CCIL Laboratory Equipment Calibration 3 — Questions and Answers
Question 1: Which calibration approach involves comparing an instrument directly against a reference standard of higher accuracy?
- Indirect calibration
- Direct comparison calibration (Correct answer)
- In-situ calibration
- Statistical calibration
Correct answer: Direct comparison calibration
Direct comparison calibration places the instrument under test alongside a reference standard to assess agreement under the same conditions.
Question 2: For a thermometer used in a CCIL-accredited laboratory, calibration points should ideally be chosen to:
- Minimize the number of data points needed
- Span the full working range of the thermometer in the intended application (Correct answer)
- Match the manufacturer's factory test conditions only
- Use only the ice point as the reference
Correct answer: Span the full working range of the thermometer in the intended application
Calibration points spanning the working range ensure the thermometer performs accurately across all temperatures used in practice.
Question 3: What does 'out-of-tolerance' mean when found during a calibration check?
- The instrument is beyond its service life
- The instrument's readings fall outside the specified acceptable limits (Correct answer)
- The calibration label has expired
- The instrument requires firmware update
Correct answer: The instrument's readings fall outside the specified acceptable limits
Out-of-tolerance means the instrument's error exceeds the maximum permissible error defined in specifications or the calibration procedure.
Question 4: In gravimetric calibration of volumetric glassware, which physical property of water is used to convert mass to volume?
- Surface tension
- Density (Correct answer)
- Viscosity
- Boiling point
Correct answer: Density
Water density at the measurement temperature is used to calculate volume from the measured mass of water dispensed or contained.
Question 5: Which document type formally defines the step-by-step process a laboratory must follow when calibrating a specific instrument?
- Quality manual
- Standard operating procedure (SOP) (Correct answer)
- Accreditation certificate
- Equipment log
Correct answer: Standard operating procedure (SOP)
A Standard Operating Procedure (SOP) provides detailed, repeatable instructions for calibrating specific instruments consistently.
Question 6: What is the recommended action when a piece of laboratory equipment is found out of calibration after being used for testing?
- Continue using the equipment until the next scheduled calibration
- Quarantine the equipment and assess the impact on previous test results (Correct answer)
- Immediately destroy all test records from that period
- Replace the equipment without further investigation
Correct answer: Quarantine the equipment and assess the impact on previous test results
ISO/IEC 17025 requires that nonconforming equipment be quarantined and a risk assessment conducted to determine if previously reported results are valid.
Question 7: A spectrophotometer's wavelength accuracy is verified using:
- A NIST-traceable mass set
- Holmium oxide or didymium glass filters with known absorption peaks (Correct answer)
- A certified pH buffer solution
- A calibrated thermocouple
Correct answer: Holmium oxide or didymium glass filters with known absorption peaks
Holmium oxide and didymium glass filters have well-characterized absorption peaks used as wavelength references for spectrophotometer calibration.
CCIL Laboratory Equipment Calibration 3
Which calibration approach involves comparing an instrument directly against a reference standard of higher accuracy?