National rules on gravity zones in Germany

On July 15, 1999, the Working Group “Metrology and Verification“ approved the “Directivefor the verification of non-automatic weighing instruments -EA 9-“.

The Directive comes into force on July 15, 1999.

It replaces the “Directive for the verification of non-automatic weighing instruments -EA 9-“ of November 13, 1996.

Directive

for the verification

of non-automatic weighing instruments

-EA 9-

of July 15, 1999

...

5.3 Special regulations for weighing instruments whose measurement result depends on the acceleration due to gravity

90/384/EEC Annex II No. 5

Weighing instruments may be verified at any place for a different place of use, provided the accuracy test includes an appropriate correction for the acceleration due to gravity. The influence of the acceleration due to gravity depends on the number n' (n' is the number of scale division values influenced by the acceleration due to gravity in the range of self-indication or the number of scale division values in the partial weighing ranges of a multi-interval or a multiple-range weighing instrument).

For self-indicating balances with e = const.: n' = n.

For weighing instruments with a number of scale division values of nI 1 000 (for example weighing instruments of accuracy class ), this correction need not be made as the influence of the acceleration due to gravity is negligibly small.

Weighing instruments of accuracy class must be adjusted to the local conditions at the place of installation.

5.3.1 Consideration of the acceleration due to gravity during the test

90/384/EEC Annex II No. 5.2

When the accuracy of weighing instruments whose measurement result depends on the acceleration due to gravity is tested, the load m in the range of self-indication must be corrected by a positive or negative additional weightm, calculated according to the formula shown below; for calculation, the local acceleration due to gravity gp must be known to at least 3 digits after the decimal sign (± 0,5 10-3 m/s2 ):

5.3.1.1 Gravity zones

For Germany, the values of the acceleration due to gravity were summarized in zones. The individual zones comprise the following areas, and the values of the acceleration due to gravity in these zones are:

Zone 1:Bavaria – South (Lower and Upper Bavaria, Swabia):

gz = 9,8070 m/s2

Zone 2:Baden-Württemberg, Bavaria - North (Franconia, Upper Palatinate):

gz = 9,8081 m/s2

Zone 3:Hesse, North Rhine-Westphalia, Rhineland-Palatinate, Saarland, Saxony, Thuringia:

gz = 9,8107 m/s2

Zone 4:Berlin, Brandenburg, Bremen, Hamburg, Mecklenburg-Western Pomerania,

Lower Saxony, Saxony-Anhalt , Schleswig-Holstein:

gz = 9,8130 m/s 2

5.3.1.2 Consideration of the acceleration due to gravity for different scale division values

For gz must be entered:

a) For weighing instruments

- of class with n' greater than 500 to 1 000 and

- of class with n' greater than 1 000 to 3 000

the mean value of all zones

gz = 9,810 m/s2

b) For weighing instruments

- of class with n' greater than 1 000 to 2 000 and

- of class with n' greater than 3 000 to 5 000

the mean value of two neighbouring zones:

zones 1 and 2: gz = 9,8077 m/s2

zones 2 and 3: gz = 9,8094 m/s2

zones 3 and 4: gz = 9,8118 m/s2

c) For weighing instruments

- of class with n' greater than 2 000 to 3 300

- of class with n' greater than 5 000 to 10 000

the value determined for the respective zone

d) For weighing instruments

of class with n' of more than 3 300, verification may be carried out only at the place of use or directly for a place of use (not for a zone of use). In the latter case, the acceleration due to gravity at the place of use gg must be known to at least 3 digits after the decimal sign (± 0,5 10-3 m/s2 ).

Example:

Verification of a medium accuracy weighing instrument which depends on the acceleration due to gravity, with Max = 12 kg and e = 2g.

Let us assume Stuttgart as the place of verification and Bad Kreuznach as the intended place of installation. As the weighing instrument has n = 6 000 scale division values, the value of the respective zone of the place of installation must be entered for the calculation of m (in this case: zone 3).

The acceleration due to gravity at the test place Stuttgart is: gp = 9,80884 m/s2

The mean acceleration due to gravity of zone 3 is: gz = 9,8107 m/s2

Calculation of the correction value  m at max. load results in:

m  2 g (rounded up/off to the scale division value)

In the case of correct adjustment, the weighing instrument must, thus, indicate in Stuttgart for a 12 kg load a value of 11,998 kg.

5.3.2 Additional designations

In the case of weighing instruments which depend on the acceleration due to gravity, the user must be informed by an adequate note for which zone the verification of the weighing instrument is valid. Designation of the zone may be as follows:

indication of the respective federal states in optical characters or a comprehensible abbreviation.

In addition, the note must comprise the information that a change of the place of use beyond the borders of the range of use stated requires another verification.

The following notes are valid for the Federal Republic of Germany:

for weighing instruments according to 5.3.1.2 a):

“Verification is valid for the Federal Republic of Germany"

for weighing instruments according to 5.3.1.2 b) and 5.3.1.2 c):

“Verification is valid for....."

(Statement of the respective federal states)

for weighing instruments according to 5.3.1.2 d):

“Verification is valid only for ....."

(Statement of the place of use)

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