|Åkes' AGA Dual Oxymatic
The AGA Dual Oxymatic is a
closed circuit oxygen rebreather, O2 CCR. The Oxymatix was
developed in the late 1950's by the Swedish company AGA, nowadays known as
Interspiro, well known for full face
masks and the rebreathers DCSC and Oxydive. The rebreather was designed as a
competitor to the Draeger Norge II as a possible successor to the Draeger Lt
Lund II used by the combat swimmer teams in the Swedish Navy. A total number
of about 50 units were manufactured in 1960 and all but three were destroyed
in the mid 1960's.
The design of the Oxymatic was partly based on the work on a
counter weight balanced breathing bellows developed by Dr's Måns Arborelius
and Claes Lundgren in the mid 1950's, see their patents
listed far below after the pictures. Their idea was to use a weight acting
upon a back mounted hinged bellows, thus compensating for the negative
hydrostatic imbalance, see figure below.
The combat swimmers at that time, i.e. mid 1950 - mid 1960,
used the UK designed midget submarine Spiggen as a transport vehicle for
their operations and the size of the rebreather was critical for the
successful lock-out and lock-in from and into the submarine. The Oxymatic is
rumoured to have been beaten by the Draeger Norge II during the field trials
primarily due to the smaller size of the Norge II and thus easier exit from
the small cramped wet/dry lockout chamber of the Spiggen.
The Spiggen, "the Stickleback", was an XE class midget
(XE-51) that nowadays can be found on display on Duxford Airforce base
outside Oxford, UK. The XE class was the successor of the very successful X
class of Tirpitz and operation Source fame. The nasty saying among the old
divers is that the combat swimmer teams operating from the Spiggen were so
successful in embarrassing the officers of the large surface ships that the
Spiggen was sold back to the UK to get a stop of that. It is also sometimes
said that their success is the reason why the surface fleet "forgot" the
midget submarine threat and that is explains the lack of technology and
expertise to hunt midget submarines obvious in the early 1980's.
The AGA dual oxymatic can be seen as the unknown ancestor of
both the later Interspiro designs
and several features can be seen in an early development version, for
the weight compensated bellows (ACSC/DCSC)
the bellows volume controlled dump valve ACSC/(DCSC)
the (volume) adjustable demand valve (Oxydive)
the low positioning of the scrubber canister (Oxydive)
In the pictures below two units are shown, one prototype
(the one with the cut bellows and orange harness) and one 0-series product.
Both units are owned by the Swedish Historical Diving Society (see www.shdf.se) and the author hereby
expresses his gratitude for the opportunity to photograph the units. I am
also in dept to Mr Imre Botos at Interspiro and Mr Rolf Craftman (involved
in the field trials) for information and anecdotes about the units.