A priori models in the testing of diving life support equipment

A priori models have been effectively used at the Navy Experimental Diving Unit (NEDU) to aid in the design of tests for diving equipment. These models are computer simulations conducted prior to the initial testing effort, using mechanistic models derived from first principles or based on prior testing. One example of such a model involves the freeze-up susceptibility of SCUBA regulators used in very cold water at depths to 58 msw (190 fsw). The influence of various dive profiles on the risk of regulator freeze-up was estimated for a variety of model parameters. In a second example, a simple model of CO2 canister duration was used to reveal the relative benefits of various competing diver work/rest profiles. The a priori modeling efforts helped NEDU define relatively efficient and unambiguous designs for testing diving equipment.