When to Scrap and Replace RTD Sensors?

Proper determination of scrap criteria and replacement timing for platinum resistance temperature detectors (RTDs) is critical to maintaining measurement accuracy, process stability and industrial safety. Operating out-of-tolerance or damaged sensors not only distorts temperature data but also introduces quality risks, production losses and potential safety hazards. As a professional expert in thermal measurement and sensor lifecycle management, this article defines clear, standardized scrap criteria, replacement triggers and operational guidelines to help maintenance teams make correct decisions and avoid risky continued use of defective components. RTD sensors must be immediately scrapped and replaced under specific, non-repairable conditions. The primary scrap criterion is unrecoverable accuracy deviation, where measurement error exceeds the allowable tolerance of Class A or Class B and cannot be corrected through instrument offset or slope compensation. Another strict threshold is insulation resistance below 10 MΩ, indicating severe moisture ingress, insulation aging or internal contamination that cannot be resolved by drying or cleaning. Irreversible electrical faults, including open circuits and short circuits that cannot be fixed by rewiring or terminal maintenance, also require immediate scrapping. Physical damage such as cracked protection tubes, broken sheaths, damaged sealing structures or deformed packaging compromises structural integrity and exposes the sensing element to media corrosion and thermal shock, making the sensor unfit for further service. Long-term drift exceeding 0.3 ℃ represents permanent degradation of the platinum sensing element, which cannot be reversed or adjusted. A sharp decline in thermal response speed, caused by layer separation, internal contamination or heat conduction blockage, also renders the sensor unable to provide real-time, reliable temperature feedback. In addition, any sensor that has reached its designed service life under continuous harsh conditions must be replaced preventively, even if no obvious fault is detected. Continued operation of defective RTDs, known as "sick operation", is strictly prohibited. Such practice leads to unstable process control, unqualified product quality, material waste, system misalignment and even fire or explosion risks in high-temperature, flammable or reactive processes. The cost of sensor replacement is negligible compared with potential production downtime, safety incidents and compliance failures. Replacement must be performed immediately once any scrap criterion is met. The new sensor should be calibrated, inspected and verified before being put into operation to ensure compliance with accuracy and performance requirements. Establishing a lifecycle management system with regular inspection, drift tracking and calibration records helps predict degradation and schedule replacement in advance, minimizing unplanned downtime. In summary, clear scrap criteria and timely replacement are essential to ensure the reliability and safety of RTD-based temperature measurement systems. Adhering to these standards eliminates hidden dangers, ensures consistent product quality and maintains safe, stable and efficient industrial operations. Strictly rejecting faulty sensors and avoiding extended service is a fundamental principle of responsible thermal system management.