Measurement Library

Measurement Science Conference Publications (1995)

Calibration Documentation In The Process Environment
Author(s): Richard Pirret
Abstract/Introduction:
Calibration in the Process Industries is a rapidly changing field. Driven by quality standards, regulations, and economic pressures, the Process Industries are focusing new attention on documented. traceable calibration. As a result, the metrology professional is seeing the emergence of a new client group with a tremendous workload, limited resources, and a need for on-site calibration in difticult environments. This new client group is interested in carrying out their traditional role, keeping the plant on-line, as well as carrying nut new responsibilities for calibration and documentation. This challenge calls for new calibration tools that can readily document both procedures, automatically capture calibrat
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Document ID: 40E609F4

Packaging And Business Practices
Author(s): Joseph Jamora
Abstract/Introduction:
With the Supreme Courts decision governing net weight of packaged goods, testing procedures had to change radically to accommodate the variation in net weight of packages attributed to good distribution practices. Although this moisture loss allowance was directed to meat and poultry products only, which are also subject to the Wholesome Meat Act, Weights and Measures officials in California decided to allow a moisture loss allowance for any commodity which inherently contained moisture. The amount of the allowance being determined by the packaging material used.
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Document ID: A7A3A683

Current Loop Signal Conditioning: Practical Applications
Author(s): Karl F. Anderson
Abstract/Introduction:
This paper describes a variety of practical application circuits based on the current loop signal conditioning paradigm. Equations defining the circuit response are also provided. The constant current loop is a fundamental signal conditioning circuit concept that can be implemented in a variety of configurations for resistance-based transducers, such as strain gages and resistance temperature detectors. The circuit features signal conditioning outputs which are unaffected by extremely large variations in lead wire resistance, direct current frequency response, and inherent linearity with respect to resistance change. Sensitivity of this circuit is double that of a Wheatstone bridge circuit. Electrical output is zero for resistance change equals zero. The same excitation and output sense wires can serve multiple transducers. More application arrangements are possible with constant current loop signal conditioning than with the Wheatstone bridge.
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Document ID: 8D11F781

Low-Frequency Thermal Voltage Converter Calibrations At NIST
Author(s): Thomas E. Lipe
Abstract/Introduction:
It is well known that the performance of ordinary thermal voltage converters (TVCs), generally consisting of the thermoelement (TE) in combination with a current shunt or range resistor, begins to degrade at frequencies below audio frequency (20 to 30 Hz). this decrease in performance is due to the thermal time constant of the TE. At low frequencies, the TE does not thermally average the input rms waveform, and time-dependent variations of the output emf occur. The time constant of traditional vacuum-bulb TEs is on the order of a few seconds however, newer solid-state and thin-film TVCs may have time constants on the order of tens of milliseconds, with a corresponding increase in the frequency where thermal averaging begins. The work reported here is the culmination of a project to quantify the low-frequency behavior of both types of TVCs. It describes the NIST low-frequency ac-dc voltage standards and the build-up process for the NIST low-frequency calibration service from less than one volt to 100 volts. The new NIST uncertainty for low-frequency ac-dc voltage calibrations is reported and the statistical basis for the lower uncertainty presented.
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Document ID: 1D105C83

New Advances In Generating Variable Impedance For Calibration
Author(s): Arnold E. Nordeng
Abstract/Introduction:
Emerging quality standards have created a needfor the generation of variable impedance (resistance and capacitance) to support the calibration and verification of a vast array of electronic test equipment from digital and analog multimeters to Platinum RTDs.
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Document ID: 4107CE1D

Calibration Uncertainties For Microform Of Rockwell Hardness Injlenters
Author(s): Fred F. Rudder, Jr., Jun-Feng Song
Abstract/Introduction:
A microform calibration procedure has been developed at NIST to certify geometric conformity of Rockwell C hardness indenters. The interest in microform calibration is to unify national and international comparisons of hardness tests. Using accepted practice, we have determined the measurement uncertainties of each step of the calibration procedure. The measurement uncertainties are expressed and combined using IS0 and NIST guidelines. These guidelines unify the reporting of the calibration uncertainty for national and international comparisons. The problem is described, necessary terminology is explained, and an example is presented using measurement results.
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Document ID: 603319AC

Nasasmeasurementassuranceprogramfor Microwaveattenuationandrisetime
Author(s): Troy J. Estes
Abstract/Introduction:
The National Aeronautics and Space Administration (NASA) uses Measurement Assurance Programs (MAPs) to provide NASA calibration laboratories with a method to compare and improve accuracy, but MAPs meet other needs as well, such as eliminating excessive turn-around times in obtaining traceability to national standards and ensuring NASA calibration laboratories use appropriate techniques and equipment. In 1991, the NASA Metrology and Calibration Working Group initiated a MAP in the areas of microwave attenuation and rise time. This paper provides a summary of how the MAP was developed, the results of the first two rounds of measurements, and the conclusions that can be drawn at this point in the program.
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Document ID: A379CED8

Optimizing Ball Diameter Measurement
Author(s): Ralph E. Karanian, Stephen R Noonan
Abstract/Introduction:
Ball measurement presents challenges not found in parallel surface and cylindrical geometries. This paper will discuss four approaches to meeting these challenges (for balls up to 8 inches in diameter). One of the approaches presented, was developed to optimize the balance between speed and accuracy typically associated with selection of measurement methodology A brief discussion of the measuring instrument used is also presented.
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Document ID: 5BA388D9

Design Of Experiment Doe(): Application Of Technology In Changing Times To Evaluate Three Different Measurement Systems
Author(s): C.J. Litz
Abstract/Introduction:
Presented herein is a unique application of design of experiment (DOE) to the structure and conduct of tests of a Taguchi L, (3) full-factorial experimental matrix (in which nine tests are used to study two factors, each at three levels) using three different measurement systems.
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Document ID: 348A2388

The Self-Calibration Device In Electronic Balances.
Author(s): Walter E. Kupper
Abstract/Introduction:
The accuracy of a modern professional-grade balance is assured by the built-in selfcalibration device. A reference mass is either deposited on the balance internally or set on the pan manually by the operator, after which the balances microprocessor updates the value of a scaling factor which is stored in a non-volatile (power-independent) memory. Available since the early eighties, the self-calibration device should be considered a fundamental and indispensable feature of electronic balances. This paper describes the hardware and software concepts of self-calibration devices in their various forms. The merits of self-calibration are demonstrated by reviewing the calibration errors which may be introduced into a balance from several sources and which are eliminated by the proper use of the self-calibration feature.
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Document ID: 627769AB

Components Of Mass Measurement Uncertainties And The Methods Of Uncertainty Determination
Author(s): Jerry Everhart
Abstract/Introduction:
Measurement uncertainties in mass measurements include various sources of possible error. These sources include weighing equipment capability, standards used, process used, operator techniques and environmental influence. All of these sources of measurement uncertainties can be grouped into three components. The methods of determining the measurement uncertainties can also be grouped into three methods with various degrees of reliability depending on the method chosen. This paper will describe the components of mass measurement uncertainties and the importance of determining each ingredient. It will describe the methods necessary to determine uncertainties and preferences for each method.
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Document ID: 718FF0F0

Design Of A Documenting Process Calibrator
Author(s): Dan Carson
Abstract/Introduction:
There is a new category of multifunction calibrator. This paper describes the fast track development of a hand-held, battery powered calibrator for the process industry, the Fluke 702 Documenting Process Calibrator (DPC). The DPC (Fig. 1, shown with pressure module) simultaneously sources and measures electrical and physical parameters, and documents results, while maintaining isolation between source and measurement terminals. It interfaces with a PC for task development and results exporting. Firmware provides an advanced user interface that displays information in English, French, German, Italian, or Spanish.
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Document ID: 04EC8001

Measurement Errors Of Mass Determtnation At High Accuracy
Author(s): Arend Helms
Abstract/Introduction:
In mass metrology the management of measuring errors has been well defined through OIML recommendations and international standards. International recognition of different systems has led to a high grade of harmonization. This, however, applies only to a particular subject of mass metrology dealing with objects of measurement that are mass standards and weights. In this case the calculation of total measurement uncertainty is well organized on the base of maximum permissible error classification.
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Document ID: 33DDE562

Metrology Laboratory: Not Just Serving The Weights & Measures Department And Industry
Author(s): Emil Hazarian
Abstract/Introduction:
The paper focuses on two primary functions of the Metrology Laboratory within Weights and Measures Department: first to assure uniform and accurate measurements, and traceability for the measuring devices used by field inspectors throughout the County, and second to serve the industry in two major calibration fields, mass and volume.
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Document ID: 69DF20E7

Scales And Meter Inspection - Not Just Grocery Stores And Gas Stations
Author(s): Phil Livesey
Abstract/Introduction:
The lecture will discuss the many aspects of device inspections. Most consumers are aware of Weights and Measures inspection of grocery scales and gasoline station pumps. Fewer are aware of mandated inspections of meters that measure fuel to jet planes and boats. Inspections of mobile home parks and taxi meters. On the scale side, there are inspections of heavy capacity vehicle and shipping/receiving scales. Additionally, inspections are required on jewelry, railroad tract and animal scales.
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Document ID: 7E531E72

How To Measure Customer Focused Quality
Author(s): Mark E. Crumly
Abstract/Introduction:
The panel will explore customer satisfaction survey techniques from many points of view. The concept of internal customers will be explored along with the traditional customer base. Practical examples of survey techniques will demonstrate how to conduct an effective survey and identify common mistakes.
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Document ID: 6CB35204

Calibration Of Industrial Measuring Instruments
Author(s): Raghu Kacker
Abstract/Introduction:
Calibration is done in industry to reduce the errors in product measurements by correcting their intercept and slope relative to a reference scale. Thii paper deals with the errors remaining after calibration due to (1) the differences between products and reference artifacts, (2) the differences between measurement and calibration conditions, and (3) the driit in instrument response. When the influence of these sources of error is excessive, product measurements may be worthless. This paper proposes an industrial calibration system that addresses the following questions: How should one deal with the diiferences between products and reference artifacts, and with the differences between measurement and calibration conditions? In order to control errors due to the drift in instrument response, how often does a measuring instrument need to be checked and when does it need to be re-calibrated? What is the uncertainty remaining after calibration in product measurements ? The proposed industrial calibration system can substantially reduce the errors in real time product measurements, and is broadly applicable.
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Document ID: 41FF0427

Automotive Piston Grading An Application Of An Error Control System
Author(s): Jack Wood
Abstract/Introduction:
An important operation in automotive piston production is the measurement of several dimensions which affect clearances in the assembled engine. These clearances are related to noise emitted from the engine, fuel economy degradation, and other engine attributes which affect customer satisfaction. In the past, the piston skirt measurement system has been recalibrated frequently as a means of protection against misclassification. The industrial calibration system protocol, developed by Kacker, was used to evaluate this calibration practice. Results of this and other examples are presented and conclusions are drawn to guide future applications.
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Document ID: D672BD6C

An Assessment Of, And Response To, Industrial Needs For Metrological Applications Of Scanned Probe Microscopy
Author(s): T.H. Mcwaid, J. Schneir
Abstract/Introduction:
NIST personnel visited over 25 semiconductor industry companies to determine semiconductor industry needs for scanned probe metrology. NIST has initiated programs addressing the shortcomings in the technical infrastructure impeding the successful application of scanned probe microscopy to process development and control measurements.
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Document ID: 5296A21B

The NIST Frequency Measurement Service
Author(s): Michael A. Lombardi
Abstract/Introduction:
The NIST Frequency Measurement Service began operation in 1984 to assist users who need to make high-level frequency calibrations traceable to NIST. Organizations can subscribe to the service by paying a monthly calibration fee to NET.
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Document ID: 4521292D

Recent Mcs Improvements To Gps Timing
Author(s): Capt Steven T. Hutsell
Abstract/Introduction:
With the completion of a 24 operational satellite constellation, GPS is well capable of providing the timing accuracy and stability performance required by system specitications. Now that weve successfully reached this major milestone, the GPS community will need to address future timing enhancement proposals with extra prudence. This paper demonstrates how the Master Control Station @ES) recently improved four operational aspects of GPS timing. These advancements include a re-stmctore of the MCS Kahnan Filter partitions, a change to the GPS time steering magnimde, a software change allowing greater flexibiIity when utilizing United States Naval Observatory (USNO) data, and a long-awaited refinement to Rubidium clock drill rate estimation. The above enhancements have all significantly improved GPS accuracy and stability figures. As a by-product, this tine tuning has increased the MC% ability to evaluate the performance of individual atomic frequency standards and of MCS Kahnan Filter estimation.
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Document ID: EE54CB43

Uncertainties Using Multiple Piston( Gage) Instruments
Author(s): C. D. Ehrlich, K. R. Eberhardt, J. C. Houck, D. B. Ward
Abstract/Introduction:
Deadweight piston gauges are used as primary and secondary pressure standards over the nominal range lo3 to lo9 Pa. An individual high-quality piston gauge is typically capable of measuring pressure and effective area, at a reasonable level of uncertainty, from the maximum operating pressure of the gauge to somewhere between 0.1 to 0.01 of the maximum operating pressure of the gauge. This requires a laboratory to develop and maintain multiple piston gauge standards in order to provide calibration services covering the full six decades of piston gauge metrology.
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Document ID: EFBAE6E8

High Accuracy Micrometer For Cylinder And Wire Calibrations
Author(s): John Stoup, Ted Doiron
Abstract/Introduction:
We have developed a simple micrometer for the calibration of cylinders and wires. The instrument uses a laser interferometer as a length scale and provides absolute measurements by cylindrical artifacts. Eliminating the need for master artifacts allows increased accuracy and efficiency. The micrometer has been thoroughly tested against other calibration methods at NIST, and an early prototype has been used in international comparisons for optical fiber diameter measurements. The uncertainty of the current model is estimated to be better than 40 nanometers (1.6 microinches) for small wires (2 a). Basic metrological principles used in the design of the micrometer will be designed and planned developments will be discussed.
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Document ID: FCBD9E5D

A Calibrators Guide To The Use Of Vacuum Gages Between 0.01 And 100 Pa
Author(s): J. Patrick Looney
Abstract/Introduction:
Calibration service for vacuum gages has recently been extended at NIST with the completion of the NIST Primary Transition Range Vacuum Standard. This standard is designed to calibrate Ca : acitance Diaphragm Gages (CDGs) and Spinning Rotor Gages (SRGs) in the pressure range lo- and 100 Pa with total uncertainties less than 0.5% (2-u). We have found that the problem of accurate calibration of vacuum gages in the regime between 0.01 and 100 Pa is compounded by the fact that both SRGs and CDGs exhibit nonideal gage response and performance limitations the SRGs at the highest pressure, and the CDGs at the lowest pressures. In this paper we discuss the performance characteristics these gages and present typical performance data obtained with the new standard for SRGs and low-range (0.1, 1.0 Torr Full Scale) CDGs. We shall also discuss the useful range of operation of these gages and the typical measurement accuracy one may expect to achieve. Finally, we will point out aspects of gage performance that calibration laboratory users should be aware of when using CDGs and SRGs for gage calibration in this regime.
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Document ID: 569B6C6B

Commercial Leak Standards Their Properties And Reliability
Author(s): S. A. Tison
Abstract/Introduction:
Standard leaks or leak artifacts are used extensively in industrial and research environments most typically for calibration of helium leak detectors. Two types of leak are generally used which have very different characteristics. The most commonly used leak is the helium permeation type which uses a glass or quartz element to restrict the flow of helium with a diffusion process. The second type of leak, usually referred to as a capillary leak, restricts the flow with a physical restriction typically very small diameter tubing. With the advent of increased concern about atmospheric gas emissions leak standards for refrigerant and other ozone-depleting gases have become of great importance. While they do not vary much in principle of operation, these types of leak standards are usually of quite different construction and have unique limitations and applicability. The properties and reliability of the above mentioned standard leaks will be presented with particular emphasis on helium permeation leaks which are most prevalently used.
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Document ID: CC50863E

Reference Materials - A NIST Status Report
Author(s): Thomas E. Gills
Abstract/Introduction:
Standard Reference Materials (SRMs) represent one mechanism by which measurement quality and traceability to a national measurement system can be achieved when they are properly used. As a part of its congressional mandate the goals of NIST are to develop reference and definitive methods of analysis, certify, issue standards and assure their effective use in the measurement community thereby helping to achieve accurate measurements in the U.S. and throughout the world.
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Document ID: FD84B594

Verifying The Accuracy Of Analytical Spectrophotometers
Author(s): J.C. Travis, M.V. Smith, N.K. Winchester, J.C. Colbert
Abstract/Introduction:
A variety of Standard Reference Materials (SRMs) for verifying the absorbance and wavelength accuracy of UV/visible spectrometers has been developed and marketed by NIST over the past two decades. Neutral density glass is certified for transmittance density and transmittance at five wavelengths from 440 nm to 635 nm, at six nominal transmittance levels from 0.01 to 0.5. Thin film metal-on-quartz filters extend convenient solid-filter calibration into the UV at nominal transmittances of 0.1, 0.3 and 0.9. Liquid standards spanning UV/visible wavelengths offer several advantages to the user, but at the expense of more complicated procedures for their use. A solution of holmium oxide in flame-sealed quartz cuvettes is available for calibration of the wavelength axis of spectrophotometers using fourteen sharp spectral bands with certified wavelength. Current research efforts are directed to developing sealed-cuvette liquid absorbance standards, and solid filter standards for wavelength calibration and absorbance verification in near infrared spectrophotometers. NIST provides a detailed description of the accuracy uncertainty of each certified value furnished. The end user confounds this uncertainty with the measurement precision of the tested instrument and with the stated tolerance of the test to determine a confidence interval that should properly describe the experimental data for the tested instrument.
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Document ID: A6B7FC97

Chemical Measurements And The Concept Of Traceability
Author(s): William P. Reed
Abstract/Introduction:
Economic activity is one of the dominant characteristics of life in the latter part of the twentieth century. World trade and the exchange of goods across national borders is not only an ideal but is a goal and a necessity for many nations. This necessity naturally emphasizes economic competition. As in any competition, competitors seek an advantage for their product or good. So at the same time that nations attempt to gain a level playing field for their products, they also, in many cases, seek to raise technical barriers to imported products. In addition, this economic competition tends to pull the people of the world closer together with regard to certain issues as health and the environment. Many of these technical barriers as well as the issues that bring people of the world closer together have to do with chemical measurements.
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Document ID: 5ABF1623

Traceability In Physical Measurements
Author(s): Joe D. Simmons
Abstract/Introduction:
This paper will discuss the progress that has been made over the past two years and developments underway to harmonize the U.S. approach to traceability of physical measurements with those of our major trading partners, Particular emphasis will be focused on the development of worldwide traceability through a network of regional organizations. In North America, two regional organizations, NORAMET and NACC (North American Calibration Cooperation), are being developed with the United States, Canada, and Mexico. NORAMET will coordinate measurements at the national standards level and NACC will coordinate measurements at the accredited laboratory level. The purpose is to develop sufficient mutual confidence in the international traceability of the national standards and in the operation of the national calibration laboratory accreditation systems to sign mutual recognition agreements (MRAs) within the North American region and eventually with other regional organizations such as the WECC (Western European Calibration Cooperation).
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Document ID: 04DF0BEA

Traceability In Testing Measurements
Author(s): Graham Cameron
Abstract/Introduction:
This paper will discuss the need for reliable measurements in support of testing and other conformity assessment areas, in the context of accreditation and national measurement systems. The talk will demonstrate the requirement for validated measurement traceability in keeping with provisions of the North American Free Trade Agreement, emerging Mutual and Multilateral Recognition Agreements (MRAs and MLAs) and the trans.border or sectoral acceptance of results.
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Document ID: CB7EC675

Applying The IS0 Guide To The Expression Of Uncertainty In Measurement In A Mass Metrology Laboratory
Author(s): Mark Fritz
Abstract/Introduction:
The publication of the IS0 Guide to the Expression of Uncertainty in Measurement and NIST Technical Note 1297, Guidelines for Evaluating and Expressing the Uncertainty of NIST Measurement Results, has resulted in our having to rethink our approach to uncertainty in the mass measurement laboratory. In the process of changing to the IS0 Guide, I have completed a thorough uncertainty analysis. Classifying components by type A and type B. The analysis begins with the air density calculation and looks at the effects of uncertainty in the measurements of barometric pressure, temperature, and relative humidity, and the contribution of each toward the total uncertainty of the air density calculation used in the mass calculation. The next step is determining the uncertainty of the balance using a statistical process. While this analysis is statistical in nature, it also includes other components of uncertainty which must be considered. Finally all uncertainties are combined with the uncertainties of the primary standards using the root sum square technique. In this paper I will elaborate on how I analyzed each component and give rationales on why I took certain approaches. I will conclude with a comparison with the traditional approach to uncertainty reporting in mass measurements, and discuss the new smaller uncertainty numbers. Emphasizing how they do not reflect a radical improvement in measurement technology but just a new way of expressing the uncertainty.
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Document ID: 4D6C48DE

Transferring Audc Differen Crs From NIST At 5 Ppm To Product At 10 Ppm
Author(s): Bud Stott
Abstract/Introduction:
The Fluke 792A AC/DC Transfer Standard was developed to support the 5790A AC Measurement Standard and the 5700A Calibrator. This support made it necessary to provide specifications for the 792A with uncertainties as small as 10 ppm for AC/DC differences. At these points it was possible to get NIST characterizations with uncertainties of 5 ppm. The manufacturer must transfer this characterization to working standards in the Primary Standards Laboratory, then to standards for use in the factory, and finally, to the product. This paper describes the measurement methods, software, and uncertainty analysis which enables the manufacturer to specify 10 ppm uncertainty for a product while obtaining 5 ppm uncertainty from NIST.
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Document ID: A00EA933

Uncertainty Analysis For Laboratory Accreditation
Author(s): Peter Crisp
Abstract/Introduction:
NAMAS Accredited laboratories re required to follow recommended methods for the estimation of uncertainties in electrical measurements. These are well documented in the NAMAS Publication NIS 3003 and are consistent with the ISOITAG4 Guide to the Expression of Uncertainty in Measurement. The paper examines the techniques used by Waveteks Datron Division for the estimation of uncertainties in support of the companys NAMAS Accredited calibration facilities. The paper discusses the evaluation of the uncertainty contributions and in particular, the principle of Audit via Traceability - a mandatory requirement for accredited laboratories with capabilities better than 1 ppm for DC voltage.
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Document ID: B903F7DA

Applications Of Statistics And Uncertainty To Dimensional Metrology
Author(s): Brian Parry
Abstract/Introduction:
In recent years, definitions and procedures addressing the concept and consequences of measurement uncertainty have received significant attention from both metrologists and statisticians. From considerations of basic definitions in both metrology and statistics, this paper attempts to show how both disciplines may benefit by the use of common terminology and applications. The example used is the Quality Loss Function and how it may be influenced by measurement uncertainty.
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Document ID: 73C7F26A

Current Good Manufacturering Practices
Author(s): John Miche
Abstract/Introduction:
A panel discussion of the Food and Drug Administrations regulation of the manufacture of Pharmeceuticals and medical devices. Chris Cardone is a field inspector with the FDA and will be joined by Gregory Singleton, Senior Metrologist at Vestar and John Miche, a consulting Pharmeceutical Engineer, to discuss the principles and practices of the FDAs CGMPs. Particular attention will be given to the services available through the FDAs Small Business Assistance Program to promote and support the adoption of quality manufacturing practices. Questions will be taken from the floor, so come prepared.
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Document ID: A3F6887F

The Semiconductor Industry Association Technical Roadmap
Author(s): Dr. James Glaze
Abstract/Introduction:
The worldwide semiconductor industry enables a vast electronics industry which will become the worlds largest early in the next century. Advanced semiconductors are critical to both civilian and defense industrial sectors and hence national security. Most, if not all modem industrial countries are targeting this industry as it is perceived to hold the key for future economic growth. While each new generation of semiconductor devices has achieved impressive gains in productivity and has fostered new applications and markets, research and development efforts required to sustain productivity advances are escalating. These R&D efforts are beyond the ability of individual companies alone to support. Continued productivity will require participation by both public and private sectors. The National Technology Roadmap for Semiconductors provides the framework for this cooperative participation.
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Document ID: D0396FD4

Industrial Trends In Semiconductor Reference Materials
Author(s): James .I. Greed, Jr.
Abstract/Introduction:
The technical and quality challenges faced by the semiconductor industry are reflected and, in fact amplified by the gauge makers rule in the development, manufacture and certification of reference materials intended to serve the integrated circuit community. This paper examines the general contemporary trends in technology and business practices as they affect the production and evolution of reference materials. Three specific technical areas are discussed particle detection and metrology in contamination free manufacturing, thin film metrology and surface topography. The utility of the National Technology Roadmap for Semiconductors in guiding the evolution of reference materials is also discussed.
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Document ID: 4DA438A0

Using Guardbands To Justify Turs Less Than 4:l
Author(s): David Deaver
Abstract/Introduction:
This paper describes the difficulty using Test Uncertainty Ratio (TUR) alone to assure the quality of calibrations. It investigates the relationship between TUR, confidence interval, and guardbands and how they can be used cooperatively to manage the calibration process.
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Document ID: F59A75DF

Uncertainty Analysis For Risk Management
Author(s): Howard Castrup
Abstract/Introduction:
Measurement errors and error models are reviewed and measurement process error components are described. The computation of measurement uncertainty due to error sources and due to the process error components of each error source is discussed. Measurement decision risks are estimated based on the results of an uncertainty analysis example and risk management considerations are outlined. Classical measurement decision risk is also discussed, with special emphasis on the impact of process uncertainty on false accept and false reject risks. A new method for computing risks is given in Appendix B.
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Document ID: D49A2A94

Uncertainty Analysis Of Test And Measurement Processes: A Graphical Presentation
Author(s): .I. A. Ferling
Abstract/Introduction:
The mathematics underlying the study of error and uncertainty propagation in test and measurement processes is non-trivial. In a widely studied model, for example, it requires the numerical evaluation of double integrals involving the bivariate normal distribution. In the past the results of such studies have been presented in tabular form, and more recently, through interactive computer programs.
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Document ID: 1531A979

Measurement System Variation
Author(s): Dr. Bovas Abraham
Abstract/Introduction:
Many industries utilize large resources to collect data, sometimes using highly sophisticated equipment. These data may lead to very costly decisions. One should be very concerned about the actual data collection processes: methods of data collection, the equipment used, personnel involved, etc. In this paper we look at two industrial examples. The first one is concerned with the assessment of variation in a measurement system dealing with headlight aiming of an automobile and the second one deals with improvement of a gauge through design experiments. We also include some comments aabout measurement systems in other situations and other sectors.
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Document ID: F05925E7

Development Of Srms For Use In Water Quality Measurements
Author(s): Jean Kane
Abstract/Introduction:
The National Institute of Standards and Technology (NIST) produces a large number of Standard Reference Materials (SRMS) which can be used to assure the accuracy of measurements in analytical laboratories throughout the country and internationally. Many of the measurements made are related to regulatory requirements, for example drinking water regulations.
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Document ID: 61D20D89

Calibration Data Management: Solving Tbe Problems Of Sharing Data On Tbe Corporate Network.
Author(s): Nicholas B. Mason
Abstract/Introduction:
Many metrology laboratories are using personal computers (PCs) connected to a corporate network for the task of calibration management. Many labs are attempting to increase productivity by using the network to share data among users. However, simultaneous access to data files can lead to data loss if the underlying process is not well understood or implemented properly.
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Document ID: C93BF544

Measurement Uncertainty And Traceability Of Pc Based Data Acquisition Systems
Author(s): Paul R. Lantz
Abstract/Introduction:
This paper deals with calibration and measurement uncertainty problems associated with PC based data acquisition equipment both PC plug-in boards and external front-end chassis. Often with PC based instrumentation systems, the measurement hardware is calibrated with one PC, then moved back to its host PC for actual operation. For the plug-in card this procedure creates a situation where traceability cannot be reliably maintained due to the uncharacterized condition (inside the host PC) in which the measurements are made. A case can further be made that even if the measurement hardware is calibrated while situated in its host PC, noise conditions experienced during actual operation will not be the same as those experienced during its calibration simply because different software is running on the computer changing the ways in which the memory and video hardware are used. This again poses the problem of measurement uncertainty that may only ultimately be solved through utilizing measurement devices external to the PC posessing known and controlled measurement environments. Ultimately, it is up to the user to decide how important these issues are in his application.
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Document ID: 27F3C3F6

Calculating Uncertainty Of 1-D Measurement On A Cmm
Author(s): Nick Zurcher
Abstract/Introduction:
The large M-60 Coordinate Measuring Machine located in the NISTIY-12 facilities at the Oak Ridge Metrology Center in Oak Ridge, Tennessee, is being used to calibrate end standards and step gages up to 1.5 meters in length. This presentation will review the steps taken to calculate the uncertainty of these calibrations. It begins with a practical look at the sources of measuring uncertainty inherent in 1-D measurements on the M-60 and continues with identification of the methodology used to compute the uncertainty value for these sources. The method used was generated using guidance from NIST Technical Note 1297 Guidelines for Evaluating and Expressing the Uncertainty of NIST Measurement Results. Actual measurement data of known artifacts used to test the uncertainty value will also be shown. FOR ADDITIONAL INFORMATION CONTACT:
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Document ID: 14FEBC87

Interactive Calibration Procedures
Author(s): Phiiiip T. Chase
Abstract/Introduction:
A recent survey of metrology organizations reveals that over 70% of calibration processes are guided by either manufacturers manual procedures or by internally prepared paper procedures. Todays bench technician is basically following the same type of paper driven protocols used by his predecessors thirty years ago. While automatic calibrators have speeded up the process for certain classes of electronic instruments, the bulk of calibration checking is still performed manually. Additionally, while many companies have converted their calibration procedures to word processing formats for ease of maintenance, the end is still a paper process, including entering results on paper and filing them away.
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Document ID: 81AC1C8B

Realization And Dissemination Of The ITS-90 In The Range Of 0.65 K To 83.8 K At NIST
Author(s): Weston L. Tew, Christopher W. Meyer
Abstract/Introduction:
The International Temperature Scale of 1990 (ITS-90) has significantly improved the scale reproducibility and thermodynamic agreement relative to previous low temperature scales. A new program is in place at NIST to directly realize the ITS-90 from its definitions and to disseminate this scale to its user community. Two new facilities for the scale realization and for customer calibrations between 0.65 K and 83.8 K are now in use. We describe here the changes brought about by the advent of the ITS-90 relevant to cryogenic thermometry and the methods employed at NIST for the scale realization and comparison calibrations. These include the realization of cryogenic fixed points via both sealed-cell and unsealed-cell devices, the use of an interpolating constant volume gas thermometer, helium vapor pressure thermometry, and transferring the scale via standard platinum resistance thermometers (SPRTs) and rhodium-iron resistance thermometers (RIRTs). Calibration capability for other resistance and diode thermometers will also be discussed.
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Document ID: F1D24146

Gold Versus Platinum Thermocouples: A Highly Accurate Secondary Reference Thermometer
Author(s): Dean Ripple
Abstract/Introduction:
Gold versus platinum thermocouples are stable to 15 mC over 1000 hours of use at temperatures up to 1000C. Compared to high temperature standard platinum resistance thermometers, the thermocouples are more rugged and may have less long-term drift at temperatures above 960C. These factors make Au/Pt thermocouples ideal as a secondary standard for temperatures up to 1000C. Practical methods used at NIST for the preparation, calibration, and use of Au/Pt thermocouples are described in this talk. Special techniques are necessary to properly anneal the wire elements, to minimize contamination of the thermoelements by impurities, and to prevent wire strain caused by the different thermal expansion coefficients of platinum and gold. The assembled thermocouples are calibrated at the freezing points of In, Sn, Zn, Al, Ag, and Au, which arc defining fixed points of the International Temperature Scale of 1990. The deviations of the measured emf values from the reference values are fitted with a low-order polynomial to obtain a calibration function for the thermocouple.
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Document ID: 17D8771B

Calibration And Accuracy Of Secondary Standard Prts To ITS-90
Author(s): Thomas J. Wiandt
Abstract/Introduction:
The Standard Platinum Resistance Thermometer (SPRT) portion of the ITS-90 was formulated for specific, very high quality PRTs. Much work has been done to demonstrate the high accuracy of tit to the ITS-90 of these instruments. However, many secondary PRT users are unsure of the accuracy of fit that can be achieved when this family of less precise and nonstandard instruments are calibrated on the ITS-90. To further complicate the issue, many of these instruments, due to their size or shape, are not suited to fixed point calibration. Therefore the calibration points are likely to differ by some amount from the actual ITS-90 fixed points. This project was undertaken to study the behavior of this family of instruments over the temperature range of 77.65 K to 773.15 K (-195.5C to 500C). PRTs from six leading manufacturers are included. The study is composed of calibration as outlined in the ITS-90 with subsequent comparison to SPRTs in various temperature calibration baths to determine the deviations in measured temperature. The data will be fitted to the mathematical formulae as outlined in the ITS-90 as well as several different sets of equations which are either proposed for use or are already in common use.
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Document ID: AF630A54

The Role Of Legal Metrology And The Trends Of Regulations
Author(s): Bob Atkins
Abstract/Introduction:
The lecture will discuss the changing role of legal metrology and its importance in a global market environment. GATT and NAFTA demand that all products be marketed free from biased regulations which become de facto trade barriers. Clear and uniform requirements are the basis for fair competition and they must be based in terms and standards that are reliable between jurisdictions. Acceptable moisture loss and good distribution must be defined nationally and internationally. Sampling plans for all commodities are being developed nationally among the National Conference of Weights and Measures Officials, the U.S. Departments of Agriculture and Food and Drug Administration.
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Document ID: 91E7D7FA