Diving watches with ISO 6425: what it means

Dive watches designed and tested to such an extent that they are ISO certified, have you ever heard of them? Professional diving watches fitted with ISO 6425 certification, an international standard for diving watches. These high-quality diving watches are especially suitable for water sports enthusiasts, no matter if you take a splash in the bathtub or seek out the deep sea, but especially for divers. We naturally stock quite a range of these watches, all standardised with this ISO standard. But what does this standard actually mean, what does an ISO certified diving watchhave that an ordinary diving watch does not? We explain it to you in this blog.

What is ISO standardisation?

You have no doubt heard of ISO, it stands for 'International Organisation for Standardisation'. A global federation that has come up with a standardisation for almost everything. That is. And they have done the same for diving watches in order to offer a safe and good product to anyone who is serious about diving.

But what does that say, that ISO 6425 certificate?

In any case, a diving watch with the ISO 6425 certificate should guarantee that you won't find yourself with an aquarium on your wrist after just one dive to a hundred metres. What it actually comes down to is that you can go diving with such an ISO dive watch even as a professional diver.

Tip: These are our ISO certified diving watches

What does a diving watch have to meet' to get such a certificate?

A diving watch does not just 'get' this ISO certificate. For that, it is tested on a large number of points with the aim of making the watch as safe as possible for the true diving enthusiast. And yes, the toughest and most important part an ISO 6425 dive watch has to meet is (how could it be otherwise) water resistance. And we don't just mean waterproof enough to take a shower with it....

Guaranteed waterproofness

According to the specifications, most diving watches are waterproof to a certain pressure or depth. But in practice, it is full of water long before the maximum depth is reached. With dive watches with ISO 6425, this is definitely not the case. To get ISO 6425 certification, a watch must be able to withstand a water depth of 200 metres for at least 2 hours. Not only that, the watch must then be able to withstand water pressure for three hours at a depth of 3 metres.

Citizen with ISO 6425: tested at 200 metres water depth

Apple-egg such a test you might think, but the water pressure at 200 metres is really huge. So big that the watch deforms and then deforms again (back) when taking off at a much lower water pressure. Therefore, before during testing, the watch is exposed to a pressure equal to that of 200 metres of water. To make sure that the watch also survives the ascent from that depth to the water surface, the watch is then exposed to a water pressure equivalent to 3 metres of water depth for another three hours. This tests whether the watch is still waterproof not only during, but also after a dive to 200 metres.

Safe diving with a Citizen watch

It is handy if you can use a dive watch for what it is intended: keeping track of your dive times. Not only should a certified dive watch be safe to use at great depths, it should also have a setting that allows you to time your dive times during descent and ascent.

This can be done with a diving ring on the bezel, for example. To meet the ISO standard, the diving ring must also be easy to read in the dark. And for safety, the diving ring should only rotate in one direction. So if you accidentally bump into the diving ring, your dive time cannot accidentally become too long, only shorter. This will prevent you from contracting the life-threatening diver's disease (caisson disease).

Anti-magnetic watch

Another special feature is that an ISO 6425 diving watch must be anti-magnetic. After being influenced by a strong magnetic field, the deviation may not exceed 30 seconds per day. (Should you accidentally swim into a sea mine, it is reassuring that your watch will not be the cause of an ignition...). And a diving watch should certainly be able to take some beating too, it should be impact-resistant and not show a deviation of more than 1 minute per day after a hefty 4.43m/s stroke.

Diving in freshwater or saltwater also makes quite a difference. For ISO certification, the watch is placed in warm water for 24 hours. That salt water should leave no visible marks after that.

Testing, testing and more testing....

Once the watch has passed this tray load of tests, it still hasn't achieved ISO certification. Because the other parts of the watch, such as the strap and crown, also have to meet special conditions. The closed wristband is loaded with 40 kilos for a minute, during which nothing is allowed to loosen or bend. The crown is exposed to a water pressure of more than 25 per cent of the indicated depth on the watch. If you get caught in the depth with your watch, know that the bracelet can withstand a lot so you won't lose it easily.

ISO 6425 condensation testing

For the ISO 6425 certificate, the watch must also undergo a number of condensation tests. For example, the watch is loaded from above with a weight of 0.5 kg for 10 minutes. This is followed by a condensation test.

During the condensation tests, the watch is then also 's heated to 40 degrees followed by cooling with a cold damp cloth (or water) on the glass. No condensation should then remain on the glass after drying.

ISO 6425 diving watch: for hobby divers and professionals alike!

You get the picture: an ISO 6425 diving watch is a reliable device. It has to be if you are a serious diver and want to take your watch to great depths. An ISO 6424 diving watch is perfect for hobby divers, but also for professional divers.

At WatchXL, you will find ISO certified diving watches. Check out our product range here.