Page images
PDF
EPUB

CHAPTER 11-NATIONAL BUREAU OF STANDARDS

DEPARTMENT OF COMMERCE

[blocks in formation]

240 241

Barrels and other containers for lime.
Barrels for fruits, vegetables and other dry commodities, and for cranberries.

SUBCHAPTER E-FELLOWSHIPS AND RESEARCH ASSOCIATES

255

Fellowships in laboratory standardization and testing for qualified citizens

of other American Republics. Research Associate Program.

256

SUBCHAPTER F-STANDARDS FOR SAFETY DEVICES

260

Standard for devices to permit the opening of household refrigerator doors

from the inside.

SUBCHAPTER A-MEASUREMENT SERVICES

PART 200—POLICIES, SERVICES,

PROCEDURES, AND FEES Sec. 200.100 Statutory functions. 200.101 Measurement research. 200.102 Standards for measurement. 200.103 Types of calibration and test serv

ices. 200.104 Consulting and advisory services. 200.105 Standard reference materials. 200.106 Critically evaluated data. 200.107 Publications. 200.108 Broadcasts. 200.109 Request procedure. 200.110 Shipping, insurance, and risk of loss. 200.111 Priorities and time of completion. 200.112 Witnessing of operations. 200.113 Reports. 200.114 Use of results or reports. 200.115 Fees and bills. 200.116 Description of services and list of

fees, incorporation by reference. AUTHORITY: The provisions of this part 200 are issued under sec. 9, 31 Stat. 1450, as amended; 15 U.S.C. 277. Interprets or applies sec. 7, 70 Stat. 959; 15 U.S.C. 275a.

SOURCE: The provisions of this part 200 appear at 32 F.R. 21012, Dec. 29, 1967, unless otherwise noted. $ 200.100 Statutory functions.

(a) The National Bureau of Standards has been assigned the following functions (15 U.S.C. 271-278e):

(1) The custody, maintenance, and development of the national standards of measurement, and the provision of means and methods for making measurements consistent with those standards, including the comparison of standards used in scientific investigations, engineering, manufacturing, commerce, and educational institutions with the standards adopted or recognized by the Government.

(2) The determination of physical constants and properties of materials when such data are of great importance to scientific or manufacturing interests and are not to be obtained with sufficient accuracy elsewhere.

(3) The development of methods for testing materials, mechanisms, and structures, and the testing of materials, supplies, and equipment, including items purchased for use of Government departments and independent establishments.

(4) Cooperation with other governmental agencies and with private organizations in the establishment of standard practices, incorporated in codes and specifications.

(5) Advisory service to Government agencies on scientific and technical problems.

(6) Invention and development of devices to serve special needs of the Government.

(b) The calibration and testing activities of the Bureau stem from the functions in paragraph (a) (1) and (3) of this section. These activities are assigned primarily to the NBS Institute for Basic Standards. Its program provides the central basis within the United States for a complete and consistent system of physical measurement; coordinates that system and the measurement system of other nations; and furnishes essential services leading to accurate and uniform physical measurements throughout the Nation's scientific community, industry, and commerce.

(c) The provision of standard reference materials for sale to the public is assigned to the Office of Standard Reference Materials of the NBS Institute for Materials Research. It evaluates the requirements of science and industry for carefully characterized reference mate. rials, stimulates the Bureau's efforts to develop methods for production of needed reference materials and directs their production and distribution. For information on standard reference materials see Subchapter B, Chapter II, of this Title 15.

(d) The provision of technical seryices to facilitate technical innovation and industrial use of the results of modern science and technology is assigned to the NBS Institute for Applied Technology. Thé principal elements of the Institute are (1) a Center for Computer Sciences and Technology which conducts research and provides technical services designed to improve cost effectiveness in the conduct of agency programs through the use of computers and related techniques; (2) technical divisions which provide services in technology of more general applicability; and (3) the Clearinghouse for Federal Scientific and Technical Information which promotes widest effective use by the scientific community, industry, and commerce of current information in all fields of industrial technology. $ 200.101 Measurement research.

(a) The NBS Institute for Basic Standards carries out the Bureau's func

re

tions in developing an adequate national system of physical measurement, and in providing related calibration services, Its . staff continually reviews the advances in science and the trends in technology, examines the measurement potentialities of newly discovered physical phenomena, and uses these to devise and improve standards, measuring devices, and measurement techniques, As new quirements appear, there are continual shifts of program emphasis to meet the most urgent needs for the measurement of additional quantities, extended ranges, or improved accuracies.

(b) The basic research and development activities of NBS are primarily funded by direct appropriations, and are aimed at meeting broad general needs. The Bureau may also undertake investigations or developments to meet some specialized physical measurement problem of another Government agency, industrial group, or manufacturing firm, using funds supplied by the requesting organization. $ 200.102 Standards for measurement.

(a) An international treaty, the Metric Convention, was signed by 18 countries in 1875. In 1893 the United States established prototype No. 27 of the international meter bar and prototype No. 20 of the international kilogram as U.S. Prototype Standards for length and mass. Representatives of many of the 40 nations now adhering to this treaty meet periodically, in the General Conference of Weights and Measures, to consider detailed proposals concerning international standards for physical measurement. Successive Conferences have now agreed to adopt six units to serve as a practical base for an International system of Units (Système International d'Unités, abbreviated SI)—kilogram, meter, second, kelvin, ampere, and candela. These are arbitrarily chosen but precisely defined magnitudes of six physical quantities-mass, length, time, temperature, electric current and luminous intensity, respectively_which are signed unitary value in the International System. Because the system is coherent, the expressions for the other quantities of science and technology derived from these six through the equations of physics will also have unitary coeficients. The units of the English systempound, inch, second, degree Fahrenheit, etc.—and of other systems of units are

related to the SI units by agreed-upon conversion factors.

(b) The SI units for the six quantities are defined as follows:

(1) In terms of a prototype object:

(i) Mass; The "kilogram” is the mass of a platinum-irridium cylinder preserved at the International Bureau of Weights and Measures in Sèvres, France. Prototype No. 20 is kept at NBS; equivalent prototypes are kept by other countries.

(2) In terms of natural phenomena:

(i) Length: The “meter" is the length of exactly 1,650,763.73 wavelengths of radiation in vacuum corresponding to the unperturbed transition between

the levels 2p10 and 5ds of the atom of krypton 86, the orange-red line.

(ii) Time interval: The "second" was long defined as 1/86400 of the time required for an average complete rotation of the earth on its axis with respect to the sun. This, with daily corrections from zenith transits of a star, is the basis for a universal time scale (UT). With further correction for polar motion, it becomes UT1, and with further correction for annual seasonal variations, UT2. Also, the earth's average daily rotation rate has been decreasing, thereby increasing the length of each year by about 6 ms over the length of the preceding year. Because of this, and other larger random fluctuations, the universal second thus defined is not a constant. Consequently, the 11th Conference (1960) ratified the definition of a second based on ephemeris time (ET): “the fraction 1/31,556,925.9747 of the tropical year for January 0, 1900 at 12 o'clock ephemeris time.” The 12th Conference (1964) authorized the designation of a cesium atom transition as a standard of frequency to be used temporarily for the physical measurement of time. The 13th Conference (1967) abrogated the 1960 action and decided that: The unit of time of the International System of Units is the second, defined in the following terms: "The second is the duration of 9,192,631,770 periods of the radiation corresponding to the transition between the two hyperfine levels of the fundamental state of the atom of cesium 133."

(iii) Temperature: The "kelvin,” the unit of thermodynamic temperature, is the fraction 1/273.16 of the thermodynamic temperature of the triple point of water. It was decided by the 13th Conference that the same name, kelvin, and

as

the symbol K should be used for expressing temperature intervals, dropping the former convention which expressed a temperature interval in degrees Kelvin or as abbreviated, deg K. However, the old designations are acceptable temporarily as alternatives to the new ones. One may also express temperature intervals in degrees Celsius.

(iv) Electric Current: The "ampere" is that constant current which if maintained in two straight parallel conductors of infinite length, of negligible circular sections, and placed 1 meter apart in a vacuum, would produce between these conductors a force equal to 2x 10-7 newton per meter of length.

(v) Luminous intensity: The “candela” is the luminous intensity, in the direction of the normal, of a blackbody surface 1/600,000 square meter in area, at the temperature of solidification of platinum under a pressure of 101,325 newtons per square meter.

(c) Although the six base units, and others derived from them, are exactly defined, their practical use requires a realization through the development of accurate measurement standards. Measurement standards may be based on physical phenomena, specimen objects, signal sources, or reference instruments. Extensive theoretical studies and laboratory experiments are involved in their selection, design, construction, and operation.

(d) It will be noted that a kilogram mass standard can be calibrated only through a series of comparisons, starting from the International Prototype. The units for the other five base quantities, and all quantities derived from them, are in principle independently realizable in many laboratories. In practice, however, inevitable minor differences among instruments, environments, and operators are bound to introduce small discrepancies. Periodic comparison of standards and the resolution of these discrepancies is required for compatibility among domestic standards laboratories, as well as internationally.

(e) Within the United States, NBS consults with the major industrial and governmental standards laboratories, and cooperates with the Department of Defense and the National Conference of Standards Laboratories in conducting measurement agreement comparisons. Periodic inter-comparisons of NBS standards with those of other countries are made through the International Bu

reau of Weights and Measures, through international scientific organizations, or by direct arrangement. The operations of the International Bureau are supervised by the General Conference of Weights and Measures, to which U.S. delegates are appointed by the Department of State.

(f) Frequency and time comparisons within the United States are made by the National Bureau of Standards, the U.S. Naval Observatory, and other organizations which have an interest in precise time and frequency standards. The data. from worldwide astronomical observations and from standards laboratories in many countries are coordinated by the International Bureau of the Hour, which announces recommended approximations for the rate difference between atomic and universal time. as well as for epoch adjustments. $ 200.103 Types of calibration and test

services. (a) NBS has developed instrumentation and techniques for realizing standards for the six base units of the International System of Units, as agreed upon by the General Conference of Weights and Measures. Reference standards have been established not only for these six base units, but also for many derived quantities and their multiples and submultiples. Such reference standards, or equivalent working standards, are used to calibrate laboratory and plant standards for other organizations. Accuracy is maintained by stability checks, by comparison with the standards of other national and international laboratories, and by the exploration of alternative techniques as a means of reducing possible systematic error.

(b) Calibrations for many types of instruments and ranges of physical quantities are described in the itemized service schedules of SP 250. On those services for which fees have been established, the fees are also listed in SP 250. In cases where fees have not been fixed, services will be billed on the basis of actual costs incurred. (See $ 200.116 for details relating to the description of service items and listing of fees.) Changes in services and fees are announced in supplements to SP 250 and in the monthly NBS Technical News Bulletin.'

[ocr errors]

1 For sale by the Superintendent of Documents, U.S. Government Printing Office, Washington, D.C. 20402.

« PreviousContinue »