Hydrostatic Pressure test - DIY wet chamber

[Rozza72 58]

My Noobie approach 

I know this has been done before and there are YouTube vids on the subject plus details of builds on other forums, Christopher ward and watchuseek forums are where i got my inspiration so im in no way claiming this as my idea but this is my take on how i do it…in case anyone is interested or wants to have a go

 

The Chamber i use is rated at 125psi (8.6bar/8.5ATM) according to the data on its safety sticker. HOWEVER these things will be tested above that to find its burst pressure. A margin of safety in the region of between x3-x4, or between 375 to 500psi….thats 25.5 -  34.2ATM! and somewhat scary!

My Current gauge limit is 200psi (13.8bar/138m)

and my high pressure bike pump goes to 250psi so x2 the limit of my vessel and something im reasonably happy to accept the risk on.

 

Therefore I Initially tested the chamber empty to the max capability of my gage, in this case 200psi and left it pressurised for 2 hours (wrapped in a heavy blanket inside a 1000D nylon bag…in another room…just in case. 

 

I then returned, Noted any pressure drop (none) so i know the seals on the vessel and gage are ok, and decompressed it (slowly with a long metal tube from 1m away and protected…behind an OSB board…you never know) and checked for any visible signs of stress on the vessel afterwards. (None seen) 

 

Onto the watch testing

1st watch test

Run it DRY to test for crystal pop

Pump To 6 Bar, leave for 10 mins and SLOWLY depressurise. (All good)

 

2nd test pump to 8 Bar for 10 mins and slow decom.

 

3rd test WET

Pump to 10bar and leave for 10 mins with the watch suspended ABOVE the water to allow any leaks to let the air in and stabilise at pressure.

Then invert into water for 2 mins and slow decom to 2 BAR. CAREFULLY LOOKING FOR A STEADY STREAM OF BUBBLES COMING FROM ANYWHERE BUT PARTICULARLY THE CROWN, CASE BACK, CRYSTAL AND BEZEL.

 

IF LEAKAGE IS NOTED AT ANY STAGE

DO NOT DECOMPRESS TO ZERO AND RE-TURN SO THE WATCH IS ABOVE WATER BEFORE REDUCING PRESSURE TO ZERO

THIS WILL STOP WATER INGRESS

note where the leaks are and fix before going further obviously.

 

IF the watch is ok at 10ATM there is a good chance it will be at higher rated pressure (up to a point)

 

4th wet test (just for kicks)

Pump to 200psi / 13.8bar/13.6ATM or 141m (the capability of my gage) and leave for 1 hour.......SUBMERGED…if it can handle this it should be a safe bet for most situations….then slow decom etc etc yada yada….

 

NOTE My figures are shown for freshwater.

Seawater is slightly more dense but doesn’t overly change the readings for my purposes. (13.8bar in seawater is 137.4m)

 

If the watch can survive this then its a safe bet to say it will survive a swim in a pool, caught in a down pour, jumping into the pool from the side. Washing dishes, lounging in the tub, you get the idea.

 

Temperature can have a big effect on pressure so i still wouldn’t wear it in a sauna and then go jumping in a cold outside pool like are Scandinavian friends enjoy, it would probably survive but its up to you. 

 

As a final test for this you could consider a vapour test, gently heating the watch up to a nice warm temp (say 50C and then putting a drop of cold water on the crystal, any moisture inside the case should show up as fogging below this drop on the underside of the crystal…ISO dive watch testing does this as part of the requirement. 

 

I have done this with my watch builds (just started so only a few)  yes i know this is primarily rep forum and YES my reps will get the same treatment when i get them…no favouritism from me because if it cant handle this then it doesn’t deserve a spot in my collection. I like to think of it as part of my watches entrance exam….

 

 

[Rozza72 58]

I've decided that my pressure vessel 'needs working' on boy!' sooo currently it works on the basis of PUSHING air in OR working out if its capable of holding said IN. Which is not a real world approach.

My idea is now to add an additional set of pipework which will be connected to a hydraulic water pressure tester capable of >25BAR, with shut-off valves so I can isolate it from the AIR gauge and inlet. I'll also add a pressure release safety valve set to 25BAR so I don't go too mad! This will then fill the tank with water and pressurise it in a more real world test of stopping water getting in. The use of the high pressure water will negate trying to fill it to pressure with air from the hand pump via the air inlet...it makes sense in my head anyway...

anyone care to voice an opinion / better way of rigging it?