Filler is a general term used to describe an organic, non-metallic or metallic powder added to resins. They can extend material for cost reduction and/or enhance the material's mechanical properties.

Talc and calcium carbonate are soft fillers commonly used as extensions in materials. These fillers, or ones similar to them, can generally be used in pumping equipment of standard construction (mild steel hard chromed).

Silica and alumina (aluminum oxide) are fillers usually added to materials to enhance mechanical or thermal properties. These types of fillers often require special pump construction of nitrided steel or silicon carbide (ceramic) due to their hardness, physical size and/or shape.

A scale that measures the hardness of a material by its ability to indent or scratch another material was introduced in 1812 by Friedrich Mobs, a German mineralogist. The Mohs' Scale for minerals is arranged in a scale from 1 to 10, with I being the softest and 10 being the hardest. The Knoop Scale was developed as another method to determine hardness of a greater variety of materials.

Both the Mobs' Scale and the Knoop Scale provide important information concerning hardness of fillers as they relate to various pump materials of construction or other materials.

The charts below provide data on various fillers that affect the construction of pumping equipment. For specific recommendations on pump construction for a particular material, contact Liquid Control's Technical Service Department.