The initial calibration cycle of the equipment should refer to the verification rules or calibration specifications, or be determined by one or more persons with relevant measurement experience, instrument calibration experience, or knowledge of the calibration cycle of other test equipment. When determining the initial calibration cycle of the instrument, in addition to the metrological control rules/calibration conditions and methods to be used, the recommendations of the instrument manufacturer can also be referred to, and the following factors should be appropriately considered:

1. The expected range and frequency of use;

2. The influence of environmental conditions;

3. The uncertainty required for measurement;

4. The maximum allowable error;

5. Equipment adjustment (or modification);

6. Measurable influencing factors;

7. Summarized or published measurement data of the same or similar equipment.