Description
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17.10.2019
Limit
The limit is the maximum permissible leak rate. If the leak rate exceeds
the predefined limit, the watch being tested is classified as non-leak-
tight.
Relative to the diameter of the watch housing, the following standard
values apply:
Diameter of the watch glass
Volume
Limit
Ø
Glass
< 20 mm
1000 mm
3
50 µg/min
20 mm < Ø
Glass
< 40 mm
2100 mm
3
40 mm < Ø
Glass
4000 mm
3
Info
The lower the leak tightness limit, the longer the
measurement takes.
This must to be taken into account when planning production.
Leak rate
The ISO 2281 standard specifies the leak rate in µg/min and defines
50 µg/min as the limit value for leak tightness at a test pressure of 2
bar. The ProofMaster is configured by default according to these
standard specifications.
To calculate the leak rate, the measuring algorithm needs the exact air
volume in the watch case. The watch sizes suggested in the measuring
program are suitable for a qualitative consideration – we recommend
determining the inner volume of the watch beforehand.
4.7
Reference to standard ISO 22810
Leak-tight watch in ac-
cordance with stand-
ard ISO 22810
Standard ISO 22810 defines that a watch shall be classified as leak-
tight if less than 50 µg of air penetrates the watch per minute at a test
pressure of 2 bar.
Relationship between
volume and deformation
The ISO 22810 standard does not take into account the volume of the
watch. This means that the leak rate of 50 µg per minute applies to all
watches, regardless of their size.
When testing according to the principle of deformation, the reduction
depends on the free volume in the watch. In a watch with a small
volume, the reduction in deformation is more pronounced with the same
amount of penetrating air. The free volume must be programmed in the
watch for a standard-compliant test.
Interpretation of ISO 22810
The standard is based on a pressure of 2 bar or 0.5 bar. No limit value is
specified for other pressures.
It is therefore assumed that the limit of
50 µg per minute applies for all test pressures.
