The inflatable PFD makers recommend cartridges and bobbins be replaced annually, but I inspect and not necessarily replace.
You can buy replacement bobbins and green pins in bulk at a price that doesn't require a loan, but when you get "branded" CO2 cartridges from the PFD makers, that are packaged with a bobbin and pin it's in the range of $20-35! IMHO that's ridiculous. I buy my cartridges in bulk or as replacement for other things (such as bike tire inflaters) and they are much more reasonably priced for the same gram capacity.
As for inspection: A pin or bobbin that needs replacement is quite obvious just by looking at it. The cartridge can be weighed on a food scale that measures fractions of a gram. Every cartridge is stamped with either the minimum weight when full, or the actual weight when full. If it weighs less than that it should be replaced. It should be replaced if it has excessive surface corrosion or a partial dent where the trigger pin would pierce.
The other thing I do is add SOS lights and whistles to every vest, and open it up to inspect the fabric (especially near edges and folds). If I see anything that raises a question I do a test inflation by mouth and see if the vest loses air after several hours (I have heard it's not a good idea to inflate by cartridge except when needed, because the cartridge causes higher pressures and stress).
So what am I missing?
You can buy replacement bobbins and green pins in bulk at a price that doesn't require a loan, but when you get "branded" CO2 cartridges from the PFD makers, that are packaged with a bobbin and pin it's in the range of $20-35! IMHO that's ridiculous. I buy my cartridges in bulk or as replacement for other things (such as bike tire inflaters) and they are much more reasonably priced for the same gram capacity.
As for inspection: A pin or bobbin that needs replacement is quite obvious just by looking at it. The cartridge can be weighed on a food scale that measures fractions of a gram. Every cartridge is stamped with either the minimum weight when full, or the actual weight when full. If it weighs less than that it should be replaced. It should be replaced if it has excessive surface corrosion or a partial dent where the trigger pin would pierce.
The other thing I do is add SOS lights and whistles to every vest, and open it up to inspect the fabric (especially near edges and folds). If I see anything that raises a question I do a test inflation by mouth and see if the vest loses air after several hours (I have heard it's not a good idea to inflate by cartridge except when needed, because the cartridge causes higher pressures and stress).
So what am I missing?