A&D 2 Plus owner manual ZH-L8 ADT Calculation Model, Workload and Temperature

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ZH-L8 ADT Calculation Model

The Monitor 3 Air 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 Monitor 3 Air model also factors in other physiological factors, including tempera- ture, breathing rate and workload.

Workload and Temperature

Blood perfusion to the body's organs is not constant. Skin and muscle tissues are especially subject to changes in blood perfusion, depending on temperature and workload. 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 Monitor 3 Air have variable half-time periods and saturation tolerances.

Decompression information is calculated according to the diver's individual workload and decrease in skin tempera- ture. 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

Section 6: Reference

surface prior to flying can be considerably lengthened, depending on the depth, time, and temperature of a dive, as well as the diver's workload during that dive.

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

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Image 62 A&D 2 Plus owner manual ZH-L8 ADT Calculation Model, Workload and Temperature
Contents Page Copyright Notice Safety Considerations Guidelines for Using the Monitor 3 Air Page Table of Contents Memory Mode Page What is a Dive Computer IntroductionIntroduction Features of the Monitor 3 Air Computer ScreenMonitor 3 Air display zones and contact letter designations Transmitter This section Attaching the Transmitter to Your Regulator StepPairing the Wrist Unit to the Transmitter Preparation Preparation Using the Monitor 3 Air Without the Transmitter Checking the Battery PowerThis section Preparation for the Dive Diving with the Monitor 3 Air Functions During the Dive Current DepthDive Time Maximum DepthAscent Rate Ascent Rate DisplayNo-Stop Time Antenna Symbol No-stop time at Minutes remainingGraphic Air Time Remaining ATR Digital Air Time Remaining ATRHigh Air Consumption Warning Decompression Stop Information SOS Mode Total Ascent TimeUpon surfacing Surface Mode Surface mode iconFunctions at the Surface Wait-to-fly Time Wait-to-fly RecommendationsDesaturation Time Surface Interval TimeMicrobubble Warning Diving at Altitude Altitude sectorsExceeding the Altitude Limit Summary of Attention Messages and Alarms Altitude diveLost transmission after 40 seconds Alarms Low computer battery Activating Memory Mode Scrolling through logged dives Overview Downloading the Memory to a PCMemory Mode From Ready Mode or Surface Mode, touch ActivationExiting Memory Mode Scrolling through Logged DivesMemory Mode This section Ready Mode Activation from Ready-ModeMaximum allowable no-stop time at that depth Activation from Surface Mode Surface ModeIncrease Time Decrease Time Planning a Decompression Dive Step Pre-Dive Planning Mode Page Care Before the Dive Care During the DiveCare & Maintenance Operating Temperature Replacing the BatteryPage Technical Specifications Operational Performance No-Decompression ModelWorkload and Temperature ZH-L8 ADT Calculation ModelSummary