WEAR RINGS

  WEAR RINGWEAR RINGS

wear rings 

The pump case is used to contain and direct the spinning liquid and convert the velocity imparted by the impeller to pressure energy.  The pressure in the casing near the outer edge of the impeller will be higher than that at the suction eye of the impeller.  Because of this, it is inevitable that some liquid will be recirculating from the high-pressure zone to the low-pressure zone within the casing.  This leak must be minimized for two important reasons. 

 1. Increased rate of leak decreases the efficiency of the pump. 

 2. Causes wear to the impeller and casing, due to erosion. 

 Wear rings improve pump efficiency 

 This leakage is minimized by the use of impeller wear rings and casing wear rings.  The impeller wear rings rotate with the impeller and the casing wear rings are stationary.  Because the clearance between these two parts is very small, only a little leakage past them occurs. 

  Wear rings must not run dry 

 The small amount of liquid leaking acts as a lubricant and keeps the wear rings cool.  Any momentary loss of this source of lubricant allows the metal to expand by overheating and the pump will seize resulting in severe damage. 

 

Wear rings protect impeller and casing. Wear rings wear out over a period of service and the clearance increases resulting in a loss of the pump efficiency.  Therefore, they are designed to be replaceable and the cost is negligible when compared to replacement of an impeller and/or casing.