As long as it is a watch with waterproof function, we can see the text indication of the waterproof coefficient on the bottom cover of the watch, usually "XX bar" or "XX ATM". Obviously "XX m" seems simpler and easier to understand, why don't most watches just say it?
Because the number of meters of waterproofing is a conversion value, it is converted from ATM, which is a standard unit of atmospheric pressure. Physicist Torricelli proposed in 1644 that 1 standard atmospheric pressure is approximately equal to a 10.34-meter-high water column. In other words, the pressure generated by 10-meter-high water is approximately one standard atmospheric pressure. This is also 30 meters waterproof. The origin of ATM https://www.aomwatches.is/.
As a commonly used pressure unit, bar is approximately equal to 1 ATM, so some brands like to use bar to indicate the level of waterproofing.
During the waterproof test of the watch before leaving the factory, there is a very important test link called the pressure test. The watch will be placed in a pressurized equipment to simulate water pressure at different depths. This device controls the pressure exerted on the watch to test its water resistance under different water pressures.
But it should be noted that this test is a static test, which means that 30 meters of waterproof means that the watch can be guaranteed not to enter water at a still water depth of 30 meters. Once a person wears a 30-meter waterproof watch and goes into the water, sports The pressure generated during the process has long exceeded the pressure that the watch can withstand at a static temperature of 30 meters, so this is why 30-meter waterproof and 50-meter waterproof watches cannot be worn for underwater sports.
The waterproofing of watches mainly relies on the sealing design of the case, and also relies on the waterproof rubber rings on the watch mirror, bottom cover and crown to achieve waterproof standards.
With the continuous advancement of technology, more diving watches will also choose to use screw-in crowns and bottom covers to enhance waterproofing and prevent moisture from penetrating through the rotating holes. However, the increase in various waterproof methods will also increase the thickness of the watch case, so in daily life we rarely see diving watches with a thickness less than 12 mm. This is the reason.
If you want to keep the waterproofness of your watch in excellent condition, there are two elements you should pay attention to: 1. Do not adjust the crown and bottom cover of the watch when it is wet to prevent moisture from penetrating into the movement. 2. The waterproof apron is made of rubber and has the characteristics of thermal expansion and contraction. Avoid wearing the watch for hot baths, saunas, winter swimming and other activities to delay the aging of the waterproof apron.
