I have been wondering because I often get asked if watches I sell are waterproof because I took the back off a brand new watch and fitted different hands. I figure the gaskets are brand new and lubricated, the sealing faces are pristine, so if put the case back on and torque it up tight it should be water resistant? Or maybe I am being naive and there is a secret process used at the factory?
The thing I have been wondering is do Seiko individually test all their watches for water resistance, yep, all those hundreds of thousands of Seiko 5 sports watches, SKX's, SRP's etc? Or do they like me assume new components made to tolerance will be OK and pressure testing not cost effective?
What about mid and upper tier dive watches? Possibly a small percentage of the thousands of pounds purchase cost of a Spring Drive GS Diver goes in individually testing water resistance?
My guess is that, as with other types of products and industries, you can guarantee quality if you control materials and processes. I assume they can guarantee water resistance by the material control and manufacturing process.
Assuming you reinstall everything the way you should and tighten the back as Seiko does, you should still have water resistance.
Has anyone seen published specs on how much torque should be used on case backs?
Years ago when I was into G Shocks, I had read that Casio tested inhouse their Gs, and that the Frogman series was the only one to have the international DIN certification. some guys reported no problem wearing their Gs while diving.
All of Seiko's ISO-rated divers are individually tested for water resistance. Yep, every single watch, from the SKX up to the Marine Master...if it says "Divers" on the dial it's individually tested.
You may be replacing the original gasket and torquing the case back tightly, but if you've kinked the gasket or over/under tightened the case back then it may no longer be water resistant.
All of Seiko's ISO-rated divers are individually tested for water resistance. Yep, every single watch, from the SKX up to the Marine Master...if it says "Divers" on the dial it's individually tested.
You may be replacing the original gasket and torquing the case back tightly, but if you've kinked the gasket or over/under tightened the case back then it may no longer be water resistant.
That's one of the reasons I love the Vostok Amphibians. The case back sits on a large flat rubber gasket and is held in place by a locking ring. No twist or sheer force is applied to the seal when tightening up the case back.
The back floats against the gasket so the more pressure applied to the watch the seal becomes more water tight. They're rated at 200m but some people have tested them to much greater pressures with no leaks.
Which made me chuckle yesterday when replacing the battery in my Seiko 7T32 which I inherited from my late father. On removal of the back cover there was/is NO gasket yet on the face it states Water Resist 100M and rear 100Bar.
From the manual,
Water Resitance
Accidental Contact with Rain and Showers - Yes
Swimming, Yatching and Taking a shower - Yes
Taking a Bath and Shallow Diving - Yes
Scuba Diving and Saturation Diving - NO, we recommend a Diver's watch.
I can only conclude that at some point he or a watch battery changer has omitted to replace its seal.
As for the Q, I would think they only run to a Type Approval for the higher batch units.
Thanks Anthony, I was pretty sure the top range watches are individually tested but how do Seiko test the cheap ones because of the time it takes? For example I bought a Blue Lagoon Samurai reissue, this is limited to ONLY 6000 units, so for a 30 minute test, that is 3000 hours of pressure testing. Then consider the non limited units of 3-4 models of samurai reissues, got to be more than the limited edition numbers so say 10,000 each, so 20,000 production hours to test 40,000 watches and a huge bottle neck in the production process.
The big Q...when tested, do the cases contain the movements. After all it has nothing to do with the pressure rating and if a case leaked they would ruin a movement.
I don't think any water is used in the testing procedure. It'll more likely be pressurised gas. The small chamber will be pressurised and the equipment will look for a pressure drop in the chamber that would indicate the gas is seeping into the watch body. If it'll keep high pressure nitrogen or air out it'll definitely keep water out. this has the advantages of being quicker and not getting the watch wet and having to dry it which brings with it whole hornets nest of H & S issues.
If you look at the picture above of the testing equipment its definitely not a wet process.
When you put it that way; limited run of 6000 watches takes 3000 hours to pressure test, it does sound like a lot of time.
I would agree that the pressure test takes time, but in the end, if the case and seals don't keep the water out, then the whole process of building the watch in the first place would be a waste of time.
I can say that none of my divers have shown any signs of leaking after replacing seals...just one that had silicone sealing the caseback instead of an o-ring.
I would say that 3 hours is a little over the top. We test a lot of electrical enclosures where I work, the equipment we use is so sensitive it'll detect a leak (even a really small one) in seconds. The total cycle on the test bench is probably only a few minutes per watch.
Agree on this one. With a general model they would only need a few minutes at the most per watch to be able to check the resistance of it. I have not seen these models being manufactured so can not comment on the actual process.
The machines at the front on the bench are a dry pressurised gas process and you can just see some of the gas pipework at the rear below it.
The machine behind this bench with the orange traffic light lit is a wet process where the models are submerged in pressurised water. I do not recall if all watches are subjected to this machine or only the water resistant rated models.
Once you get over 20bar pretty much all testing is done hydrostatically. The failure of a hydrostatic testing machine would be no big deal but the failure of an air/gas one even at 20bar would be like a bomb going off. Factor into the equation that the watches won't be tested sequentially, they would be tested in batches in multiple machines. The Rolex factory testing machine for their Sea Dweller range was designed and built by Comex and holds dozens of watches per testing cycle.
To offer the 25% safety reserve required by the ISO 6425 divers' watches standard Rolex test the standard Sea Dweller at 152.5bar and the DSSD at 487.5bar.
The standards and features for diving watches are regulated by the ISO 6425 – Divers' watches international standard. This standard was introduced in 1996. ISO 6425 defines such watches as: A watch designed to withstand diving in water at depths of at least 100 m and possessing a system to control the time. Diving watches are tested in static or still water under 125% of the rated (water) pressure, thus a watch with a 200-metre rating will be water resistant if it is stationary and under 250 metres of static water. ISO 6425 testing of the water resistance or water-tightness and resistance at a water overpressure as it is officially defined is fundamentally different from non-dive watches, because every single watch has to be tested. Testing diving watches for ISO 6425 compliance is voluntary and involves costs, so not every manufacturer present their watches for certification according to this standard.
ISO 6425 testing of a diver's watch consists of:
Reliability under water. The watches under test shall be immersed in water to a depth of 30±2 cm for 50 hours at 18 to 25 °C and all the mechanisms shall still function correctly. The condensation test shall be carried out before and after this test to ensure that the result is related to the above test.
Condensation test. The watch shall be placed on a heated plate at a temperature between 40 and 45 °C until the watch has reached the temperature of the heated plate (in practice, a heating time of 10 minutes to 20 minutes, depending on the type of watch, will be sufficient). A drop of water, at a temperature of 18 to 25 °C shall be placed on the glass of the watch. After about 1 minute, the glass shall be wiped with a dry rag. Any watch which has condensation on the interior surface of the glass shall be eliminated.
Resistance of crowns and other setting devices to an external force. The watches under test shall be subjected to an overpressure in water of 125% of the rated pressure for 10 minutes and to an external force of 5 N perpendicular to the crown and pusher buttons (if any). The condensation test shall be carried out before and after this test to ensure that the result is related to the above test.
Water-tightness and resistance at a water overpressure. The watches under test shall be immersed in water contained in a suitable vessel. Then an overpressure of 125% of the rated pressure shall be applied within 1 minute and maintained for 2 hours. Subsequently, the overpressure shall be reduced to 0.3 bar within 1 minute and maintained at this pressure for 1 hour. The watches shall then be removed from the water and dried with a rag. No evidence of water intrusion or condensation is allowed.
Resistance to thermal shock. Immersion of the watch in 30±2 cm of water at the following temperatures for 10 minutes each, 40 °C, 5 °C and 40 °C again. The time of transition from one immersion to the other shall not exceed 1 minute. No evidence of water intrusion or condensation is allowed.
An optional test originating from the ISO 2281 tests (but not required for obtaining ISO 6425 approval) is exposing the watch to an overpressure of 200 kPa. The watch shall show no air-flow exceeding 50 μg/min.
Except the thermal shock resistance test all further ISO 6425 testing should be conducted at 18 to 25 °C temperature. Regarding pressure ISO 6425 defines: 1 bar = 105 Pa = 105 N/m2. The required 125% test pressure provides a safety margin against dynamic pressure increase events, water density variations (seawater is 2% to 5% denser than freshwater) and degradation of the seals.
...
Resistance to salty water. The watches under test shall be put in a 30 g/l NaCl (sodium chloride) solution and kept there for 24 hours at 18 to 25 °C. This test water solution has salinity comparable to normal seawater. After this test, the case and accessories shall be examined for any possible changes.
Testing diving watches for ISO 6425 compliance is voluntary and involves costs, so not every manufacturer present their watches for certification according to this standard.
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