The o-rings on a scuba tank exist to create an airtight seal between the scuba tank valve and the first stage of a scuba regulator. They serve a similar function to gaskets. Without these o-rings, tiny spaces would exist, through which air would escape.
Composition and Description
Scuba tank o-rings circular black rubber rings that look like the letter "o." Typically, they are about 3/4 of a centimeter to two centimeters in diameter and are soft and pliable.
O-rings are simple and inexpensive to maintain. Typically, a diver will apply a thin coat of silicon-based lubricant after every few uses to prevent cracks from forming and to keep the o-ring soft and pliable.
If your o-ring has become discolored, brittle or is cracked, replace it. Tank o-rings are widely available at scuba diving shops. Use only your fingers or soft metal tools designed for o-ring replacement or you may damage your equipment.
Causes of Failure
O-rings will naturally degrade with use or due to exposure to sunlight and salt air. It is advisable to keep several fresh ones with you in a dive kit. You never know when your tank's o-ring may need replacement.
Consequences of O-Ring Failure
If your o-ring fails while diving, it will probably result in the release of the air in your scuba tank. This could result in an air emergency, subjecting the diver to drowning or risking decompression illness.