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 5 ¼l to 10 ml and a diluent capacity (Ex) from 50 ¼l to 100 ml. 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. The gravimetric reference measurement procedure for the determination of volume is given in ISO 8655-6. Alternative methods for the determination of volume are described in ISO 8655-7. For safety requirements of electrically powered dilutors, see regional or national safety standards.