![](https://2.bp.blogspot.com/-v5Ff9ViUKs4/WaFZpHG8bOI/AAAAAAAAN14/9VEDxIueXroLL4Jc9nbR1BFGJfEhq6lIgCPcBGAYYCw/s1600/pumps_acid.jpg)
the casing, the impeller and the seals.
In the case of pumps which have to handle corrosive substances such as slurries, acids and alkalis, the wetted parts are covered by a protective layer made of special plastic. These protective layers can be replaced during maintenance.