National Voluntary Laboratory Accreditation Program Research Articles

Gamma Scientific Sets High Standards for Light Measurement

Gamma Scientific Sets High Standards for Light Measurement

The National Voluntary Laboratory Accreditation Program and Acoustical Testing Services Laboratory Accreditation Program

This presentation provides an overview of NVLAP, the National Voluntary Laboratory Accreditation Program of the National Institute of Standards and Technology (NIST), with particular focus on NVLAP’s Acoustical Testing Services Laboratory Accreditation Program (LAP). Through the Acoustical Testing Services LAP, NVLAP provides third-party attestation of the conformance of its accredited acoustics laboratories to the requirements of ISO/IEC 17025:2005, General requirements for the competence of testing and calibration laboratories; NIST Handbook 150, NVLAP Procedures and General Requirements; and NIST Handbook 150-8, NVLAP Acoustical Testing Services. Specific topics covered in this presentation include a brief history of the Acoustical Testing Services LAP, the accreditation process, proficiency testing, and benefits of accreditation, such as international recognition of the competence of accredited laboratories and the concept of “tested once; accepted everywhere.”

Proficiency Testing for Pressure Calibration at the National Voluntary Laboratory Accreditation Program (NVLAP)

Abstract:The National Voluntary Laboratory Accreditation Program (NVLAP) has initiated a proficiency testing program for calibration laboratories accredited for pressure, designated as NVLAP code 20/T05. This program involves measurements by the laboratory on NVLAP-provided test artifacts at specific pressure points in gas, and then comparisons of the results to similar measurements by the NIST (National Institute of Standards and Technology) Thermodynamic Metrology Group. The statistical test of the value of the En parameter is used to determine whether or not the laboratory shows proficiency at each pressure point, and the entire set of En values determines whether or not the laboratory demonstrates proficiency for their declared scope in pressure. This proficiency test can evaluate both laboratories that primarily calibrate effective area of piston gauges, and laboratories that calibrate electronic pressure instruments. The test protocol, methods of data analysis, and some results to date are presented...

E-035 Cranial Radiation Exposure during Cerebral Angiography

IntroductionRadiation exposure to patients and personnel remains a major concern in the practice of interventional radiology. Medical personnel using radiation now account for more than half of all radiation workers...

A Method of Relative Calibration Developed for very High Consistency of Internal Metrology Standards

A method of relative calibration is developed in this work to calibrate the golden Standard wafers (VLSI Standard or self-prepared Standard wafers) from each geographical site to achieve very high consistency across all sites with relevant factors under control which otherwise might affect such calibration processes. These golden wafers from all sites are calibrated against a Master golden wafer which was chosen with the smallest expanded uncertainty. The derived expanded uncertainty of each golden wafer calibrated this way relative to the Master golden wafer has proved to be much smaller than the expanded uncertainty of the Master VLSI Standard wafers which were accredited by National Voluntary Laboratory Accreditation Program and is also traceable to NIST Standards. The very high consistency among all thus calibrated golden wafers from all geographical sites respectively are therefore achieved with almost the same relative accuracy as the one obtained with the Master golden wafer travelling across all sites.

Proficiency Testing for Achieving Accreditation in Thermometry

The establishment of traceability is an essential component of laboratory accreditation for calibration laboratories accredited by the National Voluntary Laboratory Accreditation Program (NVLAP). Traceability requires that an unbroken chain of comparisons to national standards with stated and documented uncertainties be established. The use of proficiency testing is an important tool for validating uncertainty claims contained within a Scope of Accreditation. As such, the National Institute of Standards and Technology (NIST) Thermometry Group conducts proficiency testing for NVLAP-accredited contact thermometry laboratories. These proficiency tests include thermometric fixed points, standard platinum resistance thermometers, industrial platinum resistance thermometers, thermistors, thermocouples, and liquid-in- glass thermometers. The NIST Thermometry Group proficiency tests scale inversely in difficulty as a function of the uncertainties contained within a facility’s Scope of Accreditation. The offered proficiency tests are designed to establish confidence in the participant’s calibration capabilities and uncertainty claims without being an undue burden to the calibration facility. The NIST Thermometry Group proficiency tests involve measurements of NIST-owned artifact(s) at NIST, measurements of the artifact(s) at the participant’s calibration facility, and then a second set of measurements at NIST. On completion of the measurement phase of a proficiency test, a detailed report is generated to give the difference in temperature realization between that of the participant and NIST and the degree of equivalence. As part of the goal to improve the participant’s measurement capabilities, the report also gives suggested solutions to any identified measurement issues that need attention. The role of proficiency testing as part of the process in achieving NVLAP accreditation in thermometry is discussed in the article. Additionally, the descriptions of the NIST Thermometry Group unbiased third-party proficiency tests and some unidentified participant results are given.

SPRT Calibration Uncertainties and Internal Quality Control at a Commercial SPRT Calibration Facility

The Hart Scientific Division of the Fluke Corporation operates two accredited standard platinum resistance thermometer (SPRT) calibration facilities, one at the Hart Scientific factory in Utah, USA, and the other at a service facility in Norwich, UK. The US facility is accredited through National Voluntary Laboratory Accreditation Program (NVLAP), and the UK facility is accredited through UKAS. Both provide SPRT calibrations using similar equipment and procedures, and at similar levels of uncertainty. These uncertainties are among the lowest available commercially. To achieve and maintain low uncertainties, it is required that the calibration procedures be thorough and optimized. However, to minimize customer downtime, it is also important that the instruments be calibrated in a timely manner and returned to the customer. Consequently, subjecting the instrument to repeated calibrations or extensive repeated measurements is not a viable approach. Additionally, these laboratories provide SPRT calibration services involving a wide variety of SPRT designs. These designs behave differently, yet predictably, when subjected to calibration measurements. To this end, an evaluation strategy involving both statistical process control and internal consistency measures is utilized to provide confidence in both the instrument calibration and the calibration process. This article describes the calibration facilities, procedure, uncertainty analysis, and internal quality assurance measures employed in the calibration of SPRTs. Data will be reviewed and generalities will be presented. Finally, challenges and considerations for future improvements will be discussed.

USG Corp. Research and Technology Center’s Acoustical Testing Facility

The Acoustical Testing Facility at the USG Corp. Research and Technical Center was commissioned in 1996. The Facility contains structurally isolated test chambers housed within an exterior shell. The Facility includes chambers for performing sound tansmission loss tests per ASTM E90, sound absorption tests per ASTM C423, ceiling attenuation tests per ASTM E1414 and interzone attenuation tests per ASTM E1111. In addition to testing per ASTM standards, tests can also be performed to ISO Standards. The chambers are designed to provide maximum isolation from external noise. The chamber walls, roof and floor are built of a minimum of 8-in. (200-mm) solid concrete or filled concrete block. In addition the reverberation chamber is mounted on an independent spring system. The Facility is accredited under the National Voluntary Laboratory Accreditation Program (NVLAP) and under the Underwriters Laboratories Client Data Test Program. The main function of this Facility is to provide data for new product and systems development and to provide testing under the UL Acoustical labeling program.

On sound power determination: The uncertainty in sound power determined in a reverberation room based on a round-robin

In this paper I will present the results of an extensive round-robin sponsored under the NIST National Voluntary Laboratory Accreditation Program for Acoustics. The round-robin tested the interlaboratory variability of sound power measured using the reverberation room sound power standards ANSI S12.31-33 and ISO 3741-3743. Also I will discuss the ramifications of uncertainty on sound-pressure estimation.

Evaluating EPACT’s Impact

Motors affected by the 1992 environmental legislation are mostly meeting the Energy Policy and Conservation Act’s (EPACT) minimum load efficiencies. Advanced Energy Corp. (AEC), Raleigh, NC, has completed the first in a series of studies to determine if newer motors are complying with the minimum EPACT-specified energy efficiency. The Motors and Drives Laboratory of AEC was the first motor-testing laboratory to be certified through the National Voluntary Laboratory Accreditation Program, a requirement under EPACT. The AEC study tested 20-horsepower, 1800-rpm, totally enclosed, fan-cooled motors from 15 manufacturers. The goal of this study is to see if the motors meet the minimum required efficiency, which EPACT specifies as the nominal efficiency for motor nameplates defined by the National Electrical Manufacturers Association (NEMA). The results of this study will not be used to certify compliance with EPACT regulations. The AEC study is primarily for industrial motor users, which have a vested interest in ensuring that the motors they buy comply with all the rules.

Interlaboratory Study of K Factor Determination by Asbestos-Analysis Laboratories

The National Voluntary Laboratory Accreditation Program (NVLAP) of the National Institute of Standards and Technology (NIST) has been accrediting laboratories for the analysis of asbestos by transmission electron microscopy since 1990. As part of the quality assurance procedures for the program, laboratories are required to determine k factors for Na, Mg, Si, Al, Ca and Fe. An interlaboratory study has been conducted by NIST and the Research Triangle Institute (RTI) in which laboratories analyzed thin film standards SRM 2063 or SRM 2063a. This work reports results of initial analysis of the data.

Determining the Lower Limit of Detection For Personnel Dosimetry Systems

A simple method for determining the lower limit of detection (LLD) for personnel dosimetry systems is described. The method relies on the definition of a critical level and a detection level. The critical level is the signal level above which a result has a small probability of being due to a fluctuation of the background. All results below the critical level should not be reported as an indication of a positive result. The detection level is the net signal level (i.e., dose received) above which there is a high confidence that a true reading will be detected and reported as a qualitatively positive result. The detection level may be identified as the LLD. A simple formula is derived to allow the calculation of the LLD under various conditions. This type of formula is being used by the Department of Energy Laboratory Accreditation Program (DOELAP) for personnel dosimetry. Participants in either the National Voluntary Laboratory Accreditation Program (NVLAP) for personnel dosimetry or DOELAP can use performance test results along with a measurement of background levels to estimate the LLDs for their dosimetry system. As long as they maintain their dosimetry system such that the LLDs are less than half the lower limit of the NVLAP or DOELAP test exposure ranges, dosimetry laboratories can avoid testing failures due to poor performance at very low exposures.

Summary of Low-Density Glass-Fiber Reference Materials at NIST: 1980-1989

This paper reviews three programs at the National Institute of Stan dards and Technology (NIST) that provide specimens of low-density glass-fiber in sulation as reference materials. The National Voluntary Laboratory Accreditation Program (NVLAP) provides specimens as Proficiency Test Materials, the Standard Reference Materials Program (SRMP), as Standard Reference Materials; and the Center for Building Technology (CBT), as Calibrated Transfer Specimens. The pro grams of SRMP and CBT arc summarized for the years 1980 to 1989 The paper in cludes a catalogue of NIST publications covering the technical development of the low-density glass-fiber insulation used in the programs of NVLAP, SRMP and CBT.

Methods for the Calibration of Photon Personnel Dosemeters in Terms of the Ambient Dose Equivalent

A series of Monte Carlo computer calculations has been made in order to study the relationships between the quantity measured (exposure or air kerma) and the quantity desired (ambient dose equivalent) for photon irradiations. The types of irradiations considered were those required by the National Voluntary Laboratory Accreditation Program and the US Department of Energy Laboratory Accreditation Program. It was found that a dosemeter covered with 1 g.cm −2 of either polymethylmethacrylate (PMMA) or an International Commission on Radiological Units and Measurements (ICRU) four-element tissue mixture, and irradiated on a rectangular 30×30×15 cm 3 PMMA phantom, can yield a reasonable approximation to the ambient dose equivlent

The US Naval Dosimetry Centre Thermoluminescence Dosimetry System

The US Naval Dosimetry Center thermoluminescence dosimetry system is presented. The dosemeter algorithm accounts for individual chip response, reader calibration, and particular operational requirements of the navy. Lower limits of detection are used in the algorithm. Results of the United States National Voluntary Laboratory Accreditation Program are presented. The accuracy of the system is within the required performance criteria.

Round Robin Fire Safety Tests on Cellulose Insulation Testing Program: Round 2

This paper describes the California Bureau of Home Furmshmgs - Insulation Pro gram round robin fire safety, second round testing results for Cellulose Insulation material. The results of the California Bureau of Home Furnishings proficiency test ing program from manufacturer's in-house quality control testing laboratories and other National Voluntary Laboratory Accreditation Program (NVLAP) accredited laboratories are given. Tables show the statistical results of data submitted by partici pating laboratories for critical radiant flux and smoldering combustion.

Measurement assurance and accreditation

The National Bureau of Standards (NBS) has developed a concept to accredit laboratories which provide electromagnetic power, attenuation, and reflection coefficient calibration services. This program, developed under the general procedures of the National Voluntary Laboratory Accreditation Program (NVLAP) would accredit calibration laboratories for levels of uncertainty equivalent to the uncertainties of measurements made at NBS. Implementation of the program is being delayed pending funding to implement a Measurement Assurance Program (MAP) by NBS. The MAP is a quality assurance program to establish and monitor the uncertainty of measurements being made by participating laboratories on a continuing basis.

The National Voluntary Laboratory Accreditation Program for acoustical laboratories

The National Voluntary Laboratory Accreditation Program (NVLAP) administered by the National Bureau of Standards (NBS) established a program in September 1982 to accredit laboratories that provide acoustical testing services. The Acoustics Laboratory Accreditation Program (Acoustics LAP) covers 50 national and international test methods for which laboratories can apply for accreditation. The test methods cover procedures for measuring the properties of acoustical materials, sound power and sound pressure level measurements, and field measurements of noise produced by products. Applicant laboratories are evaluated through on‐site visits by experienced assessors and by participation in proficiency testing programs administered by NVLAP. Proficiency testing programs are currently in operation for test methods ASTM C423 and ASTM E90. Seven laboratories are currently accredited for various test methods and additional laboratories are in the process of being evaluated for accreditation.

Laboratory accreditation: An acoustical consultant's viewpoint

This paper will present the views of one consultant, who also heads the Laboratory Accreditation Committee of the National Council of Acoustical Consultants, towards the U.S. National Voluntary Laboratory Accreditation Program. While this program can provide significant benefits to the professional community, it unfortunately has some drawbacks that make it almost prohibitive for the involvement of small consulting businesses.

National Voluntary Laboratory Accreditation Program (NVLAP)

National Voluntary Laboratory Accreditation Program (NVLAP)