Most common pitfalls of the interchange verification method stem from a failure to control extraneous variables, leading to misinterpretations. The five most common mistakes are as follows:
1. Testing before temperature stabilization: This is the most common mistake. Testing immediately after heating: Uneven sensor temperature and inconsistent expansion will cause temporary deviations. It's easy to misinterpret temperature-related deviations as sensor-related problems.
The sensor must be kept at a stable temperature for 2 hours, with a temperature difference ≤1℃, before testing.
2. Inconsistent tightening torque after interchange: Tightening by feel instead of maintaining the same torque as before: Torque differences can cause installation deformation deviations. After interchange, the deviation changes, leading to the mistaken interpretation of the installation torque as a sensor-related problem. A torque wrench must be used to strictly align with the original torque.
3. Testing under different process conditions: Testing after interchange with different products or pressures: Process fluctuations themselves will change the magnitude of the deviation. Comparisons based on these changes are useless. Testing must be conducted using the exact same process parameters as before the interchange.
4. Drawing conclusions from a single measurement: A single measurement might encounter random fluctuations, leading to an immediate conclusion. This easily results in misinterpreting random fluctuations as fixed deviations, causing misjudgment. It's essential to measure each pressure point three times and average the results to eliminate random interference.
5. Failing to eliminate interference from the data acquisition channel: Using two sensors with different acquisition channels and swapping sensors without changing the wiring: If the acquisition channel itself has a zero-point deviation, channel errors might be mistakenly attributed to sensor problems. When in doubt, the wiring should also be swapped to eliminate channel interference.
Avoiding these five pitfalls will significantly reduce the likelihood of incorrect results and prevent wasted effort in misdiagnosing the problem.
