Italian 02 Rebreather C-96

Diver Dave's ARO C-96 Teardown

OK, here's the good stuff on this excellent rebreather:

Overall view of the system.

The nicely padded neckstrap is attached by two Fastex fasteners. If you wanted to attach it to another type of harness, it would be easy.

The DSV looks remarkably similar to the Azimuth. That's because it's identical.

The DSV is likely the nicest DSV on the market at this time. The little tab allows it to be both opened and shut with one hand, without any possibility of biting through the mouthpiece. Why can't other manufacturers get this right?

DSV has a nice neckstrap attached, with small Fastex fasteners to allow it to be removed.

This is the left side of the system, showing the on/off valve, manual add button, and the gauge.

The gauge has a little cover to keep it retained in use, and to protect the face of the instrument.

The HP Gauge is of medium size, and good quality.

The cylinder is retained at the bottom of the rig by a Velcro flap, and two nylon straps. It's positive and simple.

Here's the 2 liter cylinder for scale. Calibrations are inches.

The 02 feed line to the rig is attached with an O-ring sealed fitting, attached with a finger tightened nut. No tools are needed to service of clean the rig.

This is the 02 feed line as it passes through the wall of the counterlung.

The 02 feed tee is on a swivel, and connects the 02 supply hose to the counterlung.

The 02 feed swivel also has a removable plug into which a second gas may be injected into the counterlung, bypassing the 02 injection valve.

Hmmm.......... The mind reels with possibilities!

My finger is on the manual 02 addition button of the valve. This is large enough to be used with cold fingers, and the pressure needed is just right, not too hard to be impossible with cold fingers, not so easy that it can be depressed inadvertently.

The cylinder is filled by removing the gauge, and filling through the port that is exposed. Filler fitting is identical to the other European rigs that I've seen, including the FGT-1D, Azimuth, AKA-60, and Lt. Lund.

The valve assembly is just that, a valve with HP port in, gauge and filling port, and 02 supply to the rig. The on/off valve is the green knob. Interestingly, there is no pressure reduction regulator. This makes for a very simple system that will require virtually no servicing.

What little servicing that may need to be done will be familiar to anyone who has ever serviced any normal SCUBA cylinder valve. Even the parts are the same as are on common SCUBA equipment. No special parts are used.

Two different cylinders are available, a 1.5 liter aluminum one, and a 2 liter steel one. I chose the 2 liter ones, since I was more interested in duration than I was in having a non-magnetic system.

Fill pressure is 200 BAR, with a 300 BAR test pressure.

To service the scrubber, the first step is to remove the breathing hose plenum. You can see how inhale and exhale gas is segregated. The plenum is removed by the central nut, which loosens the screw that is visible in the center of the plenum. Then the entire assembly simply is lifted and set aside.

Here's the top of the breathing plenum, showing how the gas is sent to and from the scrubber can. The bolt with the finger-grip at the bottom is how the plenum and hose-assembly is attached to the scrubber.

Once the hose plenum is removed, the scrubber is rotated 90 degrees and then is pulled through the mouth of the counterlung for filling. The black Delrin plug is the filler port. You don't fill it in-place, the scrubber is completely removed from the bag for servicing.

With the scrubber pulled from the unit, we can see the water absorbent pad.

Once the scrubber is removed, the water-pad can be removed and dried. This lays in the bottom of the counterlung to soak up that slime and dribble that we all produce.

Here's the scrubber removed for filling. It's rated at 3+ hours, using a 1.3 kilo load of powder. The scrubber itself is chrome-plated brass, just like the old Cressi ARO-57 one. In fact, the two parts are interchangeable.

Detail of the scrubber: The rows of ports for inhalation and exhalation can be seen on the flat face on the right. The perforated periphery of the cannister is open to the counterlung.

Detail of how it all fits together.

Here's the naked counterlung, which is made from a PVC impregnated fabric identical to that used in the construction of good quality inflatable boats. Repairs can be done with patches and Aquaseal. For durability in extreme conditions, a Kevlar outer cover can be fitted to protect the lung. This is a component of the Italian Navy C96-Pro, for military use. In addition, the Italian Navy uses an integrated weight-vest that the rig simply snaps to for rapid donning and doffing.

On the side of the counterlung exactly opposite the 02 feed line, there is a reinforced area for attaching other items. An Oxygauge port would fit here nicely, as would an alternative gas-feed valve of any sort. This opens up an entire realm of possibilities for modification.

For conversion to a Nitrox CCR (or bailout rebreather), I'd add a drysuit inflation valve to that reinforced area and feed it with diluent from a small cylinder. Add PP02 monitoring and you'll be all set.

The prize for most highly modified C-96 must go to our good friend Conrad Daubanton, who is shown here with his nitrox-enabled rig. Conrad uses back-worn gas to feed the front-mounted counterlung, and has had good success with his system. Here's a quote that was sent with the photo:

""I had finished a rather short dive in a shallow cave on the northeastern coast of Spain, between L'Estartit and L'Escala. It was the unit's first dive in modified version, and yes, I had enough bailout: a 6 litre 300 bar cylinder. I don't look too happy because some #@*+?·"&!! was messy with his fins and silted out the cave basically spoiling what would have been a nicer dive. The rig is a modified chest mounted CCR-O2 rig for which I've made some injectors and run as a SCR with different nitrox mixes up to 42 metres. Chest mounted O2 cylinder comes in handy for deco purposes. Not yet a finished rig, it's still in an experimental stage. Longest dive was a two hour swim between two coves and back to test long distance reliability, total distance about 1500 metres, 70 minutes to go there and 50 minutes to go back."

OK, Guys, that's it for now on this one. I've been playing with a chest-worn bailout system using this loop and will be ready to do a web page on it shortly. It's a nice rebreather, and is certainly more bang for the buck than the LAR-V. In fact, I'd have to rate it nicer than the LAR based on technical merit, not just price. We've got 4 of these in the US now, and if anyone else wants one, just let me know. Want to see how I'm modifying it to be both an intentional rebreather and a bailout rebreather? Go see the Minimum-Rebreather Page.

Back to the Main Italian ARO Page

		Overall view of the system.
		The nicely padded neckstrap is attached by two Fastex fasteners. If you wanted to attach it to another type of harness, it would be easy.
		The DSV looks remarkably similar to the Azimuth. That's because it's identical.
		The DSV is likely the nicest DSV on the market at this time. The little tab allows it to be both opened and shut with one hand, without any possibility of biting through the mouthpiece. Why can't other manufacturers get this right?
		DSV has a nice neckstrap attached, with small Fastex fasteners to allow it to be removed.
		This is the left side of the system, showing the on/off valve, manual add button, and the gauge.
		The gauge has a little cover to keep it retained in use, and to protect the face of the instrument.
		The HP Gauge is of medium size, and good quality.
		The cylinder is retained at the bottom of the rig by a Velcro flap, and two nylon straps. It's positive and simple.
		Here's the 2 liter cylinder for scale. Calibrations are inches.
		The 02 feed line to the rig is attached with an O-ring sealed fitting, attached with a finger tightened nut. No tools are needed to service of clean the rig.
		This is the 02 feed line as it passes through the wall of the counterlung.
		The 02 feed tee is on a swivel, and connects the 02 supply hose to the counterlung.
		The 02 feed swivel also has a removable plug into which a second gas may be injected into the counterlung, bypassing the 02 injection valve. Hmmm.......... The mind reels with possibilities!
		My finger is on the manual 02 addition button of the valve. This is large enough to be used with cold fingers, and the pressure needed is just right, not too hard to be impossible with cold fingers, not so easy that it can be depressed inadvertently.
		The cylinder is filled by removing the gauge, and filling through the port that is exposed. Filler fitting is identical to the other European rigs that I've seen, including the FGT-1D, Azimuth, AKA-60, and Lt. Lund.
		The valve assembly is just that, a valve with HP port in, gauge and filling port, and 02 supply to the rig. The on/off valve is the green knob. Interestingly, there is no pressure reduction regulator. This makes for a very simple system that will require virtually no servicing.
		What little servicing that may need to be done will be familiar to anyone who has ever serviced any normal SCUBA cylinder valve. Even the parts are the same as are on common SCUBA equipment. No special parts are used.
		Two different cylinders are available, a 1.5 liter aluminum one, and a 2 liter steel one. I chose the 2 liter ones, since I was more interested in duration than I was in having a non-magnetic system.
		Fill pressure is 200 BAR, with a 300 BAR test pressure.
		To service the scrubber, the first step is to remove the breathing hose plenum. You can see how inhale and exhale gas is segregated. The plenum is removed by the central nut, which loosens the screw that is visible in the center of the plenum. Then the entire assembly simply is lifted and set aside.
		Here's the top of the breathing plenum, showing how the gas is sent to and from the scrubber can. The bolt with the finger-grip at the bottom is how the plenum and hose-assembly is attached to the scrubber.
		Once the hose plenum is removed, the scrubber is rotated 90 degrees and then is pulled through the mouth of the counterlung for filling. The black Delrin plug is the filler port. You don't fill it in-place, the scrubber is completely removed from the bag for servicing.
		With the scrubber pulled from the unit, we can see the water absorbent pad.
		Once the scrubber is removed, the water-pad can be removed and dried. This lays in the bottom of the counterlung to soak up that slime and dribble that we all produce.
		Here's the scrubber removed for filling. It's rated at 3+ hours, using a 1.3 kilo load of powder. The scrubber itself is chrome-plated brass, just like the old Cressi ARO-57 one. In fact, the two parts are interchangeable.
		Detail of the scrubber: The rows of ports for inhalation and exhalation can be seen on the flat face on the right. The perforated periphery of the cannister is open to the counterlung.
		Detail of how it all fits together.
		Here's the naked counterlung, which is made from a PVC impregnated fabric identical to that used in the construction of good quality inflatable boats. Repairs can be done with patches and Aquaseal. For durability in extreme conditions, a Kevlar outer cover can be fitted to protect the lung. This is a component of the Italian Navy C96-Pro, for military use. In addition, the Italian Navy uses an integrated weight-vest that the rig simply snaps to for rapid donning and doffing.
		On the side of the counterlung exactly opposite the 02 feed line, there is a reinforced area for attaching other items. An Oxygauge port would fit here nicely, as would an alternative gas-feed valve of any sort. This opens up an entire realm of possibilities for modification.
		For conversion to a Nitrox CCR (or bailout rebreather), I'd add a drysuit inflation valve to that reinforced area and feed it with diluent from a small cylinder. Add PP02 monitoring and you'll be all set.