Diving With The Divator Mkii Full Face Mask Formerly The Aga Full Face Mask

The Encyclopedia & Guide to Diving With a Full Face Mask is the first of its kind and gives a great deal of need to know information on virtually all the full face masks currently in production as well as those no longer being produced. The guide is packed with pictures and loaded with information presented in a way that can be easily understood by all from novice recreational, to technical, law enforcement, scientific, military and commercial divers. This guide is a must read for all divers that are contemplating using a full face masks, and especially for those currently using full face masks. The guide not only gives information on particular masks but also explains basic full face mask features, attributes, as well as the pros and conns . Matt has done an excellent job! Mike Ward President Dive Lab, Inc.

The Interspiro DP2 and Divator MK II UBAs with the Divator positive-pressure and nonpositive-pressure full face masks (FFMs) were evaluated as possible candidate UBAs for inclusion on the Authorised for Navy Use (ANU) List. Resistive effort (RE) evaluations were conducted in 38 F fresh water and 29 F salt water. A free-flow evaluation - in which one FFM was breathed with a Reimers breathing simulator while a second FFM was allowed to free flow to determine whether it would degrade the RE of a second diver's FFM - was conducted for the DP2. With 1500 and 500 psig breathing gas supply pressures, the Divator MK II scuba met the Navy Experimental Diving Unit (NEDU) RE goal of 1.37 kPa at 62.5 L/min for Category 1 UBAs to a depth of 132 fsw with both the positive-pressure and nonpositive-pressure FFMs. With a 1500 psig breathing gas supply pressure, the DP2 met the NEDU goal of 1.76 kPa at 62.5 L/min for Category 2 UBAs to a depth of 198 fsw in 38 F water with the positive-pressure and nonpositive-pressure FFMs. At 29 F this goal was met to 198 fsw with the nonpositive-pressure FFM and to 165 fsw with the positive-pressure FFM.

NEDU tested the utility and effectiveness of a modification to a second stage diaphragm retainer ring on the MK 24 Full Face Mask (FFM). The modification was designed to reduce regulator chatter without requiring an increase in second stage cracking pressure. The modification was tested with the FFM being used with both the Emergency Breathing System I (EBS I), and the EBS II. Regulator chatter was quantified by Total Narmonic Distortion (THD). TND was found to be inversely correlated with depth, and in most cases directly correlated with Respiratory Minute Volume (RMV). Therefore, chatter is expected to be the worst when a diver is shallow and breathing hard. At shallow depths where chatter is the greatest, the combination of the modified retainer with normal cracking pressure consistently resulted in lower chatter than did the Standard diaphragm retainer with an increased cracking pressure. This was true for both the EBS I and the EBS II.

The volume of oxygen used and resulting oxygen partial pressure (P202) were determined when Current predive/surface and underwater purge procedures for the U.S. Navy MK 25 MOD 2 underwater breathing apparatus were performed with the KMS 48 face mask (Kirby Morgan Dive Systems; Santa Barbara, CA). A secondary purpose was to determine maximum pulmonary pressure (max Pmask) during ascent. Regardless of mouthpiece (T-bit or oral cup) used, purges performed at surface and 15 fsw yielded mean P202 exceeding 0.65 ATA. Purges at the surface and 15 fsw averaged less than 4.7 and 8.5 liters of oxygen, respectively. Regardless of mouthpiece the proportion of purges resulting in P202 greater than or equal 0.45 ATA exceeded 94.0% and 91.8% at the surface and 15 fsw, respectively. Average max P(mask) during ascent was less than 21 cm H20 with the T-bit and 20 H2O with the oral cup. The proportion of ascents in which max P(mask) is less than 80 cm H2O was greater than 91.7% regardless of mouthpiece. Average max P(mask) during ascent from 50 fsw was less than 39 cm H2O with the T-hit and 22 H2O with the oral cup. The proportion of ascents where max P(mask) is less than 80 cm B2O was between 69.9% and 100% with either mouthpiece. Current purge procedures performed with the KMS 48 mask provide acceptable initial breathing gas P202. However, regardless of mouthpiece, it is recommended that divers always start ascent with a mostly empty breathing bag to decrease risk of pulmonary overpressurization as gas expands.