Rod-type magnetostrictive level gauges are widely used in shield tunneling storage tanks because they provide stable, high-accuracy level measurement for slurries, water, and additive fluids. However, faults can occur under harsh site conditions. Common symptoms include no signal output, fluctuating readings, fixed level values, and poor repeatability.

Signal loss is often caused by loose terminal wiring, damaged cables, or insufficient grounding. Check the power supply, shield continuity, and signal loop before replacing the gauge. Fluctuating readings may result from probe contamination, float jamming, or strong vibration near the tank. Clean the rod, confirm free float movement, and improve mounting support. A fixed reading usually indicates a stuck float, a short circuit, or electronic module failure. Verify float position and inspect the sensing rod for deformation or magnetic debris. Temperature drift and moisture ingress can also reduce accuracy, so inspect seals and cable glands regularly. During commissioning, confirm the probe length, zero point, and tank geometry settings. For maintenance, isolate the tank, follow safety procedures, clean components gently, and recalibrate after repair. Use a loop calibrator to verify the 4-20 mA output and compare it with manual tank gauging. Record fault codes, alarm history, and environmental conditions to identify repeat failures. Replace damaged probes with matching specifications and avoid bending the sensing rod during installation. Regular calibration and spare-part management are recommended for critical tanks. Early inspection and proper installation help reduce downtime and ensure reliable level monitoring in shield tunneling storage systems.