Speed of depressurization

[Ssron]

Purely theoretical question here after watching the depressurization scene in The Martian:

 

If you had a habitat in the shape of a straight line on Mars featuring room after room with automatic doors, and there was a major breach in the exterior of one end of the habitat, how quickly would depressurization occur?

 

Would a centralized habitat computer be able to close any doors in time to avoid complete depressurization and save any humans in those rooms?

Edited March 23, 2017 by Ssron

[fiveworlds]

Gas Dynamics?? There are a few equations most have to do with pipelines such as.

Simplified gas formula

This formula is recommended for most general-use flow applications.

 

Weymouth equation

The Weymouth equation is recommended for smaller-diameter pipe (generally, 12 in. and less). It is also recommended for shorter lengths of segments ( < 20 miles) within production batteries and for branch gathering lines, medium- to high-pressure (+/–100 psig to > 1,000 psig) applications, and a high Reynolds number.

 

Panhandle equation

This equation is recommended for larger-diameter pipe (12-in. diameter and greater). It is also recommended for long runs of pipe ( > 20 miles) such as cross-country transmission pipelines and for moderate Reynolds numbers.

 

Spitzglass equation

The Spitzglass equation is recommended for low-pressure vent lines < 12 in. in diameter (ΔP < 10% of P₁).

The petroleum engineer will find that the general gas equation and the Weymouth equation are very useful. The Weymouth equation is ideal for designing branch laterals and trunk lines in field gas-gathering systems.

 

 

 

http://petrowiki.org/Pressure_drop_evaluation_along_pipelines

http://www.pipeflowcalculations.com/pipe-valve-fitting-flow/compressible-gas-flow.php

Edited March 23, 2017 by fiveworlds

[swansont]

The flow rate to the outside is going to depend on the size of the hole as well as the pressure differential (which we can probably assume is about an atmosphere). The interior flow rate will depend primarily on the size of the doors that connect different modules together; there's a vacuum pump parameter called the conductance that might apply here. A long tube restricts flow more than a hole of the same area.

[Endy0816]

There would likely be enough time as power-operated doors for ships are designed to be able to close automatically in less than a minute. Would definitely depend on the hole size though.

 

An alternative option would be to only have doors open while you are passing through. Piping connecting the compartments would be easier to isolate.

[John Cuthber]

In the limit, the depressurisation can't significantly xceed the speed of sound.

The same thing limits the speed of compressed air guns.

[Ssron]

I didn't frame my question properly - I meant to say that in the hypothetical scenario each room was pressurized individually and the hole is about 2m x 1m. I screwed the question up.

 

If anyone cares to take another shot -- otherwise, thank you to all who responded. You're classy, here.

Edited March 24, 2017 by Ssron

[imatfaal]

I didn't frame my question properly - I meant to say that in the hypothetical scenario each room was pressurized individually and the hole is about 2m x 1m. I screwed the question up.

 

If anyone cares to take another shot -- otherwise, thank you to all who responded. You're classy, here.

 

Frankly any architect that didnt design a few doors that failed safe in event of a pressure drop should be shot - it is an obvious design feature. Frankly a standard door resting open on a gentle hinge that is able to swing shut would slam shut with the wind - it would then be held tight shut by the pressure. If every junction between rooms was a small (10cm) space with a door opening into the room on each side - where ever the pressure leak was one of the two doors would slam shut and be held shut. The room with the leak would be isolated by the wind rushing from the two adjacent rooms and slamming the doors into that room