@curiouskitty Yes, at max setting Rov 6 does not last that long. And the max setting (it is pulse flow) is barely equivalent to 2L continuous flow.
Definitely you want to look into a generator and know what kind of backup you have. I lived in Southwest Florida at the time of Irma, and I remember having to evacuate. When I returned, no damage but without electricity (and cable TV!) for days. And the long lines at the gas stations - people getting gas for generators. Tell your power company and fire dept you are on oxygen.