Locate your tank and regulator

Make sure your tank is all the way off

Loosen with wrench

Undo it the rest of the way with your fingers

Remove regulator carefully

Screw the nozzle guard back on the old tank

Remove nozzle guard from fresh tank

Screw on the regulator finger tight

Tighten with wrench

Make sure the regulator is completely off

Turn on the tank. It will be tight at first

You will hear a little click which will indicate that oxygen has begun flowing. Turning should be easier now.

Your capacity regulator will indicate how full the tank is