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.