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Comparison Between Melting and Freezing Points of Indium and Zinc
D. Cabana, M.J. Zhao, R. Ding, D. Chen
NCSLI Measure | Vol. 3 No. 1 (2008) | 10.1080/19315775.2008.11721415
Publisher NCSL International | Published 3/1/2008 | Pages 70-74
Abstract: In the interest of improving convenience and plateau duration, the use of melting points instead of freezing points for temperature fixed points in temperature calibration is considered. The question is whether adequately low
uncertainties can be achieved with melting plateaus. Experimental research was carried out to compare the melting and freezing points of indium and zinc by using the inter-comparison method with standard platinum resistance thermometers (SPRTs). The
influence of the furnace maintenance temperature on the performance of melting plateaus of indium and zinc was investigated and discussed. Differences in results between the melting points and the freezing points are shown. Uncertainty budget analysis
of the melting points is presented. The experimental results show that because of the small differences between the freezing points and melting points using the optimal methods of realization, it is possible to replace the freezing point with the
melting point in the calibration of SPRTs in secondary-level laboratories.
Evaluation of Dual Quartz Resonant Pressure Transducers as Military Transport Standards for High Accuracy Applications
John Ball
NCSLI Measure | Vol. 3 No. 1 (2008) | 10.1080/19315775.2008.11721412
Publisher NCSL International | Published 3/1/2008 | Pages 50-55
Abstract: The Army is considering the use of transfer standards rather than traditional, hierarchical methods to support high accuracy calibration requirements in tactical environments. Such schemes have the potential to improve accuracy,
reduce cost, shrink logistical overhead, and eliminate the need to evacuate calibration equipment from the theater of operation. The Army recently selected a new set of tactical pressure calibration equipment with transfer calibration specifically
in mind as the support concept of preference. The following presents an overview of the evolving Army transfer calibration system for pneumatic pressure and an evaluation of the expected performance of the quartz resonant transducer-based transport
standards selected for this demanding application. Relevant data from commercial and government laboratories on quartz resonant pressure transducers, along with the results of the author's engineering tests are summarized in the context of the proposed
application. These transducers were found to exhibit intercept shifts over time which make them impractical as military transport standards unless they are used in pairs so that their condition can be determined in the field. However, the use of dual
transducers not only makes QRPTs practical as transport standards but also may improve uncertainty of indication in absolute pressure measurements.
Improved Measurements in Contact Thermometry at High Temperature Through Practical Fixed Points
R. Morice, P. Ridoux, J.R. Filtz
NCSLI Measure | Vol. 3 No. 1 (2008) | 10.1080/19315775.2008.11721411
Publisher NCSL International | Published 3/1/2008 | Pages 44-49
Abstract: The development of High Temperature Fixed Points (HTFPs) based on metal-carbon eutectics, as well as improvements of contact sensors, such as platinum-palladium thermocouples, has opened new perspectives for accurate temperature
measurements in processes requiring good control at high temperature. Recently three major European laboratories, LNE, NPL and PTB, have decided to join their research efforts with the aim of developing robust HTFPs to reduce current calibration uncertainties
of noble metal thermocouples up to 1554 °C. HTFPs have also been successfully investigated at LNE for the study of tungsten-rhenium alloy thermocouples. This paper first presents general results in the development of metal-carbon fixed points and
then discusses prospects in the near future through a description of some current research activities.
NCSLI Measure | Vol. 3 No. 1 (2008) | 10.1080/19315775.2008.11721410
Publisher NCSL International | Published 3/1/2008 | Pages 36-42
Abstract: The accurate measurement and control of temperatures above 1100 °C is essential for the success of many industrial processes. However these measurements are generally difficult, leading to wide uncertainty margins, particularly
at very high temperatures above 1800 °C. Recent developments in high temperature metrology mean that there will be a step change improvement in this field in the next few years, particularly due to the advent of high temperature fixed-points and improved
thermocouple types, such as Pt/Pd. This paper reviews international developments in these areas that could ultimately lead to an improved way of realising ITS-90 above the Ag point, reduced thermocouple calibration uncertainties by factors of two
or more, and improved dissemination and measurement of high temperatures to industry.
Proposed Changes to the SI and Their Impact on Electrical Metrology
Barry Wood
NCSLI Measure | Vol. 3 No. 1 (2008) | 10.1080/19315775.2008.11721413
Publisher NCSL International | Published 3/1/2008 | Pages 56-60
Abstract: Recent proposals to fundamentally change the SI system of units have generated considerable debate and are now being seriously considered by international committees. These proposals all have a common theme: to exactly fix the
values of a set of fundamental physical constants and then to define the SI units with respect to the values of these invariants. The proposed changes and the ways in which national standards institutes would typically realize the SI units are outlined.
The expected benefits and drawbacks of these changes are reviewed as they pertain to measurement science, to fundamental constants and in particular to electrical metrology. The positions of the Consultative Committee for Units, the Consultative Committee
for Electricity and Magnetism and the Committee on Data for Science and Technology (CODATA) Task Group for Fundamental Constants are summarized, as well as outline possible schedules and the process that must be followed to implement such a change
in the SI.
Radiation Thermometry Capabilities of the PTB up to 3200 K
Klaus Anhalt , Joerg Hollandt, Juergen Hartmann
NCSLI Measure | Vol. 3 No. 1 (2008) | 10.1080/19315775.2008.11721409
Publisher NCSL International | Published 3/1/2008 | Pages 26-34
Abstract: The accuracy of the high-temperature part of the International Temperature Scale of 1990 (ITS-90) was for a long time limited by the lack of appropriate fixed-points above the freezing temperature of copper at 1084.6 °C. Recently
novel high-temperature fixed-points have been developed for temperatures up to 3200 K. Using blackbody radiators immersed in metal-carbon (M-C) or metal-carbide-carbon (MC-C) eutectic materials results in fixed-points which can be used as reference
sources for radiation thermometry, radiometry and photometry. Currently, implementation of these novel MC-C eutectics in an improved international high-temperature scale is the topic of a worldwide cooperation of several national metrology institutes
(NMI). Within this cooperation PTB determines by radiation thermometry and radiometry based on Planck's law of radiation the melting temperatures of these eutectic metal-carbon alloys with low measurement uncertainties and explores their usefulness
for an improved high temperature scale. In addition to their application at the NMI level these materials can be directly applied to guarantee stable and reproducible temperature measurements in an industrial environment, e.g. in power engineering
or aerospace industry, where a reliable high-temperature measurement is crucial for an efficient use of resources and safety issues for a long material and product lifetime. The paper gives a short overview of the radiation thermometry capabilities
of the PTB in the temperature range from 100 K up to 3200 K. The focus of the presentation then lies on the high-temperature range above 1400 K. Here the variety of metal-carbon eutectic fixed-point materials and their application for radiation thermometry
and radiometry is presented. The determination of the thermodynamic phase transition temperatures of these MC-C eutectics, which is essential for their implementation in an improved International Temperature Scale, is described in detail.
NCSLI Measure | Vol. 3 No. 1 (2008) | 10.1080/19315775.2008.11721414
Publisher NCSL International | Published 3/1/2008 | Pages 62-68
Abstract: Since 1954, the kelvin has been defined by the temperature distance between absolute zero and the triple point of water, with an assigned temperature value of exactly 273.16 K. Hence, the base unit of temperature depends on
the limited stability and reproducibility of a certain material sample. A new definition of the kelvin not based on a special material should be aspired similar to the second or the metre, where a fixed value is assigned to an atomic transition or
a fundamental constant. Following this road, the kelvin can be related to the thermal energy, kT, with the Boltzmann constant, k, as a fixed conversion factor. In order to determine a reliable value of k, currently several methods are investigated
by different research institutes. The methods with the lowest expected uncertainties are the acoustic gas thermometer and the dielectric constant gas thermometer. Other methods include Doppler-broadening thermometry and radiation thermometry. Having
obtained a sufficient agreement of the different methods of the order of 10−6, the new definition of the kelvin may read: “The kelvin is the change of thermodynamic temperature, T, that results in a change of the thermal energy, kT, by exactly 1.380
65X X × 10−23 joule, where k is the Boltzmann constant.”
Are Gas Pumps Measuring Up? The Mexican Experience
Cesar Cajica, Manuel Maldonado, Ismael Castelazo, Heinz Luchsinger
NCSLI Measure | Vol. 3 No. 2 (2008) | 10.1080/19315775.2008.11721426
Publisher NCSL International | Published 6/1/2008 | Pages 62-68
Abstract: Advances in measurement and electronics technology have allowed manufactures to produce improved fuel dispensers that offer the consumer fair and convenient transactions at the gas station. However, authorities are having a
difficult time developing reliable conformity assessment procedures that assure the consumer that the same sophisticated technology is not working against them. This paper describes the experience of CENAM in assessing the conformity of fuel dispensers
sold in Mexico to the new, more stringent regulations issued in the last two years. The issues discussed include a comparison of the measurement capabilities of modern dispensers with the tolerance accepted by the standard and the difficulties involved
in verifying the software and electronic components that compute and display the total sale amount.
Comparing and Contrasting Studies of Metrology Education and Training in Europe and North America
Georgia Harris, Leslie Pendrill
NCSLI Measure | Vol. 3 No. 2 (2008) | 10.1080/19315775.2008.11721423
Publisher NCSL International | Published 6/1/2008 | Pages 38-45
Abstract: This paper compares and contrasts two studies of the status of metrology education and training completed within NCSL International (NCSLI) and Implementing the Metrology European Research Area (iMERA). The current formulation
by NCSLI and its partners of a strategic roadmap for metrology education and training and a survey of accreditation body assessors are presented. In addition, a corresponding iMERA study in Europe of metrology knowledge transfer has been initiated
in preparation for the new European Metrology Research Program. This paper compares and contrasts the approaches and the formulations of these project and concludes with suggestions for future cooperation. Both the NCSLI and iMERA studies have shown
a coordinated forum is needed to ensure that metrology staffing requirements are met at all levels – i.e., competent personnel and the necessary resources to support them.
Design of an Electro-Optic Device for In-situ Measurement of High Voltage Pulses
Beverly Klemme, A. Roderick Mahoney
NCSLI Measure | Vol. 3 No. 2 (2008) | 10.1080/19315775.2008.11721424
Publisher NCSL International | Published 6/1/2008 | Pages 48-52
Abstract: Design of a Pockels cell based electro-optic device is described. The device is designed to measure the amplitude of high voltage pulses in our new Pulsed High Voltage Measurement System (PHVMS) with a very high signal to noise
ratio allowing a measurement precision of better than 0.5 %. However, the ultimate measurement uncertainty is limited by the uncertainty of currently available pulse high voltage standards. The PHVMS is capable of generating voltage pulses ranging
from 2 kV to 320 kV in amplitude, with pulse durations from 2.5 μs to 25 μs. The Primary Standards Laboratory's AC Project at Sandia National Laboratories is in the process of validating the PHVMS for calibrating resistive and capacitive voltage dividers.
Single voltage pulses are difficult to measure with uncertainties less than 1 % (k = 2) because of the high bandwidth involved (> 10 MHz) and their non-repetitive nature which rules out standard AC measurement and signal averaging techniques in
our system. An electro-optic voltage calibrator is in the process of being developed that will be tested as a possible candidate for in-situ voltage measurements inside the mineral oil bath of the PHVMS and in close proximity to the device under test.
Experiences with Novel Secondary Conductivity Sensors within the German Calibration Service (DKD)
Ulrich Breuel, Hans Jensen, Barbara Werner, Paul Spitzer
NCSLI Measure | Vol. 3 No. 2 (2008) | 10.1080/19315775.2008.11721422
Publisher NCSL International | Published 6/1/2008 | Pages 32-36
Abstract: International efforts concentrate on the traceability of electrolytic conductivity at the field level having small associated measurement uncertainties. Although the measurement of conductivity at the primary level has been
widely developed during the last decade, the dissemination of the small measurement uncertainty to the field level is lagging. There is a lack of easy to handle and reliable secondary calibration methods and transfer standards. This paper describes
a procedure for determination of the electrolytic conductivity on the secondary level appropriate for calibration laboratories. The procedure was developed within a joint project of the German calibration laboratory (ZMK ANALYTIK GmbH, DKD-K-06901)
together with the Physikalisch-Technische Bundesanstalt and the Danish Metrology Institute. Altogether a chain of five measuring cells has been used so that it is possible to measure the conductivity over a wide range from 2 μS/cm up to 100 mS/cm.
Experiences and first results using the five secondary cells are given including evaluation of comparisons with metrological institutes and partners from industry. The results obtained by the ZMK are in good agreement with the results obtained by
the metrological institutes.
Parametric Optimization of an Automated Weighing Comparator
J.W. Chung, S. Lee, H.W. Song, K.P. Kim
NCSLI Measure | Vol. 3 No. 2 (2008) | 10.1080/19315775.2008.11721425
Publisher NCSL International | Published 6/1/2008 | Pages 56-60
Abstract: Manual mass comparison encumbers essentially a measurement or calibration with frequent interventions. To overcome this problem and ensure concretely the traceability of national standard, an MT-a5 automatic comparator (for
the range of 1 mg to 5 g) from Mettler-Toledo (MT) has been recently introduced to Korea Research Institute of Standards and Science. In order to find the shortest operation time and lowest measurement repeatability, the stabilization time, the integration
time, and the number of measurements are selected as time optimization parameters. The repeatability is obtained based on more than 350 measurements. From the viewpoint of the uncertainty, one preference condition (stabilization time = 20 s; integration
time = 20 s; and number of measurements = 3) is found from the independent repeatability result, but its repeatability (0.24 μg) is within the manufacturer's repeatability specification (0.4 μg for 5 g). The optimum criterion of at least 19 s for
the stabilization time is proposed for the 5 g weight scale. The time performance of MT-a5 in weighing design is also discussed.
Ratio Calibration of a Digital Voltmeter for Force Measurement Using the Programmable Josephson Voltage Standard
Yi-Hua Tang, Thomas Bartel, June Sims
NCSLI Measure | Vol. 3 No. 2 (2008) | 10.1080/19315775.2008.11721427
Publisher NCSL International | Published 6/1/2008 | Pages 70-75
Abstract: Ratio calibration of a digital voltmeter (DVM) is critical for applications such as load cell response for force measurement. The National Institute of Standards and Technology (NIST) DVM ratio service provides ratio voltage
measurements that are traceable to the Josephson Voltage Standard (JVS). Previously, the service was supported by NIST JVS systems using manual measurements. The NIST JVS uses a conventional Josephson junction array which often experiences a spontaneous
step transition, caused by electromagnetic interference, during its operation. An adjustment is required to obtain a stable voltage step for the ratio calibration. The programmable JVS (PJVS), developed in the last decade, uses an array with non-hysteretic
steps to provide a stable voltage. The PJVS was implemented in the DVM ratio calibration service to improve the efficiency and reliability of the service. The new protocol can be executed automatically to reduce the labor cost of the calibration service.
The uncertainty of the DVM ratio calibration can be improved by taking automatic multiple measurements. This paper describes the DVM ratio calibration procedure and compares the conventional JVS and PJVS protocols. Results of an actual DVM ratio calibration
are presented.
An Alternative Approach to Standard Decade Series Linear Regression Dissemination of the Mass Unit by using a Weighted Least Squares Analysis
D. Dikken, C. Geppert, Shih Mean Lee
NCSLI Measure | Vol. 3 No. 3 (2008) | 10.1080/19315775.2008.11721436
Publisher NCSL International | Published 9/1/2008 | Pages 45-55
Abstract: A brief review of current practices in dissemination of the unit of mass is discussed focusing on the strengths and weakness of current practice. Based on improved mass comparators and advances in data collection/analysis systems,
an opportunity exists to employ an alternative method of calculation which uses a Weighted Least Squares Regression on measured observations to better predict a solution to the selected mass comparison design matrix. Mathematical equations employing
a Weighted Least Squares Regression approach are derived as a generalized solution for any valid mass calibration design. While this approach may be employed with demonstrated benefit over a traditional decade series approach, it also opens up an
alternative for eliminating the necessity for single restraints to be passed from decade series to decade series. The critical component in the validity of this method is to weight each mass difference measurement in the design matrix according to
an accurate estimate of each difference's uncertainty. Analysis from 1 kg to 1 mg, using both the current practice and the proposed practice, are compared. Key elements of improvement are shown to be the optimization of available mass comparators
and the increased redundancy within the weighing design.
Calculation of Effective Area and Uncertainty for a Dimensionally Characterized 50 mm Piston-Cylinder Used as a Primary Reference for Pressure
Rob Haines, Michael Bair
NCSLI Measure | Vol. 3 No. 3 (2008) | 10.1080/19315775.2008.11721435
Publisher NCSL International | Published 9/1/2008 | Pages 32-38
Abstract: Dimensional measurements of piston-cylinders for the purpose of defining effective area have improved to a level that allows laboratories to use them as primary references for pressure. Because of their relatively large size
and uniform cylindrical geometry, 50 mm tungsten carbide piston-cylinders are frequently utilized as primary standards in pressure based on a dimensionally characterized effective area. Because of the very low uncertainties in diameter, roundness
and straightness measurements, it is essential to properly model the piston-cylinder annular space based on those dimensional measurements. This paper describes a model for calculating the effective area from dimensional measurements and also provides
a method for calculating the uncertainty in the resultant effective area and final uncertainty in pressure.
Influence of Pre-Weighing Conditions on High Precision Mass Measurements
Shih Mean Lee, David, Lee Kwee Lim
NCSLI Measure | Vol. 3 No. 3 (2008) | 10.1080/19315775.2008.11721438
Publisher NCSL International | Published 9/1/2008 | Pages 66-72
Abstract: In the measurement of mass standards, thermal gradients can have an adverse influence on the uncertainty of measurement. OIML R111-1: 2004 has specific guidelines on the maximum allowable temperature changes during calibration
and the thermal stabilisation time required for different classes of mass standards. However, thermal stability is disturbed during the measurement process due to the presence of various heat sources. Further thermal conditioning can be accomplished
by performing pre-weighing operations, which simulate the actual measurement configurations. Different pre-weighing conditions, including the number of pre-weighing cycles, the sequence of pre-weighing operations, size of mass standards, and loading
positions of the standards, were investigated and were found to have varying influences on the repeatability of the measurement results. It was found that the ‘Pre-Weighing’ (PW) sequence improved overall repeatability performance by 26 % as compared
with the ‘Warming Repetition’ (WR) sequence. At least 3 to 10 cycles of PW/WR sequence should be applied for good weighing performance. Finally, larger mass size are more sensitive to thermal changes and thus these masses showed more improvements
in weighing performance.
The Use of GPS Disciplined Oscillators as Primary Frequency Standards for Calibration and Metrology Laboratories
Michael Lombardi
NCSLI Measure | Vol. 3 No. 3 (2008) | 10.1080/19315775.2008.11721437
Publisher NCSL International | Published 9/1/2008 | Pages 56-65
Abstract: An increasing number of calibration and metrology laboratories now employ a Global Positioning System disciplined oscillator (GPSDO) as their primary standard for frequency. GPSDOs have the advantage of costing much less than
cesium standards, and they serve as “self-calibrating” standards that should not require adjustment or calibration. These attributes make them an attractive choice for many laboratories. However, a few of their characteristics can make a GPSDO less
suitable than a cesium standard for some applications. This paper explores the use of GPSDOs in calibration laboratories. It discusses how GPSDOs work, how measurement traceability can be established with a GPSDO, and how their performance can vary
significantly from model to model. It also discusses possible GPSDO failure modes, and why a calibration laboratory must be able to verify whether or not a GPSDO is working properly.
A Guard-Band Strategy for Managing False-Accept Risk
Michael Dobbert
NCSLI Measure | Vol. 3 No. 4 (2008) | 10.1080/19315775.2008.11721446
Publisher NCSL International | Published 12/1/2008 | Pages 44-48
Abstract: When performing a calibration, the risk of incorrectly declaring a device as in-tolerance (false-accept risk) is dependent upon several factors. Those factors include the specified tolerance limit, guard-band, the calibration
process uncertainty and the a priori probability that the device is in-tolerance. A good estimate of the a priori probability may be difficult to obtain. Historical or device population information for estimating the a priori probability may not be
readily available and may not represent the specific device under test. A common strategy for managing measurement decision risk is to choose a guard-band that results in the desired false-accept risk given the tolerance limit, the calibration process
uncertainty and the a priori probability. This paper presents a guard-band strategy for managing false-accept risk with only limited knowledge of the a priori probability that a device is in-tolerance and with minimal increase in false-reject risk.
Comparison of Results of the Volume Determination of Mass Standards by Weighings in Air and Conventional Hydrostatic Weighing Method
Luis Peña-Pérez , Jorge Nava-Martinez
NCSLI Measure | Vol. 3 No. 4 (2008) | 10.1080/19315775.2008.11721449
Publisher NCSL International | Published 12/1/2008 | Pages 68-72
Abstract: Two methods for the volume determination of mass standards are compared. The conventional hydrostatic weighing method where the mass standards are immersed in water and weighings in air where the mass standards are subjected
to a variation in air density of ± 10% or less. The balance is installed in an air-tight chamber. Two kilogram masses were used and uncertainty analysis is compared. The En value was used in order to quantify the degree of agreement among the two
methods. The results are within the expanded uncertainty of the measurements.
NCSLI Measure | Vol. 3 No. 4 (2008) | 10.1080/19315775.2008.11721447
Publisher NCSL International | Published 12/1/2008 | Pages 50-56
Abstract: Five manganin alloy Thomas-type 1 Ω resistors serve as primary working standards at the National Institute of Standards and Technology (NIST) in the precision potentiometer direct current comparator (DCC) system used for special
1 Ω customer calibrations. To maintain and predict the values of these resistors, the value of this bank is compared to the quantized Hall resistance (QHR) standard at NIST approximately twice a year. This is accomplished through the use of several
precision 1 Ω resistors manufactured from 1975 through 1992 by the Australian National Measurement Laboratory, using the resistance alloy Evanohm. Over many years of careful monitoring, the relative values of these transfer resistors were seen to
have discrepancies that were not related to the drift in the value of the primary working standards and exceeded the Type A (statistically derived) uncertainty in the measurement systems. Some of these variations were believed to be due to power loading
in the transfer resistors. Recent experiments have demonstrated that conditions of power dissipation within the precision 1 Ω resistors and the duty cycle of the power applied to the resistors can change the value of a resistor measured at 100 mA
in the NIST precision 1 Ω measurement system by as much as 0.06 μΩ/Ω. This paper describes the experimental results and measurement uncertainty due to these power loading effects. Generally, the power loading effects in the Thomas-type resistors appear
to be dependent on the first order temperature coefficient, i.e., the larger the coefficient, the larger the change in the resistance value. However, there appears to be no similar relationship between the power loading effects and the first order
temperature coefficient in the various Evanohm resistors that were tested. Known temperature coefficient gradient contributions to the changes of resistance can explain the results observed in these measurements.
Uncertainty Estimate for the Outdoor Calibration of Solar Pyranometers: A Metrologist Perspective
Ibrahim Reda, Daryl Myers, Tom Stoffel
NCSLI Measure | Vol. 3 No. 4 (2008) | 10.1080/19315775.2008.11721448
Publisher NCSL International | Published 12/1/2008 | Pages 58-66
Abstract: Pyranometers are used outdoors to measure solar irradiance. By design, this of radiometer can measure the total hemispheric (global) or diffuse (sky) irradiance when the detector is unshaded or shaded from the sun disk, respectively.
These measurements are used in a variety of applications including solar energy conversion, atmospheric studies, agriculture, and materials science. Proper calibration of pyranometers is essential to ensure measurement quality. This paper describes
a step-by-step method for calculating and reporting the uncertainty of the calibration, using the guidelines of the ISO “Guide to the Expression of Uncertainty in Measurement” or GUM, that is applied to the pyranometer calibration procedures used
at the National Renewable Energy Laboratory (NREL). The NREL technique characterizes a responsivity function of a pyranometer as a function of the zenith angle, as well as reporting a single calibration responsivity value for a zenith angle of 45°.
The uncertainty analysis shows that a lower uncertainty can be achieved by using the response function of a pyranometer determined as a function of zenith angle, in lieu of just using the average value at 45°. By presenting the contribution of each
uncertainty source to the total uncertainty; users will be able to troubleshoot and improve their calibration process. The uncertainty analysis method can also be used to determine the uncertainty of different calibration techniques and applications,
such as deriving the uncertainty of field measurements.
Uncertainty of Gauge Block Calibration by Mechanical Comparison: A Worked Example for Like Materials
James Pekelsky, Anthony Ulrich, Jennifer Decker
NCSLI Measure | Vol. 3 No. 4 (2008) | 10.1080/19315775.2008.11721445
Publisher NCSL International | Published 12/1/2008 | Pages 30-42
Abstract: This paper presents a detailed measurement uncertainty analysis for the calibration of gauge blocks made from like materials using a mechanical comparator consisting of opposing styli and a digital readout. After discussing
the influence parameters affecting the calibration process, a mathematical model is developed that leads to a measurement equation relating the length of the client's gauge block to measurements of the standard gauge block and associated temperature
corrections. Following the ISO “Guide to the Expression of Uncertainty in Measurement,” all of the uncertainty components and their sensitivity components are calculated. These components include factors related to the calibration of the standard,
the measured difference between the client's gauge and the standard gauges, and various temperature differences. After discussing a specific measurement process in a typical laboratory environment, all of the uncertainty components are quantified
and then combined in quadrature. The resulting expanded uncertainty for the calibration of a client gauge against a working standard is given by Ucl = and a coverage factor of k = 2 is used. While the detailed characterization of any system and its
associated measurement uncertainties will be unique to a given set of conditions, by providing all the details at each step, this paper is intended to be used as a guide for other similar situations.
