OM111 5
P1972-OM-367 Rev 6 Chapter 2
CHAPTER 2 INTRODUCTION
The Divex Ultralite 2 mask is an anthropological oral/nasal based breathing system for use
by persons using a hyperbaric chamber. It is for use with breathable diving quality gases
such as pure oxygen, breathing quality oil free air and heliox (helium and oxygen) gas in a
hyperbaric diving chamber to depths down to 450 msw. The choice of gas to be breathed will
be dictated by diving table’s outwith the scope of this manual.
The following table shows which gases are technically acceptable for the mask at various
depths:
Heliox gas can be used at any working depth down to 450 msw, provided the partial pressure
of oxygen (PPO2) within the Heliox mixture, is within acceptable limits.
The mask has been designed to provide “overboard dump” i.e. exhausting the exhaled
breath to the outside of the chamber at atmospheric pressure and has been designed to
safely accept exhaust below chamber ambient pressure on its exhaust hose equivalent to –4
barg. It’s nominal design working suction, however, is –2 barg and hence at depths deeper
than 20 msw, the chamber system should be fitted with a back pressure regulator (BPR)
capable of maintaining the –2 barg suction at the required exhaled flowrate.
To prevent exhaust hose from collapsing when not in use, an inward relieving 3 barg relief
valve should be fitted between the exhaust hose and the BPR. Examples of setup
configurations are shown in ANNEX A (page 19).
The design supply pressure for the mask can range from 6 barg to 16 barg over the chamber
ambient pressure.
The Ultralite 2 mask has been designed to meet the Norwegian Petroleum Directorate’s
(NPD) work of breathing and respiratory pressures at all breathing rates to 62.5 litre/min
RMV from 3 msw to 450 msw. The mask can be used on the surface where it meets NPD
requirements up to 22.5 litre/min RMV and up to 40 litre/min RMV at 2 msw.
The Ultralite 2 mask can be supplied with or without diver communications.
The only difference between these variants is the communications cable assembly attached
to the supply hose. This manual details both variants.
This manual provides information for the user only, servicing and routine maintenance is
covered in detail in the “Service Manual for the Ultralite 2 Overboard Dump Diving Chamber
Breathing Mask” – document number OM079.
GAS DEPTH RANGE (MSW)
Oxygen 0-20
Breathing Quality Oil Free Air 0-50
Heliox 0-450
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