Ultrasonic or wiper cleaning of the optical window to survive biofouling in tropical harbors.<\/li>\n<\/ul>\nSuspended Solids Sensor<\/strong><\/p>\n\n- Absorption or optical backscatter principle, range 0 to 30,000 mg\/L, resolution better than 1 mg\/L in the 0\u2013100 mg\/L working band.<\/li>\n
- Housing rated for continuous immersion in seawater, wetted parts in titanium or PEEK.<\/li>\n
- Digital output on Modbus RTU with a temperature-compensated cell.<\/li>\n<\/ul>\n
The two work as a pair. Turbidity gives fast optical feedback tied directly to UV attenuation; suspended solids gives a mass-based measurement that correlates with filter loading. Together they tell the crew whether to run the upstream filter, dose a coagulant, or bypass to a holding tank.<\/p>\n
<\/span>Signal Interpretation Rules<\/span><\/h2>\nField data from dozens of UV BWTS installations condenses into a small set of rules that hold up in service:<\/p>\n
\n- Turbidity below 5 NTU:<\/strong> UVT typically above 85%; the chamber operates at design dose.<\/li>\n
- Turbidity 5\u201315 NTU:<\/strong> UVT drops to 70\u201385%; dose margin thins but stays above threshold if suspended solids remain under 20 mg\/L.<\/li>\n
- Turbidity 15\u201330 NTU:<\/strong> UVT typically 55\u201370%; margin is marginal \u2014 activate upstream filtration and re-check.<\/li>\n
- Turbidity above 30 NTU or SS above 50 mg\/L:<\/strong> UVT often below 55%; the chamber cannot guarantee kill. Divert or bypass.<\/li>\n<\/ul>\n
These thresholds are conservative and should be re-tuned per vessel against actual UV lamp performance curves. Shanghai ChiMay’s sensors expose the raw scattered-light and absorption signals, so engineers can build a vessel-specific correlation between the sensor pair and measured UVT.<\/p>\n
<\/span>Installation Details That Determine Reliability<\/span><\/h2>\nTwo installation choices decide whether the pair delivers usable verification data:<\/p>\n
\n- Sample tap location:<\/strong> put the sensors as close as physically possible to the UV chamber inlet, on a slip-stream that mimics main flow velocity. A tap 20 metres upstream misses transient turbidity spikes caused by pump surges.<\/li>\n
- Cross-cleaning access:<\/strong> the probes should be reachable during an operational voyage without breaking pressure containment. A five-minute wipe of the optical window at each watch change extends the interval between full service cycles by 3\u20135x.<\/li>\n<\/ul>\n
Install the sensors properly and you typically log 3,000\u20134,000 hours of continuous, calibrated service between interventions. Put them downstream of a heat exchanger or bypass valve and you’ll be chasing unusable data before long.<\/p>\n
<\/span>Integrating the Pair With the UV Lamp Control Loop<\/span><\/h2>\nA modern UV BWTS controller can take turbidity and suspended solids inputs and adjust behaviour in three ways:<\/p>\n
\n- Lamp dimming or boost:<\/strong> where the lamp ballast supports variable output, the controller raises lamp power as UVT drops. This maintains dose but shortens lamp life.<\/li>\n
- Flow reduction:<\/strong> slowing the ballast pump increases residence time in the UV chamber, restoring dose at the cost of pump-out time.<\/li>\n
- Divert or bypass:<\/strong> when inlet water is simply too dirty, divert to a holding tank or delay ballasting until the vessel reaches clearer water.<\/li>\n<\/ul>\n
Which response you pick is a policy question, not a hardware one. Fleets that use turbidity and suspended solids feedback to inform lamp dimming typically extend lamp life by 15\u201320%, because the lamps only run hard when necessary. Shanghai ChiMay’s sensor pair drives any of these responses through standard 4\u201320 mA or Modbus outputs, integrating cleanly with existing UV BWTS controllers.<\/p>\n