An Inspection Procedure For Diametral Measurements With Coordinate Measuring Machines
Author(s): Nalin Pumhirun, Philip Mathew
Abstract/Introduction:
This paper presents the development of an inspection procedure to assess diameters of cylindrical workpieces with a Coordinate Measuring Machine (CMM). The inspection procedure is developed by considering the interpretation of the diameter specification from standards, the variation in the cylindrical workpieces and the capability of a CMM. The procedure is based on a two-point measurement concept which conforms to the interpretation of size from existing standards. A program to simulate CMM inspection is developed to compare two-point measurement method to the least squares method. The results show that estimated diameters from two-point measurement method are more accurate. This will lead to the benefits of reducing the Inspection time and CMM operators requirement, especially if a Knowledge-based System is employed.
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Document ID:
932E4FCE
Integrated Manual And Automated Xml Calibration Procedure Development
Author(s): Michael Cunavelis
Abstract/Introduction:
The United States Navy is developing a specialized calibration environment used to create calibration procedures which can be performed both manually and automatically. The calibration procedures are XML documents which contain the standard text procedure as well as ActiveX automation components which control the test instruments and the calibration standards. The calibration development environment consists of a sequence driven procedure editor easily used by nonprogrammers to populate the embedded ActiveX automation components in the XML calibration procedure. The environment utilizes XML and ActiveX components to build an integrated automated and manual procedure utilizing reusable modular test methods and sequences stored in databases. The reusable modular test methods and sequences facilitate procedure standardization, rapid development of similar procedures, and future expansion capabilities.
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Document ID:
EE21F778
Transducer Compensation Adjustment After Installation
Author(s): Karl F. Anderson, Vincent Wnuk
Abstract/Introduction:
This paper describes how a transducer can be designed so that its compensation can be adjusted after the transducer is installed to minimize measurement uncertainty due to systematic errors. A compensation theory is presented along with experimental data from a signal conditioning technique based on the theory. The technique is validated experimentally by varying the temperature compensation of an installed strain gage from within its Anderson loop signal conditioner.
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Document ID:
099CC5D7
Calibration Intervals - New Models And Techniques
Author(s): Dennis Jackson
Abstract/Introduction:
This paper will develop new methods for establishing calibration intervals using parametric data, as well as binary results. Appropriate reliability models will be discussed. The interval methods developed in this paper are for discussion purposes and are not U.S. Navy policy.
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Document ID:
49B1E27B
A Laser Non-Contact Measurement Of Static Positioning And Dynamic Contouring Accuracy Of A Cnc Machine Tool
Author(s): Charles Wang, Gianmarco Liotto
Abstract/Introduction:
For accurate and fast machining, both the static volumetric positioning accuracy, including the 3 displacement errors, 6 straightness errors, and 3 squareness errors, and the dynamic contouring accuracy, including the errors due to the servo mismatch, servo lag, loop gain, acceleration and deceleration, are very important. Conventional measurement techniques, such as laser interferometers and telescoping ballbars, are complex, inefficient and time consuming. Reported here are a new laser vector measurement technique for the measurement of the volumetric positioning accuracy and a laser/ballbar technique for the measurement of dynamic contouring accuracy. Measurements have been performed on a JOBS-LINKS 5-axis linear motor machine with the laser vector technique. The volumetric positioning accuracy has been improved by 300% with the volumetric compensation. The basic theory, the hardware, the data collection and processing, and the measurement results are described.
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Document ID:
800E083B
Sub-Pixel Limitation Of Imaging Sensor
Author(s): Asif Mufti
Abstract/Introduction:
In the last two decades the optical imaging market has grown from non-existent to over 10 billion dollar market annually. The conventional thought is that imaging sensors can primarily be used for viewing purposes. Applications include such as infrared imaging sensor, astronomy, photography and as simple as security surveillance. It is only recently the technology has evolved towards other commercial applications. This paper reports the result of the experiment, exploring the limitation of a Charge Coupled Devices as it pertains to precision edge detection and present it as a potentially powerful toll in measurement science.
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Document ID:
61391341
Time Distribution Using The World Wide Web
Author(s): Andrew N. Novick, Paul R. Franchois, Michael A. Lombardi
Abstract/Introduction:
The National Institute of Standards and Technology (NIST) is currently providing users of the Internet with a running time-of-day clock on a web page. It uses a combination of Hyper Text Markup Language (HTML), Perl, Java and JavaScript to show the time for a chosen time zone. Processing and path delays are estimated to provide the client with an idea of how close the time displayed is to Coordinated Universal Time - UTC(NIST). Several future possibilities and uses of this technology will be discussed.
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Document ID:
8F9F466F
Virtual Instrumentation For Metrology Applications
Author(s): Gregory Smith
Abstract/Introduction:
Computer-based instruments in the 3U PXI form factor are ideal for use as test equipment in a variety of metrology applications. Through the use of various software front-ends, these PXI computer-based instruments can be adapted to accommodate a number of measurement challenges. This presentation reviews what the relative advantages of computer-based virtual instrumentation are, how 3U PXI fits in, what PXI is, and what the various software front-ends in the industry are that take full advantage of these resources.
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Document ID:
976D2EEA
Two-Layer Sensor Matrix And Data Acquisition System Design In Spatial Temperature And Humidity Measurement
Author(s): Tang-Jen Liu, Ming-Shing Young
Abstract/Introduction:
Spatial temperature and humidity distributions are very important for investigating the flow patterns of cooling air in a conditioned room. They are useful in the prediction of local discomfort for various air conditioning designs and provide designers with rapid quantitative information early in the design process. Because of high cost and less modifiability, commercial instruments have inhibited detailed and intensive research on the flow pattern measurement. Therefore, the re-design of the measurement system is considered essential. In this paper, we first design a humidity-to-frequency converter for the capacitance humidity sensor, and adopt a temperature sensor with a temperaturedependent duty cycle output. Without the analog to digital converter, a high-speed counter is enough to convert the digital signals to relative physical phenomena. Then, a two-layer matrix of sensing modules composed of the above-mentioned temperature and humidity sensor is constructed. Finally, a multi-channel data acquisition system is proposed to offer the temperature and humidity at any fixed position demanded by the user. Actually, the proposed measurement system is capable of giving a complete 4D (space and time) description of the temperature and humidity in the concerned environment.
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Document ID:
F9D33FFC
Doppler Global Velocimetry Dgv(): Whole Field Technique For Flow Research And Its Capabilities For Flowrate Measurements
Author(s): Harald Mller, Thomas Lehmacher, Volker Strunck, Rainer Kramer, Bodo Mickan, Dietrich Dopheide
Abstract/Introduction:
The paper describes the inherent potential of Doppler Global Velocimetry (DGV) for flow metrology. DGV is presented as an optical whole filed acquisition technique for the measurement of three dimensional velocity vector fields in pipes. The measurement plane is given by a light sheet illuminating the cross section of interest. In order to study the influence of installation effects on the flow rate measurement different pipe configurations are investigated. The aim is to show that DGV which has originally been used as whole field technique for high flow velocities in wind tunnels is also a promising technique for lower flow velocities up to 30 m/s to investigate perturbations of velocity fields downstream of special pipe configurations and their effect on flow meters installed.
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Document ID:
613E63B2
Uncertainty Analysis Of A High-Speed Dry Piston Flow Prover
Author(s): Harvey Padden
Abstract/Introduction:
This paper discusses a novel high-speed piston prover that uses a clearance seal to achieve very low uncertainties. We will review the instruments design and provide an uncertainty analysis for three sizes of our internal reference provers, designed for flows of 10 mL/min to 50 L/min. The results were expanded single-reading uncertainties at 2X coverage range from 0.064% to 0.073%. The instrument also has the capability to average a number of readings, potentially reducing the above uncertainties by a significant amount. Traditional constant-displacement piston provers utilize mercury piston seals and low piston velocities. They have long been used as primary calibration devices for gases at low flow rates. Our design is based upon our production DryCal and eliminates the seal. The attraction of such a device is its combination of primary (dimensionallybased) flow measurement, simplicity and high speed and small size. However, this instrument has unique uncertainty sources that must be analyzed and controlled.
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Document ID:
2EF3DF88
A High Precision Ultrasonic System For Fast Temperature Measurements Of Indoor Air
Author(s): C. F. Huang, K. N. Huang, m. S. Young, Y. C. Li
Abstract/Introduction:
A high accurate continuous wave (CW) ultrasonic system used in air temperature measurement is described. Two ultrasonic transducers, a transmitter and a receiver, are set face to face and fixed at a constant distance. In operation, a 40-kHz ultrasound will be transmitted from the ultrasonic transmitter continuously and received by the ultrasonic receiver simultaneously. When the distance between the transmitter and the receiver is 1m, the temperature range determined by the difference of phase shift from 0 to 2p is only 5 ?. We have developed an ingenious method to reconstruct the temperature from the acquired data of the phase difference changes when the range of the fluctuation of the temperature exceeds 5 ?. The measured accuracy of the sound speed and the temperature are within 0.005 m/s and 0.01 ?respectively. The main advantages of this ultrasonic temperature measurement system are high resolution, low cost, and it can measure temperature distribution of long-range zone.
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Document ID:
854D2FB7
Improving The Efficiency Of Multifunction Calibrator Calibration Systems
Author(s): Martin L. Kidd, John Morton
Abstract/Introduction:
There are an ever-increasing number of small lab customers that depend on one multifunction calibrator for their standard. These customers require expedited calibration service because they are essentially shut down while their calibrators are out for calibration. This poses a problem for the calibration laboratories that service multifunction calibrators. Automated test systems have been developed to maximize efficiency but as the features of calibrators expand, these systems require 10, 20, even 30 standards. How can throughput be improved without a large investment and maintenance of capital equipment for additional systems? Here is one calibration labs solution.
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Document ID:
817C4F86
The Effectiveness Of Artifact Calibration In Computing Internal Resistance Values
Author(s): David F. Martson
Abstract/Introduction:
Originally intended as part of a process to characterize a 5720A calibrator for subsequent use calibrating the Datron (Fluke) 4950 Multifunction Transfer Standard (4950MTS), external verification of the 5720As available resistance values utilizing state-of-the-art measurement apparatus ultimately provided valuable insight into the accuracy with which the internal Artifact Calibration process characterizes the calibrators resistance function. Based on the results of this investigation, however, it is believed the artifact calibration function and specifically its ability to measure the internal resistance of the 5720A (5700A) calibrator, in particular, deserves a further look.
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Document ID:
07741DA6
Combined Result And Uncertainty From Interlaboratory Evaluations Based On The ISO Guide
Author(s): Raghu Kacker, Raju Datla, Albert Parr
Abstract/Introduction:
We address the problem of determining the combined result and the associated uncertainty in measurement of a common measurand by a set of competent laboratories. The issues include the following. What is the combined result and what uncertainty is associated with it? What to do when the expanded uncertainty interval associated with the combined result excludes a non-negligible fraction of the individual laboratory results that are believed to be plausible values of the measurand. We discuss these issues and propose a three-step approach based on the ISO Guide to determine the combined result and the associated standard uncertainty so no result believed, based on scientific judgment, to be plausible is put outside the expanded uncertainty interval. We will illustrate the proposed approach through an application to the recent results of the international comparison of cryogenic radiometers organized by the Consultative Committee for Photometry and Radiometry (CCPR).
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Document ID:
B382CB7E
Diffraction Corrections In Radiometry: A Proposed Method To Estimate Uncertainties
Author(s): Eric L. Shirley, Raghu Kacker, Raju U. Datla
Abstract/Introduction:
Radiometric determination of certain quantities, such as source radiance, geometrical aspects of an optical system (e.g., throughput, aperture areas), and detector response, relies on the mathematical principles governing geometrical optics. These principles permit one to predict the values of quantities sought to be analyzed with measurements. Such analysis is hampered, however, by diffraction effects on the performance of optical systems, because of the actual wave-like nature of light, which differs from the conceptual ray-like nature assumed in geometrical optics. Diffraction corrections, which are designed to compensate for diffraction effects, have uncertainties that constitute a component of the total uncertainties of final results obtained from a radiometric measurement. Here, we propose an empirical method to estimate the uncertainties of diffraction corrections.
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Document ID:
EA03D00E
Absolute Area Measurements Of Circular Radiometric Apertures
Author(s): Maritoni Litorja, Joel Fowler
Abstract/Introduction:
One of the major factors that limit the overall accuracy of many radiometric measurements is the uncertainty associated with the measurement of the aperture area. NIST has established an absolute aperturearea measurement facility for circular and near-circular apertures. The instrument is composed of an interferometer-feedback system for highaccuracy positioning of the aperture and detection of the aperture edge using video microscopy. Measurement is made by locating the edge points along the internal aperture circumference and using fitting routines to determine the geometric aperture area. In this paper we present a description of the instrumentation and measurement methodology, based on the work started and described by Fowler, Durvasula and Parr.1 Analysis and estimation of various contributions to the overall measurement uncertainty, including the effects of diffraction and partial coherence of the light source on the edge location are also discussed.
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Document ID:
CE2FB945
A Laser Tracker Calibration System
Author(s): Daniel Sawyer, Bruce Borchardt, Steve Phillips, Charles Fronczek, Tyler Estler, Wadmond Woo, Robert W. Nickey
Abstract/Introduction:
We describe a laser tracker calibration system developed for frameless coordinate metrology systems. The system employs a laser rail to provide an in-situ calibrated length standard that is used to test a tracker in several different configurations. The system is in service at the National Institute of Standards and Technology (NIST) and at the Naval Surface Warfare Center, Corona Division (NSWC, Corona Division). The system description, calibration procedure, and uncertainty budget are presented.
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Document ID:
B7AC07F0
Recent Advances In Ac-Dc Transfer Measurements Using Thin-Film Thermal Converters
Author(s): Thomas F. Wunsch, Joseph R. Kinard, Ronald P. Manginell, Thomas E. Lipe, Otis P. Solomon, And Kenneth C. Jungling
Abstract/Introduction:
New standards for ac current and voltage measurements, thin-film multijunction thermal converters (MJTCs), have been fabricated using thin-film and micro-electro-mechanical systems (MEMS) technology. Improved sensitivity and accuracy over single-junction thermoelements and targeted performance will allow new measurementapproaches in traditionally troublesome areas such as the low frequency and high current regimes. A review is presented of new microfabrication techniques and packaging methods that have resulted from a collaborative effort at Sandia National Laboratories and the National Institute of Standards and Technology (NIST).
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Document ID:
A3A3B363
Deformation Of Gauge Blocks
Author(s): Ted Doiron, Eric Stanfield, Dennis Everett
Abstract/Introduction:
When a force is exerted on any material, the material deforms. Most of the time the effect is small and is neglected. In the measurement of gauge blocks, where the uncertainty goal is stated in nanometers, the deformation is a very large effect, and can be the largest component of uncertainty in calibration by mechanical comparison. We will present the results of a number of studies of the contact deformation of gauge blocks, which shows agreement with the results of calculations based on the work of Puttock and Thwaite 1. We will also discuss why the use of corrections based on the calculations are not practical in practice, and present a new method for finding the corrections for any comparator, in situ, by using specially prepared set of gauge blocks to calibrate the comparator scale.
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Document ID:
B17263CA
Sector-Specific Accreditation Requirements
Author(s): Chester Franklin
Abstract/Introduction:
This paper discusses the process for documenting sector-specific accreditation requirements, and implementing them through the Technical Requirements Committee of the National Cooperation for Laboratory Accreditation (NACLA). Accreditation to ISO/IEC 17025 requires compliance with all of the provisions of 17025, however, as stated in Annex B of that standard, Depending on the application at hand, it may be necessary to establish applications for the technical requirements of this International Standard. And, Alternatively, it may be necessary to develop a separate document of applications supplemental to this International Standard for specific types or groups of tests or calibrations, products, materials or technical fields of tests or calibrations.
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Document ID:
96F343AE
The Effectiveness Of Artifact Calibration In Computing Internal Resistance Values
Author(s): David F. Martson
Abstract/Introduction:
Originally intended as part of a process to characterize a 5720A calibrator for subsequent use calibrating the Datron (Fluke) 4950 Multifunction Transfer Standard (4950MTS), external verification of the 5720As available resistance values utilizing state-of-the-art measurement apparatus ultimately provided valuable insight into the accuracy with which the internal Artifact Calibration process characterizes the calibrators resistance function. Based on the results of this investigation, however, it is believed the artifact calibration function and specifically its ability to measure the internal resistance of the 5720A (5700A) calibrator, in particular, deserves a further look.
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Document ID:
9C59D98D
Improving Accuracy Of Power And Power Quality Measurements
Author(s): Dave Coombes
Abstract/Introduction:
To calibrate power and power quality measurement instruments such as flicker meters or harmonic measurement devices, several alternative techniques are generally used or proposed: Using a reference device to make measurements which can be compared against those made by the UUT. Applying variable loads to a static, impedance loaded power line to induce required conditions. Generating the required signals with a precision signal source. This paper discusses the third option. There are a number of benefits to this approach, as well as a number of difficulties to overcome and decisions to be made to implement it effectively.
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Document ID:
D5BA4EE5
Virtual Test Equipment Vte() In An Automated Maintenance Environment Ame()
Author(s): Jeff Walden, Catherine Fajardo
Abstract/Introduction:
The goals of maintaining high confidence in Navy combat systems reducing fleet man-hours for maintenance are of particular concern for the Navy Metrology R&D Program. By creating an automated maintenance environment, the Navy can potentially address the simultaneous goals for high combat system confidence, reduced crew size, and the improved quality of life. An automated maintenance environment will use new technology to improve business processes and at the same time implement improved maintenance practices and place new tools in the hands of the Sailor. This paper will describe the application of Virtual Test Equipment in the Navys new Automated Maintenance Environment. We will describe how portable computers will automate Virtual Test Equipment how the computer will upload and down load maintenance information through a wireless Local Area Network (LAN) and how Virtual Test Equipment will be calibrated. Finally we will describe how the integration of these new technologies will allow the Sailor to more effectively perform routine maintenance tasks in the new Automated Maintenance Environment.
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Document ID:
8D09500E
A Comparison Of Two Inter-Laboratory Measurement Comparison Methods
Author(s): Ricardo A. Nicholas
Abstract/Introduction:
This paper provides a description and an example of a statistical method of inter-comparison, which utilizes F and t significance tests to compare the variability and systematic measurement differences (precision and bias), respectively. A Chi-square ( ?2) test is additionally used to assess the significance of measurement data with respect to a reference data set. A fabricated example set of laboratory comparison data is evaluated. The evaluation results are compared to the results obtained by a method based on ISO 5725 Accuracy (Trueness and Precision) of Measurement Methods and Results 1. In addition to utilizing repeatability, the conventional index of variability, the ISO method utilizes the statistical evaluation of reproducibility which, simplistically stated, treats systematic differences among measurement values as random quantities. Even when the differences are truly systematic in nature, it is statistically valid to evaluate the differences by this method, as long as the evaluation is statistically justified. A comparison is made between the two methods of evaluation. In addition, a Microsoft Excel program tool1 is described which is used to perform the calculations.
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Document ID:
DF34EB0D
Consumer Risk For Non-Gaussian Measurand Distributions
Author(s): Ricardo A. Nicholas
Abstract/Introduction:
A previous paper titled Measurement Decision Risk Simplified 1 dealt with Consumer and Producer Risk based on Normal probability densities for both the measurand and the measurement system. It treated each density as if the historical data was representative of a Normal random variable, which generally is not the case. For a finite sample size, assuming the population is Normally distributed and bilaterally symmetric about the mean, the historical data is best represented by a t density. Since, in real-world metrology, with its inherent finite sample sizes, it is not the Normal but the t density that must be the basis for the calculation of Consumer and Producer Risk. The main focus of this paper is to extend the approximation method of the previous paper to the treatment of real-world t and Uniform densities.
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Document ID:
B333CE8A
Balance Repeatability And Reproducibility Effects On Measurement Uncertainty
Author(s): A. Harper Shull, John P. Clark
Abstract/Introduction:
Most balance manufacturers do not list an uncertainty estimate for measurements made with their balances. Their specifications usually include eccentricity, linearity, and repeatability. The latter is a measure of the random variability of the instrument, usually expressed in scale divisions. Further, the repeatability is usually based on 10 consecutive measurements of a mass standard. The authors have previously described methods currently being used to estimate the uncertainty of measurements made with electronic balances. The random errors associated with mass measure-ments obscure the true value of the artifact being weighed. Therefore, it is important to include the best estimate of the magnitude of these errors in the stated uncertainty.
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Document ID:
79A42869
Recommended Guide For Determining And Reporting Uncertainties For Balances And Scales
Author(s): Val Miller
Abstract/Introduction:
[Abstract Not Available]
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Document ID:
52AA36C4
Maintaining Traceability Of Multiple Flow Measurement Standards
Author(s): Tom Kegel
Abstract/Introduction:
This paper describes a method to indirectly compare flowmeter standards to one another. Several artifacts are used to make the comparisons, in some cases the artifactes have extensive calibration histories. The uncertainty analysis is presented using test results as an example. A preliminary estimate of the uncertainty is +-0.15% at a 95% level of confidence.
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Document ID:
BC46FBF7
Basic Dynamical Modeling Of Expanding Volume Flow Calibrators
Author(s): Thomas O. Maginnis
Abstract/Introduction:
Standard flow calibrators using the constant pressure expanding volume method employ a circular cylinder as the collection volume, with the volume expansion occurring parallel to the axis. The volume of gas collected in a given time is related to the measured axial displacement through a meter K-factor, (with dimensions of volume per unit axial displacement), that corresponds geometrically to the average interior cross-sectional area of the cylinder. The K-factor should be independent of displacement for a cylinder. This makes such a device flexible as to total volume collected and time consumed per run. Yet these meters as used do not take advantage of this displacement flexibility, but instead operate between geometrically fixed start and stop points. This leads to long run times at low flowrates. Any acceleration of the movable mass that seals the collected gas will frustrate the desired linear expansion of the collection volume at constant flow. It is necessary to understand these effects to optimally choose the start and stop points for each flowrate. The purpose of modeling the dynamics is to understand how dynamic factors limit the useful flow range of each such meter, so that such effects may be overcome or minimized.
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Document ID:
4E30DE7E
Progress In Developing NIST Standard Casings
Author(s): J. Song, T. Vorburger, m. Ols
Abstract/Introduction:
Standard casings and bullets are currently under development to support the National Integrated Ballistics Information Network (NIBIN). The master casings are obtained from the ATFs (Bureau of Alcohol, Tobacco and Firearms) National Laboratory Center at Rockville, MD, by a standardized shooting procedure. The electroforming technique, which we have previously tested for replication of surface roughness specimens, is used for replication of the prototype NIST (National Institute of Standards and technology) standard casings. Initial testing results show high agreement and reproducibility between the casing signatures of different standard casings. Further testing is still in progress. The standard casings, combined with standard bullets, aim to provide reference standards for ballistics laboratories of the ATF and FBI (Federal Bureau of Investigation) for instrument calibration, measurement quality control and measurement unification. In this paper, technical requirements, design, manufacture and testing of the standard casings are discussed.
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Document ID:
369CC3CC
Special Topics In Uncertainly Calculation
Author(s): Philip Stein
Abstract/Introduction:
By now, the majority of practitioners in the measurement science community should know the basics of calculating measurement uncertainty according to the GUM. Some issues remain conceptually difficult, such as how to deal correctly with correlated influence quantities, but simplifying shortcuts have largely bypassed the need for rigor here. Still, some issues linger, including some that seem simple or obvious, but maybe theyre not. The speaker(s) will discuss the proper way to calculate and report uncertainty due to limited resolution of the measuring instrument, including subtle issues such as differential nonlinearity of embedded electronic digitizers. Repeatability and reproducibility studies will be discussed with emphasis on how best to design them and how to correctly analyze and report the data that result. Finally, the speaker will elucidate the fine points of measurement assurance, showing how the use of check standards and control charts can make uncertainty budgeting and calculating much simpler while at the same time providing a powerful context for continual improvement of the measurement process, and will demonstrate a complete uncertainty calculation based on measurement assurance results.
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Document ID:
5F1E9D63
The 1st Uk National Standard Static Torque Calibration Machine - New Design Concepts Lead The Way.
Author(s): Francis A. Davis
Abstract/Introduction:
This paper considers the needs of a national torque calibration facility and how the National Physical Laboratory surveyed UK industry and European national measurement institutes to develop the specification for the first UK static torque standard calibration machine. In common with other national standard torque calibration machines, torque will be generated using a lever-deadweight system. Designs based upon horizontally and vertically mounted transducers are reviewed. Despite the greater difficulty in applying torque forces to a vertically mounted transducer this design was selected as it enables a symmetric pure torque to be applied. In addition, this design provides adaptability, enabling comparisons with the application of asymmetric torque and onthe- fly torque calibrations to be studied.
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Document ID:
818283D6
Further Analysis Of Piston Gage Calibration Data By The Development Of Linear And Quadratic Equations
Author(s): Frank E. Jones, A. Harper Shull
Abstract/Introduction:
In three earlier papers, it has been shown, that the conventional treatment of piston gage calibration data to determine effective, A, and subsequent use of A to calculate pressure, P, from force, F, impressed on the piston leads to non-constant values of A. Conventionally, A is the ratio F/P. In the earlier papers, it was shown that the relationship between P and F was represented much better by an equation of the form P a + bF derived from linear least squares analysis of calibration data. In the present paper, calibration data for 10 piston gages were analyzed to produce linear and quadratic equations relating P to F. These equations are shown to be much more efficient for calculating pressure, P, from force, F. Detailed analysis will be presented.
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Document ID:
AD30B227
A New Method For Automated Calibration Of Low Pressure Transfer Standards
Author(s): Robert Haines, Michael Bair
Abstract/Introduction:
Maintaining traceability for transfer standards in the range of 10 Pa to 5 kPa is critical to many calibration laboratories. However, standards with suitable uncertainty that can also be practically implemented in the typical laboratory have not been available. A new pressure standard based on piston-cylinder technology has been developed that provides the measurement uncertainty needed to support todays rapidly improving transfer standards, requires no special facilities and runs fully automated calibration sequences. The new standard has been implemented in the DH Instruments, Inc. (DHI) accredited metrology laboratory. Various laboratory transfer standards have been calibrated, in particular capacitance diaphragm gauges, giving new insight into the behavior of these devices.
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Document ID:
9CEFA879
Flow II
Author(s): Mattingly
Abstract/Introduction:
[Abstract Not Available]
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Document ID:
71062557
The Components Of A Quality Pipette Calibration
Author(s): Kenneth Bonnell
Abstract/Introduction:
There are many factors that comprise a quality volumetric calibration. These parameters are usually encompassed in three main areas: the operator, the equipment, and the environment. Therefore, it is critical to know how to control and account for these variables, since they can dramatically impact your uncertainties. This study will not only reveal those items that are required to produce a high quality calibration on any volumetric instrument, but it will also enumerate how to account for those factors that impact your measurement uncertainties.
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Document ID:
A491D749