Ballast Tank Flood 



This system vents the air from the end ballast tanks 

 to make the bathyscaph negatively buoyant. It is actuated 

 by manually operated valves located at each end of the 

 float. The valve consists of two parts: a mechanical stop 

 and a plunger-depressed valve disk. First, the stop is 

 opened and, when all diving preparations have been made, 

 upon command from the crew in the sphere the spring-loaded 

 plunger is depressed allowing air to vent from the end tanks. 

 The plungers are constructed with a cork wedge that allows 

 them to stay open until the buoyancy of the cork overcomes 

 the friction with which it is wedged into place, and the 

 valve closes. By this time the tanks have been completely 

 vented. Each ballast tank is fitted with a blow line which 

 is connected to a central manifold in the conning tower. 

 After surfacing from a dive, an air hose from the work 

 boat is connected to the manifold to blow these tanks; the 

 antechamber, also, can be blown by this system. 



Cathodic Protection 



The purpose of this system is to retard corrosion of 

 the metals of the float and its associated equipments. As 

 a result of its experimental mission, the craft utilizes 

 many metals and is therefore highly susceptible to corro- 

 sion due to galvanic action. Any loss of thickness of the 

 thin metal of the float would involve great reduction in 

 strength. Therefore, a protection system more efficient 

 than a paint film is essential. The system now installed 

 on TRIESTE is a passive one that uses a series of 40- 

 pound magnesium Cathanodes. * These Cathanodes gradually 

 deteriorate, depending on the amount of galvanic activity 

 that occurs. However, the set that was installed originally 

 on TRIESTE during the spring of 1959 has provided contin- 

 uous protection, is still in good order, and is still in use. 

 The system roughly corresponds to the circuit of a battery 

 in that the Cathanode may be considered as one plate of a 

 battery, the bathyscaph and its associated equipments as 

 the other plate, and sea water as the electrolyte. In the 

 Cathanode circuit is a variable resistance that can be 

 "tuned" to the required values. The values of current and 

 voltage can be read out on instruments inside the sphere. 

 This system has virtually prevented all external galvanic 

 deterioration of the craft below the waterline during the 

 past three years. 



* Patented name. 



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