Versatile Control Unit (VCU)

Common issues

• Signal loss or erratic level readings from radar antenna fouling (cargo residue, condensation) inside the tank nozzle
• Water ingress into cable glands or the junction box causing intermittent faults or complete gauge failure
• Calibration drift versus manual ullage/sounding checks over time
• Communication faults between the field unit and the cargo control room display
• Antenna horn/waveguide damage or misalignment during tank cleaning or cargo operations
• Power supply or UPS backup failure interrupting continuous level monitoring
• False high-high or low-low alarms after configuration errors post tank cleaning
• Firmware lockups requiring a field unit reset

Inspection checklist

• Compare radar reading against an independent manual ullage/sounding at several tank levels
• Inspect the antenna horn/waveguide for residue, coating or physical damage where accessible
• Check cable glands and junction box for water ingress and terminal corrosion
• Verify alarm setpoints (high, high-high, low, low-low) against the cargo/loading plan
• Test the communication link to cargo control room, IGS or ESD system where interfaced
• Check power supply voltage and backup battery/UPS condition
• Confirm housing and mounting flange corrosion, gasket integrity and gas-tightness
• Review the last calibration/verification certificate and firmware version

Service intervals

Critical spares

• Radar transmitter/field unit (complete replacement)
• Antenna horn/waveguide assembly
• Cable gland kit and junction box seals
• Cargo control room display/interface module
• Power supply module

Safety

• The gauge is part of overfill protection - malfunction can contribute to a tank overfill during cargo operations
• Work on tank-mounted gauges may require gas-free/enclosed space entry precautions
• Electrical work on intrinsically safe circuits must preserve the Ex-certification - unauthorised component substitution voids hazardous-area approval

Class survey

Cargo tank level gauges form part of the overfill/high-level alarm chain reviewed under Continuous Survey Machinery or the cargo systems survey; class expects calibration records and confirmation that the gauge and its high-level alarm are functionally tested, typically annually.