Make sure you video tape it and show it on MythBuster on the Discovery Channel. They are use to blowing up things!
jk
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Build a Pressure Tester for 30 Dollars
- Thread starter mucrewbtp
- Start date
Make sure you video tape it and show it on MythBuster on the Discovery Channel. They are use to blowing up things!
jk
Can you clarify "far more pressure"? From where? Do you mean the pressure of my arm slamming into the water?
And when you say that being labeled as OK for 100m, am I correct that that you mean ignore the number and just go with the conventional wisdom of don't dive with it?
watch doc not taking a jab at you just the physics!
Okay when you put the watch into the water lets say at 100m then the watch will be fine as that is the watch rating. However as soon as you move the watch even a little the movement increases the pressure on the watch as the water is moving over the watch.... so it can be used at the 100m just not moved at all. As in this is the pressure the watch can take when NOTHING moves.
So in a swimming pool at lets say 10m the pressure could be considerably more as you are swimming and putting a large amount more stress on the watch!
basically follow these rules:
watch rating - use
WR - splashproof only
WR 30 - washing hands
WR 50m - shower safe
WR 100m- swimming
WR 200m - scuba (not saturation)
WR DIVER's 200m+ all diving.
hope this helps =)
Okay when you put the watch into the water lets say at 100m then the watch will be fine as that is the watch rating. However as soon as you move the watch even a little the movement increases the pressure on the watch as the water is moving over the watch.... so it can be used at the 100m just not moved at all. As in this is the pressure the watch can take when NOTHING moves.
So in a swimming pool at lets say 10m the pressure could be considerably more as you are swimming and putting a large amount more stress on the watch!
basically follow these rules:
watch rating - use
WR - splashproof only
WR 30 - washing hands
WR 50m - shower safe
WR 100m- swimming
WR 200m - scuba (not saturation)
WR DIVER's 200m+ all diving.
hope this helps =)
No offense taken, I appreciate the clarification. Last time I did physics was...a LONG time ago.
Last time I got in a pool and didn't move was...never.
Last time I went to 10 meters was...never.
Last time I got in a pool and didn't move was...never.
Last time I went to 10 meters was...never.
Lol well the Biochemichal engineers amongst us luckily have a very small amount of physics still.
The issue is getting the point across..... erm how to expain....
int he shower the pressure of the water hitting the watch from such a height is quite high (no idea what it is but you can feel the impact of the water) this pressure happens even when the watch is above the water at 0m .....
the same principle applies underwater - the water when you swim or make a wrist flick will at certain points have a much higher pressure than the static pressure.
This is why we have these silly ratings.
generally I'll happily swim with a 6atm pressure tested rep.... but a 10 atm gen Im nervous about!
The issue is getting the point across..... erm how to expain....
int he shower the pressure of the water hitting the watch from such a height is quite high (no idea what it is but you can feel the impact of the water) this pressure happens even when the watch is above the water at 0m .....
the same principle applies underwater - the water when you swim or make a wrist flick will at certain points have a much higher pressure than the static pressure.
This is why we have these silly ratings.
generally I'll happily swim with a 6atm pressure tested rep.... but a 10 atm gen Im nervous about!
tested my zodiac, but I think my bike pump's valve failed. Was pumping the bottle, then the handle shot up, and I couldn't pump any more. Got it to about 38 lbs, there was a slow bubble that came out near the bezel at 11:00 on the watch. Not a fast stream. Might use my electric pump to get it a bit higher. Will do that in the garage in case the bottle "fails" (which I believe is the term that engineers use for "explodes").
if the bottle fails it will really hurt you
I got to some respectable figures before the seals on the bottle fails... almost a safety feature =)
I got to some respectable figures before the seals on the bottle fails... almost a safety feature =)
- 30/3/08
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No, a vacuum tester draws a vacuum and measures deflection of the crystal but a pressure tester works exactly the same way this one does. Problem with a vacuum tester is you there is a leak but have NFI where. The idea is that you never let the pressure hit zero with the watch in the water. That way if there is a leak the pressure will still be positive in the watch.
Col.
Col.
this method I fell is the better one as its a really cool piece of physics....
basically as trail said R2 the pressure when the watch is in air is increased in the tester lets say to 5 atm. Water cannot be compressed as its a liquid. So once the air is high inside the watch is placed in water... as you gently release the pressure the pressure from the bottle goes out and the pressure (assuming the watch leaked to let air in) is higher so the air pressure moves from the watch into the bottle as bubbles....
hope that makes sense!
basically as trail said R2 the pressure when the watch is in air is increased in the tester lets say to 5 atm. Water cannot be compressed as its a liquid. So once the air is high inside the watch is placed in water... as you gently release the pressure the pressure from the bottle goes out and the pressure (assuming the watch leaked to let air in) is higher so the air pressure moves from the watch into the bottle as bubbles....
hope that makes sense!
- 15/4/07
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Ok, now I want to build one. LOL My thoughts are to buy a 3/16" Thick Polycarb tube and then sandwich it between two thick metal plates. My compressor will only go to 125PSI. So if this figure is correct 14.695PSI = 1 ATM I should be able to get 125PSI/14.696 = 8.5ATM 10.3 Meters X 8.5 ATM is 87.55 Meters depth.
125PSI would be 87.55 Meters or 262.65 Feet. I think for snorkling the recommend a minimum of 100M and free diving 200M is that right?
That should be enough for me I would guess.
125PSI would be 87.55 Meters or 262.65 Feet. I think for snorkling the recommend a minimum of 100M and free diving 200M is that right?
That should be enough for me I would guess.
Hmm that would work in theory but laminate the insides of the tube and outside then if it explodes the shrapnel won't go everywhere....
I can get to 300psi at work but the bottle seal fails before that....
I can get to 300psi at work but the bottle seal fails before that....
Gentlemen,
Long story short, the "wet" pressure testing is relevant and harmless ( if conducted properly) ONLY in case the leak of the case is VERY fine.
If the leak is important - like having a hole drilled into the case ( to make an extreme analogy), regardless of the method and/or apparatus, the moment the watch is submerged and the outside pressure released, there will be a huge air bubble coming out and a lot of liquid going inside the watch.
This is why the professionals, before anything, are doing a "dry" pressure test: it uses only vacuum and they are looking for the crystal slightly changing shape. At least this is what I understood from a description I have seen somewhere..
The next best thing being to remove everything from the case before doing the wet test.
Long story short, the "wet" pressure testing is relevant and harmless ( if conducted properly) ONLY in case the leak of the case is VERY fine.
If the leak is important - like having a hole drilled into the case ( to make an extreme analogy), regardless of the method and/or apparatus, the moment the watch is submerged and the outside pressure released, there will be a huge air bubble coming out and a lot of liquid going inside the watch.
This is why the professionals, before anything, are doing a "dry" pressure test: it uses only vacuum and they are looking for the crystal slightly changing shape. At least this is what I understood from a description I have seen somewhere..
The next best thing being to remove everything from the case before doing the wet test.
personally the wet test works better. I put an SOCH into the tank at 5atm with NO gasket as a test.... screwed it in.... bubbles galore and literally the amount of water let in was TINY like a drop....
Hi. I know it's an old thread but as a noob I was going over it. Very nice idea for the pressure tester, might go over it
You have your numbers a little mixed up on the table, by a factor of 10.
So , in a depth of 330 feet, the pressure will be 149 psi or 10.1 atm
erm I'm not sure.... I believe 1bar is approx 1atm which is approx 10m
btw my nalgene exploded at 7 bar
sorry you were using feet so 10 bar = 100m or 330 ft yes
btw my nalgene exploded at 7 bar
sorry you were using feet so 10 bar = 100m or 330 ft yes
This I´ll have to try!
I´ve always wondered if my watches were waterproof enough to swim with.
Getting the answer to that, and the fact that I might get to blow somethings into pieces in the process is tempting!
I´ve always wondered if my watches were waterproof enough to swim with.
Getting the answer to that, and the fact that I might get to blow somethings into pieces in the process is tempting!
- 30/3/08
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Lerolv: yes that is pretty much it. The watch goes into a chamber and a vacuum is applied to the chamber. A device much like a machinist's or engineer's dial indicator gauge then measures the minute deflection of the crystal, no deflection means no pressure differential so there must be a leak. The problem there is that a vacuum test does not show you where the leak is and is usually used as a precursor to a water test to ensure that there is no major issues like a crystal that is going to pop or for a quick test after a battery change. A vacuum tester is a handy piece of kit but IMO does not replace a water tester.
As for water entering a watch during a water test, I have had crystals pop during testing and you still only get a few ml of water in the watch. At any rate, you should be using distilled water and a drowning in that won't hurt a MVT as long as you dry it out immediately.
To be sure about the crystal before you do an in water test do a reasonably rapid decompression with the watch still above the water. If the crystal is going to pop it will then and not under water.
R2: I'll measure the acrylic on my tester for you to get the correct thickness tubing.
Epimetheus: You don't want it to blow mate
The polycarbonate those bottles are made of shatters in the worst way, lots of sharp pieces so eye protection with a home made rig would be a good idea.
Col.
As for water entering a watch during a water test, I have had crystals pop during testing and you still only get a few ml of water in the watch. At any rate, you should be using distilled water and a drowning in that won't hurt a MVT as long as you dry it out immediately.
To be sure about the crystal before you do an in water test do a reasonably rapid decompression with the watch still above the water. If the crystal is going to pop it will then and not under water.
R2: I'll measure the acrylic on my tester for you to get the correct thickness tubing.
Epimetheus: You don't want it to blow mate
The polycarbonate those bottles are made of shatters in the worst way, lots of sharp pieces so eye protection with a home made rig would be a good idea.
Col.