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The Dry Deck Shelter (DDS) is a hyperbaric system used on submarines to transport SEAL delivery vehicles into an operating area. The system uses diver quality air (DQA) air from submarine banks to ventilate the DDS and provide breathing air to the divers, as well as for other diving operations. Currently approved procedures employ three instruments to check the quality of air prior to diver use on SSGN and VIRGINIA class submarines: (1) the TVA-1000B toxic vapor analyzer (Thermo Fisher Scientific, Franklin, MA) with both a photoionization detector (PID) and flame ionization detector (FID) to screen for volatile inorganic and organic contaminants, (2) the current Geotech HB 1.2A hyperbaric CO2/O2 analyzer (Geotechnical Instruments, Leamington Spa, UK) to measure CO2, and (3) the ship's CAMS to measure O2, CO, and two refrigerants. The recent replacement of the TVA-1000B with the TVA2020 by the manufacturer now requires that the current procedures for screening DQA be revised. This report describes NEDUs evaluation of the TVA2020 for its acceptability as a replacement to the TVA-1000B, and NEDUs recommendations about incorporating the TVA2020 into any revised DQA procedures. Additional NEDU recommendations address the need for changes in the DQA procedures (1) due to the divers new breathing air standards in revision 7a of the U.S. Navy Diving Manual, (2) for use of the new Geotech hyperbaric monitor that is replacing the current Geotech HB 1.2A, and (3) to correct errors in the current procedures and improve the effectiveness of the screening process. NEDUs task of revising the DQA procedures was assisted by its review of past Air Purity Reports that have been completed by shipboard personnel using the current DQA screening procedures on SSGN and VIRGINIA class submarines.