INTRODUCTION This Item presents conversion factors between sets of units in common use in pump engineering. It may be used with the other Items in the series which give guidance to the non-specialist on the selection of pumps. The other Items in the series are as follows: Radial@ mixed and axial-flow pumps. Introduction@ Item No. 80030 Radial@ mixed and axial-flow pumps. Size estimation and specification@ Item No. 80031 Radial@ mixed and axial-flow pumps. Glossary of terms@ Item No. 81001.