CMO Equipment Calibration & Diagnostics 2 — Questions and Answers
Question 1: When performing a zero-point calibration on a load cell, which condition must be met before proceeding?
- The cell must be at operating temperature with no load applied (Correct answer)
- The cell must be loaded to 50% capacity
- The cell must be cooled to ambient temperature
- The cell must be connected to an external reference standard
Correct answer: The cell must be at operating temperature with no load applied
Zero-point calibration requires the sensor to be at its normal operating temperature with absolutely no load applied so the baseline offset is accurate.
Question 2: A Mobilyze operator notices the diagnostic display shows a 'Sensor Drift' fault code. What is the most appropriate first step?
- Replace the sensor immediately
- Perform a span calibration to determine if drift is within tolerance (Correct answer)
- Ignore it if equipment is still functioning
- Reset the ECU and resume operation
Correct answer: Perform a span calibration to determine if drift is within tolerance
Span calibration confirms whether the drift magnitude exceeds allowable tolerance before deciding on corrective action.
Question 3: Which tool is used to verify the accuracy of a torque wrench before calibration work begins on Mobilyze equipment?
- Digital multimeter
- Torque tester or torque analyzer (Correct answer)
- Feeler gauge
- Oscilloscope
Correct answer: Torque tester or torque analyzer
A torque tester or torque analyzer provides a traceable reference measurement to confirm the wrench is applying the correct torque value.
Question 4: During diagnostic testing, a pressure transducer reads 5% higher than the reference gauge at all test points. This is an example of:
- Non-linearity error
- Hysteresis error
- Offset (bias) error (Correct answer)
- Random noise
Correct answer: Offset (bias) error
A consistent error of the same magnitude across all measurement points indicates a fixed offset or bias error, not a linearity problem.
Question 5: What does the term 'traceability' mean in the context of calibration?
- The ability to log calibration activity in software
- Linking measurements to a national or international standard through an unbroken chain (Correct answer)
- The physical path a calibration technician follows
- Recording sensor serial numbers in maintenance logs
Correct answer: Linking measurements to a national or international standard through an unbroken chain
Traceability means every calibration can be connected back to a national metrology institute (e.g., NIST) through a documented, unbroken chain of comparisons.
Question 6: A Mobilyze system's hydraulic pressure gauge is suspected to have hysteresis error. How would you test for this?
- Apply maximum pressure only and check reading
- Take readings while increasing pressure and again while decreasing pressure, comparing both sets (Correct answer)
- Replace the gauge and compare outputs
- Calibrate only at ambient temperature
Correct answer: Take readings while increasing pressure and again while decreasing pressure, comparing both sets
Hysteresis is revealed by comparing ascending and descending readings — a difference between the two paths indicates the error.
Question 7: Which calibration method applies known input values across the full measurement range to generate a correction table?
- Single-point calibration
- Multi-point calibration (Correct answer)
- In-situ calibration
- Substitution calibration
Correct answer: Multi-point calibration
Multi-point calibration maps the sensor response at multiple known inputs across its range, allowing a correction curve or table to be established.
CMO Equipment Calibration & Diagnostics 2
When performing a zero-point calibration on a load cell, which condition must be met before proceeding?