Poor Man's pressure test chamber: Does this sound feasable?
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# Thread: Poor Man's pressure test chamber: Does this sound feasable?

1. ## Poor Man's pressure test chamber: Does this sound feasable?

First, let's make sure my math is right:

1 ATM = 10m = 14.4 psi, right?

I have a big air compressor in the garage. Assuming I don't need to test to depths of 200M (I just want to know if some of my homages can be worn in the pool) could I hook it up to, say, a length of pipe with a cap on each end filled with water? Shouldn't be too hard to drill and tap a hole for a brass air fitting or maybe even a Schrader valve.

Then I stick my watch case in the pipe, screw it shut, and introduce 60psi of air pressure to the pipe/chamber (gradually). Leave it for half an hour, then take the watch case out and see if any water got in. If the inside of the case is dry, then I can safely assume that the watch can take 4ATM of real pressure (not 3 "Marketing Atmospheres" of pressure that most fashion watches claim) and can probably survive a day at the pool/beach, right?

Everybody shoot holes in this until I a) am able to build a good pressure test chamber or b) say "eff it" and buy a real pressure test setup

2. ## Re: Poor Man's pressure test chamber: Does this sound feasable?

That would work.

But you could also build one that could check an assembled watch, without getting anything wet. (This would be like a professional pressure tester.)

To do this, you would need a clear container or pipe. The idea is to fill the container half way with water, and pressurize it while keeping the watch above the water. You then lower the watch into the water, while releasing the pressure from the container.

If the watch has leaks, they will allow air into the case when it's under pressure. Then, when the pressure is lowered (while the watch is under water) that air will escape from the case through those same leaks. This will appear as bubbles streaming from the case.

If you see bubbles, you can simply remove the watch from the water, and everything inside should be dry (remember, the pressure was higher inside the case, which does not allow water to leak into the the watch).

One arrangement to do this is to use a Nalgene water bottle, with a Schrader valve mounted (I found this suggestion on another forum). Here is my version:

The idea with this one would be to fill halfway with water, and hang the watch from a hook glued to the top of the bottle. After the pressure has been introduced, just invert the bottle, and look for bubbles.

Of course, anything involving high pressure has the potential to be dangerous or fatal, so proceed at your own risk. I know that people have pressurized these to over 5 ATM without incident. However, I'm chicken to put more than about 3 ATM in mine.

In fact, it makes me so nervous that I broke down and ordered a copy of the Bergeon tester (for less than \$300).

3. ## Re: Poor Man's pressure test chamber: Does this sound feasable?

Wow that's way simpler than what I had in mind. And I don't have to worry about screwing it up when I put the guts back in the case. I guess 3ATM (about 45psi) is enough to know that I can go swimming with the watch on.

4. ## Re: Poor Man's pressure test chamber: Does this sound feasable?

If you want to try this, a couple of notes:

Go with a Nalgene bottle only...They are very substantially made, have a large mouth opening, and are the only one's that I've seen used in this manner.

Also, you will need to re-tighten the lid one or more times as you pressurize the bottle.

5. ## Re: Poor Man's pressure test chamber: Does this sound feasable?

I've heard stories about Nalgene bottles :D

A friend of mine works at REI and told me a story about how someone left a smoothie or something fermenting in one on top of the break room fridge for several weeks until it exploded violently, lodging the lid in an acoustic ceiling tile.

So as long as I don't pass the "explode violently" threshold, the Nalgene should be capable of containing a good amount of pressure.

6. ## Re: Poor Man's pressure test chamber: Does this sound feasable?

The Nalgene bottle is a sensational idea! I've been toying with using SCH40 PVC pipe that is readily available (should be good to - gulp - 240pis, IIRC), but it's SOOO much more fun to watch the critter squirm rather than waiting to check the results.

I especially like the process of pressurizing first and checking for bubbles vs. checking for water inside after the fact. Quality tech!

FWIW, Mythbusters did some sort of rocket test using 2L soda bottles, and put a HUGE amount of pressure in to them. They did manage to make bottles fail, and they did so in spectacular fashion, but befor they did they balooned up to probably 2x their normal size. Now this says nothing about the ability of the threads in the cap to retain said cap, so that's almost certainly the weak link in the Nalgene Pressure Tester system.

Now I've got ONE MORE THING to go spend money on... Argh!

Clair

7. ## Re: Poor Man's pressure test chamber: Does this sound feasable?

Maybe zip-ties would be a reasonable precaution to prevent the lid becoming a projectile in the case of a catastrophic failure...

And maybe I should be working on my final paper instead of brainstorming new toys...

8. ## Re: Poor Man's pressure test chamber: Does this sound feasable?

There's a pretty interesting thread here: http://www.tz-uk.com/forum/viewtopic...st=0&sk=t&sd=a
This is obviously a heavy duty homemade tester.
He's a WUS member also.
He could maybe offer some tips?

9. ## Re: Poor Man's pressure test chamber: Does this sound feasable?

Originally Posted by Tragic
There's a pretty interesting thread here: http://www.tz-uk.com/forum/viewtopic...st=0&sk=t&sd=a
This is obviously a heavy duty homemade tester.
He's a WUS member also.
He could maybe offer some tips?
That's *way* heavier-duty than I'll ever need lol.

And someone over there called WUS a bunch of wankers

10. ## Re: Poor Man's pressure test chamber: Does this sound feasable?

great great great

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