Oh yes. But that is a procudure done when before you rack your beer to the keg. First sanitize your keg, hook it up to gas, open the valve for a couple seconds then close it. Now vent the keg. Repeat this a few times. This will purge the air from the keg and now CO2 will form a protective layer at the bottome.
Look at this pic. The mist in the keg is CO2 from purging.