Author/Editor     Mekjavić, IB; Morariu, GI
Title     Ventilation requirements within wet submersibles
Type     članek
Source     Ocean Eng
Vol. and No.     Letnik 18, št. 4
Publication year     1991
Volume     str. 317-27
Language     eng
Abstract     The efficacy of an air delivery system to maintain PCO2 levels within acceptable limits in the cockpit of a commercially wet submersible was evaluated under simulated diving conditions in hyperbaric chamber. Sixteen subjects were compressed, in pairs, successively to 4.55 and 2.73 ATA in a mock-up cockpit of a commercially available wet submersible capable of two-diver occupancy; the duration of the sojourn at each pressure was 15 min. The accumulation of CO2 with time indicate that an equilibrium level of 0.025 +- 0.004 ATA was reached at both isobaric conditions, for this particular submersible. Thus, for the particular dive protocol simulated, at the air delivery system was capable of maintaining the cockpit PCO2 level at the maximum recommended level (0.025 ATA). A prediction equation, derived to simulate the CO2 accumulation in the cockpit under dynamic conditions, estimated the actual asymptotic value of PCO2 for the dive simulations to be 0.54 ATA (at t=eternity). Thus designing an air delivery system based on steady-state parameters only, and disregarding the transient component of CO2 accumulation, results in high cockpit ventilation requirements. This will result in unrealistic short dives, due to the limited on-board air supply of most wet submersibles. In contrast, accounting for the transiet component of CO2 accumulation decreases the cockpit ventilation requirement, and thus enhances dive duration. Until specific requrements regarding parameters of life support systems for wet submersibles are regulated, the latter approach may lead to dangerous consequnces, unless each particular submersible design is tested for efficent operation and crew safety.
Descriptors     DIVING
VENTILATION
ADULT
CARBON DIOXIDE