the kegs wont' go flat if they are actually kept sealed. if you already got the beer carb'd up fully, and the temperature doesn't change...it stays at equilibrium. the beer is 15psi, the headspace is 15psi...so as long as you don't dispense beer or have a leak...it stays 15psi.
Primary: English Mild
On tap: Pale Ale, Lancelot's Wheat, English Brown Ale, Steam Beer, HoovNuts IPA
Bottled: MOAM, Braggot, Raspberry Melomel, Merlot, Apfelwein, Pyment, Sweet mead, Cabernet
Gal in 2009: 27, Gal in 2010: 34, Gal in 2011: 13, Gal in 2012: 10