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  Partner: UNT Libraries
 Department: Department of Engineering Technology
 Decade: 2000-2009
 Year: 2000
 Collection: UNT Theses and Dissertations
Effect of engineered surfaces on valve performance.

Effect of engineered surfaces on valve performance.

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Date: December 2000
Creator: Pope, Larry G.
Description: Performance of air operated valves is a major maintenance concern in process industries. Anecdotal information indicates that reliability of some high maintenance valves has been improved by using an ion deposition process to achieve engineered surfaces on selected components. This project compared friction for various surface treatments of selected valve components. Results indicate valve performance may be slightly more consistent when an engineered surface is applied in the valve packing area; however surface treatment in this area does not appear to have a dominant affect on reducing valve friction. Results indicate a linear relation between stem friction and torque applied to packing flange nuts, and even after a valve is in service, controlled packing adjustments can be made without significantly changing valve stroke time.
Contributing Partner: UNT Libraries
Effects of a surface engineered metallic coating on elastomeric valve stem seal leakage

Effects of a surface engineered metallic coating on elastomeric valve stem seal leakage

Date: December 2000
Creator: Taylor, John Abner
Description: Valve stem seal leakage is a major source of fugitive emissions, and controlling these emissions can result in added expense in leak detection and repair programs. Elastomeric O-rings can be used as valve stem seals, and O-ring manufacturers recommend lubrication of elastomeric seals to prevent damage and to assure proper sealing. In this research, a metallic coating was applied as a lubricant using a vacuum vapor deposition process to the surface of elastomeric valve stem seals. Valve stem leak measurements were taken to determine if the coated O-rings, alone or with the recommended lubrication, reduced valve stem seal leakage. This research determined that the metallic coating did not reduce valve stem leakage.
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Linearity and monotonicity of a 10-bit, 125 MHz, segmented current steering digital to analog converter

Linearity and monotonicity of a 10-bit, 125 MHz, segmented current steering digital to analog converter

Date: May 2000
Creator: Bittle, Charles C.
Description: The purpose of this research is to determine the linearity and monotonicity of the THS5651IDW digital to analog converter (DAC), a prototype of the future Texas Instruments TLV5651, 10-bit, 125 MHz communication DAC. Testing was conducted at the Texas Instruments facility on Forest Lane, Dallas, Texas. Texas Instruments provided test equipment, software and laboratory space to obtain test data. Analysis of the data found the DAC to be monotonic since the magnitude of the differential nonlinearity (DNL) was less than ± 1 least significant bit (LSB) and the integral nonlinearity (INL) was less than ± 0.5 LSB. The study also showed that the DAC has primarily negative DNL although the DNL is well within the desired specification.
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