Counter Lungs

ABEL Mark 5 Breathing Loop Review

There are two counter lungs generally of equal volume in the system, a "dirty" one and a "clean" one. The diver breathes out via the mouthpiece and hoses into the dirty lung and here any excess gas in the system is dumped through the vent valve. The dirty counter lung also forms the primary water trap, but please remember it is not a sink! From here gas is also fed to the clean lung via a third one way valve and scrubber, hence cleaned. In the clean lung additional gas is also added at a pre-set flow rate according to the Nitrox mix being used. The diver then breathes in again via mouthpiece and hoses from the clean lung and so continues the cycle.

C/ls sizes/volumes come in four standard sizes, 2.7, 3.1, 3.6 and 4 litres each. This then enables the most appropriate size to be selected on the basis of individual lung capacity and desired end system configuration.

The C/ls are made from a combination of extremely strong materials that are light in weight, abrasion resistant and have a low friction coefficient. This then keeps the breathing loop resistance to a minimum. The C/ls are secured with clips to the spine plate and cambuckle bands to the diving cylinders for single and twin set configuration. Since the C/ls are back/cylinder mounted, this then leaves the chest area free for tools etc. and also acts as a form of "wings" for swimming stability. Trim tabs are also fitted to the outer covers for final set buoyancy adjustments. The additional buoyancy provided by the counter lungs is countered by a ditchable ballast system that is contained in the spine plate. Once set up correctly, sets should be just positively buoyant by approximately 2kg when fully charged. If less absorbent material is used in the scrubber, additional weighting will be required.

Cleaning of counter lungs and breathing hoses is facilitated by the provision of a self sealing slider/zip arrangement at the bottom of each lung. Cleaning of the whole breathing loop only takes about 10 minutes!!