Abrasive fluids are typically categorised as those that can cause wear and erosion to other surfaces when in forced contact, usually due to the presence of solids. The hardness and size of the solids play a part in how abrasive a fluid, but so does the viscosity of the fluid itself. Thick liquids can cushion the presence of solids which can reduce their level of abrasion, meaning solids in water-based fluids can be the worst culprits. When handling these liquids, abrasion resistant pump technologies should be selected. Certain pump types such as gear and screw pumps are not good as abrasive liquid pumps, as they are unable to handle such fluids or solid content without significant wear and damage due to their tight clearances. Peristaltic, diaphragm and progressive cavity pumps on the other hand are often selected as the solution when an abrasion resistant pump is required, often in a larger size run at a lower speed to reduce the force and scale of erosion.