Can somebody please explain me the Pros and Cons of Self-priming Centrifugal Pumps,,,, and its advantage over Regular centrifugal model pumps. Thanks in Advance

A self priming centrifugal pump has higher Suction Lift than a normal Centrifugal Pump. It can work even if the pump is not fully primed. It has lower efficiency.

Main advantage is that it can suck out the air from the suction pipeline. Selfpriming does not necessarily improve NPSH

It is ideal for emergency applications,no priming required

Self-priming pumps are used in applications where:
a) there is potential danger of losing prime, and
b) when you are in a high suction lift condition.

I don't see any pros and cons actually. It depends on the application..... Is it needed or not ? Self-priming pumps are more expensive to regular end-suction due to the casing size. If not needed, there is no economic sense to use it.

Thank you all for your valuable points,,,, I just heard that using of Self-priming centrifugal was recommended more for flammable liquids and paper Industries, was it True??? If yes what is the specific reason for that????

I am not aware of any reason why selfpriming pumps would be used more for flammabe liquids and paper industry.... only if priming is required by itself.
Sometimes you have stripping systems but that is different.

In a flooded application there is no advantage in using a self priming pump unless other aspects of that pump are advantageous for your application (such as solids handling). In lift applications a self priming pump will prime and reprime without the use of a foot valve, something a standard centrif simply cannot do. The advantages to this are that you no longer lose lift due to overcoming the foot valve losses, and you dont need to worry about the foot valve plugging with solids.

In my experience with Gorman Rupp pumps I have found that sometimes their trash pumps are used in flooded applications due to the solids handling and ease of maintenance. Since Gorman Rupp also offer a line of self priming pumps with materials suitable for pumping fuel it is entirely reasonable that somebody who has had experience with Gorman Rupps has made a very generic recommendation to you without considering the details of your application. It is also possible that the recommendation was based on a comparison with submersible pumps.

My suggestion is to review the details of your specific application and determine what is important and choose a pump style accordingly.

Will there be cavitation problem

Well Mr.Damir, the fact is that am too not sure of that point but just heard that self priming Cent.pump is more safer than regular in such flammable areas,,,, I don't even know that whether this one too a real fact r not,,,, but just thought someone can give clarification over this matter (If there is any such)

If a standard Centrifugal Pump looses priming then it will heat up and inflammable liquid may catch fire. A Self-Priming Centrifugal Pump is not likely to loose priming and hence the hazard of inflammable liquid catching fire due to heating up of pump will be eliminated.