Why should you put the cabin altitude at 8000 ft or above after having a cargo fire?

Please be more specific. Walt, Matt %26amp; Jason have provided you with some good information but if you provide the aircraft in question then you may receive more specific answers.Why should you put the cabin altitude at 8000 ft or above after having a cargo fire?
Its not so much that you are setting 8000'





What you are doing is raising the internal cabin altitude so that when you decompress, the effects are not as drastic. The decompression from 5000' to FL350 is more drastic than the difference between 8000 and FL350.





Also, I hope you are talking about a cabin fire rather than a cargo fire. The cargo bins seal themselves off from the rest of the cabin anyway and Halon floods them. It snuffs the fire and prevents re-ignition. There would be no reason at all to decompress during a cargo fire.Why should you put the cabin altitude at 8000 ft or above after having a cargo fire?
Less oxygen, less fire
the low air pressure almost kills the fire making it easier to extinguish
8000ft is kind of a random number...usually what happens is a complete dump of cabin pressure selected from the cockpit. What this does is open the outflow valves in the back of the aircraft completely, allowing the air from the inside to force the poorer quality air outside. This can provide temporary exhaustation of smoke for the passengers while the pilots try to get the aircraft on the ground.
The lower air pressure probably starves the fire, making it easier to put out, or keep out.