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UV Intensity Thresholds

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The three UV intensity thresholds

All three values are defined in lib/constants.ts under THRESHOLDS.UV_INTENSITY:

ThresholdValueSourcePurpose
IMO_MIN252 W/m²IMO G8 guidelinesMinimum for IMO D-2 compliance
USCG_MIN530 W/m²33 CFR Part 151Minimum for USCG compliance
OPTIMAL650 W/m²System design specFull-rated output target

How 252 W/m² is used

The IMO_MIN value is the primary compliance gate. Any BALLAST or DEBALLAST operation where UVR_INTENSITY < 252 represents a D-2 non-compliance event. In the dashboard:

  • Compliance tab: IMO D-2 item shows red (NON-COMPLIANT)
  • Compliance tab treatment bar: fills to UVR_INTENSITY / 252 — when below 100%, compliance is at risk

How 530 W/m² is used

The USCG_MIN is the secondary compliance gate, relevant for vessels operating in US waters. Between 252 and 530, the system is in a “marginal zone”:

  • IMO D-2 compliant ✅
  • USCG non-compliant ⚠️

The Compliance tab shows the USCG item as WARNING (yellow) in this range. The USCG treatment bar fills to UVR_INTENSITY / 530.

How 650 W/m² is used

The OPTIMAL value represents the system’s full rated output under ideal conditions. It is used as:

  • The denominator for efficiency calculations where intensity is expressed as a percentage of optimal
  • The reference point for the UV Health component of the health score

Values above 650 W/m² are possible in cold, clear water conditions where UV transmittance is high.

Operating zones

0 ────── 252 ─────────── 530 ──────── 650+ W/m²
  FAIL    │  IMO ONLY    │  BOTH OK  │  OPTIMAL
          │              │            │

Lamp efficiency thresholds

Separate from UV intensity, individual lamp efficiency is tracked against these tiers, defined in THRESHOLDS.LAMP_EFFICIENCY:

TierEfficiency rangeColourRecommended action
GOOD≥ 90%GreenNo action
WARNING70–89%YellowMonitor, plan future replacement
DEGRADED50–69%OrangeSchedule replacement at next port
CRITICAL< 50%RedUrgent replacement required

Lamp runtime thresholds

Defined in THRESHOLDS.LAMP_RUNTIME:

ThresholdValueAction
WARNING2,500 hoursBegin planning replacement
MAX3,000 hoursEnd of rated lamp life

UV intensity vs lamp efficiency: the relationship

Individual lamp efficiency affects aggregate UVR_INTENSITY. As lamps degrade, the system cannot maintain the intensity setpoint without increasing UVR_POWER_OUTPUT.

POWER_COMPENSATION_PCT quantifies this: a value of 20 means the system consumes 20% more electrical power to achieve the same UV intensity that new lamps would produce at rated power. This is visible in the Trend Analysis tab’s runtime charts — the power line climbs as the efficiency line falls.

References