Regarding the timing of instrument calibration

Equipment needs to be calibrated for two reasons: 1. It generates test data on its own. 2. Its operating status affects the final test data. Calibration is divided into mandatory calibration and self-calibration. Most devices that generate test data are **subject to mandatory inspection, which goes without saying. Self-calibration is further divided into two types: 1. Instruments (including glass measuring devices) that, according to the Technical Supervision Bureau, are required to undergo mandatory calibration, are calibrated in a self-calibration manner. It is necessary to establish a testing quality system within the organization; upon approval and issuance of a certificate by the Technical Supervision Bureau, self-inspection can be carried out, which is equivalent to having authorization from the Technical Supervision Bureau. 2. There are **no calibration procedures available; the Technical Supervision Bureau cannot provide calibration services either. One must establish its own calibration protocols, which are generally based on the evaluation methods provided by the instrument manufacturers. Such protocols are recognized by the Technical Supervision Bureau, and no registration is required. During certification, an oral explanation to the assessors is sufficient (requirements may vary from one Technical Supervision Bureau to another, so it is advisable to consult the assessors in advance). Self-calibration method verification: 1. When based on external technical documents and materials, it is essentially the same as the verification for using non-standard methods ； 2. For self-developed methods, they are prepared in accordance with the procedures for drafting technical documents, by persons with technical expertise, who are responsible for their preparation, review, approval, and subsequent implementation. After it is prepared, try to arrange a comparison to verify it, so as to be more convincing during the review. Methods must have a technical or theoretical basis. Refer to the formatting style of the calibration specification. The equipment used in the calibration should be calibrated or consist of certified reference materials to ensure that the measurement values can be traced back to a standard. Personnel performing self-calibration must have certificates, with the same requirements as those for calibration personnel

Reply to 2# dalian*aochao: I’m asking out of curiosity – is it a real profile picture? Then they asked: I work in instrument calibration, but I’m new to this field, so I’d like to know the general situation – do all instruments that are subject to mandatory inspection need to be sent to a metrology authority for testing?

Reply to 3# iamsharing: Yes, it’s genuine. Further, it must be inspected/calibrated by a **metrology department or a calibration institution authorized by such a department**; there is a list of items that are subject to mandatory inspection