The Experts below are selected from a list of 117 Experts worldwide ranked by ideXlab platform
G A Jones - One of the best experts on this subject based on the ideXlab platform.
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on the tribological behaviour of mechanical Seal Face materials in dry line contact part i mechanical carbon
Wear, 2004Co-Authors: G A JonesAbstract:Abstract Mechanical Face Seal performance is critically dependant on the tribology of the Seal Face materials. In this research the tribology of the premier Seal Face materials under dry running contact has been examined. It is shown that the PV (pressure×velocity) capability, of these premier Face materials, is dependant on the development of a carbon graphite contact film. Experimentation has shown that these contact films breakdown via a seizure mechanism. The breakdown of the contact film is shown to result in a transition from a very low wear rate regime to a severe wear rate regime. Analysis of the results and the performance profiles produced has allowed the mechanisms of contact film formation and the functionality of the film in solid contact to be identified. A contact model is proposed that describes the low friction characteristic of mechanical carbon by combining the theories of Lancaster and Savage. The model is finally related to the mechanical Seal Face design.
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on the tribological behaviour of mechanical Seal Face materials in dry line contact part ii bulk ceramics diamond and diamond like carbon films
Wear, 2004Co-Authors: G A JonesAbstract:Abstract The evolving tribological demands of mechanical Face Sealing applications such as those associated with high-duty fluid Seals and gas Sealing technology are driving the need for the development of new and novel Seal Face material solutions. Under conditions where the combination of high pressure and high surFace speeds create high levels of PV the Seal designer will specify two hard Faces, typically a combination of reaction bonded silicon carbide, alpha sintered silicon carbide or tungsten carbide. Work has been carried out here aimed at evaluating and increasing the understanding of the tribological nature of these hard Face combinations and evaluating the potential of polycrystalline diamond (PCD) and diamond-like carbon (DLC) films. Experimentation has shown that under dry moderate contact conditions mild deformation-controlled wear takes place with a polishing of the contact surFaces. Progressively increasing the contact pressure was shown to eventually produce a transition to severe microcrack-controlled wear. Coating one of the contact surFaces with a PCD or DLC film modified the contact dynamics producing low friction coefficients and in the case of the PCD film shifted the wear transition to a much higher contact severity. A linear elastic contact model is developed that provides a framework for rationalising the results of this work and enables the key features of mechanical Face Seal design to be related to the critical tribological characteristics of the Seal Face material systems.
S He - One of the best experts on this subject based on the ideXlab platform.
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Frictional characteristics of mechanical Seals with a laser-textured Seal Face
Journal of Materials Processing Technology, 2002Co-Authors: X.q Yu, S HeAbstract:Abstract The frictional characteristics of laser-textured mechanical Seals with a porous Face are investigated. Compared with conventional mechanical Seals, the temperature rise, friction torque and friction coefficient of laser-textured mechanical Seals with a porous Face are much lower. The results show substantial hydrodynamic effects and a better frictional condition between the two Seal Faces.
X.q Yu - One of the best experts on this subject based on the ideXlab platform.
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Frictional characteristics of mechanical Seals with a laser-textured Seal Face
Journal of Materials Processing Technology, 2002Co-Authors: X.q Yu, S HeAbstract:Abstract The frictional characteristics of laser-textured mechanical Seals with a porous Face are investigated. Compared with conventional mechanical Seals, the temperature rise, friction torque and friction coefficient of laser-textured mechanical Seals with a porous Face are much lower. The results show substantial hydrodynamic effects and a better frictional condition between the two Seal Faces.
S.l. Chen - One of the best experts on this subject based on the ideXlab platform.
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Studies on electric-discharge machining of non-contact Seal Face grooves
Journal of Materials Processing Technology, 2003Co-Authors: S.l. ChenAbstract:Abstract In this paper, the electric-discharge machining (EDM) of non-contact Seal grooves was studied. Two types of material, namely: tungsten carbide and silicon carbide were tested by EDM due to their hard machining behaviors. The geometry of Seal grooves is another reason why grinding or other precision machining processes cannot be applied. Four parameters of EDM processes were studied, namely: electrode material, pulse duration, discharge current, and polarity. According to experimental results, the optimal process parameters were obtained based on the specimen’s qualities, such as surFace roughness and depth of cut. An industrial example was also studied in the final stage of the proposed paper.
Samuel Fink S - One of the best experts on this subject based on the ideXlab platform.
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DEVELOPMENT OF A ROTARY MICROFILTER FOR RADIOACTIVE WASTE APPLICATIONS
Savannah River Site (S.C.), 2008Co-Authors: Poirie M, David Herma D, Samuel Fink SAbstract:The processing rate of Savannah River Site (SRS) high-level waste decontamination processes are limited by the flow rate of the solid-liquid separation. The baseline process, using a 0.1 micron cross-flow filter, produces {approx}0.02 gpm/sq. ft. of filtrate under expected operating conditions. Savannah River National Laboratory (SRNL) demonstrated significantly higher filter flux for actual waste samples using a small-scale rotary filter. With funding from the U. S. Department of Energy Office of Cleanup Technology, SRNL personnel are evaluating and developing the rotary microfilter for radioactive service at SRS. The authors improved the design for the disks and filter unit to make them suitable for high-level radioactive service. They procured two units using the new design, tested them with simulated SRS wastes, and evaluated the operation of the units. Work to date provides the following conclusions and program status: (1) The authors modified the design of the filter disks to remove epoxy and Ryton{reg_sign}. The new design includes welding both stainless steel and ceramic coated stainless steel filter media to a stainless steel support plate. The welded disks were tested in the full-scale unit. They showed good reliability and met filtrate quality requirements. (2) The authors modified the design of the unit, making installation and removal easier. The new design uses a modular, one-piece filter stack that is removed simply by disassembly of a flange on the upper (inlet) side of the filter housing. All Seals and rotary unions are contained within the removable stack. (3) While it is extremely difficult to predict the life of the Seal, the vendor representative indicates a minimum of one year in present service conditions is reasonable. Changing the Seal Face material from silicon-carbide to a graphite-impregnated silicon-carbide is expected to double the life of the Seal. Replacement of the current Seal with an air Seal could increase the lifetime to 5 years and is undergoing testing in the current work. (4) The bottom bushing showed wear due to a misalignment during the manufacture of the filter tank. Replacing the graphite bushing with a more wear resistant material such as a carbide material will increase the lifetime of the bushing. This replacement requires a more wear resistant part or coating to prevent excessive wear of the shaft. The authors are currently conducting testing with the more wear resistant bushing. (5) The project team plans to use the rotary microfilter as a filter in advance of an ion exchange process under development for potential deployment in SRS waste tank risers
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TESTING AND EVALUATION OF THE MODIFIED DESIGN OF THE 25-DISK ROTARY MICROFILTER
Savannah River Site (S.C.), 2006Co-Authors: Herma D, Michael Poirie M, Samuel Fink SAbstract:This report details redesign of a commercially available rotary microfilter to meet the operational and maintenance requirements for radioactive service. Personnel developed the design and coordinated procurement of two filters followed by testing of one unit. System testing examined the ability to rinse soluble material from the system, filtration performance using several insoluble solids loadings, effectiveness in washing sludge, amount of wear to parts and maintenance of the system including the insertion and removal of the filter stack, and the ability to flush solids from the system. The test program examined flushing the filter for soluble material by filling the system with a Rhodamine WT dye solution. Results showed that draining the system and rinsing with 50 gallons of water resulted in grater than 100X reduction of the dye concentration. Personnel determined filter performance using various amounts of insoluble sludge solids ranging from 0.06 to 15 weight percent (wt%) insoluble solids in a 3 molar (M) sodium simulated supernate. Through approximately 120 hours of start-and-stop (i.e., day shift) operation and various insoluble solids loadings, the filter produced filtration rates between 3 and 7 gallons per minute (gpm) (0.12-0.29 gpm/ft{sup 2}) for a 25-disk filter. Personnel washed approximately 80 gallons of simulated sludge using 207 gallons of inhibited water. Washing occurred at constant volume with wash water fed to a well mixed tank at the same rate as filtrate removal. Performance measurement involved collecting and analyzing samples throughout the washing for density and sodium content. Results showed an effective washing, mimicking a predicted dilution calculation for a well mixed tank and reducing the sodium concentration from 3.2 M to less than 0.3 M. Filtration rates during the washing process ranged between 3 and 4.3 gpm for one filter unit. The filter system then concentrated the washed 15 wt% insoluble solids slurry to approximately 20 wt% insoluble solids with no operational problems with the exception of the entrainment of air due to leaking packing in the feed pump. Prior to the air entrainment, the filtration rate was approximately 4.2 gpm for one filter assembly with the process fluid temperature adjusted to 35 C. Personnel measured the turbidity of filtrate samples from all phases of testing. All samples measured were less than 3 NTU, with the majority of samples less than 1 NTU. Thus, all measurements fell below the process acceptance criterion of less than 5 NTU. After slurry operations, personnel rinsed the filter with the equivalent of 250 gallons of water by re-circulating 50 gallons of water. The residual sludge solids remaining on the filter stack weighed approximately 685 grams. This amount of solids corresponds to an equivalent activity of 15.1 curies (Ci) beta and 0.38 Ci gamma radiation dose for Sludge Batch 4. Workers completely disassembled the filter system and examined it for signs of wear and component operation. An evaluation by a John Crane Inc. representative concluded that the wear observed on the mechanical Seal resulted primarily from the numerous stops and starts, the abrasive nature of the process fluid and the possibility that the Seal Faces did not receive enough lubrication from the process fluid. No measurable slurry bypassed the mechanical Seal. While it is extremely difficult to predict the life of the Seal, the vendor representative indicates a minimum of one year in present service is reasonable. Changing the Seal Face material from silicon-carbide to a graphite-impregnated silicon-carbide is expected to double the life of the Seal. Replacement with an air Seal might be expected to increase lifetime to five years. The bottom bushing showed wear due to a misalignment during the manufacture of the filter tank. Minor adjustments to the alignment with shims and replacement of the graphite bushing with a superior material will greatly reduce this wear pattern