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Watch case pressure testing - how to.........

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I noticed from the Price survey that whilst many are now doing watch batteries only around half those offer a pressure testing service.


So how’s it done? Well there are two ways of pressure testing a watch case. I have been running BOTH ways for some time and feel they like so many things both have there uses.


(A) Elma Leak controller 2000.


RRP around £590




Compact, waterless tester with built-in vacuum pump. Checks water tightness by measuring case deformation in a controlled vacuum.

The Key advantage of this tester is that NO water is used for the test, it is really quick (around 5 minutes from start to finish) & in the majority of cases the watch doesn’t have to be dismantled to perform the test.


This tester has 2 draw backs.


1. There is no true depth value as the tester works by a dial gage showing movements in the watch case through differences in pressure (explained further down)

2. If a watch does show a leak, it doesn’t show where the leak is.


So how does it work?


works on the principal of sucking air out of the chamber causing a vacuum around the watch, the pressure around the watch is therefore reduced and the case of the watch will expand as the air pressure inside the watch becomes greater than that around it. A dial gage is put on the watch which measures this expansion.


So how’s it done?


1. Place watch onto dial bed.




2. Set dial to Zero.


3. Place chamber over watch.


4. Switch on machine for one minute or until the case deformation has reached +20.




5. Observer gage, for any loss of pressure (I usually allow 5 minutes)




If the watch is not leaking the gage will remain at its reading position.

If the watch leaks, the air pressure in the watch will equalise the air around it thus allowing the gage to return to its zero point.

If the watch has a large leak the gage may not move at all as the air rushes out of the watch case.


6. Release pressure & remove watch.


As mentioned before this tester is not without its faults, But I use it for any watch which states on the case “Water Resistant” with no depth specified. The main advantage of this tester is it does a large majority of the tests I get asked for very quickly and easily. This was the first tester I brought and although I quickly realised I needed a wet tester also I am mighty please I have this one its so easy!


(B) Bergeon 5555/98


RRP around £290




This controlled immersion tester offers an accurate check up to 6 atmospheres.

The Key advantage of this tester is you can give an accurate indication of the pressure (see below) you have tested to & Identify exactly where a leak is. Typical time to perform a test is around 15 minutes (including set up and clean down)


This tester has 2 drawbacks


1. The watch has to be taken apart to put it in the tester.


2. Its time consuming.


So how does it work?


The principle of this tester is the water & air around the watch is pressurised in the chamber before the watch is immersed in the water and allowed to “sit” then the pressure is returned to atmospheric pressure. If the watch leaked before being put in the water the pressure in the watch is increased along with the water around it.

When the pressure is returned to normal the extra pressure in the watch will try to escape, forming bubbles from within the watch, showing up the leak and where it is.


So how’s it done?


1. Remove the strap from the watch




2. Fill the tester to the water line (I recommend cleaning out the tester daily to stop the chamber glass from growing bacteria and going green)


3. Hang the watch on the hook in the lid.




4. Pressurise the chamber to the manufacturers specification (do not immerse watch until optimum pressure is reached)




5. Sink watch into water after about 5-10 minutes this allows the pressure to equalise in the watch should it have a leak.


6. SLOWLY (to fast could result in the glass pooping out of the case) release the pressure.



7. Observe watch for bubbles escaping from it. No bubbles no leak!


8. Do not release ALL the pressure but return the watch to its out of water position before releasing all the pressure as this will stop water entering the watch when the pressure equalises.


9. Remove watch.


As mentioned this tester is more time consuming yet more accurate than the dry tester. I only use this one if I have too!


What are you actually testing?


The word bar has its origin in the Greek word βάρος (baros), meaning weight. Its official symbol is "bar"; the earlier "b" is now deprecated, but still often seen especially in "mb" rather than the proper "mbar" for millibars.

The bar and millibar were introduced by Sir Napier Shaw in 1909 and internationally adopted in 1929.

Atomospheric air pressure is often given in millibars where sea level pressure is defined as 1.01325 bar.

As a rough approximation for each Bar/ATM just put a nought on the end. eg; 3 bar =30 metres 10 bar =100 metres 20 bar= 200 metres. This test is for short periods underwater. The only watch designed to withstand these pressures are the true divers watches and should be returned to the manufacturers for testing. As another guide 3bar is ok for the rain. 5bar is ok for swimming. 10bar is ok for snorkelling. 20bar is ok for water sports/scuba diving 30bar Manufacturer only.


I hope this article helps you make a decision as to which tester too buy, and whether to start testing. Its really easy and can bring some valuable revenue and can make your set up look really professional




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Who the hell goes swimming at even 1 bar (30 or so feet down) unless you have aqua lung equipment? and even then you would have a professional watch. Would you trust a "Cobbler" with your life dependant Watch?


Answers on a postcard to:


Hugh Candoit

Diving Centre For The Aged

Portsmouth Harbour



Anyone know of a service centre for myDetoxification chamber?


BTW nice post Lee, very well thought out and executed.

One thought though and it's taken 3 hours to think of this so just picture my brain hurting :lol:

What about Health & Safety? If these things are pressurised to 3 Atmospheres and you have a tank that has scratches on it, will it blow up when you pump it up to the required pressure?

What should they be looking for and what preventative measures should be enforced to ensure safety.

Good job I've never worked one of those devices, dont think I would still be around to tell the tale :lol:


Are not the customers terrified that you will damage their watch?

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just one question: if you do find a leak in a watch, is it beyond the capacity of most people who offer the testing service to rectify the fault?




No its usually really easy to rectify, most leaks come from the watch back. Replace the gasket (which you can buy in packets of a zillion!) Grease the gasket with Ring & Gasket lubricator job done. The next most common problem is around the glass, this means removing the glass and cleaning & reseating. Fine glue/sealers are available. Then the final less common leak is the stem these usually have a fine (small) rubber gasket which is easily replaced.


BUT the key issue here is that 80%-90% of watches give a positive result with NO extra work. Extra revenue for you with out any parts needed, just labour.


I started doing testing before I started fixing the leaks I found! If I found a leak I didn’t charge for the test. Told the customer where the leak was and recommended a repairer near by.


You can’t run before you can walk but now I am more competent and can fix the leak as well!


Lee, Would be interesting to know what charges can be levied for testing


I have a controversial approach to pressure testing, I charge £4 for a battery or £8 for a battery with test but using the dry tester is so easy, around 50% off customers yes when I offer the service for peace of mind. I tried testing for more when I started the service but found it was only then a certain type of customer that went for it.



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However rick do the rule prohibit you from offering an agency i.e take in work do it at home and return to customer?


Do the other 3 outlets do straps? pressure testing? strap alterations? a smaller slice of the cake but still the icing?



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wouldn't be worth taking it in for home Lee. two of the others near me do mostly while you waits or within the hour for most jobs.

thanks for the advice though :)


hey tel, they gave us a rule that we couldn't sell any giftware unless it was engraveable.....we get round that by slapping a plate on anything which we sell that can't actually be engraved :lol:



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  • 9 years later...


I just need to clarify something about pressure testing using an Elma leak controller.


During the initial post Lee says  "If the watch has a large leak the gauge may not move at all as the air rushes out of the watch case", which is perfectly understandable.


But I have recently read that you can also get no movement on the gauge when you are testing a more modern divers watch, because the glass and case are so much stronger now that they don't distort. 


So, having just tested a Tag 200 metre watch and got no movement from the gauge, should I be telling the customer that it has passed or failed?


Thanks, Valerie

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the elma won't test to 200 metres anyway. if he's using for actual diving, life or death I wouldn't test it, with either of these two. even with the elma though I've never had a watch that hasn't showed some case deformation on the dial, even the tiniest amount from the case back will show.

given a tag divers watch is probably around the 1k mark, personally if you have any doubt. I'd say you couldn't test it, because it was beyound the tolerance of your tester, or something like that.

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  • 5 weeks later...

Thanks Lee, very informative.


Do you give out any sort of disclaimer with the watch once a test has been done? What's to stop the customer altering the time when he goes on holiday, not putting the crown back to the proper position or tightening it and then come back to claim 'you said this was waterproof' etc etc.


Also, any chance of a quick tutorial on how to choose the correct gasket? I've a couple of boxes of assorted sizes from cousins but never seem to have the right size!

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yes I give an "at time of testing disclaimer. I buy gaskets in all the sizes & do it from experience, after all to skimp on the right selection of gaskets seems overly mean when you've invested so much in a tester.

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  • 3 weeks later...

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