[hopfenundmalz]

When I dry hop;
I purge a keg by filling it with sanitizer and then pushing the sanitizer out with CO2,
Open the keg and drop in the dry hops,
Attach the keg "beer in" connection to my fermenter,
Attach a tube to the "gas in" connection and run it into a container of water,
Once fermentation has reached the target, I do a closed transfer from the fermenter to the keg.

My assumption is that the fermentation will (and does) fill the keg with CO2 and hopefully purge out the O2 that was admitted by opening the keg to place the hops and the CO2 that is contained in the hops themselves. I don't have any data to back this up but it seems logical and doesn't take much time to set up. I bag my hops and use a Clear Beer floating dip tube.

Fermentation produces many volumes of CO2. This should work great. The only drawback is the planing involved. 

I might try this soon.

[EnkAMania]

When I dry hop;
I purge a keg by filling it with sanitizer and then pushing the sanitizer out with CO2,
Open the keg and drop in the dry hops,
Attach the keg "beer in" connection to my fermenter,
Attach a tube to the "gas in" connection and run it into a container of water,
Once fermentation has reached the target, I do a closed transfer from the fermenter to the keg.

My assumption is that the fermentation will (and does) fill the keg with CO2 and hopefully purge out the O2 that was admitted by opening the keg to place the hops and the CO2 that is contained in the hops themselves. I don't have any data to back this up but it seems logical and doesn't take much time to set up. I bag my hops and use a Clear Beer floating dip tube.

Fermentation produces many volumes of CO2. This should work great. The only drawback is the planing involved. 

I might try this soon.

You could use a spunding valve to capture the CO2 and carbonate the beer.  (Unless I'm missing something on this technique.)

[mainebrewer]

When I dry hop;
I purge a keg by filling it with sanitizer and then pushing the sanitizer out with CO2,
Open the keg and drop in the dry hops,
Attach the keg "beer in" connection to my fermenter,
Attach a tube to the "gas in" connection and run it into a container of water,
Once fermentation has reached the target, I do a closed transfer from the fermenter to the keg.

My assumption is that the fermentation will (and does) fill the keg with CO2 and hopefully purge out the O2 that was admitted by opening the keg to place the hops and the CO2 that is contained in the hops themselves. I don't have any data to back this up but it seems logical and doesn't take much time to set up. I bag my hops and use a Clear Beer floating dip tube.

Fermentation produces many volumes of CO2. This should work great. The only drawback is the planing involved. 

I might try this soon.

You could use a spunding valve to capture the CO2 and carbonate the beer.  (Unless I'm missing something on this technique.)

This suggestion just takes advantage of all the CO2 that the fermenter puts out to finish purging a keg. I do transfer the beer to the serving keg with 3-4 points remaining and, when finished, the beer is fully carbonated. A spunding valve is helpful in reducing the chance of over carbing the beer.