JFD B44771, Operation And Maintenance Manual, Page: 23 / 136

OM131 11
P1939-OM-131 R11 Chapter 1
1.3.3 Carbon dioxide scrubbing / thermal performance
The thermal protection in the SLS System is provided by a combination of passive means and
recovery of the heat generated by the exothermic absorption of CO
2
in sodalime.
Thermal protection consists of:
a. Stored heat from hot-water system.
b. Thermal regeneration to prevent heat loss from gas in the counterlungs.
Fig 1.13 shows the inspired CO
2
level in the SLS System as a function of time when breathed at a
continuous 40 RMV (moderate work) at 400 msw on a breathing simulator. It may be seen that the
SLS System maintains gas within primary breathing system specification for a period well in excess
of the bottle endurance.
N
OTE
A constant supply of hot water to the hot water jacket significantly increases the duration and
efficiency of the scrubber and should always be used.
Fig 1.14 SLS system carbon dioxide levels endurance of the SLS system
The endurance of the SLS System is shown in Table 1.1. This shows the minimum time taken for
either the cylinders or the CO
2
scrubber canister to become depleted. It also shows the minimum
recommended cylinder charging pressures (to achieve 10 min. bailout is defined by NPD) at depths
between 50 msw and 400 msw.
N
OTE
At shallow depths there is no advantage in charging the cylinders to higher pressures.