The inflatable type PFD uses what as the inflating agent?

The inflatable type personal flotation device (PFD) primarily uses carbon dioxide as its inflating agent. This choice is correct because carbon dioxide can be stored in a compressed form within a small cylinder, allowing for a compact design that can effectively inflate the PFD upon activation. When the device is deployed, a mechanism punctures the CO2 cylinder, releasing the gas and rapidly filling the PFD to provide buoyancy.

Carbon dioxide is chosen because it is non-flammable, readily available, and its quick release allows for immediate inflation, which is critical in emergency situations. Furthermore, while air can naturally fill the PFD over time, it would not provide the instant buoyancy needed in emergencies. Nitrogen and helium, while also gases, are not practical for this application due to reasons like availability and performance characteristics. Consequently, carbon dioxide remains the standard inflating agent for inflatable type PFDs, ensuring safety and reliability for users on the water.