SALT-WATER SYSTEM AT ST. ANDREWS BIOLOGICAL STATION 



129 



Routine late-fall cleanout eliminates much 

 of the yearly accumulation of mussels and 

 silt. 



Condensation on pipes conducting cool 

 water throughout the laboratory is trou- 

 blesome, particularly during hot humid 

 weather. Aside from personal annoyance, 

 drip from overhead pipes on electrical 

 equipment is dangerous. Pipes distrib- 

 uted through laboratory areas should be 

 insulated. 



HEATING AND OTHER FACILITIES 



The heater system consists of a standard 

 heating boiler of the horizontal return 

 tube type, fired by a thermostatically con- 

 trolled oil burner. The fresh-water boiler 

 output feeds into the shell of the heat ex- 

 change. Heat is transferred to salt water 

 contained within stainless-steel (type 316) 

 heat-exchange tubes. The salt water leav- 

 ing the exchanger is heated to 180° F. 

 This 180° F. salt water is in turn mixed 

 with cool sea water by means of an auto- 

 matic motorized 3-way valve to produce 

 salt water at 85° F. for distribution to the 

 laboratories. The system has the capacity 

 to heat 20 gallons per minute of salt water 

 from 32° F. to 85° F. (fig. 2). Required 

 temperatures at the experimental tanks 

 are controlled by blending hot (85° F. 

 water) and cool sea water to achieve the 

 desired temperatures. 



Thermoregulators 



Thermoregulators, relays, and small 

 pumps for either hot or cool sea water are 

 used on individual tanks to overcome tem- 

 perature fluctuations resulting from slight 

 changes in flow, changes in room tempera- 

 ture, and changes in temperature of the 

 cool sea water. By this means, it is possi- 

 ble to control temperatures to within 

 0.2° F. in tanks of 100- to 200-gallon ca- 

 pacity without insulation. This system 

 eliminates the use of dangerous electrical 

 immersion heaters. 



Aeration 



Two interconnected 5-horsepower De- 

 Vilbiss air compressors supply compressed 

 air for aeration of the water in individual 

 tanks. Copper piping distributes the 

 compressed air around the laboratories. 

 To avoid carryover of any toxic metal 

 ions, an expansion valve at the outlet of 

 the compressor dries the air as it leaves 

 the compressor. Additional drying tubes 

 can be fitted to individual outlets when 

 necessary. Compressed air is distributed 

 in the experimental tanks with "air clif- 

 fuser" or "air breaker stones." 



Refrigeration 



Special facilities to refrigerate salt 

 water have not yet been acquired. Low 

 temperatures are obtained naturally dur- 

 ing the winter months. Some individual 

 tanks are maintained in a controlled- 

 temperature walk-in cold room. With no 

 flow of water through tanks in the cold 

 room, the water is aerated to maintain 

 suitable oxygen content. A small portable 

 refrigeration unit w4th a stainless-steel 

 cooling coil is used to cool single experi- 

 mental tanks. 



Reduced salinity 



When required, reduced salinities are 

 obtained for individual experimental 

 tanks by mixing suitable constant flows of 

 salt and fresh water. 



Filtration 



AVhen required, filters with disposable 

 cellulose cartridges are used on the water 

 supply to individual tanks. 



SPECIAL PROBLEMS 



Electrical-power or equipment failure 

 has been anticipated at St. Andrews. 

 Auxiliary generating equipment has not 

 been installed to date but a gasoline-driven 

 emergency pump and a standby electric 

 pump are available. In addition, the res- 

 ervoir has sufficient capacity to maintain 

 flows of water to the experimental and 



