Water Resistance, how to define the meter?

# Thread: Water Resistance, how to define the meter?

1. ## Water Resistance, how to define the meter?

most of watch have water resistance like 50m, 100m, 200m, 300m and so on

my question is, how do we actually differentiate the meter ? izzit like 50m can go 50meter deep water, no rite? is there any specific theory for it ? thanks :)

2. ## Re: Water Resistance, how to define the meter?

Originally Posted by Davidtan
most of watch have water resistance like 50m, 100m, 200m, 300m and so on

my question is, how do we actually differentiate the meter ? izzit like 50m can go 50meter deep water, no rite? is there any specific theory for it ? thanks :)
According to ISO 2281 and ISO 6425, the two main industry standards on watch water resistance, watches are tested to a given pressure.

The "depth rating" is defined as: 10 meters equals 1 atm.

So a watch tested to 30 atm is given a depth rating of 300 meters.

(One cubic meter of pure water at 4 C weighs 1000 kg, therefore the pressure exerted on the square meter it would theoretically sit on would be 1000kg/m^2. One technical atmosphere is defined as 0.0001 kg/m^2, so we can see that under one meter of water the pressure is 0.1 atm. Of course this assumes pure distilled water. Sea water runs somewhere around 1025 to 1030 kg/cubic meter.)

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5. ## Re: Water Resistance, how to define the meter?

thanks for the reply lysander and tj5515 :)

lysander, the theory u given is too complicated for me, but i'll take time to learn out the calculation, really appreaciated, thanks :)