A&D 2 Plus - Manual (Page 10)

If you ever doubt the accuracy of the M2+’s depth readings, DO NOT
dive with it until you have it inspected by an Aqua Lung dealer.
Some dive stores who provide this service do not have test gauges on
their pressure chambers as accurate as the depth sensor on the M2+.
Therefore, if you request a depth check, verify that the test chamber
gauge accuracy is better than ±2 feet.
If the facility does not have the special tools to follow these service
procedures, have the dealer return the M2+ directly to Aqua Lung.
HOW TO OBTAIN SERVICE
Factory service for the M2+ was discontinued in 1997. If a battery
change is needed, please contact one of the following Aqua Lung
dealers:
1. Sea Sports, Houston, TX
281-894-4488
e-mail: [email protected]
2. Underseas Scuba Center, Villa Park, IL (Chicago area)
630-833-8383
e-mail: [email protected]
OPERATING TEMPERATURE
The M2+ operates normally between 12 o F to 122 o F (-10 o C to 50 o C).
You may notice the liquid crystal display (LCD) becoming sluggish at
extremely low temperatures. This is normal and will not affect the
computer’s accuracy.
It is possible to damage the electronics if left exposed to direct
sunlight or in a hot, confined space (like a car trunk). After the dive,
cover the computer and keep it out of the sun. If inadvertently left in
direct view of the sun, the LCD may become totally black. If this
occurs, immediately immerse the M2+ in cool water. The display
should recover its normal appearance after a few minutes. Damage
from extreme heat or cold is not covered under the two-year limited
warranty.
REPLACING THE BATTERY
The M2+'s battery is not user-replaceable. It must be returned to the
dealer or factory for replacement. If you notice any low battery
warnings, have the battery changed as soon as possible. Refer to the
previous section "How to Obtain Service" for information on return-
ing the M2+ to U.S. Divers Co.
TECHNICAL SPECIFICATIONS
NO-DECOMPRESSION MODEL
• ZH-L8 ADT
• 8 tissue compartments, 5 to 640 minutes
• Decompression stop depths at 10 to 80 feet in 10-foot increments
OPERATIONAL PERFORMANCE
Depth Range: ....................... 0-330 feet
Time Measurement: ............ 0-199 min.; Quartz timing
Temperature Range: ........... 14 o F to 122 o F (-10 o C to 50 o C)
Display: ................................. High contrast, custom liquid crystal with
back luminescence
HP Hose Connection: .......... 7/16" UNF regulator HP port
Dive Log Mode ..................... Stores last 37 dives in memory
After 37 dives, adds latest dive to
memory, deletes oldest dive (37 most
recent dives are retained in memory)
Altitude Range: .................... 0-13,200 feet above sea level;
Full computer functions up to 13,200 ft.
Battery: ................................. LR07 long life lithium battery (factory
replaceable only)
Module Weight ..................... 150 g (5.29 oz)
Module Dimensions ............. 3.875" tall x 2.28" wide x .9" deep
ZH-L8 ADT CALCULATION MODEL
The M2+ uses a new calculation model known as the ZH-L8 ADT.
This model uses eight compartments or "tissue" groups with half-
times ranging from 5 to 640 minutes. This calculation model is based
on the most current research conducted by the late Dr. A.A.
Buhlmann. Most computer decompression models only take into
account time and depth; the M2+ model also factors in other
physiological factors, including temperature and ascent rate.
TEMPERATURE
Blood perfusion to the body's organs is not constant. Skin and muscle
tissues are especially subject to changes in blood perfusion, depend-
ing on temperature. Changes in blood perfusion to these organs
change their nitrogen saturation tolerance. The ZH-L8 ADT model
takes these effects into account and thus the "skin" and "muscle"
compartments in the M2+ have variable half-time periods and
saturation tolerances.
Decompression information is calculated according to the diver's
individual decrease in skin temperature. The decrease in skin
temperature is based upon the water temperature and the dive time.
By considering these changes in saturation, the time that must be
spent at the surface prior to flying can be considerably lengthened,
depending on the depth, time, and temperature of a dive.
ASCENT RATE AND MICROBUBBLE FORMATION
The ZH-L8 ADT model considers nitrogen in both its dissolved and
gaseous phase (microbubbles). Formation of microbubbles is
considered to be a strong indicator of a high risk of decompression
sickness. The model calculates the formation of microbubbles
depending on various assumed influences in arterial and venous
blood. During normal, slow ascents, microbubbles form mainly in
venous blood. During fast ascents, microbubbles may also form in
arterial blood and the body's tissues. If a particular dive profile
results in the formation of microbubbles, decreased bottom time and/
or increased decompression times, and increased wait-to-fly times,
will be indicated.
Microbubbles can form if the diver makes a fast ascent, ignores
decompression stops, or makes repeated ascents during a dive (yo-yo
diving). These microbubbles can form in arterial blood and body
tissues. If these microbubbles partially impair circulation, the rate of
gas diffusion and saturation tolerance of surrounding tissues are
changed. If required, both decompression time and remaining bottom
time will be adjusted in such a way that already existing
microbubbles will stop growing. Increased decompression time will
also assist those local areas of impaired circulation to desaturate
with less risk of decompression sickness.
The calculation of microbubbles results in altered ascent instruc-
tions. If microbubbles are assumed to be present based on the data
used by the M2+, the ascent rate is reduced to 23 feet/minute. This
will help prevent the formation of microbubbles in the arterial
circulation and minimizes formation of microbubbles in the venous
circulation after the dive.
SUMMARY
With its new decompression model, the M2+ is a versatile tool which
can increase your diving comfort and safety. As with any diving tool,
however, ultimate responsibility for diving safety remains with the
individual diver. The same responsible diving practices taught by all
diving certifications are still absolutely necessary in order to safely
dive with the M2+.