Limited Unmanned Evaluation of the DIVEX SLS MK IV Backpack at Sea Level and 1000 FSW

Abstract

Resistive efforts, inhalation gas temperatures, and carbon dioxide (CO2) canister and bottle durations were measured from two Secondary Life Support (SLS) system MK IV backpacks attached to the SLS helmet (Divex, LTD) in simulated conditions. Resistive effort at 0 feet of seawater (fsw) was assessed at three different backpack orientations (0 degrees, 45 degrees, 90 degrees), and all of the dependent measures were assessed at depth (1000 fsw) at the 45 degree orientation. A breathing simulator maintained a respiratory minute volume (RMV) of 62.5 liters per minute (L/min) throughout testing. As anticipated, breathing resistance at 0 fsw increased as backpack orientation was adjusted from 0 to 90 degrees, and breathing resistance was greater at 1000 fsw than at 0 fsw. The increase in breathing resistance at depth is not expected to preclude human use. Measured CO2 canister and bottle durations were no less than 12.7 (0.5percent surface equivalent value [SEV]) and 22.4 minutes, respectively, and mean inhalation gas temperature was 69.5 degrees F. Results from these limited simulations indicate that the SLS MK IV backpack and helmet are safe for controlled man testing and are expected to provide sufficient secondary life support for a saturation diver to return to a diving bell at 1000 fsw.