An Investigation Into The Effect Of Vacuum Exposure On Mass Standards
Author(s): Stuart Davidson
Abstract/Introduction:
A programme of work has been undertaken to investigate the behaviour of mass standards when transferred to and stored in vacuum. Special sets of kilogram artefacts, one of stainless steel and one of platinum-iridium, were manufactured to evaluate the behaviour of these materials both when transferred into and out of vacuum and when stored in vacuum over long periods. Mass measurements were performed using two one kilogram mass comparators, one in air and one under vacuum. The results of the measurements made over an 18 month period are given and conclusions drawn regarding the change in mass per unit surface area for the two materials as well as their long term stability in vacuum.
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Document ID:
D6FF155A
1999 Measurement Science Conference A Century Of Measurements
Author(s): Raimundo A. Gil
Abstract/Introduction:
[Abstract Not Available]
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Document ID:
7FE7FBDF
Introduction To Antenna Calibration Methods Used At The Boeing Metrology Laboratory Field Strength Facility
Author(s): David Archer
Abstract/Introduction:
The purpose of this paper is to describe the measurement techniques implemented at the Boeing Metrology Laboratorys Electromagnetic Field Strength Calibration Facility. They are based on the gain extrapolation technique developed at the National Institute of Standards and Technology (NIST). In addition, this paper will describe the facility itself and present a detailed error analysis beyond what is provided in NIST publications.
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Document ID:
2C36F9E1
Microwave Network Analyzers - A Discussion Of Verification Methods*
Author(s): Ronald A. Ginley
Abstract/Introduction:
Verification of Vector Network Analyzers (VNAs) is very important to the measurement process as well as to establish confidence in the uncertainty of the system. This paper presents a basic discussion about VNA verification including what verification is, check standard selection, and different verification methods. Verification methods explored include: quick check, check standards, calibration at a higher-level laboratories, interlaboratory comparisons, error separation, calibration comparison, VNA system comparison, and traveling verification kits.
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Document ID:
8C276020
Developing Standard Uncertainties For Piston Gauge Pressure Measurements Through Predictive Uncertainty Analysis
Author(s): Michael Bair
Abstract/Introduction:
As uncertainties on piston gauges effective areas are reduced, uncertainty specifications provided with the calibration of piston gauges become less and less adequate for estimating a global uncertainty specification on pressure. Many of the parameters or effects introducing uncertainties when measuring pressure are not covered in the calibration reports or mentioned in commercial documentation. A predictive uncertainty analysis has been performed on a new line of piston gauges to derive standard uncertainties for several configurations and operating modes.
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Document ID:
F7B77329
Maintenance And Calibration Of Hart Field Instrumentation
Author(s): Richard Pirret, P.E.
Abstract/Introduction:
The field instrumentation in process plants is beginning to come under more sophisticated metrological discipline. Most new field instruments are now smart digital instruments. One popular digital protocol is the HART (Highway Automated Remote Transducer) protocol, which shares characteristics of both analog and digital control systems.
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Document ID:
675807E2
A Hybrid Technique For Calibrating Flowmeters With Compressible Fluids
Author(s): Thomas m. Kegel
Abstract/Introduction:
Flowmeters for compressible fluids can be calibrated by one of two basic methods: primary or secondary. A primary calibration involves comparison with a system based only on primary measurements (mass, length and time). A secondary calibration involves comparison with a transfer standard that has been characterized by a primary system. Primary calibrations are more costly and have lower associated uncertainty than secondary calibrations. This paper describes a hybrid calibration technique that has lower cost than a primary calibration and lower uncertainty than a secondary calibration. An analysis of the uncertainty is proposed that is based on a novel application of a traditional statistical technique.
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Document ID:
20D0B11C
A New Method For Noise Reduction In Resistance Measurements
Author(s): Philip Dangelo, Roger Fell
Abstract/Introduction:
This paper describes a patent pending method for resistance measurements. The technique uses a high speed A/D converter and a DSP microprocessor, operating in real time, to correct for both DC errors and AC noise in high speed measurements. It eliminates the need for low pass filters, line cycle A/D integration and other traditional noise filtering techniques. For this particular implementation the resultant noise free resistance reading is available to the user more than four times faster than readings based on the traditional techniques. At present this speed is limited by the analog front end circuitry.
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Document ID:
BB057214
Measurement Uncertainty Considerations When Using An Array Of Critical Flow Ventur
Author(s): Richard W. Caron
Abstract/Introduction:
The critical flow venturi (CFV) is an excellent device for generating a known measured flowrate. The CFV exhibits a nominally linear relationship between inlet pressure and mass flowrate. A particular flowrate can be established by applying the proper value of inlet pressure. The range of available inlet pressure values will limit the range of flowrates that can be generated.
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Document ID:
FBA9A0E6
Tele-Calibration Of Gas Flow Meters
Author(s): Pedro I. Espina
Abstract/Introduction:
At present, the paradigm used to deliver flow meter calibration services relies on the operation of in-house calibration facilities for providing metrology infrastructure. This approach has led to the construction and operation of many similar calibration facilities worldwide. The recent emergence and popularity of information technology offers an opportunity to change the way in which metrology services are provided to customers worldwide by enabling the use of existing calibration facilities by more than one metrology team.
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Document ID:
56E9977A
How Reliable Is Pitch Diameter Size Transfer From Setting Plug To Adjustable
Author(s): Arthur G. Strang
Abstract/Introduction:
The ASME standard procedure for transferring the measured pitch diameter of thread setting plug gage to an adjustable ring gage is by fit or feel. To determine the size variation, pitch diameter of the internal thread was measured after each assembly. Ten different manufacturers of 0.5-13 UNC setting plugs were used to set ten different manufacturers adjustable ring for both GO and NOT GO gages. The fit was controlled between 15 and 50 inch ounces of breakaway torque. The difference in pitch diameters was as great as 0.0014 inch on some of the 200 different combinations of interchanges, made to ASME B1.2 tolerances.
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Document ID:
821B5969
Diode Lasers In Length Metrology: Application To Absolute Distance Interferometry
Author(s): Jack A. Stone, Alois Stejskal, Lowell Howard
Abstract/Introduction:
Diode lasers are becoming increasingly important in length metrology. In particular, the tunability of diode lasers makes them attractive for applications such as absolute distance interferometry (ADI). In this paper we describe the current status of our research on the use of diode lasers in ADI and we discuss, more generally, the unique strengths and weaknesses of diode lasers for dimensional metrology. In selected applications the capabilities of the diode can provide significant advantages.
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Document ID:
BD0DC91C
Measurement Traceability In Certification And Accreditation Schemes
Author(s): Dr Roberto Perissi
Abstract/Introduction:
This paper presents the role of accreditation and the European Communitys policy in the field of Conformity Assessment. The so called global approach to technical specification, testing and certification, is based on the general objective of ensuring the free circulation of products throughout the Community, both by legislative means and by developing a favourable technical environment of national accreditation network for the assessment of product conformity to the essential requirements of a Directive or to harmonised standards. Thus, anyone agrees that, providing the basic language for all the measurement activities, metrology and calibration are playing a very important role in establishing a correct dissemination chain and in providing traceability to the national standards.
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Document ID:
03F17684
New Organization Orientation, National Association For National Association For Proficiency Testing - Napt
Author(s): Charles Ellis
Abstract/Introduction:
[Abstract Not Available]
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Document ID:
13DCE575
Supporting New Calibrators With Existing Equipment
Author(s): Steven G. Haynes
Abstract/Introduction:
New calibrators are being introduced not only with new functions and better performance, but also with expanded output ranges. These calibrators can present some new challenges for the cal lab. Resistance up to 1GW, capacitance up to 100mF and AC current to 30kHz can be measured, but at what cost? This paper will present one approach to making these tests without huge investments in capital equipment. Data presented will demonstrate that, with a modest investment, you can extend the capability of your existing instrumentation to get the performance necessary to test state-of-the-art calibrators
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Document ID:
334B5CBC
The New Measurement Headache - Return On Investment!
Author(s): R A Clarke
Abstract/Introduction:
Facing the demands of increasing calibration workloads and reductions in available resources the calibration laboratory is under pressure. There is a need to increase the efficiency of calibration with new innovative solutions. Yet, the Managing Director and Finance Director appear to have little or no interest in the latest requests for capital expenditure from the calibration laboratory. The only solution for the Calibration Laboratory Manager is to provide the Directors with the measurement they require - Return on Investment. This paper will demonstrate how to optimize calibration efficiencies and provide the necessary financial justification to the management team.
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Document ID:
DE3B0ADA
Calibration Of Non-Automatic Weighing Instruments Expression Of Uncertainty For Displayed Net Values
Author(s): Jrgen Ober
Abstract/Introduction:
In 1994 the first calibration laboratories for electronic balances were accredited in Germany by the German calibration services DKD. The method for calculating the value of uncertainty differs from the methods in other countries and for other measuring instruments.
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Document ID:
8679E742
Design And Assessment Of An Automatic 50 kg Weight Exchanger
Author(s): Gordon Peattie, Stuart Davidson
Abstract/Introduction:
The following report outlines the tests which were conducted to assess the suitability of a commercially available top pan electronic balance for use with an automatic weight exchanging mechanism. The conceptual design, manufacture and testing of the weight exchanger are described and the current performance of the system discussed. Suggestions are made for future work on the balance with a view to further improving its performance.
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Document ID:
4BDFE47C
The Importance Of Uncertainty Data From Instrument Drive
Author(s): Wayne C. Nancarrow
Abstract/Introduction:
State of the art equipment includes complex devices with very low uncertainties relative to the analog devices of the past. The use of automated test equipment in the calibration field have greatly improved measurement capabilities, uncertainties and reduced labor cost. The certification of many devices may begin to push the old criteria of a test uncertainty ratio (TUR) of 10:1 or 4:1. These ratios assume that a proper worst-case analysis has been accomplished prior to the commencement of the measurement process, with standards and instruments assumed to be in known stable states. Today many of these items are certified using criteria that mandates greater scrutiny and control of all the associated measurement errors in the calibration process. The purpose of this paper is to recommend a framework for calibration software that will allow the proper calculation of measurement uncertainties with respect to a single or series of measurements made from any one instrument under calibration software program control under all possible states of any measurement system.
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Document ID:
0D672C22
Cloning Metrology How Are Others Doing?
Author(s): Emil Hazarian
Abstract/Introduction:
The paper describes the similarities and the differences between our metrology structure and the European one, with references to Romania, discovered on the occasion of an advisory trip.
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Document ID:
6E031E96
Reporting Requirements Of ISO Guide 25 And The Prospective Replacement ISO/DIS 17025
Author(s): Patrick Kershaw
Abstract/Introduction:
ISO Guide 25, General Requirements for the Competence of Testing and Calibration Laboratories, has been a defining standard in the calibration industry. Prospective standard ISO/DIS 17025 is currently under review to become the replacement for Guide 25. In order to validate the routines used in transfer of measurement between instruments, transfer standards and prime standards, the guide establishes reporting criteria for laboratories providing calibration verification and adjustment. This paper compiles a compact list of those reports required by the guide and provides a crossreference which may prove useful as laboratories transition to the superceding document. Draft ISO/DIS 17025 identified CS981040033 was referenced during the writing of this pap
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Document ID:
406E076E
Rockwell Hardness Testing - A Users Perspective
Author(s): Jeffrey W. Dean
Abstract/Introduction:
In the past decade there has been a marked increase in the number of problems associated with the calibration and operation of Rockwell Hardness testers. This has resulted in increased product rejection and ambiguous test results. This presentation will present a users perspective of why this occurred, how the new NIST Rockwell C Scale SRM will improve the calibration process for Rockwell hardness test machines and a discussion of the impact of proposed changes to theASTM E18 standard. Introduction
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Document ID:
0D1B929A
The Effects Of The New NIST Rockwell Hardness Standards On The Hardness Products Manufacturers And Related Astm Standards
Author(s): Edward L. Tobolski
Abstract/Introduction:
The National Institute of Standards and Technology has introduced new Rockwell HRC Scale hardness standards. These standards took several years to develop and represent a major improvement in the traceability and repeatability of our hardness measurements. As a result of this new standard, the hardness industry has some new tools. To gain full benefit of these tools, the manufacturers of hardness products must change the way they operate and ASTM, the organization in the USA that establishes the standard test methods for Rockwell testing, has to revise their documents.
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Document ID:
D5FE8122
Software Strategies For On-Site Calibration
Author(s): Nicholas Mason
Abstract/Introduction:
Many laboratories are using personal computer (PC) based calibration and management stations connected to a centralized database to collect and report information. This system is ideal for fixed computers because they must be constantly connected to a local area network (LAN) to access the centralized database.
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Document ID:
83040439
Simplified Support Of Oscilloscope Calibration Equipment In The Cal Lab.
Author(s): Paul Roberts
Abstract/Introduction:
Equipment manufacturers are able to devote the resources needed to develop complex systems to fully automate the calibration of their products, but typical calibration laboratories usually do not have this luxury. For many common workload items such as Dmms there are automated calibration solutions available commercially, but the available solutions do not extend to more sophisticated equipment such as oscilloscope calibrators.
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Document ID:
6F0457F6
Measurement Decision Risk Simplified
Author(s): Ricardo A. Nicholas
Abstract/Introduction:
Every measurement decision has the potential of being incorrect. When the results of a measurement process indicate that the unit under test (UUT) is of acceptable quality, there is a calculable probability that the UUT is actually of unacceptable quality. The converse is also possible. Those probabilities can be referred to as Consumer and Producer Risks, respectively. Calculating those probabilities is a mathematical challenge, since double integration is the standard process used. The main focus of this paper is to present an approximation method which can be more easily intuitively grasped. Elaborate software is not needed. A general description using Microsoft Excel is provided. This approximation method can easily be made to give consumer and producer risk estimates within 0.1% of the more sophisticated double integration method. A comparison of results verifies the accuracy of those estimates.
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Document ID:
0F49CB5C
What Tur Do You Really Need? Putting Statistical Theory Into Practice
Author(s): Warren Wong
Abstract/Introduction:
The ageless question in metrology is, What Test Uncertainty Ratio (TUR) is required to properly calibrate an instrument? Numerous papers on guardbanding and statistical techniques have been published to address this question. Most recently, these discussions have focused on the very conservative in-tolerance conditions proposed by ISO Guide 25, draft 5. Although ISO Guide 25 is being replaced by ISO 17025, and the present draft (DIS 17025) does not have the strict guardbanding requirements, the draft 5 proposal presented a perspective that has merit. 12 The philosophies of other guardbanding methods have also been discussed in detail, especially by Dave Deaver of the Fluke Corporation.
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Document ID:
EBE2CB24
The Concept Of Conventional Mass In Astm E 617 And Oiml R 111.
Author(s): Walter E. Kupper
Abstract/Introduction:
ASTM Standard E 617 has recently been revised, and a major revision of OIML R 111 is currently in process. The concept of conventional mass, which is essential to both standards, is discussed in detail. A known problem with this concept exists at higher altitudes (starting as low as 1000 to 2000 feet above sea level) where the density of air is substantially different from 1.2 mg/cm3. The paper describes solutions that have been proposed for the revision of OIML R 111, including a formula for calculating correction values to be applied at higher altitudes.
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Document ID:
84CA6D85
Calibration Of Balances
Author(s): Emil Hazarian
Abstract/Introduction:
A brief review of the types of balances, starting in ancient times, continuing in our industrial century, to today electronic balances, is attempted. Methods, metrological requirements and technical specifications are examined with references to national (e.g. ANSI/NCSL Z540-1) and international standards (ISO 9000 series, ISO Guide 25). Criteria for choosing the right method to check scales and balances are proposed.
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Document ID:
46A1DA8C