User guide

Using the NiTek
NiTek Dive Computer User Manual 17
Understanding FO2 default
In your entry-level Enriched Air Nitrox training, you learned that
among the greatest risks Nitrox (EANx) use poses is CNS
oxygen toxicity. CNS oxygen toxicity can occur if Nitrox is
breathed at depths where the partial pressure of oxygen (PO2)
exceeds safe limits.
The NiTek is designed to help divers avoid such situations by
presenting information and warnings regarding current PO2
levels and cumulative exposure to elevated PO2s. To do so, the
NiTek must be set to an FO2 that accurately matches the
concentration of oxygen in the gas mixture being breathed.
Similarly, the NiTek is designed to help divers avoid
decompression illness by providing no-decompression limits
(NDLs) or mandatory decompression stop information. Again, to
do so, the NiTek must be set in a manner that accurately matches
the concentration of nitrogen being breathed.
When this information is not available, the NiTek attempts to
protect divers by basing its oxygen- and nitrogen-exposure
calculations on a “worst case” assumption. This is, that
calculations are based on a mixture containing up to 79 percent
nitrogen and 99 percent oxygen. This “worst case” calculation is
what is referred to as the FO2 default setting.
Default warning indicated by a dashed line for the gas mix and
NDL