We must not forget that the serpent is a water to water heat exchanger device whereas the charge air cooler is a water to air temp reducer device. I have never heard of a serpent called a charge air cooler. DW, your tell tale holes reminds me of torpedo tube drillings, by opening the cock if no water came out then the tube was empty of water.Sadly many lives were lost through this device as blockages in the drill holes concealed the fact that the outer door was open and by opening the inner door seawater at terrific pressure entered the torpedo room and whole subs have been lost as a result of a blocked drilling. Reports I have read depicted crew closing the torpedo room door thereby sealing the fate of crew in the torpedo room in order to prevent the ship from sinking. Best stick to surface ships methinks.
Remembering The Good Old days, when Chiefs stood watches and all Torque settings were F.T.