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Steel Vertical Door
Calculating pressure required in a tube to resist outside pressure?
Ok, so I have an inflated tube that is sealing a gap between two parts (one stainless steel, one oak). On one side (the inside) the pressure is atmospheric, on the other side (the outside) there is 1m of water (so assuming 10kPa). The two parts are a door and frame to make things clearer, so the door is vertical, but the water is applying a horizontal force.
Is there a way of calculating the minimum pressure required inside the tube to prevent the water passing through?
Is it just a case of opposite and equal, ie the pressure in the tube is at least the same as the pressure due to the water?
Any suggestions much appreciated!
It seems to me as if the sealing tube between door and frame will behave very much like an air pinch valve. These tend to need an actuation pressure that's 20 to 40 psi higher for reliable restraint of the controlled fluid
Here's how air-pinch valves work
http://www.airpinch.com/index.html?page=Operation
Also remember the total force exerted by the water, is going to need supported by a lip on the edge of the door. If this force is trying to swing a door open a door, it's likely to "pop" the hinges/lock. Maybe easier to resist if it's a sliding door?
Fairly sure in naval designs they just use a strip of sealing rubber, which the door is tightened onto/pushed by water pressure. Less to go wrong then...
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