To all Camera Housing Manufacturers

[AstroDad]

If it fails then it's going to fail on the surface, so no great loss.

The contra is true - it'll fail at the bottom, where the pressure is greatest. One minute you're looking into the viewfinder, the next minute you're looking into a flooded housing. With no warning. Flex stress works that way....

If I was DAN insurance then I would insist

But since you're not....

 

[azcaddman]

there used to be a product, called Sub-Alert, that did this exact modification, to Nikonos cameras, they replaced the latch, you used a hand powered vacuum pump, and they installed 2 LED's in the viewfinder.. green = good vacuum, red.. no vacuum.

they had a 2nd product, for housings, that put a small lcd display, which displayed the internal pressure, and the vacuum pump for them was air powered (off LP inflator hose as i recall).

Barry Lipman did a review of it, as well as California diving news

 

[victor]

The contra is true - it'll fail at the bottom, where the pressure is greatest. One minute you're looking into the viewfinder, the next minute you're looking into a flooded housing. With no warning. Flex stress works that way....

Once the dimple is in then the cap is at it's strongest. The only way it can split is if the tensile strength of the metal is insufficient or repeated use has caused work hardening and a crack in the metal.

As the cost of the cap will me minimal and it will be very easy to cycle sufficiently often to learn how long it takes to work harden the material.
Divide the average number of work cycles by 4 to give a 75% safety margin and recommend replacement then.

Insurance companies recommend safety devices for cars, alarms for houses, if we had a cheap and reliable safety device to reduce the number of floods the I bet they would be on to that bandwagon quickly.

No need for you to install it, just pay the higher premiums and loose out on the remainder of your dive vacation when a dropped hair floods your camera.

 

[victor]

Maybe, maybe not. The cap would need to be flexible enough the move back and forth on the surface, but strong enough to withstand the pressure at depth. The light suction needed at the surface is nothing compared to 4 atmospheres of pressure at depth. And even then, some Ikelite housing go much deeper than that, necessitating a much stronger cap which would likely not work on the surface.

I have never tested one however I bet that a standard jamjar lid would withstand 4 atmospheres. The metal of the lid is quite thick, it's only deformed slightly to allow it to spring in and out. I am sure that the tensile strength is sufficient to withstand 5 to 6 atmospheres, thats only 100lb per square inch.

The only issue with a jamjar lid would be whether the preasure would distort the outside area where the thread is sufficiently to allow air in.

If anyone knows a friendly watch shop with a presure chamber they could test an empty jam jar for us and see where and what collapses at what preasure. Could be interesting to watch.

I would use a smaller cap, thicker outside material, an inner o-ring so that the added preasure would seal the thread from the inside of the housing.

 

[AstroDad]

Once the dimple is in then the cap is at it's strongest. The only way it can split is if the tensile strength of the metal is insufficient or repeated use has caused work hardening and a crack in the metal.

As the cost of the cap will me minimal and it will be very easy to cycle sufficiently often to learn how long it takes to work harden the material.
Divide the average number of work cycles by 4 to give a 75% safety margin and recommend replacement then.

This is not how metallurgy works.... You can't rely on empirical tests to tell you when a potential failure will occur. Due to the wide variance in temps and depths this material will be subject too, you can't reliably predict a failure due to flex stress. This is all very well documented in any (college level) materials science course. And probably why this product isn't already on the market.

No need for you to install it, just pay the higher premiums and loose out on the remainder of your dive vacation when a dropped hair floods your camera.

Pay higher premiums because I don't have this non-product installed? A dropped hair ruining my vacation? It more likely that your metal disc implodes at 60ft than a hair causing a flooded housing.... You seem rather confident in your position regarding the success of this device. Should we presume that you have a prototype you can report on?

 

[Midnight Star]

Thats an interesting thought, which reminded me of a friend working on my cars airconditioning. The problem was the a/c wasnt cooling the cab properly. He figured the o-rings were leaking so he did a reverse pressure test. He attached "something" (i'm not a mechanic) to the a/c line and put the system under a vaccum. He waited to see if the pressure changed, if it did then he knew an o-ring was leaking somewhere. It seems like it would be possible to put such a simple port, with a one way valve (allows pressure to leave, but nothing to enter), then simply get a small handpump vacuum tester made especially for camera housings. The tester would have a small ball suspended to show the current state of the vaccum. This would allow the housing, including the camera, to be tested for o-ring leakage before the dive began. Even the ability to vacuum test a few pounds psi should be enough.

-----

Mike.

 

[3ddiver]

Bonica used to offer something like this on their 35 mm Snapper cameras. It was called GOALI-Ground Operated Advanced Leakage Indicator. It used a vacuum pump to purge the camera and move a small bellows. If it stays in position for 30 minutes it is sealed. I searched and do not find this on any of their digital cameras.

 

[Web Monkey]

Buy an Ikelite case. Keep the o-ring clean and shouldn't have any problems.

They're clear and have extra room inside, so if it does leak:

• You can see if you have a leak
• You can send the camera up to the surface on a lift bag to stop the leak.

Don't buy a camera housing that includes instructions to put it in a bathtub to see if it leaks (actually on the canon housing instructions).

Terry

Stop Us Flooding our expensive toys

It would be quite easy for the manufacturers of housings to give us a system similar to the safety checks on jam jar lids.

All that is necessary is
A metal cap with the dimple similar to the top of a jam jar
A valve and small hand (bicycle) pump to create a vacuum to pop the dimple in or

 

[victor]

Buy an Ikelite case. Keep the o-ring clean and shouldn't have any problems.

They're clear and have extra room inside, so if it does leak:

• You can see if you have a leak
• You can send the camera up to the surface on a lift bag to stop the leak.

Don't buy a camera housing that includes instructions to put it in a bathtub to see if it leaks (actually on the canon housing instructions).

Terry

Touch wood so far I have never had a leak with the Nikonos or my digital, however I only have a few dives with my PT-023.
The PT-023 is huge, and clear so I could see if there was water inside the housing.

Everything I have read indicates that if you have a flood, your digital camera is a paperweight. By the time you know something has gone wrong the housing has flooded and wrecked the electronics.

I have been advised to check my housing in a deep bucket before each dive, leave submerged for about 10 to 20 minutes and check for any water in the housing. Whether it makes any difference I don't know.

One major advantage of putting a small vacuum inside the housing is that it will preload all the seals. A number of users have reported failures when their cameras were bumped in the rinse box or on entry into the water. At these times the O-rings are only under the preasure of the latches and it was assumed a sudden jar, or impact with the water allowed the o-ring to move creating the leak. The preload should stop this occuring and the dimple would give an instant verification if it had occured. While I have no personal experience of this I can see how it is a posibility.

I know that flooding is a problem, I am sure there is a cost effective solution that could be implemented. All thats needed is the will.

 

[JessH]

Hydroflex has a very simple system similar to what is being discussed here. Their housings have an air valve on them similar to the ones on tires. After sealing the housing you hook up a vacuum pump to it to create a slight vacum in the housing. The pump has a guage on it to let you know if the housing is holding a vacuum. You can also wait a little bit and then press the center of the valve, if you hear/feel air going in then it is holding a vacuum. They use this system on their 16mm housings, I would assume that they use it for others (such as their IMAX and 3D housings). Just for the record, some of those cameras are worth more than your house.

~Jess