article by hydration; and firing the molded article to a maximum temperature of between about 1000.degree. C. to 1400.degree. C.
    Type: Grant
    Filed: September 25, 1992
    Date of Patent: February 8, 1994
    Inventors: Kazuyuki Kawai, Kazumasa Goto, Takayuki Shirai
  • Patent number: 5203915
    Abstract: It is disclosed that the properties of a ceramic mullite-kaolinite based passivating coating composition applied as a collar to metal oxide varistor valve block cylindrical surfaces are improved by including in the coating composition from 0.03 to 15% by weight of the coating composition one or more of the following additive compounds: TiO.sub.2 ; Y.sub.2 O.sub.3 ; ZrO.sub.2 ; ZnO; Boroflux (2ZnO.multidot.3B.sub.2 O.sub.3 .multidot.7H.sub.2 O; or 3ZnO.multidot.2B.sub.2 O.sub.3 .multidot.5H.sub.2 (O); or Si.sub.3 N.sub.4. The coating composition comprises by dry weight a mixture of 55-85% mullite and 15-45% kaolinite, one or a mixture of the above additive compounds, and sufficient water to form a sprayable slurry. The inclusion of the additive compound results in enhanced contact adhesion between the collar and the metal oxide varistor peripheral surface.
    Type: Grant
    Filed: March 23, 1992
    Date of Patent: April 20, 1993
    Assignee: Hubbell Incorporated
    Inventor: Mohammed A. Alim
  • Patent number: 5175133
    Abstract: A calcined microsphere of ultrafine bauxite particles having a mean particle size in the range 0.01 to 0.3 micrometers, said microsphere having a particle size less than 30 micrometers and being characterized by a substantially solid form having a pycnometric density substantially falling in the range 3.2-3.9 g/cm.sup.3, a BET surface area substantially falling in the range 0.05 to 0.5 m.sup.2 /g and a crystal grain size less than 4 micrometers, the surface chemistry of the microsphere being modified to enhance the wettability of the microsphere and to improve its ability to bond strongly with matrix materials in use.
    Type: Grant
    Filed: December 21, 1990
    Date of Patent: December 29, 1992
    Assignee: Comalco Aluminium Limited
    Inventors: Thomas K. Smith, Raymond W. Shaw, Christopher J. Heathcock, Leslie C. Edwards, Malcolm J. Couper, Kenong Xia
  • Patent number: 5153153
    Abstract: Sintered ceramic material which comprises doped aluminum titanate and mullite having the composition:50-61.5% by weight Al.sub.2 O.sub.3,36-47.5% by weight titanium oxide, expressed as TiO.sub.2,2.5-5% by weight SiO.sub.2,with the sum total of the three components adding up to 100%, and which further comprises 0.3 to 1% by weight MgO and up to 1% by weight impurities, useful as, inter alia, filters, catalyst supports and internal combustion engine parts, are prepared by mixing and shaping materials of suitable composition and then sintering the shaped composition at temperatures of 1250.degree. to 1600.degree. C. over a holding time of 0.5 to 100 hours.
    Type: Grant
    Filed: June 10, 1991
    Date of Patent: October 6, 1992
    Assignee: Bayer Aktiengesellschaft
    Inventors: Bernhard Freudenberg, Johannes Seyer, Ernst Gugel
  • Patent number: 5096858
    Abstract: A method of producing ceramic composites of Al.sub.2 O.sub.3 reinforced by shaped SiC particles preferably shaped as fine particles (random), platelets, whiskers or fibres by in situ production of SiC particles by heating a mixture of carbon particles of the desired shape with silicates of Al.sub.2 O.sub.3 to a temperature above 1500.degree. C., convert the silicates and carbon to Al.sub.2 O.sub.3 and SiC to produce in situ SiC particles of the desired shape and provide a ceramic powder that may be densified by techniques such as hot pressing, isostatic pressing or sintering.
    Type: Grant
    Filed: March 12, 1991
    Date of Patent: March 17, 1992
    Assignee: The University of British Columbia
    Inventors: Asoke C. Das Chaklader, Sankar Das Gupta
  • Patent number: 5011799
    Abstract: A method of producing ceramic composites of Al.sub.2 O.sub.3 reinforced by shaped SiC particles preferably shaped as fine particles (random), platelets, whiskers or fibres by in situ production of SiC particles by heating a mixture of carbon particles of the desired shape with silicates of Al.sub.2 O.sub.3 to a temperature above 1500.degree. C., convert the silicates and carbon to Al.sub.2 O.sub.3 and SiC to produce in situ SiC particles of the desired shape and provide a ceramic powder that may be densified by techniques such as hot pressing, isostatic pressing or sintering.
    Type: Grant
    Filed: September 14, 1990
    Date of Patent: April 30, 1991
    Inventors: Asoke C. Das Chaklander, Sankar Das Gupta
  • Patent number: 4874726
    Abstract: A refractory composition comprising a fused silica composition comprising a silica compound and a binder and for each 100 parts by weight of said fused silica composition from about 3 to 15 parts by weight of alumina-silica based hollow microspheres.
    Type: Grant
    Filed: November 18, 1987
    Date of Patent: October 17, 1989
    Assignee: Dresser Industries, Inc.
    Inventors: Thomas R. Kleeb, Berhl E. Wishon
  • Patent number: 4803182
    Abstract: A ceramics-based manufacturing material and a coating material are disclosed, both of which are used in high-temperature structures and applications. The ceramics-based manufacturing material may be used for building structural blocks or members, such as refractory bricks, that require the mechanical strength and thermal resistance when they are exposed to the high temperatures of 1,500.degree. C. or above. Those bricks made of the material disclosed provides the mechanical strength and heat resistance better than the conventional ones. The coating material may be used for forming a thermal resistant layer on metal or other material bases. Both materials have substantially the similar compositions, either of which may have the alternative use, such as the manufacturing material or the coating material. Simply adding an appropriate amount of water to either makes it a coating material. In either case, the requirements for the high temperature resistance and mechanical strength can be satisfied.
    Type: Grant
    Filed: December 14, 1987
    Date of Patent: February 7, 1989
    Inventor: Sadanobu Ishikawa
  • Patent number: 4713203
    Abstract: A superior proppant having very high permeability at formation pressures up to 20,000 psi, very high compressive strength, low specific gravity, and good acid resistance, is produced by a process comprising: (a) separating a fine fraction from a naturally occurring bauxite containing same; (b) pelletizing the separated fine fraction in the presence of water; (c) treating the pellets produced in step (b) to remove water therefrom; and (d) sintering the product of step (c) to produce a low density material suitable for use as a proppant.
    Type: Grant
    Filed: December 24, 1985
    Date of Patent: December 15, 1987
    Assignee: Comalco Aluminium Limited
    Inventor: William H. Andrews
  • Patent number: 4476235
    Abstract: There is disclosed a green moulded product suitable for preparing shaped fired units comprising (a) at least 55% to 99% by weight of non-calcined asbestos tailings, the remainder comprising (b) at least one of (i) a heat decomposable metal salt selected from sodium, potassium, lithium, calcium, barium, magnesium, aluminum and mixtures thereof in an amount of from 1% to 15% by weight, (ii) a natural aluminum silicate in an amount of from 1% to 30% by weight, and (iii) mixtures of (i) and (ii). The properties of fired units are such that they can be used as structural bricks, medium refractory bricks, firebricks, tiles and the like.
    Type: Grant
    Filed: November 24, 1982
    Date of Patent: October 9, 1984
    Assignee: Societe Nationale de Liamiante
    Inventors: Jean-Pierre Chevalier-Bultel, Jean-Pierre Drolet
  • Patent number: 4292084
    Abstract: A vibratable plastic refractory composition which is based upon calcined kaolin and a non-basic calcined refractory aggregate, in which the -325 mesh fraction of the batch is controlled to between about 30 and 45%.
    Type: Grant
    Filed: April 21, 1980
    Date of Patent: September 29, 1981
    Assignee: Dresser Industries, Inc.
    Inventors: Stephen W. Thrower, George H. Criss, Thomas R. Kleeb