Pump and medium circulation apparatus

摘要

A pump has a rotor made of synthetic resin in a fixed housing which are adjacently arranged while forming a gap between the housing and the rotor to force-feed a medium containing water moisture, in which the rotor is made of a resol-type synthetic resin so that a dimensional change rate of the rotor is 0.15% or less for a medium having a moisture content rate of 10 wt% or less, whereby a sufficient pump performance can be obtained while relatively increasing the degree of freedom of the moisture content rate of the medium to reduce the corrosiveness of the medium.