146 



DONALD K. JOICE AND DEMOREST DAVENPORT 



circulating centrifugal pump for several 

 hours even though the sea- water intake is 

 temporarily interrupted by a low tide. 

 As the rising tide covers the filter unit the 

 suction from the venturi automatically re- 

 establishes the sea-water flow. The cen- 

 trifugal pump is protected from running 

 dry by a float switch in the head tank 

 which breaks the circuit in the event the 

 tank water level drops too low. 



The economy of the jet system stems 

 from its versatility of location. It can be 

 located considerably above the source 

 water level and still afford a reliable auto- 

 matic priming function. To have in- 

 stalled a centrifugal turbine pump, which, 

 budget permitting, would have been seri- 

 ously considered, the pump would have 

 had to be located at elevation 1.5, the 

 terminal level of the pipe from the filter 

 unit. Priming could have been assured 

 only by having the pmnp at this elevation, 

 w^hich is below the level of the ocean. 

 The higher comparative cost of this instal- 

 lation w^ould have developed from the 

 pump house itself. Instead of being 

 located in a frame structure on the shore 

 at elevation 9.0 as was the jet-pump 

 installation, the turbine pump would have 

 required a reinforced-concrete vault with 

 foundations at elevation —4.5. 



Although the simplicity of the jet-pump 



automatic priming and control system pre- 

 sents great advantages, in view of the 

 demands made upon it by the specific 

 environmental conditions, the relative in- 

 efficiency of its operation as compared to 

 a turbine pump should be considered. For 

 example, in the system exhibited in figure 

 1, a 10-horsepower motor for the jet-pump 

 system is required to deliver 30 gallons 

 per minute of ocean water, whereas a 1- 

 horsepower motor would accomplish the 

 same work with a direct turbine pumping 

 unit. This ratio of 10 to 1, if reflected in 

 electrical energy costs, becomes highly 

 significant in equipment that operates con- 

 tinuously. 



The above described system at present 

 serves a small temporary laboratory con- 

 taining approximately tw^enty 10-gallon 

 and eight 25-gallon aquariums. There are 

 three large table aquariums receiving run- 

 ning sea water in an outdoor installation. 



Building schedules call for a tenfold 

 expansion of present facilities in a perma- 

 nent building, partially funded by the Na- 

 tional Science Foundation, by Jmie of 

 1964. All laboratories will be provided 

 with running sea water. The sea-water 

 system of this new permanent plant will 

 be a modification of the present installa- 

 tion, employing multiple units of the same 

 filter box. 



