Regular inspection of test sieves ensures that they, especially when under constant use, remain compliant with the standard for which they were manufactured and provides additional confidence in constant and reliable screening results, minimizing deviations and allowing for reproducible sieving results over an extended period.

When using test sieves as measuring instruments, operators are obligated under a number of standards, laws and regulations to periodically inspect their sieves – either through visual inspection in house to detect any larger irregularities or through detailed optical inspection using norm-compliant instrumentation. Defined as measuring instruments in ISO 3310, test sieves are subject of national laws governing technical and legal metrology (e.g. Bundesgesetz über das Messwesen MessG in Germany & Switzerland, MEG in Austria) as well as quality assurance regulations such as ISO 9001. Additionally, when used for specialized applications, test sieves and their operation is subject to requirements and guidelines of various agencies (e.g. grain sieves are subject of regulations imposed by government intervention boards).

Generally, under the legal terms of the majority of metrology laws, test sieves – when employed as measuring instruments in a legal sense – are to be “inspected regularly,” though the periods between inspections and the nature of the inspections themselves is left to the discretion of the operator. According to ISO 9001, an inspection is needed “at regular intervals or prior to use” whereas internal inspection by the operator or re-certification by an authorized entity are both permissible. For grain sieves, many regulations call for a mandatory annual re-certification (ref. German Federal Office for Agriculture and Food).