Centrifugal Pump Components, Functions, Working

   Some of the most common components found in centrifugal pumps are wearing rings, stuffing boxes, packing, and lantern rings.

Impeller

> It is a wheel or rotor which is provided with a series of backward curved blades or vanes

> It is mounted on the shaft which is coupled to a motor which impart the liquid energy to the impeller there by making it rotate. 

Casing (Volute) 

> The casing contains the liquid and acts as a pressure containment vessel that directs the flow of liquid in and out of the centrifugal pump.

> The volute is a curved funnel that increases in area as it aproches the discharge port.

Wear rings

> Wearing rings are replaceable rings that are attached to the impeller and/or the pump casing to allow a small running clearance between the impeller and the pump casing without causing wear of the actual impeller or pump casing material. 

>  Centrifugal pumps contain rotating impellers within stationary pump casings. 

> To allow the impeller to rotate freely within the pump casing, a small clearance is designed to be maintained between the impeller and the pump casing.

>  To maximize the efficiency of a centrifugal pump, it is necessary to minimize the amount of liquid leaking through this clearance from the high pressure or discharge side of the pump back to the low pressure or suction side.

>  Wearing rings are designed to be replaced periodically during the life of a pump and prevent the more costly replacement of the impeller or the casing.

 

Must Read:> Why Discharge valve closed During Starting Of Centrifugal Pump

Stuffing box 
> One of the simplest types of shaft seal is the stuffing box.

> The stuffing box is a cylindrical space in the pump casing surrounding the shaft. > Rings of packing material are placed in this space. Packing is material in the form of rings or strands that is placed in the stuffing box to form a seal to control the rate of leakage along the shaft. The packing rings are held in place by a gland. 

> Stuffing boxes are normally designed to allow a small amount of controlled leakage along the shaft to provide lubrication and cooling to the packing. 

> The leakage rate can be adjusted by tightening and loosening the packing gland. 

Lantern Ring

  A lantern ring is a perforated hollow ring located near the center of the packing box that receives relatively cool, clean liquid from either the discharge of the pump or from an external source and distributes the liquid uniformly around the shaft to provide lubrication and cooling. The fluid entering the lantern ring can cool the shaft and packing,

Mechanical Seals 
   If packing material is not adequate for sealing the shaft. Mechanical seals are used as an alternative method for sealing the shaft. Mechanical seals consist of two basic parts, a rotating element attached to the pump shaft and a stationary element attached to the pump casing. Each of these elements has a highly polished sealing surface. The polished faces of the rotating and stationary elements come into contact with each other to form a seal that prevents leakage along the shaft.

Working

 The rotatory motion of the impeller drives the fluid to the outside of the

You can answer following questions

  Fluid flows from areas of high pressure to areas of low pressure. Pump operate by creating low pressure at the inlet which allows the liquid to be pushed into the pump by atmospheric or head pressure.

You can answer following Questions

> What is Lantern Ring?

> Use of wear rings How it affect efficiency of pump

> Different parts of centrifugal pump