CPV code 51230000 designates Installation services of testing equipment in the Common Procurement Vocabulary (CPV 2008), the EU classification used to describe the subject of public contracts.
51230000 is a leaf code — the most specific level of its branch — so it can be used directly as the main CPV code of a contract notice. If it does not quite fit, check the neighbouring codes under 51200000 (Installation services of equipment for measuring, checking, testing and navigating).