§6 · prism 2 operational checklist 3 / 5

Operational Checklist

This is the in-the-water-in-30-minutes sequence. The manual orders it deliberately: gas analysis first (because everything else depends on it), then electronics calibration, then leak verification, then a real 5-minute pre-breathe, then a final sweep before you step off.

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Gas analysis

§6 · 2: install analyzed

Analyze every cylinder yourself, every time. Trust no label.

⚠ warning Analyze O2 supply. Mark cylinder. Within ±1% of label. unverified
O2 % (%) O2 pressure (PSI)
⚠ warning Analyze diluent (O2 fraction). MOD calc must cover planned depth + 10%. unverified
Diluent O2 % (%) Diluent He % (%) Diluent pressure (PSI)
⚠ warning Analyze every bailout. MOD on each, marked, pressure recorded. unverified
Bailout O2 % (%) Bailout pressure (PSI)

Electronics power-on + calibration

§6 · 3: turn on wrist

Power on handset. Confirm boot, firmware version, time/date correct. unverified
Handset firmware
Record cell mV in pure O2 (PO2 = 1.0). Range 47–66 mV typical. unverified

Why this matters

The O2 calibration point is the cell test divers actually care about. The slope from this against the air reading tells you whether the cell is linear.

Cell #1 (O2) (mV) Cell #2 (O2) (mV) Cell #3 (O2) (mV)
⚠ warning Calibrate all three cells via handset menu. All three accept calibration. unverified
Voting logic test: cover/expose each cell in turn, verify handset votes match the cell you isolated. unverified
HUD power on, all LEDs visible, voting indicator matches handset. unverified
Confirm dive plan loaded: low setpoint, high setpoint, gradient factors, diluent/O2/bailout gases in computer. unverified

Positive + negative pressure leak check

§6 · leak check

Five minutes each, watched. No drift, no shrinkage. Catch the leak now.

⚠ warning POSITIVE pressure leak test: inflate loop through MAV until OPV cracks, close DSV/BOV, observe 5 minutes. No deflation. unverified
⚠ warning NEGATIVE pressure leak test: evacuate loop, close DSV, observe 5 minutes. No swelling. unverified
Visual + audible check during both tests: no hissing, no bubbles when sprayed with soapy water. unverified

Pre-breathe — minimum 5 minutes

§6 · pre-breathe

Watch your PO2 climb to your low setpoint and hold. Watch for CO2 hits. Watch for water in the loop.

Pre-breathe started. Timer running. Sitting still, full minute of slow breaths to settle. unverified
PO2 climbs to setpoint and holds. Solenoid fires when expected. unverified
⚠ warning No CO2 symptoms (headache, breathlessness, tunnel vision, lightheadedness). If yes — bail out, abort dive. unverified
⚠ warning Counterlungs respond naturally to breathing rhythm. Wet-pad sound = water in loop = abort. unverified
Full 5 minutes complete. Cells still tracking together within ±0.05 PPO2. unverified

Final pre-dive

§6 · final pre-dive

BCD/wing inflation verified. unverified
Weight check (no surprise loss). Backplate STA bolts torqued. unverified
Bailout reg breathed and stowed; bottle valves cracked open per dive standard. unverified
Mask defogged, on. Computer wet-contacts verified before water. unverified
Buddy check: BWRAF + CCR-specific (loop state, setpoint, bailout location). unverified
ID10T test (read as "idiot"): mouthpiece, gas open, computer on, bailout routed, wing/drysuit, mask/weights, buddy check, loop in / hand on BOV. unverified

Why this matters

Last 30-second sweep before stride. If anything is missed, this is when you catch it.