Diving For Science 2005 Proceedings Of The American

pO2, Ata
2.00
1.80
1.60
1.40
1.20
1.00
0.80
0.60
0.40
0.20
Diving For Science 2005 Proceedings Of The American Academy Of Underwater Sciences
22.5 Lpm
Pure O2
MK25 and
CSCR-190 (closed)
62.5 Lpm
Comparison of Circuit Oxygen Levels
0.00
0.00 20.00 40.00 60.00 80.00 100.00 120.00 140.00 160.00 180.00 200.00
Resistive Breathing Effort (WOB)
Depth, FSW
38
CSCR-190 (semiclosed)
MK 16
Open circuit
(air)
Figure 5: Comparison of circuit oxygen levels in the CSCR 190 (EVR = 10, 28% oxygen makeup gas, and
17 slpm shallow water injection between 0-30 FSW) with the MK 25 Closed Circuit Rebreather, the MK
16 Closed Circuit Rebreather, and open circuit SCUBA with air.
Additionally, Figures 6 and 7 show that the mechanically-coupled CSCR 190, a semi-closed
rebreather, has breathing resistances comparable to the MK 16, an electronically controlled,
closed circuit rebreather. Although Figure 6 shows that the WOB values exceed the NEDU
guidelines established by NEDU Test Standard 01-94 at depths beyond 33 FSW, they are
comparable to the MK16 (Figure 7).
Canister Duration
Table 2 summarizes the results of canister duration tests conducted on the CSCR 190 at
depths of 25 FSW in the closed circuit mode and 66 FSW in the semi-closed circuit mode.
Axial and radial flow canisters were evaluated with both 4-8 Sofnolime and 8-12 Sofnolime.
Figure 8 shows that the axial canister consistently out performed the radial flow canister at
both depths tested. It should be noted however that most, if not all, of this performance
enhancement could be attributed to the additional absorbent weight available when using the
axial canister.