Smoke simulation times

Hi all!

I looked for this topic but couldn’t find one, so I’m sorry if this has been discussed before. I have Blender2.6x and was wondering if it’s possible to increase the smoke duration past 250 frames. I’ve tried increasing animation and bake end times but, no matter what I try, I can’t get the damned flow object to emit smoke for more than ten seconds. Is this ten-second limit just how Blender operates, or is there a setting somewhere that I’m missing? I’ve watched Andrew Price’s smoke tutorial, and his post-apocolypse scene lasted longer than ten seconds, so I’m assuming he changed something to allow the longer simulation time…