Re: coffin feedwater pump

I can't say if this is a turbine driven centrifugal pump or not, however I think that might be likely.
I can however try to explain how a centrifugal pump work. It's been a few years since I had to study this but here goes.
A centrifugal pump is little more than a spinning disk with ribs or vanes on it. The vanes are usually curved and the distance between them gets large at you move away from the center of the disk. The suction of the pump is at the center of the disk and discharge is on the outside. As the disk spins the spinning motion is imparted on the water and therefore the kenetic energy is increased.
As the water leaves the spinning disk it enter the volute part of the pump which is part of the casing. The volute curves around the disk and gets larger in diameter as it reaches discharge opening. This is how the water increases in pressure. As the water goes through the volute is slows down and increases in pressure as the area gets larger. This is the venturi principal in reverse. Effectivly the pump converts kenetic energy to potential energy in to form of pressure. Unlike a recriprocating pump a centrifugal pump will only work on liquids. A centrifugal pump often will not self-prime and therefore needs to be located below the liquid level, hence the reason the pump is low on the frame.
Hope this helps.
Aaron Zorko