I picked up a keg of Sierra Nevada ruthless rye and I don't have a kegerator set up yet. I've got the fridge space to keep the keg in, but I'll be using a party tap for the time being. If I untap the keg when I'm done using it, how long can I expect the beer to stay good? I understand that by using a party tap I'll be pumping air in to the keg so it's going to drastically reduce the life of the beer as far as oxidation and going flat, but what kind of time frame can I expect? Days, weeks? Thanks for the help.