PRACTICAL SUGGESTIONS FOR CONSTRUCTION 

 AND MAINTENANCE OF LARGE-VOLUME 

 SEA-WATER SYSTEMS 



By John T. Hughes, Marine Biologist 



Massachusetts Division oF Marine Fisheries, Vineyard Haven, Mass. 



Abstract. — A brief description is given of a sea-water supply system in use in a 

 lobster hatchery and research station in a region wliere the winters are severe. Two 

 electrically driven pumps supply a maximum of 900 gallons per minute to an overhead 

 tank holding 15,000 gallons. The water flows by gravity to station aquariums. Thirty- 

 four concise suggestions are presented to allay problems of fouling, siltation, equipment 

 breakdown, and toxicity. 



The CommoiiAvealth of Massachusetts 

 built a sea-water system in 1948 to supply 

 water to the new lobster hatchery and re- 

 search station located in Oak Bluffs on the 

 island of Martha's Vineyard. The salt- 

 water system supplying the station con- 

 sists of two 450-gallons-per-minute cast- 

 iron centrifugal pumps, each with its own 

 6-inch plastic suction line and cross-valved 

 so that both pumps can use either suction 

 line. The suction lines are approximately 

 400 feet long lying on the bottom of the 

 sea, with the foot valve supported 5 feet 

 off the bottom in 10 feet of water. The 

 foot valves are kept off the bottom by lash- 

 ing them to pilings, the tops of which are 

 below the surface of the water at the lowest 

 tide level in order to prevent the ice from 

 moving them in the winter. 



Just before the suction lines enter the 

 pumps, each line has a basket strainer to 

 catch mussels or other fouling organisms 

 which might plug the pump impeller. 

 The pumps alternate in filling the storage 

 tank when the water level drops 3 feet. 



Contribution No. 10 of the Division of Marine 

 Fisheries, Massachusetts Department of Natural 

 Resources, Boston, Mass. 



The pumps are electrically driven; one 

 pump is made so that it can be coupled to 

 an auxiliary gasoline engine. The water 

 is pumped into a cylindrical 15,000-gallon 

 steel tank which is supported 15 feet off 

 the ground. The water then passes to the 

 station by gravity through a 6-inch pipe 

 from which 2-inch lines lead to the various 

 tank systems. 



The following is a list of methods and 

 features which are suggested, on the basis 

 of our experience, to combat problems, 

 such as fouling, siltation, equipment 

 breakdown, and toxicity of components. 



1. After one has carefully figured out 

 what size pipe and pump will be necessary 

 to supply sea water to an installation, 

 double the size of everything. 



2. Install one more pump than is neces- 

 sary to take care of all possible emergen- 

 cies. 



3. Have a separate suction line for each 

 pump and have each suction line cross- 

 valved (with good high-pressure valves) 

 so that any suction line may be used with 

 any pump. 



4. Use plastic pipe for suction and dis- 

 charge lines. Use no pipe with copper. 



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