Mordem Aro

Database Italian Oxygen rebreathers

Mordem ARO

Designed by Demetrio, the MORDEM’s owner. The new scuba diving technique uses oxygen only. This technique allows you to dive for some hours in a safe way with simple equipment. More complex equipment (heavier and more expensive),  using a gas mixture whose main component is oxygen, allow you to dive at bigger depht.
ARO Mordem is suitable for scuba diving at small depht for about 3 hours without decompression. ARO MORDEM is the best solution for scuba diving schools , for taking pictures, for boat maintenance (check of the hull), etc,…
The first oxygen breathing apparatus have been used during World War 2 and since then no particular improvements have been implemented.
The 2 main features of ARO Mordem are:
– The automatic opening closing of the mouthpiece
– The soda lime located in an appropriate container externally to the lung bag.

ARO MORDEM can be easily assembled and disassembled without any tool. We suggest to check the equipment before diving:

Breathe at least for 1 minute clenching your teeth (in order to open the white pellet) and try a  few times to empty out the lung bag.

Configuration

ARO MORDEM is composed by:

  • tank
  • valve
  • filter
  • mouthpiece

The tank contains 2 litres of oxygen at 200 atm. The valve is controlled by a light pressure on the knob (with the left hand). In the lung bag the ‘’ already breathed ‘’ air is mixed with the oxygen supplied by the valve. The lung bag is shielded by a transparent container and its capacity is 6 litres.
You have to clean the lung bag every 5/10 minutes:

–  Breathe in all the air contained in the lung bag and breathe out with your nose
–  afterward fill the lung bag with oxygen pressing the valve’s knob.
The filter is composed by 2 bags (0.5 kg. Each) filled with soda lime (easy to replace)
The filter rigenerates the ‘’ already breathed ‘’ air recovering the oxygen and eliminating the residual gas.
It is very easy to check the status of the filter; it changes its colour while exhausting..
The mouthpiece opens automatically when you put it in the mouth and closes automatically when you take it off.

ARO MORDEM is very silent and does not make any bubbles.
Only one airflow pipe links the filter to the mouthpiece.
(also available a configuration with 2 pipes; in this case you can put it on your shoulders)
ARO MORDEM weighs only 7 Kg. and is floating; therefore in order to dive with it you need a ballast.
ARO MORDEM  is cheaper and lighter than  a complete equipment (like ARA)
For your safety use the MORDEM RAFT : tether to it with a 10 mt. lanyard.

ATTENTION

Hyperoxia: too much oxygen when diving below 10 mt; you can faint
Hypoxia: lack of oxygen; fill the lung bag with oxygen.
Lung Bag Cleaning: Change often the air , breathing in from the mouthpiece and breathing out with your nose or with your mouth.
Afterward fill the bag with oxygen.

Good Morning, I was a friend of MORdem DEMetrio, ARO. I send more pictures of the unit and a nice picture of the two of us before the last dive of his life. A few months later MORDEM lost life through a heart problem.
Sincerely Alfonso Gangemi, Scuola Subacquea Laudense Organization Manager

Information about the Mordem Aro was kindly offered by alfonso.gangemi1959@gmail.com

Thank you very much Alfonso!

Mordem Oxygen rebreather template

ModelDateAuthor
Mordem Aro11-5-2019JW. Bech
ManufacturerMordemDemetrio Morabito
ModelAro
Country of originItaly
Design Year50's
Production yearsunit was last build in 2003The years known this model was produced
Breathing typePendulumDual hose or Pendulum
User groupCivilCivil / Military
Other name used for this modelMordem
Working PrincipleManual additionConstantmass flow, Manual addition, Valve operated, On demand, Electronic
GasOxygen
Cylinder volume2 liters
Max cylinder pressure200 bar
Cylinder materialsteel
Loop volume6 liter
LongtypeSingleSingle/Dual
Scrubbersize2x500 gram
ScrubbertypeRadialAxial/Radial
Scrubber volume1 kgs
Factory adviced scrubber medium-
Divetime duration-
Operating temperature-
Magnetic signaturemagneticMagentic/
Nonmagentic
Weight on land
Weight in water
Factory advised maximum operating depth
ColorBlack, acrylic
WornFront, chestFront/Back/Both
Mouthpiece styleAutomatic open in the mouth, closes when taken out of the mouthFixed/ with valve / with position to ambient air
Additional info 1
Additional info 2
Additional info 3
Infosource
Thanks toAlfonso Gangemi
Revision date11-5-2019

Video of Sea Hunt where the Mordem Spearguns were used

JW

Therebreathersite was founded by Jan Willem Bech in 1999. After a diving career of many years, he decided to start technical diving in 1999. He immediately noticed that at that time there was almost no website that contained the history of closed breathing systems. The start for the website led to a huge collection that offered about 1,300 pages of information until 2019. In 2019, a fresh start was made with the website now freely available online for everyone. Therebreathersite is a source of information for divers, researchers, technicians and students. I hope you enjoy browsing the content!