Can this be a possible cause of flooding?

I have had two floods over a period of time. On both days the outside weather was hot and the water cold. Can the suction created by the contracting air on the inside contributed to these floodings?

It was a point and shoot housing, so not as sturdy as an Aluminium one.

Hi there!

I doubt it can be the cause of air temperature differences... I have assembled my gear (Ikelite housing) inside a car where ambient temp. was about 27 C. and then jumped in water with temp. 1 C - no problems. Changes in ambient pressures versus the pressure inside the housing while diving should be much more greater than the effect caused by air cooling off when entering the cold water. Maybe someone with more experince about the subject will join in..!?

Karel

I was looking at how much suction is created when i put warm food into an air tight container:)

But can argue with your example:)

I went from between 35-37 degrees to 11-10 degrees.

The pressure change from taking a gaws filled sealed object from 37C to 10C is slightly less than 9%, assuming the gas acts as an ideal gas in thermodynamics - which is a good assumption for air. Thus the inside pressure drops to 0.91 atm in the container.

If you dive to approx 10 meters, the pressure changes from 1 atm to 2 atm. If you dive to about 30 meters, the pressure rises to 4 atm outside your container.

On your hot day, the pressure difference is 4-0.91 = 3.1 atm

On your ave day, the pressure difference is 4-1.0 = 3.0 atm.

Thus it is unlikely your floods were related to pressure differences.

But perhaps your actions were different on the hot days. Perhaps focus on proper sealing, handling, elimination of particles/hair on the O-ring, etc.

When going into cold water, you likely have on protection that would make you very hot prior to entry on such a hot day. Perhaps the relationship you search for is related to the heat but not the pressure differences.

hope that helps,

Dave

Hi Dave, that sure was a cool answer:)

I you don't mind, could you forward me the equations for how this calculation is done.

I fitted the camera the night before.

Afterwards I could not find any hair/particles on the o-ring.

In another thread recently, i read that these "cheap" plastic housings do have a limited life span, maybe that also played a role.

Anyway time to upgrade:)

The full equation is PV=nRT for ideal gases but you have to use matching units.

P=pressure (atmopsheres)

V=volume (liters)

n=moles (related to the number of molecules)

R = ideal gas constant

T=temperature (degrees Kelvin)

we have a comparison of 2 of conditions and the container is sealed:

Initial PV/nRT = final PV/nRT

we can reduce it to these 2 equations since n and R are constant. No gas leaves or enters after sealing. R is always a constant.

PV/T = PV/T Where the values on one side are where you start and the value on the other is in the cold water.

And this reduces further since the volume is identical in your container. We are ignoring the trace shrinkage from getting cold. Its not enough to matter for this.

P/T = P/T

P initial is 1 atm

T initial is 37 C plus 273 = 310K (kelvin - a unit of temp measurement that matches the equation)

P final is what we want to know = X

T final is 10C plus 273

So you have: (1)/310 = X/283

solve for X, 283/310 = 0.91 atm

So the pressure drops from 1.0 atm to 0.91 atm.

When you dive, there is about 1 atm of pressure for each 33 ft or 10 meters of seawater.

And there is one atm pressure at the surface

So at 30 meters, you have 1 atm at the surface plus 3 for the depth = 4.

The 0.09 atm change inside the container is not likely to make a difference.

I have used these cheap housings for yrs and not had a leak ever - except when I did not seal it correctly once. But I change cameras every few yrs and do not get to dive that often so they do not get that much work out.

Hope the equations were what you were looking for.

By the way, I am a nerd for knowing and you could be one for wanting to know.

IMHO,

Dave

...okey - this sounds more like a discussion in NASA etc. LOL

Way to go Dave

...okey - this sounds more like a discussion in NASA etc. LOL

Way to go Dave

Actually, my and and uncle used to design missle guidance systems for NASA for the moon lauches yrs ago.

Then she switched to writing romance novels and made a bundle. Go figure!

Maybe I should switch to writing.

Aqua-soul,

You said you set up your rig the night before. The cases are set up for outside pressure pushing in, not the reverse.

If a case was sealed in cooler temps, then exposed to really hot temps - sealed car with sun, sitting in sun on dive boat, etc. it will have slight positive pressure inside the case, not unlike the calc's above in reverse. This might displace an O-ring and cause you trouble. But this is certainly speculating. The pressure difference is still slight and not certain to cause trouble but the temp difference would likely cause fogging inside the case while diving.

This reverse pressure effect is why its important not to have these sealed when air traveling. The pressure differences are much higher than these temp effects and could push out an O-ring on one of the buttons - just where we would not find it in time.