Deposits

In contrast to surface or protective layers, deposits are unwanted effects which impinge upon the values necessary for optimum operation of the centrifugal pump. 

Examples of deposits

• By corrosion products
• By salts (e.g. carbonates, sulphates, phosphates) due to a chemical imbalance (see water hardness,  pH value) 
• By precipitation of dissolved salts from the evaporation of water (e.g. on shaft seals
• By colloids (particles dispersed in another substance) or coarsely dispersed substances (which are not, or only slightly, dissolved in or chemically bonded with each other)
• By sand (see Erosion)
• Fouling (e.g. algae, bacteria) in sedimentation, brackish water and seawater tanks