Altitude Diving
The atmospheric pressure is lower at high altitudes than at sea level. After trav-
eling to a higher altitude, the diver will have additional nitrogen in his body,
compared to the equilibrium situation at the original altitude. This “addition-
al” nitrogen is released gradually in time and equilibrium is reached within a
couple of days.
Before high altitude diving the IQ-400 must be set to high altitude diving
mode to take this into account. The maximum partial pressures of nitrogen
allowed by the mathematical model of the IQ-400 are reduced according to the
lower ambient pressure. As a result the allowed no-decompression limits are
considerably reduced.
Surface Intervals
The IQ-400 requires a minimum surface interval of 10 minutes between dives.
If a surface interval is shorter than 10 minutes, the IQ-400 dive counter and
dive timer treat the next dive as a continuation of the previous dive. It adds the
dive times, and calculates no-decompression limits or decompression stops
based on excess nitrogen absorbed on both dives. In this regard, it is similar to
the U.S. Navy tables.
Depth Limits
However, the IQ-400 will calculate below that depth to provide a wide margin
of flexibility if, through carelessness or emergency, you are forced to exceed this
recommended depth limit for a dive.
6.2 TECHNICAL SPECIFICATIONS
Dimensions and weight (wrist model):
• Diameter: 61.5 mm [2.42 in]
• Depth: 29 mm [1.14 in]
• Weight: 105 g [0.23 lb]
39
WARNING
TUSA STRONGLY RECOMMENDS THAT SPORT DIVERS
LIMIT THEIR MAXIMUM DEPTH TO 40 m [130 ft]!
