CMO Equipment Calibration & Diagnostics 4 — Questions and Answers
Question 1: A Mobilyze operator calibrates a flow meter and finds the 'as-found' reading is within tolerance. What is the correct action?
- Adjust the meter to a perfect reading regardless
- Document the as-found reading and return the instrument to service without adjustment (Correct answer)
- Replace the meter with a newer model
- Perform a full system flush before re-testing
Correct answer: Document the as-found reading and return the instrument to service without adjustment
If the as-found reading is within tolerance, no adjustment is needed; the result is documented and the instrument is returned to service without alteration.
Question 2: Which symptom most strongly suggests a Mobilyze encoder has lost its reference (home) position?
- Consistently slow motor speed
- Erratic or absolute position drift after power cycling (Correct answer)
- High current draw at startup
- Low system voltage alarm
Correct answer: Erratic or absolute position drift after power cycling
Absolute position drift or incorrect position after power cycling indicates the encoder's reference point has been lost, requiring re-homing.
Question 3: What is the effect of performing calibration outside the specified temperature range of the instrument?
- The calibration is unaffected as long as reference standards are used
- Thermal expansion and sensor response changes may introduce errors into the calibration (Correct answer)
- The instrument will display a warning code automatically
- Only humidity affects calibration, not temperature
Correct answer: Thermal expansion and sensor response changes may introduce errors into the calibration
Temperature affects sensor response characteristics, material dimensions, and electronics, so calibrating outside the specified range introduces errors not present under normal operating conditions.
Question 4: A Mobilyze diagnostic readout shows 'ADC Saturation' on a sensor channel. What does this indicate?
- The analog-to-digital converter is receiving a signal beyond its measurable input range (Correct answer)
- The hydraulic fluid is oversaturated with air
- The battery voltage is too low for accurate conversion
- The sensor has failed open-circuit
Correct answer: The analog-to-digital converter is receiving a signal beyond its measurable input range
ADC saturation means the input voltage exceeds the converter's maximum range, producing clipped or maximum output values and making accurate measurement impossible.
Question 5: During vibration diagnostics on a Mobilyze platform, an FFT spectrum shows a dominant peak at exactly twice the shaft rotation frequency. This is typically associated with:
- Imbalance
- Misalignment (Correct answer)
- Bearing defect
- Resonance
Correct answer: Misalignment
A dominant vibration peak at 2× rotational frequency (2X) is a classic signature of shaft or coupling misalignment.
Question 6: Why is it important to allow warm-up time before performing calibration on electronic measurement instruments?
- To ensure the display has fully initialized its graphics
- To allow internal components to reach thermal equilibrium, stabilizing their electrical characteristics (Correct answer)
- To complete any pending firmware updates
- To charge the internal battery to full capacity
Correct answer: To allow internal components to reach thermal equilibrium, stabilizing their electrical characteristics
Electronic components change their resistance and gain characteristics as they heat up; warm-up time ensures stable, repeatable readings during calibration.
Question 7: A Mobilyze system uses a 4–20 mA current loop for sensor signals. A reading of 2 mA most likely indicates:
- The sensor is reading at 10% of its range
- An open-circuit fault in the wiring or sensor (Correct answer)
- The sensor is at its zero-point calibration
- Normal operation at minimum range
Correct answer: An open-circuit fault in the wiring or sensor
In a 4–20 mA loop, 4 mA represents the live zero (minimum range); any signal below 4 mA, such as 2 mA, indicates a wiring break or sensor failure (open circuit).
CMO Equipment Calibration & Diagnostics 4
A Mobilyze operator calibrates a flow meter and finds the 'as-found' reading is within tolerance.
What is the correct action?