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Hypobaric Systems

Analox have many years experience in providing atmosphere monitoring equipment for use in hyperbaric chambers.  This technology can also be used in hypobaric chambers, typically used as flight simulators and for training purposes for flight crews.

A hypobaric chamber is very similar in construction to a hyperbaric chamber in that it is sealed.  The difference occurs in the operation, where a hyperbaric chamber positively pressurises, the hypobaric chamber negatively pressurises.  The chambers are used to simulate high altitude conditions by removing the atmosphere.

Typically modern aircraft such as airliners fly at altitudes of 30 to 40,000ft where military aircraft such as fast jets fly at altitudes of 15 to 25,000ft.  The hypobaric chamber is used to train pilots and aircrew to recognise the effects of hypoxia. This is caused when there is insufficient oxygen in the atmosphere.  The effects range from disorientation, inability to concentrate or even carry out simple tasks and can lead to unconsciousness and in extreme cases death.  By training the pilots and aircrew in a controlled environment they can experience the early stages of hypoxia that they would experience at those altitudes in the event of a sudden and rapid loss of cabin pressure.

While the pilots undergo this training they are breathing pure oxygen this is undertaken for a period before the training commences to help reduce the risks of decompression sickness more commonly known as the bends in diving circles.  Pilots experience what it is like to be exposed to a hypoxic atmosphere and what physical effects they can expect to experience.  This is all carried out in a controlled and safe manner.

The chambers are manned both internally and externally.  However, like a hyperbaric chamber once the training has started the chamber can not be entered until the internal and external atmospheres are the same.  It could therefore be some time before anyone would  be able to gain access to the inside of the chamber in an emergency situation should something go wrong.

Typically hypobaric chambers are set up in the same configuration as hyperbaric chambers with the exception that the training is done over a much shorter period (say 2 to 4 hours) where a hyperbaric chamber can be occupied for many days and in the case of a SAT diving systems weeks.

Prior to entering the chamber and during the simulated flight the aircrew being tested are breathing 100% oxygen.   Analox has a range of analysers including the new SDA that can be employed to monitor this supply for purity.  Using a Paramag sensor the SDA can monitor the purity of the oxygen in the feed line ensuring a consistent supply of 100% O2 to help prevent decompression sickness when training for rapid decompression.

The internal chamber atmosphere should be monitored for O2 as a means of fire prevention.  The following Analox equipment can be supplied.

  • Sub MkIIIF
  • Sub Aspida.  For use by the attending staff 
  • Both the Sub Aspida and the Sub MkIIIF contain a sensor that will continue working up to an altitude of 55,000ft.

 

The Sub MkIIIF can be configured with either a single REM 1 in the case of a single chamber or with 2 REM 1’s for a double chamber.

Or with a REM 1 and a REM 2

The climate inside the chamber is subject to fluctuations in temperature and humidity whilst the pilot training is carried out. Configuring the Sub MkIIIF with a REM 2 will help monitor these fluctuations’.

The Sub MkIIIF is a tried and tested unit that has been employed around the world to monitor the atmosphere inside hyperbaric chambers. Using the REM modules both the operator and the staff inside the chamber can monitor oxygen, carbon dioxide, temperature, pressure and humidity.  The Sub MkIIIF has a serial output so that data can be exported to a computer for analysis. 

For internal analysis Analox can offer the Sub MkIIIF as a fixed atmosphere monitoring system to monitor the O2 and CO2 as well as temperature and relative humidity inside the chamber during training.  

Analox also offer the Sub Aspida that can be worn by the training staff to monitor for increased O2 levels as they move around the chamber, to a maximum working altitude of 55,000ft.

Due to the nature of the hypobaric chamber external sampling of the atmosphere for monitoring is difficult and expensive where as monitoring the internal atmosphere can be achieved more cost effectively using existing Analox products reconfigured for the task.