The following is a list of common BCD terminology.
The power inflator is a low-pressure direct feed of gas from the first-stage regulator. You press a button to inflate the BCD and deflate with another button. Some power inflator systems have their own separate air source (demand valve) that might also serve as a backup air supply.
When oral inflating, inflate the BCD by pressing a button. Then physically blow into the power inflator’s small mouthpiece (either system works).
The dump valve is used to let air out of the BCD. It is located on the left shoulder where the inflator hose is and can be found at the bottom of the bladder. The valves are activated by pulling a cord. Some BCDs have two or more dump valves, and they can be in varying locations. These are quick and easy to use so that you can dump air to descend or dump air in case you are ascending too fast.
Pressure Release Valve
The pressure release valve is there to keep the BCD from bursting due to over inflation, which could happen during a rapid ascent. The pressure release valve and the dump valve are often combined into a single system.
The waistband/cummerbund is a fairly thick waistband that is part of the abdominal harness strap keeping the BCD in place.
Some BCDs have pockets for weights in various locations to help with body trim. The main sections for the weights have a quick release system that can easily be pulled free for positive buoyancy.
Quick-Release Shoulder Straps
The quick-release shoulder straps allow the diver to get easily in and out of the BCD.
Generally located in the front, accessory rings allow the diver to clip on additional items, such as a camera or flashlight.
Among the main purposes of any BCD is providing lift. Lift depends on how much air that the bladder of the BCD can hold. Manufacturers provide these details on the BCD.