NDL – No Decompression Limit

The NDL or No Decompression Limit is a period of time that a diver can stay according to the depth before decompression is required. The NDL is used in recreational diving to calculate the maximum time a diver can stay and is used when planning dive. Dive computers will calculate this limit at set interval normally in just a few seconds to accommodate changes in depths through the dive.

WOB – work of breathing

The work of breathing or WOB is in simple terms, the effort required by the lungs to breathe. But to be more accurate it refers to the energy expended to inhale and exhale a breathing gas. The WOB is usually expressed as work per unit volume.

OC – Open Circuit

Open circuit is the breathing system most commonly used for scuba diving. It is called open circuit because all the gas exhaled by the diver is expelled in the environment. A basic OC breathing apparatus is composed of a cylinder, a regulator first and second stage and a pressure gauge. The other systems are called CCR for closed circuit rebreather or SCR for semi-closed rebreather because they reuse in a loop all or part of the diver exhaled gas.