The happy zone

Now wc can see the iniporraiiee of rlie eoneenrrie ellipses of effieieney on the pump family eurve. As mueh as possible we should find a pump whose primary effieieney are eovers the needs of the system. Certainly the needs of the system should fall within the seeond or third effieieney ares around the pump s REP. If the system s needs require the pump to eonsistently run too far to the left or right extremes on its eurve, it may be best to eonsider pumps in parallel, or series, or a eombinarion of the two, or some other arrangement, possibly a PD pump. We ll see this later. 

As elevations ehange in the proeess of draining one tank and filling another, the pump moves on its eurve from one elevation extreme to the other. If we ve selected the right pump for the system, it will move from one extreme of its happy zone, through the RHP to the other extreme. 

This is the beginning of many problems with pumps. A pump is sf d with at one set of system coordinates. Then the system (the TDH) goe mi and the pump moves on its curve away from its BEP out to one or the oth( i It is necessary to determir- i -num and minimum tions in the design the pump within these elev ions. If the system continues to pump, you ll either have to modify t ... /stem or modify or change the pu.-you really like to change bearin, . .d seals. 

The system s AHp should tall within the pump s primary or. secondary sweet zone. At the beginning of the operation, with the cold reactor vessel, the pump operates to the right of the BEP but within the. sweet zone, and as the reactor ve.s.sel is heated, the pump migrates on its curve toward the left, crossing the BEP, to the other extreme of its sweet zone. When the reaction is completed and the tank cools, the pump 

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