Pumps handle various applications with different types of fluids. When fluid enters pump, depending upon type of impeller of pump & rotation of the shaft, fluid is discharged. Discharge pressure pushes fluid back into pump & there might be leakage of material through rotating drive shaft. Spillage of toxic or expensive fluid incurs costs & also damage shaft & bearing. Nowadays companies are adopting zero spillage policy to reduce losses. This is reason why pumps require sealing.
Using different packing materials is the simplest & cost effective way to prevent leakage. However maintenance is high and leakage is more compared to mechanical seals. Packing however can be used for handling corrosive material & aggressive fluids where packing will last longer mechanical seals will deteriorate fast. Packing is also easy to replace and install.
More effective sealing than packing is mechanical seals where fluid is critical & any spillage will be expensive. They have option of single or double mechanical sealing depending upon requirement. Initial cost of mechanical seal is high but it’s used when fluid is critical and reduction in spillage will save cost over long term. Mechanical seal increases overall life of pump as it prevents bearing failures and sleeve damage but replacing & installing them is not easy compared to packing.
Seal less Magnetic Drive Pumps:
Mechanical Seal requires small amount of fluid to be leaked providing lubrication to seal faces & this might leak outside. Mechanical Seal or Packing loses their effectiveness overtime as it wears out during usage. Seal less pumps uses magnetic field to rotate the impeller of the pump. Drive magnet attached at end of motor shaft rotates around rear housing and another magnet spins in synchronization on which impeller is fixed which rotates and pump is operated. There is no maintenance involved as seal isn’t present. It can be used for volatile and hazardous liquids. Initial cost is high compared to other sealing methods.
It is for the user to choose the right solution for sealing and increase pump’s lifespan & to save cost.