I like the MtG cards in the background.

 

I'm guessing it works by unscrewing the black knob full out, filling with water, hanging watch on holder, screwing on the lid and then screwing the black knob in to compress the fluid (sorry, pressurise the fluid).

If the case isn't watertight some liquid will be forced into the case.

Or is it used differently?

BTW, I like it. Haven't got a pressure tester yet so I'll have to look around.

 

wow, that is a beauty. Correct, if the case leaks then water will get in the case. After this test you are supposed to heat the case with a hot plate and then put a drop of water on the crystal. Condensation will appear on the crystal if any water was forced into the case by the machine. If no condensation appears on the crystal then the case is leak free.

 

Here is how I did it

https://omegaforums.net/threads/at-screwdown-crown.9669/

AT on hotplate

 

Yep - it's a baby version of this...



The one shown above is only a 20 bar tester, where mine is capable of 125 bar.

Typical testing regime is as follows:

1 - Assemble empty case.
2 - Run through dry testing machine first.
3 - Place case in wet tester, fill with water, close it up and leave for 30 minutes.
4 - Increase pressure to rating of watch +25%, and leave for 1 hour.
5 - Reduce pressure to atmosphere again, and leave for another 30 minutes.
6 - Remove from testing chamber, and place on hot plate that will raise temperature to 47 degrees C.
7 - After 30 minutes on hot plate, place drop of room temperature water on crystal and leave for 1 minute.
8 - Wipe away drop and check for condensation on inside of crystal using bright lighting and at least 4X loupe.
9 - If none, assemble watch and repeat steps 2 to 8.

Total testing time is about 5 hours...and if you are wondering why I do it first with the case empty...well because shit happens...





Cheers, Al

 

This little guy looks so scared.