A fire pump is designed to suck up a carp from the pond, cook it down to bouillabaisse in a locked rotor condition and send it on down the line when the impeller frees up.
LOL, Greg. And Testa's more serious explanation makes a lot of sense. Put the fire out!!
Thanks to all for the answers, and it's good to be able to run stuff by such a collective mass of experience and knowledge---both from the engineering and tradesman's side of things. Ken