Specifications

No Decompression Dive Time Remaining

No Decompression Dive Time Remaining is the maximum amount of time that

you can stay at your present depth before entering a decompression situation.

It is calculated based on the amount of nitrogen absorbed by twelve hypotheti-

cal tissue compartments. The rates each of these compartments absorb and

release nitrogen is mathematically modeled and compared against a maximum

allowable nitrogen level. Whichever one of the twelve is closest to this maxi-

mum level is the controlling compartment for that depth. Its resulting value

will be displayed numerically (Fig. 12a) along with the No Decompression Dive

icon and graphically as the Nitrogen Bar Graph (Fig. 12b).

As you ascend from depth following a dive that has approached the no decom-

pression limit, the Nitrogen Bar Graph will diminish as control shifts to slower

compartments. This is a feature of the decompression model that is the basis

for multilevel diving, one of the most important advantages the 500AI offers.

The no decompression algorithm is based upon Haldane’s theory using maxi-

mum allowable nitrogen levels developed by Merrill Spencer. Repetitive diving

control is based upon experiments designed and conducted by Dr. Ray Rogers

and Dr. Michael Powell in 1987. Diving Science and Technology

(DSAT), a

corporate affiliate of PADI

, commissioned these experiments.

Fig. 12 - No Decompression

Dive Time Remaining

140

210

280

350

5000

4000

3000

2000

1000

MAX