Description
34 / 112 28.03.2022
4.6 Definitions
Deformation measurement
The measuring method of the ProofMaster is based on the principle of
deformation. The watch is subjected to positive pressure to compress
the watch housing, or a vacuum to expand it. The faster the
deformation is compensated, the larger the leak in the watch case. The
deformation of the case within a certain time serves as the basis for the
measurement to determine whether the watch is leakproof or not.
Leak-tight watch
Under constant pressure, the deformation of the watch housing remains
constant.
Leaky watch
Under constant pressure, the deformation of the watch housing is
reduced.
The difference between the pressure in the test chamber and the
pressure in the watch housing is being compensated at a rate which is
above the limits of the leak rate.
Limit
The limit represents 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
<20mm 1000mm
3
50µg/min
20mm<Ø
Glass
<40mm 2100mm
3
40mm<Ø
Glass
4000mm
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 22810 standard specifies the leak rate in µg/min and defines
50µg/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. The inner
volume can be determined from the watch's design data.
Info
Negative leak rate
A negative leak rate may be displayed at the start of the measurement.
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