REVIEWS AND REPORTS APPLICATION

OF NEW M E A S U R I N G U N I T S IN T H E GERMAN

D E M O C R A T I C REPUBLIC I. A. K o m a r o v a Translated from Izmeritel'naya Tekhnika, No. 9, pp. 59-60, September, 1962

New notations for measuring units have been recently introduced in technical literature of the German Democratic Republic. These notations, owing to the absence of the required explanation, often perplex Soviet readers of foreign technical literature and sometimes lead to incorrect understanding and conversion to the units adopted inour country. The new measuring units have been introduced and developed in the GDR as a result of the decisions of the 10th General Conference on Weights and Measures, held in 1954o The Council of Ministers of the German Democratic Republic by its decree of August 14, 1958 [1], has established the following six basic units of measurement: the meter (m); kilogram (kg); second (s); ampere (A); degree Kelvin (~ and candle (cd). Other measurement units are "derived from the basic units." The table (see p. 793) contains a list of the most important legalized measurement units which differ from the old units or replace them. Multiples and fractions of the above units or of their parts are formed by appropriate decimal prefixes similar to those adopted by GOST (AllUnion State Standard) 7663-55. In the view of the Metrologieal Administration of the GDR (Deutsches Amt fttr Messwesen) one of the most important consequences of the new decree consists in the strict separation of mass from force (weight). Mass and not force is taken as the basic unit, since the body has always the same mass, whereas force (weight) is a variable quantity, changing with the acceleration due to gravity, which differs at different points of the earth. The kilogram and gram have been adopted as units of mass and the newton, kilopond, pond and dyn as units of force. The newton is a force which provides a mass of 1 kg with an acceleration of 1 m / s e c z. The force which provides a mass of 1 kg with an acceleration of 9.80665 m / s e c 2 (the normal acceleration due to gravity adopted by the 3rd General Conference on Weights and Measures) is called the kilopond. This unit for a long time had no name of its own and was known as "kilogram-force" (kgf), which often, owing to negligence and accidental omissionof the letter f, led to errors in calculations; moreover, it did not provide the possibility of forming derived units, which was yet another of its defects. Derived units are formed from the kilopond (kp) by adding the appropriate decimal prefix to the name pond. The most commonly used are the megapond (Mp),equal to 10e p, the kilopond, equalto 103p or 9.80665 kg. m . sec "z, and the pond, equal to 10"~ kp. Units of mass (i.e., kilogram, gram, ton) are still being used in commercial transactions of the GDR, but in statics and the greater part of technical measurements units of force are used. In the opinion of the GDR Metrological Administration the correct use of the concept of "weight" is impeded by the wide meaning ascribed to it in everyday language. "Weight" in the GDR can mean either the mass, or the embodiment of that mass in an object, or else the force exerted by that object. At present it is still rather unusual to speak of the "mass ~ of a body instead of its "weights but in the interests of accuracy it is necessary to strive for the eradication of incorrect names. A decagram, equal to 10 g, which has been successfully adopted in Austria, Czechoslovakia, Yugoslavia and other countries, is introduced for the first time among the units of mass derived from the gram and the ton. A hectogram, equal to 100 g, established as long ago as 1935 as a legal unit, has not yet been generally adopted. The term "double centner" is abolished and replaced by the deciton or 100 kg. It should be noted that in forming derived units by means of decimal prefixes it is recommended that the most common and customary units be used. For instance, from the unit "ton," since it has its own name. it is possible

792

"d Former names

0

LENGTH Micron Millimicron

N e w names

O

"2,

of measurement units

0

of measurement units 0

Expressed in basic units

9

~O

O

Micrometer Nanometer

nm

qkm qm qdm qcm mm

Square Square Square Square Square

km 2 m2 dm 2 cm 2 mm 2

cbm cdm

Cubic Cubic Cubic Cubic

L

10 -8 m 1 0 -9 m

AREA

kilometer meter decimeter centimeter millimeter

106 m 2 10 -2 m 2 10-4 m 2

lO-S m ~-

VOLUME

ccm cram

meter decimeter centimeter millimeter

m3

m3

dm s cm 3 mm 3

10 -s m a i0 "s m 3 10 -9 m 3

MASS Double c e n m e r

Centner

dz Z

Pound

Gamma FORCE Kilogram-force Gram -force Ton-force

100 kilograms or deciton 50 kilograms 500 grams, 0.5 kilogram Decagram Hectogram Microgram

kgf or k~ Kilopond Pond g Megapond t

dt

I0 "I t

50 kg 500 g 0.5 kg dag

50 kg 0.5 kg

hg Pg

kp P Mp

10g 102 g 10 -6 g

9.80665 m . kg 9 s-z 10 -3 kp lOs kp

ACCELERATIO~ Gall ENERGY Gram-meter

mkg

Ktlopond-meter

ANGLES

gal

kpm

gl

New degree or gon New m i n u t e New second

CI I CC

Candle

cd

cm/s 2

9.80665 m 2 9 kg 9 s -2

(~r / 200) (1/100~ = (10"2)g ( 1 / 1 0 0 ) ~ = (10"4)g

LUMINOUS INTENSITY New candle

NK

to form by means of d e c i m a l prefixes such units as m i l l i t o n (10 -~ t = 10 s g = 1 kg), nanoton (10 -9 t = 10 "s g = 1 mg), and picoton (10 - ~ t = 10 -6 g = 1 pg). However, it is recommend replacing such uniform units by well known units which are equal m them, n a m e l y by kilogram, m i l l i g r a m and microgram. Any unit formed by the ratio of a unit of force and a unit of area can be used as a unit of pressure in the GDR. In addition such units as the bar (1 bar = 10s N/mZ), the technical atmosphere, equal to 1 k p / e r a z, the physical a t mosphere,equal to 101325 N / m 2, the tort (1 torr = 1 / 7 6 0 arm) have also been l e g a l i z e d . Among the derived units 0.1 of a technical atmosphere, denoted by one meter of water, 0o001 of a technical atmosphere, denoted by 1 c e n t i m e ter of water, and 0.0001 of a t e c h n i c a l atmosphere, denoted by 1 m i l l i m e t e r of water have been accepted. The

793

former notation of 1/760 of a physical atmosphere (equal to 1 torr) as 1 mm Hg at 0*C has not been legalized and will not be used. The use of former notations at/l and ata are no longer permitted, since the unit of pressure inboth instances is now the technical atmosphere or a kilopond per square centimeter. In this connection inthe future, excess and absolute pressure will have to be denoted as "at" or k p / c m 2. Among other legalized mechanical units mention should also be made of the units of worte joule, watt-second, newton-meter and erg; the thermal unit, caloric equal to 4.1868 J; the unit of power, watt, equal to 1 J/see. Moreover, the horsepower, equal to 75 kp. m / s e e can still be used. This unit is losing its significance with the spreadof electrification, and will fall into disuse. With respect to temperature units it should be noted that degree Celsius (~ a legal unit side-by-side with degree Kelvin. To the sign degree (~ only the letter K or C should be added in future. The accepted abbreviated conventional notation (deg) is the same for the Kelvin or Celsius scales, since on either scale the difference of 1 degree is the same. The new method of notation differs from the old one, however, by the fact that a difference of temperatures should now be designated by the abbreviated conventional notation (deg) and not by the sign of a degree (*). For instance,one should write 20":~0.5 deg (instead of the former notation 20i 0.5~ Decimal prefixes for expressing multiple or fractional values of degrees Kelvin or Celsius are not used. Considerable attention is being paid in technical literature of the German Democratic Republic to the problem of adopting the new units. In particular a fairly extensive discussion on the use of the terms "weight," "specific weight" and "density" has been published. However, this discussion has not as yet elucidated a completely clear understanding of the question. Measuring units in electricity and light are also dealt with, but since in these fields there are only a few differences between the old and new systems we are not giving any data about them. 1. 2. 3. 4. 5.

794

LITERATURE CITED Gesetzblatt der DDR. I, S. 647, Sonderdruck, No. 9 (1958). E. Padelt, Units of Pressure ACcording to the Table of Legalized Measurement Units (Report of the Weights and Measures Administration of the GDR). Standardisierung, No. 11, p. 1/518 (1959). E. Padelt, Mass-force, Density-Specific Gravity (Report of the Weights and Measures Administration of the GDR). Standardisierung, No. 12, p. 1/565 (1959). E. Padelt, Instruction on the Adoption of Physico-Technical Measurement Units (Report of the Weights and Measures Administration of the GDR). Schiffbautechnik, No. 1, p. 41 (1959). Adoption of Physico-Technical Measurement Units, Schiffbautechnik, No. 9, p. 481-482 (1959).