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Comment by idoco | Hacker News Reader

I disagree, and I can tell you from first hand experience that this is how a tank NBC protection system works - The crew cabin is pressurized with high flow of filtered air.

http://elbitsystems.com/Elbitmain/files/Kinetics_NBC-CBRN.pd...

[Edit - adding this] I can also say, that this creates a very uncomfortable sensation in your ears while the cabin is being over-pressurized (about 2 minutes)

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Yes but it's the positive pressure that's important, not the high flow rate. You may need a high flow rate to maintain whatever pressure you're aiming for but the thing that's keeping out any contaminants is the fact that every tiny leak is only going to have air going from the inside to the outside other than the filter itself. If you've got a big room with only one tightly sealed door, you don't need a lot of flow to keep out any contaminants.

Thing is you can't maintain positive pressure in a battletank without high flow rate. Tanks are not fully sealed.

Are they not? Many tanks can traverse rivers driving on bottom with special attachment to the main hatch. Leopard 2 does that.

As this sounded intriguing, here's a video I've found of this: https://www.youtube.com/watch?v=C26rJiOnKLk.

It appears the tank commander needs to guide the driver on directions, though...

It also appears that the tank is not waterproof, as you can see quite substantial leaking at around 30 seconds in.

Correct. The commentary says it's equipped with 2 water pumps to remove whatever leaks through.

I guess that's German engineering for less-than-perfect road and maintenance conditions. I like the redundancy too!

Learn something everyday, quite surprising that solution with pumps was even considered and that it actually safe for crew and tank internal systems.

That's the most practical solution. A tank is not a space capsule, sealing a multi-ton rotating turret is unrealistic.

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