PUMPS - QUESTION AND ANSWERS

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 PUMPS - QUESTION AND ANSWERS

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1). WHAT IS MEANT BY PUMPING? 

• Pumping is a addition of energy to a fluid to move it one point to another and not, as is frequently thought in a addition of pressure. Since energy is capacity to do work, the addition of energy to a fluid causes it do work such as following thorough a pipe or rising to a higher level.  In the closely allied field of centrifugal compressors,  "pumping" Describe on unstable surging that occurs in many compressors as a partial capacity. 

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2). WHAT IS CENTRIFUGAL PUMP? 

• It is one that employs Centrifugal force for pumping liquids. Liquid coming in at the center (eye) impeller is picked up by the vanes And accelerate to the high velocity by the rotation of the impeller and thrown out by centrifugal force into an annular channel, or volute and to the discharge, as indicated. 

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3). WHAT ARE THE ESSENTIAL STRUCTURAL ELEMENT OF CENTRIFUGAL PUMP? 

• A centrifugal pump as a technical system consists of the following major structural sub- systems: the impeller blades, the discs of the impeller, the body, the discharge nozzle, and the suction nozzle.

4). HOW WAS CENTRIFUGAL PUMP CLASSIFIED? 

5). WHAT IS VOLUTE TYPE CENTRIFUGAL PUMP? 

• A pump named from it's spiral - volute from of casing which acts as a collector for the fluid discharged by the impeller. Wall T, divided the beginning of the volute and the discharge nozzle,  is called the "volute tongue" Or "cut water"

6).  WHAT IS DIFFUSER TYPE CENTRIFUGAL PUMP? 

• In this pump diffuser vanes converts the velocity energy imparted to the liquid by the impeller to the pressure energy. The diffuser vanes assembly is known as the "diffuser". 

7). WHAT IS SINGLE STAGE PUMP? 

• It is one in which the total head is developed by a Single impeller

8). WHAT IS MULTISTAGE PUMP? 

• It is total head required too high for single impeller to produce,  two or more impellers may be used in series, the second impeller taking it's suction from the discharge of the 1 st impeller.  If all impellers acting in series are in a single casing, the pump is a multi design. 

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9). WHAT IS BI-ROTOR PUMP? 

• Bi-rotor and even tri-rotor designs were fairly common in the early development of centrifugal pumps. This pumps were in effect, two one-half or three one- third capacity pumps in one casing,  operating in parallel. 

10). WHAT IS SINGLE SUCTION IMPELLER? 

• It is one In which the liquid pumped enters the impeller from one side. 

11). WHAT IS DOUBLE SUCTION IMPELLER? 

• It is in effect two single suction impellers cast back to back so that liquid enters the impeller simultaneously from both sides. Normally the suction chambers one at each side of the impellers connect to a common suction passage and nozzle. Some large pumps have two separate suction passage and nozzle connected to opposite sides of a double suction impeller. 
• This construction was used in a early development of double suction pumps for unit quite small in size. 

12). WHAT IS STRAIGHT VANE IMPELLER? 

• It is one in which tha vane Surfaces are generated by straight Lines Parallel to the axis of rotation.  Vane of this design is also called "single-curvature vane"

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13). WHAT IS FRANCIS VANE IMPELLER? 

• Its vane surface have a double curvature,  and it is called "Francis screw vane" or "screw vane" impeller. 

14). WHAT IS PROPELLER OR AXIAL FLOW IMPELLER? 

• It is one having a flow solely parallel to the axis of rotation in other words strictly axial

15). WHAT IS AN OVERHUNG IMPELLER? 

• If the IMPELLER is supported by bearing on one side only and shaft does not extend beyond the suction side of the impeller hub it is called overhung impeller. The design makes possible the end suction pump. 

16). WHAT IS SUCTION EYE OF AN IMPELLER? 

• The inlet just before the point where the vanes start it is called the "suction eye". In a closed impeller pump the diameter of the suction eye is the taken As the smallest diameter of the shroud. 

• When determining the area of the suction eye, deduct that occupied the impeller hub. 

17). WHAT IS CASING WEARING RING? 

• Sometime called an "impeller guide ring". It is inserted in a pump casing to protect the latter from wear. 

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18). WHAT IS AN IMPELLER WEAR RING? 

• To protect the impeller from wear at its running joint within a casing or casing ring, it is fitted with a removable ring called an "impeller wear ring".

19). WHAT IS FLAT WEAR RING? 

• It is a design in which leakage joint is a straight annual clearance. This type of ring has been replace extensively by l shaped and labyrinth designs. 

20). WHAT IS AN INTERMESHING RING? 

• A labyrinth ring with two annual clearance joints of different diameters involving a reversal of flow is often called "intermeshing ring"

21). WHAT IS DYNAMIC BALANCE? 

• A pump rotor is dynamic balance if all the various centrifugal forces resulting from it's rotation balance each other. Such rotor runs at full speed without vibration. 

22). WHAT IS STATIC BALANCE? 

• A pump rotor is static balance if  when supported an parallel and level knife edges or their Equivalent.  It will remain Stationary in any position in which it may be placed. 

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23). WHAT IS MEANT BY RIGID AND FLEXIBLE SHAFT? 

• A rigid shaft has a first critical speed higher than it's operating speed. 

• A flexible shaft has a operating speed higher than it's critical speed

24). WHAT IS A PUMP BOWL? 

• In vertical turbine pump and propeller pump practice, the bowl is the stationary part containing the diffusion vanes. 

25). WHAT IS INTER STAGE OR DISTANCE, SLEEVE? 

• The sleeve that protects the shaft between the impellers of a multistage pump. In some designs impellers have long hubs that make distance sleeves unnecessary.