Laboratory Equipment Calibration Flashcards

In the context of a CCIL certified laboratory's quality management system, what does the term 'metrological traceability' primarily signify?

Answer: The measurement results from an instrument can be related to a national or international standard through an unbroken chain of calibrations.

Metrological traceability is a core concept in ISO 17025 and laboratory certification. It is the property of a measurement result that allows it to be linked to stated references, usually national or international standards, through a documented and unbroken chain of calibrations. This ensures that measurements are accurate, comparable, and have a known level of uncertainty.

A technician is performing a two-point calibration check on a digital thermometer used for measuring fresh concrete temperature. Which two reference points are most commonly used for this procedure in a materials testing laboratory?

Answer: An ice bath (approximately 0°C) and the boiling point of water (approximately 100°C).

For the temperature range relevant to most construction materials testing, the most reliable and internationally recognized calibration points are the freezing point (ice bath at 0°C) and the boiling point (100°C at standard atmospheric pressure) of water. These points are physical constants that are easily and accurately reproduced in a laboratory setting.

According to general laboratory quality management principles (e.g., ISO 17025, CSA A283), which of the following is the LEAST important factor when establishing the calibration frequency for a concrete compression testing machine?

Answer: The manufacturer's original purchase price of the machine.

Calibration frequency is determined by factors that affect the equipment's accuracy and reliability over time. The frequency of use, severity of conditions, requirements of standards, and the equipment's own performance history are all critical. The original purchase price has no bearing on its metrological performance or calibration needs.

During a routine internal verification of a 4.75 mm sieve, a technician discovers that several openings exceed the maximum permissible individual opening size specified in ASTM E11. What is the most appropriate immediate action?

Answer: Remove the sieve from service, label it as 'out-of-tolerance,' and quarantine it.

Once a critical piece of equipment like a sieve is found to be non-compliant with its specification, it must be immediately removed from service to prevent its use in testing. This action prevents the generation of invalid test data. The sieve should be clearly marked and segregated until it can be properly dealt with, which typically involves replacement, not repair.

Which of the following elements is MOST essential for ensuring metrological traceability on a calibration certificate for a piece of laboratory equipment?

Answer: Identification of the reference standards used and evidence of their traceability.

Metrological traceability is the unbroken chain of comparisons back to a national or international standard. A valid calibration certificate must identify the specific reference standards (e.g., serial numbers of reference masses) used to perform the calibration and state their traceability to a recognized body (like the National Research Council of Canada - NRC), thereby documenting a link in that chain.

A laboratory's primary reference balance is returned from an external calibration service with a certificate indicating an 'As-Found: Out-of-Tolerance' condition. According to standard quality procedures, what is the laboratory's MOST critical next step?

Answer: Assess the impact of the out-of-tolerance condition on all tests performed since the last valid calibration.

When equipment is found to be out-of-tolerance, the validity of all measurements made with that device since its last successful calibration is called into question. The laboratory must have a procedure to assess the impact of this non-conformance on previous test results and take appropriate corrective action, which may include re-testing or notifying clients if their results were affected.