NATIONAL BUREAU OF STANDARDS

\Q0*\

4341

REPORT

ON

THE LUMINOUS INTENSITY OF 8 LAMPS

AND

THE LUMINOUS FLUX OF 8 LAMPS

FOR

INTERCOMPARISONS TO BE CARRIED OUT

AT

BUREAU INTERNATIONAL DES POIDS ET ME SURE

S

U. S. DEPARTMENT OF COMMERCE

NATIONAL BUREAU OF STANDARDS

By

Ray P. Teele

Velma I* Burns
U. S. DEPARTMENT OF COMMERCE

Sinclair Weeks, Secretary

NATIONAL BUREAU OF STANDARDS

A. V. Astin, Director

THE NATIONAL BUREAU OF STANDARDS

The scope of activities of the National Bureau of Standards is suggested in the following listing

of the divisions and sections engaged in technical work. In general, each section is engaged in

specialized research, development, and engineering in the field indicated by its title. A brief

description of the activities, and of the resultant reports and publications, appears on the inside

of the back cover of this report.

Electricity and Electronics. Resistance and Reactance. Electron Tubes. Electrical Instru- ments. Magnetic Measurements. Process Technology. Engineering Electronics. Electronic

Instrumentation. Electrochemistry.

Optics and Metrology. Photometry and Colorimetry. Optical Instruments. Photographic

Technology. Length. Engineering Metrology.

Heat and Power. Temperature Measurements. Thermodynamics. Cryogenic Physics.

Engines and Lubrication. Engine Fuels.

Atomic and Radiation Physics. Spectroscopy. Radiometry. Mass Spectrometry. Solid

State Physics. Electron Physics. Atomic Physics. Nuclear Physics. Radioactivity. X-rays.

Betatron. Nucleonic Instrumentation. Radiological Equipment. AEC Radiation Instruments.

Chemistry. Organic Coatings. Surface Chemistry. Organic Chemistry. Analytical Chemistry.

Inorganic Chemistry. Electrodeposition. Gas Chemistry. Physical Chemistry. Thermochemistry. Spectrochemistry. Pure Substances.

Mechanics. Sound. Mechanical Instruments. Fluid Mechanics. Engineering Mechanics.

Mass and Scale. Capacity, Density, and Fluid Meters. Combustion Controls.

Organic and Fibrous Materials. Rubber. Textiles. Paper. Leather. Testing and Specifications. Polymer Structure. Organic Plastics. Dental Research.

Metallurgy. Thermal Metallurgy. Chemical Metallurgy. Mechanical Metallurgy. Corrosion.

Mineral Products. Porcelain and Pottery. Glass. Refractories. Enameled Metals. Concreting Materials. Constitution and Microstructure.

Building Technology. Structural Engineering. Fire Protection. Heating and Air Conditioning. Floor, Roof, and Wall Coverings. Codes and Specifications.

Applied Mathematics. Numerical Analysis. Computation. Statistical Engineering. Mathematical Physics.

Data Processing Systems. Components and Techniques. Digital Circuitry. Digital Systems.

Analogue Systems.

Cryogenic Engineering. Cryogenic Equipment. Cryogenic Processes. Properties of Materials.

Gas Liquefaction.

Radio Propagation Physics. Upper Atmosphere Research. Ionospheric Research. Regular

Propagation Services.

Radio Propagation Engineering. Frequency Utilization Research. Tropospheric Propagation

Research.

Radio Standards. High Frequency Standards. Microwave Standards. • Office of Basic Instrumentation • Office of Weights and Measures
NATIONAL BUREAU OF STANDARDS REPORT

REPORT

ON

THE LUMINOUS INTENSITY OF 8 LAMPS

AND

THE LUMINOUS FLUX OF 8 LAMPS

FOR

INTERCOMPARISONS TO BE CARRIED OUT

AT

BUREAU INTERNATIONAL DES POIDS ET ME SURE S

Ray P. Teele

Velma I* Burns

Photometry and Colorimetry Section

Optics and Metrology Division

(File Ref

o

1100)

NBS PROJECT

0201-20-0205

NBS REPORT

October 10, 1955

By

U. S. DEPARTMENT OF COMMERCE

NATIONAL BUREAU OF STANDARDS

The publication, re

unless permission li

25, D.C, Such pei

cal ly prepared if t

Approved for public release by the

director of the National Institute of

Standards and Technology (NIST) on October 9, 2015

in part, is prohibited

andards, Washington

rport has been specifieport for its own use,
-
THE LUMINOUS INTENSITY OF 8 LAMPS

AND

THE LUMINOUS FLUX OF 8 LAMPS

FOR

INTERCOMPARISONS TO BE CARRIED OUT

AT

BUREAU INTERNATIONAL DES POIDS ET ME SURE S

By

Ray Po Teele

Velma I c Burns

This report describes the method of measurement and gives

the values of luminous intensity and luminous flux of lamps

representing the photometric units as maintained at the National

Bureau of Standards „ These units are, (1) the candela at 2042°K

(2) the candela at 2353°K, (3) the lumen at 2353°K, and (4) the

lumen at 2788°K e

1. PURPOSE

This report gives the values found in 1954 and 1955 to

represent the four photometric units maintained at the National

Bureau of Standards

.

2 c MATERIAL

The lamps are all of special construction in accordance

with the desires of the Bureau International des Poids et

Me sure s, which supervised the manufacture of the lamps in

France,

3. STANDARDS

The lamps were calibrated in terms of groups of standards

representing the four photometric units maintained at the

National Bureau of Standards, These groups of standards are

as follows:

(a) Candela at 2042°K o Group consisting of lamps BS 2395?

BS 2398, BS 2399, BS 2400, BS 2401, BS 2402, BS 240?,

and BS 2270. The mean of the eight lamps is I6.0I0 candelas.

This group of lamps was originally calibrated against the prim°

ary platinum black body in 1937 and is assumed to have remained

constant since that time.

- 2 -

(b^ Candela at 2353°K» Group consisting of lames

BS 2987, BS 2990, BS 2991, BS 2992, and BS 2993 . The mean

of the five lamps is 33.60g candelas. This group of standards is the current reference group and is the same group

used as a base for t*e lamps sent to the BIPM previously,

NBS Test 1.5/122762-2, November 2, 1949. Lamp BS 2986 has

been damaged in the interim and is not part of the reference group at this time.

(c) Flux at 2353 °Ko Group consisting of lamps BS 5470,

BS 5472, BS 5473, BS 5477, BS 5478, BS 5485. The mean of

the six lamps is 444 .

q

lumens. This group of standards is

the current reference group and is composed of lamps from

a larger group, part of which were used as a base for the

lamps sent to *he BIPM previously, NBS Test 1.5/122762=3?

November 2, 1949.

(d) Flux at 2788°K. Group consisting of lamps

BS 5872A, BS 5873, BS 5875, BS 5876, BS 5877, BS 58780

The mean of the six lamps originally (1927) was found to

be 1.0550 times the mean of group BS 1724 or 7564 lumens.

Group BS 1724 was the base used at the NBS prior to 1955 But

there is evidence of a small change (less than 0.2 percent)

in group BS 1724. We have made careful intercomparisons of

our four groups of reference standards and find that group

BS 5872A is consistent with the other groups and is within

0.1 percent of the value used (7564 lumens). Accordingly,

this group of standards has been used for this intercomparison.

4. METHOD

(1) Seasoning. The lamps were burned for a period

of 17 hours and then measured for current at a specified

voltage. They were subjected to an additional hour of

burning and the current again measured. This was continued

until no change in current occurred with additional burning

for 1 hour.

(2) Luminous Intensity. The luminous intensity meas=

urements were made by a substitution method on a horizontal

bar photometer with the lamps operating in a base down

position. The orientation was such that the plane of the

filament was perpendicular to the photometer axis and the

glass supporting structure was turned away from the photometer. The perpendicularity of the clane of the filament was

determined by sighting across the plane of the filament at

its reflection in a vertical cylinder mounted on the lamp

carriage, the center of the lamp socket and the center of

the cylinder being on a line at right angles to the photometer axis.

- 3

-

The photometric distance (measured to the plane of the

filament) for the lamps at 2042°K was 1.5t> meters. The photometric distance for the lamps at 2353°K was 1.25 meters.

(3) Luminous Flux. The luminous flux measurements

were made by a substitution method in an 88- inch integrating

sphere with the lamps operating in a base-up position.

(4) Photometric Measurements. All measurements were

made photoelectrically by using a modified form of the

photometer described in NBS J. Research 2_g, 703 (December

1940), RP 1348. With the voltage held constant at the

designated value, readings were taken of the current and

luminous intensity or luminous flux. Measurements were made

in the following order: three standards, the test lamps,

and the remaining standards. Three or more sets of measurements were made, the order of taking the readings being

reversed in alternate sets. The results given in 5* Results

are the averages of all readings taken.

5. RESULTS

The results are given in Tables A, B, C, and D. The

uncertainty of the luminous value (intensity or flux) for

each individual lamp was calculated at the 0.1 percent confidence level from the variations in the results in the

several sets of measurements. The uncertainty of the average

was also computed in this way, and, in addition, was estimated

as one-fourth the square-root of the sum of the squares of the

uncertainties of the individual lamps. The latter uncertainty

estimates are shown in parentheses.

Table A. Luminous Intensity at 2042°K (BIPM 1951 scale)

( ^039°& NBS Scale) Measured at 1 . *6

K Lamp No. Volts Amperes uandela Uncertainty

NBS 3757 97.200 o.554i9 11.85 ±0.10

NBS 3759 97.900 .55939 11.84 ±0.10

NBS 3760 98.600 . 55770 11.88 ±0.17

NBS 3762

Average

98.200 .55903 12.14

11.928

±0.13

±0.02 ]_ (±0.064

)

Table B.

- 4

Luminous Intensity at 2353°K (BIPM 1951 Scale)

(2352°K NBS Scale). Measured at 1 0 25 meters.

Lamp No. Volts Amperes Candela Uncertainty

NBS 3764 92.300 U3402o 22.38 ±0.1 2

NBS 3765 91.700 •34256 21.90 ±0.19

NBS 3769 91.800 .34023 22.03 ±0.15

NBS 3770 97.800 .3543 x 26.93 ±0.11

Average 23.308 ±0.11

(±0.07)

Table C, Luminous Flux at 2353°K

(2356°K NBS Scale)

(BIPM 1951 Scale

)

Lamp No. Volts Amperes Lumens Uncertainty

NBS 3780 99.000 0.32053 232.7 ±0 0 2

NBS 3782 98.500 •32056 231.6 ±0.6

NBS 3783 98.200 .31963 226.3 ±0.7

NBS 3784 99.100 •32i5x 233.7 ±0.2

Average 231.1 ±0.3

(±0 . 2 ) Table D. Luminous Flux at 2788°K

(28ll°K NBS Scale)

(BIPM 1951 Scale

)

Lamp No. Volts Ampe re s Lumens Uncertainty

NBS 3772 108.900 1.7369 2719 ±12

NBS 3773 110.000 1.7580 2778 ±15

NBS 3775 109.000 1.7336 2730 ±27

NBS 3776 108.900 1.7437 2733 ±11

Average 2740 ±16

(± 9)

THE NATIONAL BUREAU OF STANDARDS

Functions and Activities The functions of the National Bureau of Standards are set forth in the Act of Congress, March

3, 1901, as amended by Congress in Public Law 619, 1950. These include the development and

maintenance of the national standards of measurement and the provision of means and methods

for making measurements consistent with these standards; the determination of physical constants and properties of materials; the development of methods and instruments for testing materials,

devices, and structures; advisory services to Government Agencies on scientific and technical problems; invention and development of devices to serve special needs of the Government; and the development of standard practices, codes, and specifications. The work includes basic and applied

research, development, engineering, instrumentation, testing, evaluation, calibration services, and

various consultation and information services. A major portion of the Bureau’s work is performed

for other Government Agencies, particularly the Department of Defense and the Atomic Energy

Commission. The scope of activities is suggested by the listing of divisions and sections on the

inside of the front cover. Reports and Publications The results of the Bureau’s work take the form of either actual equipment and devices or published papers and reports. Reports are issued to the sponsoring agency of a particular project or program. Published papers appear either in the Bureau’s own series of publications or in the

journals of professional and scientific societies. The Bureau itself publishes three monthly periodicals, available from the Government Printing Office: The Journal of Research, which presents complete papers reporting technical investigations; the Technical News Bulletin, which presents summary and preliminary reports on work in progress; and Basic Radio Propagation Predictions, which provides data for determining the best frequencies to use for radio communications throughout

the world. There are also five series of nonperiodical publications: The Applied Mathematics

Series, Circulars, Handbooks, Building Materials and Structures Reports, and Miscellaneous

Publications. Information on the Bureau’s publications can be found in NBS Circular 460, Publications of the National Bureau of Standards ($1.25) and its Supplement ($0.75), available from the Superin- tendent of Documents, Government Printing Office. Inquiries regarding the Bureau’s reports and

publications should be addressed to the Office of Scientific Publications, National Bureau of Standards, Washington 25, D. C.
NBS
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H.3201

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