JFD B44771, Руководство по эксплуатации и обслуживанию

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14 OM131
Chapter 2 P1939-OM-131 R11
2.1 S
YSTEM
D
ESCRIPTION
A schematic diagram of the SLS System is shown in Fig 2.1. As the diver exhales, gas passes via
the diver's mouthpiece through the Helmet Interface Assembly and is directed by the check valves
through an insulated hose to the Backpack. It then passes through the CO
2
scrubber canister and
up through the thermal regenerator into the counterlungs. The thermal regenerator removes and
stores the heat from the warm gas.
As the diver inhales, the now cold gas passes back through the thermal regenerator and picks up
the stored heat. The gas then passes up through a second insulated hose assembly and back into
the diver’s mouthpiece via the Helmet interface assembly.
The oxygen make-up to the SLS System is provided by means of a constant bleed of oxygen rich
gas from storage cylinders located at the base of the Backpack. This gas bleed mixes with the
exhaled gas at the inlet to the CO
2
scrubber and will maintain a safe oxygen partial pressure within
the SLS System at all times. The gas is supplied from the gas cylinders through a two-stage
regulator to the injection orifice which regulates the flow rate.
During normal diving operations the SLS System is worn in stand-by mode with the mouthpiece
retracted within the Helmet interface assembly. The counterlungs are mounted one on each of the
diver’s shoulders’ and are stored packed in strong fabric enclosures to protect them from damage.
Water ingress into the SLS System, whilst in its stand-by mode, is prevented by positively
pressurising the breathing circuit. A single stage regulator, set at 138 mbar (2 psi) supplies this
positive pressure. The regulator obtains its gas from the diver’s main umbilical via a connection on
the Helmet sideblock assembly.
The overpressure valve ensures that this pressure can never exceed 172 mbar (2.5 psi) above
ambient pressure. Visual indication of this overpressure is provided by means of the overpressure
indicator, which changes from green to red if a significant loss of pressure occurs.
N
OTE
The overpressure within the SLS System will vary slightly as a diver excurts up or down (138 mbar
(between 2.0 psi) and 172 mbar (2.5 psi)) and this may cause a temporary change to the Rotowink
until the umbilical gas (single stage) regulator injects enough gas.
The hot water supply to the diver’s primary demand regulator shroud heater is directed through the
SLS System Backpack. This water jacket surrounds the CO
2
scrubber housing and keeps the
chemical absorbent warm and ready to start work when needed. The outlet from this jacket is
positioned at the top of the backpack and from here the hot water is normally connected to the
helmet.
It should be noted that the diver's primary demand regulator will normally require a shroud heater
when diving deeper than 180 msw. A hot water supply to the SLS System Backpack is required at
all diving depths.
Should a situation occur during normal diving operations which requires activation of the SLS
System, it may be brought into use by two actions, as follows:
1. The interface valve on the right hand side of the Helmet has to be rotated through 180
o
. This
action pushes the mouthpiece into the Helmet oral / nasal, where the diver can bite onto it.
2. The actuation handle on the harness has to be pulled. This allows the counterlungs to deploy
and also pulls a spool valve, which switches on the bleed for the enriched gas make-up.
N
OTE
If the actuation handle is not pulled the diver will run out of breathing gas as the system has now
became open circuit.