Mr Selfish,
This old chestnut.........fixed, heavyweight, pan, lightweight etc etc......
It is confusing with so many variations offered by different, and within, manufacturers.
As usual identifying the system you have fitted and ensuring you have the correct Service Instruction (Bell lingo) is half the battle. Add to that the various PMA kits for firing mechanisms - explosive squib, electrical valve, hypodermic needle etc etc...... (Your kinda getting the drift by now!)
Needless to say, as a general rule, at some time, an installed floatation system does have to be "fired" from the activation method. This of course tests the whole system not just the bags which generally are manually inflated during (typical) 180 day checks.
Some operators are loath to test systems by "firing". This is perhaps understandable when some of the refurbishment kits for explosive squibs are big $$$, however many a defective system has been found out by conducting this mandatory check so go figure the logic of some
Do your research, knowledge is power.