How to Determine if a Hot Runner Sensor Has Reached Its Lifespan Limit

The primary criterion is "accuracy still exceeds the limit after calibration + recurring malfunctions." The sensor has reached the end of its useful life if it satisfies two of these requirements. The following are specific requirements:

1. Core Criterion: Accuracy Exceeds Limits

If any of the following circumstances continue after routine calibration, the component has reached its aging limit:

Zero-point drift surpasses the nominal permitted range by more than 0.2%FS, and soon after calibration, it surpasses the limit once more;

The full-scale accuracy deviation is greater than twice the nominal accuracy (for example, the Kistler 6125A is supposedly 0.25%FS, but the variance is more than 0.5%FS);

The sensitivity drops by more than 10% from its initial value, and recalibration is unable to make up for this.

2. Physical/Sealing Failures That Are Irreversible

Sealing Leakage: The housing/seal has aged and failed if there is frequent molten material leakage at the sensor tail or mounting site that cannot be fixed by replacing the seal.

Signal Abnormalities: Fatigue damage to internal components is indicated by frequent jumps and disconnections in the output signal that continue even after the wiring and amplifier have been inspected.

Diaphragm Damage: Disassembly reveals deformation and corrosion cracks on the sensor diaphragm, which cannot be fixed by calibration.

3. Fast Reference Evaluation

If the sensor has reached its lifespan: If a high-end corrosion-resistant model (like the 6125A) has been in use for more than 3.5 years or a standard sensor has been in use for more than 2 years and displays any of the aforementioned issues, it can usually be concluded that the sensor has reached its lifespan limit and direct replacement is advised.

The sensor has not yet surpassed its lifespan limit and can still be utilized if the drift is minimal and can be corrected after calibration.