1. What is a pump ? What are its applications ?
Ans. Pump is a device which adds energy to the fluid which is used transfer fluids from one place to another .
Ans. Pump is a device which adds energy to the fluid which is used transfer fluids from one place to another .
It is used to transfer sea water , fresh water , fuel such as diesel , hfo , lubricating oil, hydraulic oil which is essential for auxiliary purposes.
2. What is the classification of pump?
Ans. There are two types of pumps .
A. Positive displacement pump
B. Rotodynamic pump.
Ans. There are two types of pumps .
A. Positive displacement pump
B. Rotodynamic pump.
3. What is the difference between these two pumps?
Ans.
Postive Displacement Pump
A. Displacement of fluid is achieved by mechanical variation in the volume .
B. Capableof handling with small quantity of fluid with high pressure .
C.Energy addition is periodic.
D. Self priming pump.
E. Displacement of fluid will results in increase in pressure.
Rotodynamic pump
A. Kinetic Energy is added with the help of rotating impeller.
B. Capable of handling large quantity of fluid with relatively low pressure .
C.Energy addition to the fluid is continuous .
D. Priming is required.
E. Increase in kinetic energy of the fluid will be results in increase of pressure through volute casing.
Ans.
Postive Displacement Pump
A. Displacement of fluid is achieved by mechanical variation in the volume .
B. Capableof handling with small quantity of fluid with high pressure .
C.Energy addition is periodic.
D. Self priming pump.
E. Displacement of fluid will results in increase in pressure.
Rotodynamic pump
A. Kinetic Energy is added with the help of rotating impeller.
B. Capable of handling large quantity of fluid with relatively low pressure .
C.Energy addition to the fluid is continuous .
D. Priming is required.
E. Increase in kinetic energy of the fluid will be results in increase of pressure through volute casing.
4. What is priming ?
Ans .Priming is the process in which impeller of the centrifugal pump get fully immerged in liquid without any air trap inside.
Ans .Priming is the process in which impeller of the centrifugal pump get fully immerged in liquid without any air trap inside.
Required
a. when suction is below the pump position and depends on the lift of the pump (NPSH).
why air is removed
air comes inside in the casing cause expansion and donot allow water to come inside and hence during priming air is removed from the pump.
a. when suction is below the pump position and depends on the lift of the pump (NPSH).
why air is removed
air comes inside in the casing cause expansion and donot allow water to come inside and hence during priming air is removed from the pump.
5. What is cavitation ?
Ans. It is the phenomenon in which bubbles formation , cavities formation happens in low pressure area of impeller due to drop in absolute pressure of liquid below its vapor pressure . the imploding or collapsing of bubbles trigger the intense shock waves which will damage the impeller and pump housing .
There are teo types of cavitation
a. Suction cavitation
b.Discharge cavitation
a. Suction cavitation - when pressure in the suction side reduces or in the high vacuum codition when rpm is very high , pump starvs the fluid and in the vacuum region bubbles explodes .
b. Discharge cavitation - it happens when pressure in the discharge side is very high when efficiency of pump reduces by 10% can cause difficulty for fluid discharge and hence fluid moves inside the pump with very high velocity can cause impeller shaft to break.
Symptoms
noisy pump
Cause
a. Clogged filter and strainer
b. blockage in the pipe
c. higher rpm of the impeller
d. liquid is volatile
e. high temperature of the fluid
f. poor pipe design
g. poor suction conditions (NPSH)
Effects
a. Failure of pump housing
b. destruction of impeller
c. Excessive vibration leads to bearing failure and seal defects
d. Higher power consumption
e. lower flow rate/pressure
Remedies
Prevention is better than cure ,
a. prevent clogging ,check the filters and strainers in the suction and discharge side to reduce unnecessary pressure
b.check the pump performance by means of flow meter and pressure guage match it with the curve of manufacturer.
c.ensure the path of fluid i ideal for the pump design .
Source: E-learning (Dg website)
https://blog.craneengineering.net/what-is-pump-cavitation
Ans. It is the phenomenon in which bubbles formation , cavities formation happens in low pressure area of impeller due to drop in absolute pressure of liquid below its vapor pressure . the imploding or collapsing of bubbles trigger the intense shock waves which will damage the impeller and pump housing .
There are teo types of cavitation
a. Suction cavitation
b.Discharge cavitation
a. Suction cavitation - when pressure in the suction side reduces or in the high vacuum codition when rpm is very high , pump starvs the fluid and in the vacuum region bubbles explodes .
b. Discharge cavitation - it happens when pressure in the discharge side is very high when efficiency of pump reduces by 10% can cause difficulty for fluid discharge and hence fluid moves inside the pump with very high velocity can cause impeller shaft to break.
Symptoms
noisy pump
Cause
a. Clogged filter and strainer
b. blockage in the pipe
c. higher rpm of the impeller
d. liquid is volatile
e. high temperature of the fluid
f. poor pipe design
g. poor suction conditions (NPSH)
Effects
a. Failure of pump housing
b. destruction of impeller
c. Excessive vibration leads to bearing failure and seal defects
d. Higher power consumption
e. lower flow rate/pressure
Remedies
Prevention is better than cure ,
a. prevent clogging ,check the filters and strainers in the suction and discharge side to reduce unnecessary pressure
b.check the pump performance by means of flow meter and pressure guage match it with the curve of manufacturer.
c.ensure the path of fluid i ideal for the pump design .
Source: E-learning (Dg website)
https://blog.craneengineering.net/what-is-pump-cavitation
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