AQUA LUNG I550C (01) PDF DOCUMENT

To ensure responsible computer diving with your AQUA LUNG I550C, please follow these guidelines:

• Always plan each dive.

• Always limit your dive to the level of your training and experience.

• Always make your deepest dive first.

• Always make the deepest part of every dive first.

• Check your computer often during the dive.

• Do a safety stop on every dive.

• Allow adequate surface interval between each dive.

• Allow adequate surface interval between each day of diving (12 Hours or until your computer clears).

• Read and understand this manual thoroughly before using the i550C.

To activate the AQUA LUNG I550C, press and release either button. The computer will also turn on if its metal contacts become wet and you descend greater than 1.5 m (5 ft) for 5 seconds. This water activation feature can be disabled if you prefer.

Upon activation, the following occurs:

• The unit enters a Diagnostic Mode, checking the display and voltage to ensure they are within tolerance.

• It checks the ambient barometric pressure and calibrates the present depth as 0 m (ft). At altitudes of 916 m (3001 ft) or higher, it will adjust the depth for the higher altitude.

• After the Diagnostic check, the AQUA LUNG I550C will display the surface screen in Dive Mode.

The AQUA LUNG I550C has no off button. If no buttons are pressed or dives are made within 10 minutes, it will enter Sleep Mode to save battery life. To wake the computer, press any button. The unit will completely shut off after 2 hours of inoperation. However, it will stay on in Sleep Mode for a 24-hour period after a dive to count down Fly (time to fly) and SAT (desaturation time).

The AQUA LUNG I550C uses two control buttons: ADV (Advance) and SEL (Select). These buttons allow you to select mode options, access information, enter settings, activate the backlight, and acknowledge audible alarms. Different press combinations navigate through the menus.

DTR (Dive Time Remaining): The computer constantly monitors No Decompression status and O2 Accumulation, displaying the least amount of time available as DTR. This is identified by either the NO DECO or O2 MIN icons.

NO DECOMPRESSION: This is the maximum time you can stay at your present depth before entering decompression. It’s calculated based on nitrogen absorption in hypothetical tissue compartments.

O2 MIN (Oxygen Time Remaining): For nitrox dives, this time is based on your Oxygen Saturation (O2 SAT). As O2 SAT increases, O2 MIN decreases. When O2 MIN becomes less than the No Decompression time, it will be displayed as the DTR.

BAR GRAPHS:
• ASC Bar Graph (Ascent Rate): Provides a visual representation of your ascent speed. If you ascend faster than 9 mpm (30 fpm), all segments will flash, and the display will show “SLOW”.
• N2 Bar Graph (Nitrogen Loading): Represents your relative No Decompression or Decompression status. Segments are added as your depth and dive time increase.

ALGORITHM: The i550C uses the Z+ (based on Bühlmann ZHL-16C algorithm model) to calculate nitrogen tissue loading. A Conservative Factor (CF), Deep Stops, and Safety Stops can be added for greater safety margins.

CF (Conservative Factor): When ON, the Dive Time Remaining is reduced to the values available at an altitude level 915 m (3,000 ft) higher than your actual altitude, providing a more conservative dive profile.

DS (Deep Stop): When ON, it triggers after descending deeper than 24 m (80 ft). The computer calculates a Stop Depth equal to ½ the Max Depth. This feature only works in DIVE Mode within No Decompression times.

SS (Safety Stop): Upon ascent to a specified depth on a No Decompression dive, a safety stop timer will appear on the Dive Main display, counting down from the set time.

The ASC Bar Graph on your AQUA LUNG I550C provides a visual representation of your ascent speed. When your ascent is faster than the recommended 9 mpm (30 fpm), all segments will flash, and the air pressure reading will temporarily be replaced with the message SLOW.

LOW BATTERY WHILE ON THE SURFACE

• Warning Level: Functions continue, but the backlight is disabled. The Battery icon appears solid.

• Alarm Level: All operations cease. The Battery icon flashes for 5 seconds, then the unit shuts off.

Change the battery before diving if your AQUA LUNG I550C indicates a Battery Low Warning or Alarm.

LOW BATTERY DURING A DIVE

• Warning Level: Functions continue, but the backlight and Bluetooth are disabled. The battery icon appears solid upon entering Surface Mode.

• Alarm Level: Functions continue, but the backlight and Bluetooth are disabled. The Battery icon appears flashing. 5 seconds after entering Surface Mode, the i550C will shut down.

While in Dive or Gauge mode, the audible alarm will emit 1 beep per second for 10 seconds when an alarm is triggered (unless set to OFF). It can be silenced by pressing the SEL button. The following situations activate the 10-second alarm:

** Items activate only in Dive mode.

• Descent deeper than the Depth Alarm set point.

• Dive Time Remaining at the set point.**

• Elapsed Dive Time at the set point.

• PO2 at the set point.**

• High O2 of 300 OTU (100%).**

• N2 Bar Graph at the set point.**

• Ascent rate exceeds 9 MPM (30 FPM) for 8 seconds or more.

• Entry into Decompression Mode (Deco).**

• Conditional Violation (above a required Decompression Stop Depth for less than 5 minutes).**

• Delayed Violation (above a required Decompression Stop Depth for more than 5 minutes).**

• Delayed Violation (a Decompression Stop Depth greater than 18 M/60 FT is required).**

• Delayed Violation (Max Operating Depth of 100 m/330 ft is exceeded in Dive or 120 m/399 ft in Gauge mode).

A single short beep (which cannot be disabled) sounds after 10 minutes on the surface after a Violation dive.

A 10-second continuous tone followed by a 5-second steady beep (which cannot be silenced by acknowledgement) will occur in these situations:

• Ascent above a Decompression Stop for more than 5 minutes.

• Decompression requires a Stop Depth deeper than 18 m (60 ft) or deeper.

• On the Surface during a Conditional Violation.

To view logs, change settings, or switch modes on your AQUA LUNG I550C, you must navigate through the Surf Main Menu. Enter the menu by pressing the ADV button. Continue pressing ADV to cycle through the options. You can hold the ADV button to scroll quickly. When you reach the end of the menu, the computer will return to the Dive Surface Main screen.

Press the SEL button to select a menu option or access sub-menus and settings.

The Main Menu options appear in the following order:

• ALT 1

• ALT 2

• ALT 3 (nitrox only)

• FLY/SAT

• PLAN

• LOG

• SET GAS

• SET AL

• SET UTIL

• SET TIME

• SET MODE

• TOTAL DIVES

• HISTORY

1. From the Dive Surface Main screen, press ADV until “SET GAS” is displayed.

2. Press SEL to enter the Set Gas menu.

3. The screen will show “SET” and “EAN” (or “AIR”). Press ADV to toggle between EAN (Enriched Air Nitrox) and AIR. Press SEL to save your selection.

4. If you select EAN, you will be taken to the Gas 1 FO2 setting screen.

5. Press ADV to adjust the FO2 percentage (21-100%). Press SEL to save.

6. You will then be taken to the Gas 1 PO2 Alarm setting screen. The setting will be flashing.

7. Press ADV to adjust the PO2 Alarm setpoint. Press SEL to save.

8. The process can be repeated for Gas 2 and Gas 3 if you wish to use multiple gases. Gas 1 cannot be set to OFF.

Note: The AQUA LUNG I550C can only monitor and record the onboard, tank 1, gas pressure. When Gas 2 or 3 is the active gas, the gas pressure will not be displayed on the Main screen.

1. From the Dive Surface Main screen, press ADV until “SET AL” is displayed.

2. Press SEL to enter the Set Alarms sub-menu.

3. Use the ADV button to cycle through the alarm types and the SEL button to select and save settings.

• 1. Aud AL (Audible Alarms): Press ADV to toggle between ON and OFF. Press SEL to save.

• 2. DEPTH AL (Depth Alarm): Press ADV to set a maximum depth alarm (10-100 m or 30-330 ft) or turn it OFF. Press SEL to save.

• 3. Edt AL (Elapsed Dive Time Alarm): Press ADV to set a predetermined dive time alarm (10-180 min) or turn it OFF. Press SEL to save.

• 4. N2 AL (Nitrogen Alarm): Press ADV to set an alarm based on a specific number of N2 bar graph segments, or turn it OFF. Press SEL to save.

• 5. dtr AL (Dive Time Remaining Alarm): Press ADV to set an alarm for a designated reserve of dive time remaining (5-20 min) or turn it OFF. Press SEL to save.

• 6. TURN AL (Turn Pressure Alarm): Press ADV to set a turn pressure alarm (70-205 BAR or 1000-3000 PSI) or turn it OFF. Press SEL to save.

• 7. PRESS AL (Pressure Alarm): Press ADV to set a designated end pressure alarm (20-105 BAR or 300-1500 PSI). This alarm only considers gas 1. Press SEL to save.

1. From the Dive Surface Main screen, press ADV until “SET UTIL” is displayed.

2. Press SEL to enter the Set Utilities sub-menu.

3. Use the ADV button to cycle through the options and the SEL button to select and save settings.

• 1. H2O TYPE (Water Type): Press ADV to toggle between SALT and FRESH. Press SEL to save.

• 2. H2O ACT (Water Activation): Press ADV to toggle between ON and OFF. Press SEL to save.

• 3. UNITS (IMP/MET): Press ADV to toggle between MET (metric) and IMP (imperial). Press SEL to save.

• 4. DEEP STOP: Press ADV to toggle between ON and OFF. Press SEL to save.

• 5. SS (SAFETY STOP): Press ADV to toggle between ON and OFF. If ON, you can then set the stop time (3 or 5 min) and stop depth (3, 4, 5, or 6 m / 10, 15, or 20 ft). Press SEL to save each setting.

• 6. CF (Conservative Factor): Press ADV to toggle between ON and OFF. Press SEL to save.

• 7. BLUETOOTH: Press ADV to toggle between ON and OFF. Press SEL to save.

• 8. LIGHT (Backlight Duration): Press ADV to select OFF, 5 sec, or 10 sec. Press SEL to save.

• 9. SR (SAMPLE RATE): Press ADV to select 2, 15, 30, or 60 seconds. Press SEL to save.

The download memory capacity for Dive & Gauge Mode on the AQUA LUNG I550C depends on the selected sample rate. Shorter intervals provide a more precise record but consume more memory.

1. From the Dive Surface Main screen, press ADV until “SET TIME” is displayed.

2. Press SEL to enter the Set TIME Sub Menu.

3. Set Date Format: The first screen is FORMAT. Press ADV to toggle between M-D (Month-Day) and D-M (Day-Month). Press SEL to save.

4. Set Hour Format: The next screen is HOUR FORMAT. Press ADV to toggle between 12 or 24 hour format. Press SEL to save.

5. Set Time: The TIME screen will appear. The hour will be flashing. Press ADV to change the hour. Press SEL to save. The minutes will then flash. Press ADV to change the minutes. Press SEL to save.

6. Set Date: The DATE screen will appear with YEAR flashing. Press ADV to change the year. Press SEL to save. The month will then flash. Press ADV to change the month. Press SEL to save. Finally, the day will flash. Press ADV to change the day. Press SEL to save.

All dives begin with GAS 1. Gas switches can only be made when a Dive Main screen is displayed and gases 2 and/or 3 are set to ON in the Set Gas menu. Gases cannot be switched while on the surface.

To switch gases during a dive:

1. From the Dive Main screen, press and hold the SEL button to enter the Gas Switch menu.

2. The current PO2 value and the next available gas (e.g., GAS 2) will be displayed. The screen will show “USE GAS 2”.

3. To switch to this gas, press and hold SEL to confirm the switch.

4. To cycle to the next gas (e.g., GAS 3) or return to the Dive Main screen without switching, press ADV.

If the current PO2 value for the gas you are switching to is greater than 1.6, a warning “STOP USE” will be displayed. The computer will maintain the current gas. You can override this warning by pressing the SEL button, but this is extremely hazardous and should be avoided.

To properly care for your AQUA LUNG I550C, follow these steps:

• Protect the unit from shock, excessive temperatures, chemicals, and tampering. Use an Instrument Lens Protector to guard against scratches.

• At the end of each day of diving, soak and rinse the i550C in fresh water. Check that the areas around the Low Pressure (Depth) Sensor, water contacts, and buttons are free of debris.

• To dissolve stubborn salt crystals, use lukewarm water or a slightly acidic bath (50% white vinegar/50% fresh water). After this bath, place the i550C under gently running fresh water.

• Towel dry the unit before storing.

• Keep your i550C in a cool, dry, and protected place during transport.

Perform battery replacement in a dry, clean environment to prevent moisture or dust from entering the compartment. Damage due to improper battery replacement is not covered by the warranty.

Battery Cover Removal

1. Turn the module over to expose the battery cover.

2. Unscrew the cover by turning it counterclockwise using a coin ONLY.

3. Remove the battery cover.

4. Remove the cover O-ring by hand. Do not use tools.

Battery Removal

1. Carefully lift the 3 volt type CR2450 lithium battery out of the housing. Do not bend or damage the battery terminals.

Inspection

1. Closely check all threads and sealing surfaces for any signs of damage.

2. Inspect the buttons, lens, battery cover, and housing for cracks or damage.

3. Check the metal contacts for any signs of stress or corrosion.

Battery Installation

1. Place a new 3 volt type CR2450 lithium battery into the compartment with the (-) negative side down.

Battery Cover Installation

1. Lightly lubricate a new, genuine Aqua Lung cover O-ring with silicone grease and install it on the O-ring groove of the battery cover. Ensure it is evenly seated.

2. Carefully install the battery cover, turning it clockwise until secure (using a coin ONLY).

Final Inspection

1. Activate the unit and watch as it performs a full diagnostic and battery check.

2. Observe the LCD display to ensure it is consistently clear and sharp.

The AQUA LUNG I550C measures altitude (ambient pressure) upon activation and then every 15 minutes until a dive is made. Measurements are only taken when the unit is dry.

• When diving in high altitude waters from 916 to 4,270 m (3,001 to 14,000 ft), the i550C automatically adjusts to provide corrected depth and reduced NO DECO (decompression) and O2 MIN (O2 saturation) times.

• If the Conservative Factor is ON, No Decompression Limits (NDLs) are calculated based upon the next higher 915 m (3,000 ft) altitude level for an added margin of safety.

• The AQUA LUNG I550C will not function as a dive computer above 4,270 m (14,000 ft).

The following table shows the No Decompression Limits in hours and minutes (HR:MIN) based on the Z+ Algorithm at various metric depths and altitudes.

The following table shows the No Decompression Limits in hours and minutes (HR:MIN) based on the Z+ Algorithm at various imperial depths and altitudes.

The oxygen exposure limits are based on the NOAA Diving Manual.

Operational Performance:

• Depth Accuracy: ±1% of full scale

• Timers Accuracy: 1 second per day

Dive Log Mode:

• Stores 24 most recent DIVE/GAUGE dives.

Altitude:

• Operational from sea level to 4,270 m (14,000 ft) elevation.

Power:

• (1) 3v, CR2450, Lithium battery.

• User replaceable (annual replacement recommended).

Battery Icon:

• Warning: icon on solid at 2.75 volts.

• Alarm: icon on flashing at 2.50 volts.

Operating Temperature:

• Out of the water: -6.6 to 60 °C (20 °F to 140 °F).

• In the water: -2.2 to 35 °C (28 °F to 95 °F).

Max Functional Depth:

• DIVE: 100 M (330 FT)

• GAUGE: 120 M (399 FT)

N2 Bar Graph Segments:

• No Decompression Normal Zone: 1 to 3

• No Decompression Caution Zone: 4

• Decompression Zone: 5 (all)

ASC (Ascent) Rate:

Numeric Displays Range and Resolution: