Each year one should test personal floatation devices (PFD) to make sure they will keep you afloat in an emergency. It's simple to test, just jump in the water. The PFD you use should be designed to keep you high in the water with your head raised. Larger adults need devices rated for more buoyancy than smaller adults and children.
If your PDF is an inflatable design, it must be recharged following each test. If the PFD is automatic, it contains a pill that dissolves in water and allows the mechanism to discharge air into the inflatable bladder. Both the pill and air cartridge must be replaced. Manual inflatable PFDs have only the cartridge to replace.
Beth volunteered to test her PFD in a small lake that her family has gone to for decades of summers, Stony Lake. Her brother, Bob, took her out in his boat and Beth jumped in the lake. Following are pictures of Beth wearing an inflatable PFD before and after immersion.