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NATIONAL BUREAU OF STANDARDS

The National Bureau of Standards was established by an act of Congress March 3, 1901. The Bureau's overall goal is to strengthen and advance the Nation's science and technology and facilitate their effective application for public benefit. To this end, the Bureau conducts research and provides: (1) a basis for the Nation's physical measurement system, (2) scientific and technological services for industry and government, (3) a technical basis for equity in trade, and (4) technical services to promote public safety. The Bureau consists of the Institute for Basic Standards, the Institute for Materials Research, the Institute for Applied Technology, the Institute for Computer Sciences and Technology, and the Office for Information Programs. THE INSTITUTE FOR BASIC STANDARDS provides the central basis within the United States of a complete and consistent system of physical measurement; coordinates that system with measurement systems of other nations; and furnishes essential services leading to accurate and uniform physical measurements throughout the Nation's scientific community, industry, and commerce. The Institute consists of a Center for Radiation Research, an Office of Measurement Services and the following divisions:

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Applied Mathematics Electricity Mechanics Heat - Optical Physics - Nuclear
Sciences 2
Applied Radiation 2
Electromagnetics 3 Time
Quantum Electronics
and Frequency - Laboratory Astrophysics - Cryogenics 3.

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THE INSTITUTE FOR MATERIALS RESEARCH conducts materials research leading to improved methods of measurement, standards, and data on the properties of well-characterized materials needed by industry, commerce, educational institutions, and Government; provides advisory and research services to other Government agencies; and develops, produces, and distributes standard reference materials. The Institute consists of the Office of Standard Reference Materials and the following divisions: Analytical Chemistry Polymers Radiation

Physical Chemistry.

Metallurgy

Inorganic Materials Reactor

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THE INSTITUTE FOR APPLIED TECHNOLOGY provides technical services to promote the use of available technology and to facilitate technological innovation in industry and Government; cooperates with public and private organizations leading to the development of technological standards (including mandatory safety standards), codes and methods of test; and provides technical advice and services to Government agencies upon request. The Institute consists of a Center for Building Technology and the following divisions and offices: Engineering and Product Standards - Weights and Measures - Invention and Innovation Product Evaluation Technology Electronic Technology - Technical Analysis Measurement Engineering - Structures, Materials, and Life Safety - Building Environment - Technical Evaluation and Application Fire Technology.

THE INSTITUTE FOR COMPUTER SCIENCES AND TECHNOLOGY conducts research and provides technical services designed to aid Government agencies in improving cost effectiveness in the conduct of their programs through the selection, acquisition, and effective utilization of automatic data processing equipment; and serves as the principal focus within the executive branch for the development of Federal standards for automatic data processing equipment, techniques, and computer languages. The Institute consists of the following divisions:

Computer Services - Systems and Software - Computer Systems Engineering - Information Technology.

THE OFFICE FOR INFORMATION PROGRAMS promotes optimum dissemination and accessibility of scientific information generated within NBS and other agencies of the Federal Government; promotes the development of the National Standard Reference Data System and a system of information analysis centers dealing with the broader aspects of the National Measurement System; provides appropriate services to ensure that the NBS staff has optimum accessibility to the scientific information of the world. The Office consists of the following organizational units:

Office of Standard Reference Data - Office of Information Activities - Office of Technical Publications Library Office of International Relations.

1 Headquarters and Laboratories at Gaithersburg, Maryland, unless otherwise noted; mailing address Washington, D.C. 20234.

2 Part of the Center for Radiation Research.

3 Located at Boulder, Colorado 80302.

Part of the Center for Building Technology.

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U.S. DEPARTMENT OF COMMERCE, Frederick B. Dent, Secretary NATIONAL BUREAU OF STANDARDS, Richard W. Roberts, Director

Issued October 1974

100 4516 1412

Library of Congress Catalog Number: 74-600164

National Bureau of Standards Special Publication 412
Nat. Bur. Stand. (U.S.), Spec. Publ. 412, 193 pages (Oct. 1974)

CODEN: XNBSAV

U.S. GOVERNMENT PRINTING OFFICE
WASHINGTON: 1974

For sale by the Superintendent of Documents, U.S. Government Printing Office, Washington, D.C. 20402 (Order by SD Catalog No. C13.10:412). Price $2.65

Stock Number 0303-01341

ABSTRACT

Papers followed by verbal discussions were given in a seminar and workshop sponsored by the National Bureau of Standards and the Food and Drug Administration to define the state of development of aerosol measuring instruments. The instruments discussed were based upon a variety of operating principles including laser light scattering, optical imaging, Doppler shift, electromobility, piezoelectric effect, and beta-ray absorption. Two review papers were given which described other phenomena upon which aerosol measurements are based. The general summary includes a table which lists the specifications of the instruments discussed to illustrate the range of capabilities available in this field. Discussion among seminar attendees revealed that many questions remain to be answered before the more difficult aerosol measurements problems can be solved. For example, in the analysis of very dense aerosols questions arise concerning coincidence losses or agglomeration effects that may result from collisions between particles as they are drawn into the measuring volume. Volatilization or condensation effects may alter the size distribution if the measurements are made late in time. Finally, variations in particle shape or index of refraction can alter the instrument response and cause difficulties in interpretation.

Key Words: Aerosol instrument performance; aerosol measuring instruments; beta-ray absorption; Doppler shift; electromobility; laser light scattering; optical imaging; piezoelectric effect

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