I'm hesitant to mention this, because most of the equipment you're referencing is low-pressure equipment, and I don't want anyone to misapply this and fail a tank. This method of inerting a vessel is much more efficient (uses a lot less N2) but you must be very careful and utilize the necessary safeguards when applying this to low-pressure equipment. I'm referring to the procedure of sequentially pressurizing and depressurizing the equipment. That will purge out the O2 more quickly, and with less N2 usage, as compared to a continuous purge. Just be sure, especially when doing this to low-pressure equipment, that you have reliable protection against excessive N2 pressure for the vessels being purged.