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Mass Calibrations

Description: Abstract: The NIST calibration service for standard masses is described. Weights which are accepted for calibration range in nominal values from 1 mg to 13,600 kg (30,000 pounds). We also accept weights used to generate standard pressures in piston gages. Cleaning procedures used on weights prior to calibration are described. The measurement algorithms (including density determinations of single-piece kilogram weights) and the uncertainties assigned to calibrated weights are discussed. We also describe the system now in place to monitor the quality of calibrations. Finally, we assess the limitations of the present controls on measurement quality and outline improvements which are underway.
Date: January 1989
Creator: Davis, R. S.
Partner: UNT Libraries Government Documents Department

Formation of Lubricating Films at Elevated Temperatures from the Gas Phase

Description: Abstract: Conventional liquid lubricants, when subjected to temperatures of 250*C and above for extended time in an air atmosphere, degrade rapidly to make large amounts of solid sludge and deposits. Based on boundary lubrication of bearings, these same lubricants, when subjected to 250*C to the melting point of the bearing metal, produce in the micro- to milli-second residence time in the bearing contact enough "friction polymer" to result in good lubrication. This report describes the use of these conventional liquid lubricants delivered in a homogeneous vapor phase where the carrier gas is nitrogen, air or mixtures of these two gases. The lubricants studied include alkyl and aryl phosphate esters, organic acid esters, polyphenyl ethers, and mineral oil.
Date: September 1988
Creator: Klaus, E. Erwin; Duda, J. L.; Naidu, S. K.; Munro, R. G. & Hsu, S. M.
Partner: UNT Libraries Government Documents Department

AC-DC Difference Calibrations

Description: Abstract: This publication collects and summarizes the specialized information needed to operate the ac-dc difference laboratory and calibration service at NIST (Gaithersburg). It also serves as a convenient reference source for the users of this calibration service and other interested people by documenting the service and its underlying background in considerable detail. It contains the following: an annotated table of contents, a topical index, and a glossary of common ac-dc acronyms; an overview of the service; selected published papers; instructions for the operation of the comparator systems; a schedule for the recalibration and periodic checks of the NIST thermal converters; and a sample report of calibration.
Date: May 1989
Creator: Kinard, J. R.; Hastings, J. R.; Lipe, T. E. & Childers, C. B.
Partner: UNT Libraries Government Documents Department

Liquid-in-Glass Thermometer Calibration Service

Description: Abstract: This document gives a description of the calibration of liquid-in-glass thermometers at the National Bureau of Standards. The calibration equipment and procedures used at NBS are discussed in detail. Calculations and stem-temperature corrections are shown and a discussion of the sources of error encountered in calibration and estimates of uncertainties is presented.
Date: September 1988
Creator: Wise, Jacquelyn A.
Partner: UNT Libraries Government Documents Department