130 



D. S. MANN, D. W. McLEESE, AND L. R. DAY 



storasre tanks for several lioiirs. Pro- 

 vided there is no electrical failure, animals 

 can be kept alive during breakdowns in the 

 pumping system by aeration in individual 

 tanks with compressed air. In an emer- 

 gency, the salt-water fire-fighting unit can 

 be used to maintain the required level of 

 sea water in the reservoir. 



Although two possible causes of super- 

 saturation with gases are eliminated in our 

 system by using a submersible pump and 

 avoiding air-cushion pressure tanks, 

 heated water from the furnace equipment 

 may be supersaturated at times. To over- 

 come this, equilibration columns are used 

 for individual tanks or groups of tanks. 

 Similar columns, using nitrogen from cyl- 

 inders of compressed gas, are used to pro- 

 vide water with a low content of dissolved 

 oxygen for special experiments. 



ALARMS 



At St. Andrews, an alarm system signals 

 when water levels in the reservoir fall be- 

 low a predetermined level indicating a 

 pump or waterline failure. A second 

 alarm system monitors water supply to 

 experimental tanks. Alarms at the tanks 

 can be at the discretion of the researcher. 

 At St. Andrews, alarms are incorporated 

 in an automatic, multipoint temperature- 

 recording system. 



SUMMARY 



At the present stage of evolution of the 

 salt-water system at the St. Andrews Sta- 

 tion, certain difficulties have been over- 

 come. 



Submersible pumps eliminate air leaks 

 at the suction end, a major cause of super- 

 saturation with gases. Except for the 

 aluminum and stainless steel in the pumps, 

 all metals have been eliminated by use of 

 plastic pipes and fittings. 



The reservoir tank provides an almost 

 constant pressure head and, in addition, 

 a reserve supply for several hours in case 

 of breakdown. 



Thermostatically controlled heated sea 

 water maintained by an oil-fired furnace 

 eliminates practically all potentially 

 dangerous electrical equipment in and 

 around the experimental tanks. 



Although compressed air for aeration 

 is distributed in copper pipes, an expan- 

 sion valve dries the air as it leaves the 

 compressor to eliminate possible carryover 

 of toxic metal ions. 



Design of the system for easy cleanout 

 helps to overcome difficulties arising from 

 clogging with mussels and silt. 



The system functions well at present, but 

 is not trouble free. Continued improve- 

 ment is required. 



A separate feed line from the reservoir 

 to the laboratories is planned to overcome 

 present surge difficulties. 



Greater duplication of the system is re- 

 quired, including greater attention to 

 placement details for readily accessible 

 shutoffs and convenient shunt lines. 



Partial filtration of the system is re- 

 quired to combat occasional heavy silting 

 caused by wave action on the beach or 

 heavy rains. As an alternative, relocation 

 of the intake into deeper offshore water 

 where there may be less silt is being 

 considered. 



All the water from the tanks runs to 

 waste. Although possibly desirable, the 

 furnace heater is not equipped with a 

 feedback system to conserve energy. 



Refrigeration of part of the supply is 

 desirable to extend the scope or flexibility 

 of the maintained environmental condi- 

 tions. 



Insulation of pipes, fittings, and tanks 

 would be an improvement for easier main- 

 tenance of required conditions, foi" con- 

 serving energy, and to increase the safety 

 standards of the establishment. 



Standby generating equipment is re- 

 quired to maintain basic facilities during 

 periods of power failure. 



