Flooding camera housing with gaseous nitrogen

Has anyone ever considered flooding a camera housing with gaseous nitrogen?

The idea is to replace the ambient air that has moisture and will compress.

Since GN is very dry, I would think this would cure fogging.

Since GN does not compress well, it would serve to strengthen the housing.

I'm not quite sure what you are talking about. Are you talking about pressuring the housing with N2, or just blowing N2 into it before closing at ambient pressure? There have been several threads that have discussed pressurized housings, but the general consensus is that although it might work, the housings are plenty strong, and if you pressurize to less than your ambient pressure at depth, the o-rings will move in the their grooves as the ambient pressure begins to exceed the internal pressure. This could cause a poor seal.

Getting rid of the moisture by flushing with a dry gas is a fine idea, but desiccant packs are cheap and effective.

I am confused about your comment that N2 does not compress well. N2 is very close to an ideal gas, it compresses the same as all other ideal gases, that is to say it obeys Boyles law; its volume is inversely proportional to pressure (at constant temperature).

The camera itself can also contain a great deal of moisture. I agree that closing the housing in a cool dry environment is the best - and use dessicant packs to absorb the remaining water vapor.

Cheers

James

My intent is to flood the case and purge the case of mixed gases. The remaining volume would be almost all gaseous nitrogen. I agree that there would be little benefit to increasing the pressure inside the case. My idea does include any pressure increase.

Some have said that I would need to add a in port and outlet to the housing to induct the gas into the housing . I agree that this only adds another weakness.

If you want to 'purge' the case of mixed gas, you'd need an inlet and and outlet to allow a blow-thru, then close both off.

But still, I don't see the point (and I'm one of the ones who asked the endlessly recurring 'why not pressurize a case with depth change like a drysuit' questions ... in retrospect not a great idea. You perhaps benefit from needing less 'structural strength' from the housing to withstand outside pressure, but that outside pressure is also what keeps o-rings seated. That and the camera might conceivably have components that don't operate at high ambient pressures...imploding a sealed lens structure would be bad news! ). I guess you're getting rid humidity, but so is closing the case inside an air conditioned and thus low-humidity room. I don't know of any benefit to getting rid of the 'mixed gases' to optics designed to work in an atmosphere of those 'mixed gases'.

If you want to 'purge' the case of mixed gas, you'd need an inlet and and outlet to allow a blow-thru, then close both off.

 

But still, I don't see the point (and I'm one of the ones who asked the endlessly recurring 'why not pressurize a case with depth change like a drysuit' questions ... in retrospect not a great idea. You perhaps benefit from needing less 'structural strength' from the housing to withstand outside pressure, but that outside pressure is also what keeps o-rings seated. That and the camera might conceivably have components that don't operate at high ambient pressures...imploding a sealed lens structure would be bad news! ). I guess you're getting rid humidity, but so is closing the case inside an air conditioned and thus low-humidity room. I don't know of any benefit to getting rid of the 'mixed gases' to optics designed to work in an atmosphere of those 'mixed gases'.

It's a lot of fun bringing your rig out on the dive deck of a liveaboard straight from the AC. The outside of the houding gets all foggy, and the divemaster will invariably scold you, saying you should keep your rig outside so it wont fog. Then you just dip it in the water and show no fogging at all.