No-timing-bezel divers

[lysanderxiii]

There are two ISO standards relating to water resistant watches, everyone here seems to know about ISO 6425, BUT I think you are overlooking the ISO 2281 standard.

**NOT ALL 300 m WATER RESISTANT WATCHES ARE EQUAL IN WATER RESISTANCE**

ISO 6425 standards set forth minimum requirements for mechanical watches* - a unidirectional bezel with elapse minute markings, visability at 25 cm in total darkness, indication that the watch is running in total darkness, shock and magnetic resistance, thermal shock resistance, and a minimum of 100 meter depth rating.

The testing of the last item is where things begin to differ from non-dive watches.

Water resistance testing of a diver's watch consists of:
-immersed in 30 cm of water for 50 hrs,
-immersed in water under 125% rated pressure with a force of 5 N perpendicular to the crown and buttons (if any) for 10 minutes.
-immersed in 30cm of water at the following temperatures for five minute each, 40 C, 5 C and 40 C again, with the transition between temperature not to exceed 1 minute, and
-immersion of the watch in a suitable pressure vessel and subjecting it to 125% of the rated pressure for 2 hrs, no evidence of water intrusion is allowed.

When a watch is tested IAW ISO 2281, it is subject to:

-immersed in 10cm of water for 1 hour,
-immersed in 10cm of water with a force of 5 N applied perpendicular to the crown and buttons (if any) for five minutes,
-immersed in 10cm of water at the following temperatures for five minute each, 40 C, 20 C and 40 C again, and
-and immersed and subjected to an overpressure equal to the rated pressure (6 ATM in this case) for 10 minutes.

You can see that there is a big difference in what is require between the two standards.

If a watch does not have a rotating bezel it is automatically disqualified from being a "true Diver's", but the question is, do they perform the remainer of the tests required by ISO 6425, or do they use the more relaxed standards of ISO 2281?

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*quartz and digital have slightly differing readablity requirements.