Dive Terminology
- Central nervous system (CNS)
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A measure of central nervous system oxygen toxicity caused by exposure to increased partial pressure of oxygen (PO2) while diving.
- Maximum operating depth (MOD)
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The greatest depth at which a breathing gas can be used before the partial pressure of oxygen (PO2) exceeds the safe limit.
- No decompression limit (NDL)
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A dive that does not require decompression time while ascending to the surface.
- Oxygen toxicity units (OTU)
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A measure of pulmonary oxygen toxicity caused by exposure to increased partial pressure of oxygen (PO2) while diving. One OTU is equivalent to breathing 100% oxygen at 1 ATM for 1 minute.
- Partial pressure of oxygen (PO2)
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The pressure of the oxygen in the breathing gas, based on depth and oxygen percentage.
- Surface interval (SI)
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The amount of time that has elapsed since the completion of the last dive.
- Time to surface (TTS)
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The estimated amount of time required to safely ascend to the surface.
Decompression stops are included in the calculations, but safety stops are not.