1. Technological Solutions to Chronic Hypoxia Amongst Aviators
Gp Capt (Retd) Dr V N Jha; Sc F
MBBS, AMD, MD
DEBEL, DRDO, Bangalore, India

3. Hypoxia amongst Aviators
Hypoxia defined as inadequate supply of oxygen at tissue level.
Increasing altitudes adversely affects:-
Night visual Fn beyond 4-5Kft AMSL
Novel Task Fn
Cognitive Fn,
Skilled task Fn,
Physical performance,
Effects of dysbarysm beyond 18Kft.
Life sustenance becomes difficult beyond 20Kft.

4. Hypoxia amongst Aviators
By Defn, Hypoxia is prevalent in almost all aviation flights exceeding 4-5kft cabin altitude. Standard acceptable values varies:-
Aircrew Night Ops without O2 <5000 ft
Aircrew Day Ops <10000 ft
Aircrew Day Ops <12000 ft (for <30 min)
No Std acceptable values laid down for acclimatised aircrew.

6. The requirements of supplemental O2
Aviation standards mandate usage of supplemental oxygen for aircrew above ft AMSL to prevent hypoxia whether ‘acute’ or ‘acute-on-chronic’.
Oxygen systems for aircrew mandate the requirement of a technology that provides sea level oxygenation and is approved by appropriate Certification Agencies.

7. Aviation Breathing systems
Helicopter Oxygen System
Consists of following LRUs:-
Oxygen gas source :GASOX/LOX/OBOGS/Chemical
Breathing regulator:-
Continuous flow or demand type.
With or without dilution function.
With or without pressure breathing functions
Personal equipment connector
Oxygen mask
Hoses and connectors

8. Integrated Life Support System of Fighters

9. Oxygen Gas Source LOX system consists of :-
GASOX system Consists of :-
High / Low Pressure cylinder: Steel / Aluminum / Composite
Reducer Head
Aviation Std Oxygen gas
LOX system consists of :-
LOX & its converter
OBOGS consists of air separation technologies:-
PSA through MSOC (single / dual stage)
Hollow Fiber membrane (HFM)
Ceramic membrane
Chemical Oxygen from Na/K Chlorate, Super-oxide

10. Pressure Reducer Valve
It reduces the service pressure of the high pressure cylinder to a value required for the optimum functioning of the DDOR hence, it is design specific.
It is also designed to meet the specific flow & pressure requirements of the DDOR.
Apart from charging & output ports, it has pressure gauge, safety valve and an on-off switch.
Various design specs available:

11. Performance Tests : HPOS11

12. Oxygen Gas Aviation grade O2 to be used. Mil-PRF-27210G (Type-I)
Purity >99.5%; -Moisture <7 ppm vapour
CO2 <10 ppm -Methane <50 ppm
N2O <4 ppm -Ethane <6 ppm
Filter 10 & 40 micron nominal & absolute.
No discernable odour.

13. DDOR : The requirements
Prevent hypoxia upto specified altitude.
O2% raised up to 100% by Kft.
Provide PBA beyond Kft.
Provide gas flow with minimal resistance, within the specified limits of physiological requirements.
Provide 100% O2 breathing option.
Flow indication to be provided.
Redundancy for gas supply in pneumatic failure.
Provide safety pressure breathing.

14. Performance Tests : DDOR14

16. DEBEL DDORs Dilution Demand Oxy Regulator (DDOR).
Man / Harness clipped.
Low Pr Br Regulator (2.8 bar).
Performance meets Defence Std & Mil-R-6018C.
Has ‘Air Mix’ and 100% modes of breathing.
DDOR certified for Hptr upto ft AMSL.

17. DEBEL DDOR Aircraft mounted DDOR. Low Pr Br Regulator (2.8 bar).
Performance meets Defence Std & Mil-R-6018C.
Has ‘Air Mix’, 100% and Emergency modes of breathing with safety pressure.
It has electronic flow sensor imparting night O2 capability.

18. Performance Tests : Flexible hoses

19. Performance Tests : PMA
Passengers’ Mask 19

20. Hptr Oxy Systems in diff configurations
Mod-A
Hose
PBC
HPOS
Passengers’ Mask
DDOR 20

22. HELICOPTER OXYGEN SYSTEM
OXYGEN MASK
DILUTION DEMAND OXYGEN REGULATOR
SEAT SIDE
INSTRUMENT PANEL SIDE
OXYGEN HOSES
CARBON COMPOSITE CYLINDER
PRESSURE REDUCING VALVE

23. Actual Flight Trials
Ground trials of fitment & interface – Satisfactory.
In-flight trials – Satisfactory
In-flight sPO2 upto 18kft in air-mix mode -99%
Extensive flight trials carried out over 6 months and accepted for introduction in services.

25. conclusion
Aviators are always at the risk of ‘acute’ or ‘acute-on-chronic‘ hypoxia in-flight.
Supplemental oxygen is mandatory for flights above ft AMSL thru’ dedicated systems.
The systems consist of high Pr O2 gas source, a Pr reducer, a breathing regulator and delivery sys.
Aviation Oxygen Systems are specially certified.
DEBEL has successfully designed and developed the oxygen systems which in various configurations, can sustain aircrew operations within large envelop of aircraft Ops.

26. Thank you