This part of ISO 8655 specifies — metrological requirements, — maximum permissible errors, — requirements for marking and — information to be provided for users, for dilutors with a sample uptake capacity (In) from to and a diluent capacity (Ex) from to . They are designed to deliver the sample and diluent together in measured proportion and measured volume. NOTE General requirements and definitions of terms for piston-operated volumetric apparatus are given in ISO 8655-1. Conformity testing (type evaluation) of piston-operated volumetric apparatus is given in ISO 8655-6. Alternative test methods such as photometric and titrimetric methods will be the subject of a future Part 7 to ISO 8655. For all other tests (e.g. quality assurance by the supplier, analytical and measuring equipment quality assurance by the user) see ISO 8655-6 or alternative test methods. For safety requirements of electrically powered piston dilutors, see IEC 61010-1.