Citizen D710/D716 instruction manual Diving Terms Used by this Watch

Diving Terms Used by this Watch

The following provides an explanation of the diving terms displayed by this watch along with their basic meanings.

<Algorithm>

This watch employs the calculation formula of the Canadian Defense and Civil Institute of Environmental Medicine (DCIEM).

<Scuba Diving and Skin Diving>

This watch automatically distinguishes between skin diving and scuba diving according to the following conditions, and records log data separately for each type of diving.

•Scuba diving: Continuously diving for 3 minutes or more to a depth of 1 m (4 ft) or more

•Skin diving: Continuously diving for less than 3 minutes to a depth of 1 m (4 ft) or more

<No-Decompression Diving and No-Decompression Limit (NDL) Time>

No-decompression diving (NDL = No-Decompression Limit) refers to diving that allows the diver to ascend to the surface without stopping for decompression during the course of ascending following completion of a dive. The limit time during which this no-decompression diving is allowed is referred to as the no-decompression limit time. No-decompression limit time varies according to the diving depth and diving time of the previous dives.

<One Dive>

In this watch, one dive constitutes the time from initially diving to a depth of 1 m (4 ft) (start of dive) from the preliminary dive mode state to the time the dive mode is terminated (end of dive).

<NITROX Diving>

NITROX diving refers to diving in which a mixed gas of oxygen and nitrogen is used that has a higher oxygen concentration than ordinary air tanks. This watch allows the oxygen concentration (O2%) to be set within the range of 22% to 50% in the dive plan mode.

*NITROX diving reduces the diver’s risk of decompression sickness by reducing the nitrogen ratio (%) to a level lower than ordinary AIR diving. However, increasing the oxygen ratio (%) also invites the risk of “oxygen toxication” for the diver, a condition that is unpredictable in the case of AIR diving. In the case of performing NITROX diving, always make sure to receive safety training relating to NITROX diving in advance.

<AIR Diving>

AIR diving refers to diving using an ordinary air tank (compressed air having an oxygen concentration of 21%). This watch uses the term AIR diving to distinguish it from NITROX diving in which the oxygen concentration is 22% or higher.

<High-Altitude Diving and Altitude Setting>

High-altitude diving refers to diving at a high altitude of 300 m (1,000 ft) or more above sea level (such as in lakes, ponds or rivers). Since this watch calculates no-decompression time when diving by calculating body nitrogen level based on actual atmospheric pressure periodically measured while on land prior to diving, special settings are not required during high-altitude diving. However, water depth is displayed based on seawater (specific gravity: 1.025) even when diving in fresh water.

*Since atmospheric pressure at high altitudes differs from that at lower altitudes where ordinary diving is performed, high-altitude diving requires special skills. In the case of performing high-altitude diving, always make sure to receive safety training regarding high-altitude diving in advance.

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