R404 required for cascade system

Good day ,

my doubts and questions are the following:
How many bottles of R404 need to refill an empty cascade system on fully ref lpg tanker for ethylene?
The system is standard, with screw compressor. Size of ship’s tank are about 7000 cbm

Thanks in advance

How long is a piece of string?

How deep is the draft of a ship?

How big are the bottles?

Bottles normally contain 45kg of R404.
The ship is 14000DWT fully ref.

Assuming this is not a troll - RTFM.