Evaluation of Carleton Technology Incorporated Mouthpiece Utilized in LAR V UBA with Two Grades of Sofnolime CO2 Absorbent

One of the major contributions to the breathing resistance of underwater breathing apparatus (UBA) is the mouthpiece. Recently, Carleton Technology, Inc. supplied NEDU with a modified mouthpiece for evaluation. Reduced breathing resistance was obtained using the Carleton Technology mouthpiece in the MK 16 MOD 0 UBA. NEDU evaluated breathing resistance of the Carleton mouthpiece and standard MK 16 UBA breathing h fitted to the LAR V UBA using 4-8 mesh (2.5-5.0 m) and 8-12 mesh (1.0-2.5 m) Sofnolime C02 absorbent (Molecular Products, United Kingdom), comparing it to the standard Draeger LAR V mouthpiece using 4-8 mesh Sofnolime. Using Sofnolime 4-8 mesh absorbent, the Carleton mouthpiece reduced overall breathing resistance in the LAR V UBA 31.5 percent, and 20.4 percent when 8-12 mesh Sofnolime was used. These findings support the future use of smaller C02 absorbent mesh sizes in the LAR V UBA, using the enhanced canister equipped with a modified absorbent retaining screen, in combination with the Carleton mouthpiece. This would allow Longer canister durations yet simultaneously provide tower breathing resistance to the diver.