Reliable measurements cannot be achieved without appropriate measuring instruments. The range of measurement, resolution capability, and operating conditions must be compatible with the characteristics of the object being measured, rather than simply ensuring that the instrument can display values.

Suitability is more important than the name of the equipment

When selecting a measuring instrument, we should consider the characteristics of the object being measured and the conditions under which it will be used. The range of measurement, method of contact, resolution capability, and measurement technique all play a role in the results obtained. A high precision of the equipment does not mean that reliable data can always be obtained under any circumstances or on any piece of equipment.

The relationship between calibration and daily use

Calibration information helps us understand the performance of the instrument under specific conditions. However, it is still important to monitor the status of the instrument during regular use. After an instrument has been subjected to abnormal impacts, maintenance, or has been left unused for a long time, its suitability should be re-evaluated according to management requirements. It is not enough to just check the date on the label.

Daily management should include records of the instrument’s identification, effective status, and operating environment. Equipment that has experienced abnormal impacts, drift, or decreased accuracy should be evaluated for its impact on previous measurement results.

Establishing a connection between the instrument and the results

Keeping the instrument number recorded in key measurement records helps in identifying the affected products when an abnormality is detected. Without this information, it becomes difficult to determine which results need to be rechecked, potentially leading to unnecessary extensive rework.

Understanding measurement uncertainty

The reliability of measurement results depends on the equipment, environment, personnel, and methods used. Measurement traceability focuses on establishing a scientifically supported relationship between measurement results and reference standards, rather than simply having a certificate. Results that are close to the limit of accuracy should be handled according to established rules.

Process example: Analysis of the impact after detecting an abnormality in an instrument

Assuming that a measuring instrument is found to be abnormal during inspection, we can first identify the products it has been used on and the time range in which these measurements were taken. Based on the nature of the abnormality, we can then decide whether further verification is necessary. If the instrument number is not recorded, it may be difficult to accurately determine the scope of the problem. Therefore, keeping a small amount of relevant information during regular use can help reduce unnecessary repeated inspections when abnormalities occur, and also allow for prioritization of those results that truly require attention.

Common questions: Does having a valid certificate mean that no pre-use inspections are required?

The certificate provides information about the calibration activities performed on the instrument. However, the state of the instrument can change over time. Regular checks and proper use are essential to ensure that the information on the certificate remains valid in actual measurements.

Key points for verification during implementation

• Instrument suitability
• Effective status
• Abnormalities can be traced back
• Clear decision-making rules

When there are disputes over measurement data, using standardized methods and conditions is usually the starting point for rechecking. If necessary, further evaluation should be conducted by qualified personnel.

Further reading：NIST: Metrological traceability and measurement results