Thoughts on the rEvoII

My thoughts on the rEvoII
By Dave Cooper
Zero Gravity Diving


Last Thursday, I drove from Strasbourg over to Bruges to visit Paul Raymaekers and take a closer look at his rEvo II.

The rEvo II is a constant mass oxygen flow manual closed circuit rebreather.

Paul explained his journey through the world of CCR and how he had decided to make his own rebreather starting with the rEvo.

This has been a popular MCCR in France, with some 30 or so units in the field.

Paul showed me around his factory and I was able to see the multiple components for the 100 units he plans to build next year. Paul did a strip down of the rEvo II for me and I was impressed by its simplicity.

There are only four points of entry to the loop, the P-Port connections for the breathing hoses, and the two scrubber pods.

The unit has dual bag rear-mounted counterlungs and when gas is exhaled it goes into the exhale lung through the first scrubber, along channels in the scrubber cover, through the second scrubber and then into the inhale lung.

Loop direction is counterclockwise, like the Meg and the MK15 series.

The exhale lung also sites the ADV, a simple lever design like a second stage and the orifice, set for a flow rate of 0.80l/min (though adjustable to cover the range of 0.62 to 0.88l/min). Also here we find the manual oxygen and diluent addition piping that is activated by cleverly thought-out and placed buttons on the bottom of the case. Diluent is added with the left hand and oxygen with the right, the buttons have a very strong spring and like a trigger they have play so simple touching does not activate, you have to take up the slack first (a bit like gliding for anyone who knows the principle!).

The inhale lung contains up to four oxygen cells that may be connected in pairs or singularly to two independent rEvodream PPO2 monitors that are fixed to the diluent and oxygen pressure gauges and also have independent HUDS. There is also adequate room for a moisture sponge. The cells are cleverly positioned so that even after extensive gas flushing the cells remain dry (more later).

All of this is contained in a configuration that with backplate wing, rear mounted counterlungs, scrubbers and cylinders increases your profile by no more than 15 centimetres!!

Weight fully loaded, 28 Kgs with steel tanks and 17.5Kgs without.

There is also a titanium shell version which when married up with some exciting carbon fibre 3 litre cylinders I saw, that will weigh considerably less.

Paul also showed me the mini-rEvo which will take 2 litre cylinders.

By now I was extremely eager to give this unit a spin and see if it’s WOB and swim positioning would live up to my high expectations.

We went to Paul’s local swimming pool after setup and calibration I jumped in and swam to the bottom of the 5 metre Olympic swimming pool which would be my home for the next hour or so.

Firstly, I hate swimming pools, the chlorine, the plasters on the bottom, the lighting, I just hate it. However, I didn’t even notice the environment as I started to put the rEvo through its paces.

She swims like no other rebreather I have dived, her compactness when swimming horizontally is perfect, I am looking forward to scooting along with this beauty and my UV-26 for sure.

WOB is very good when horizontal and changeable but manageable when you move away from this position. The hydrostatic work of breathing IMHO is very good, of course if you spend the whole time on your back you may find it difficult!

One important test for me was how the unit breathed in the vertical plain. The rEvo uses a Draeger Ray hoses assembly and a modified Ray mouthpiece. The hoses are agreeably short and the unit is fitted with a gag retainer for the mouthpiece, nice!

My reasoning for this is that I sometimes ascend up a shot line and it is important that I can breath comfortably while doing so. There was no problem the unit breathed well in this position.

There were 3 other rEvo divers in the pool and I was also able to see how the unit profiled on them and again I was impressed.

One of the guys was using a 2 cell rEvodream configuration and a plumbed in VR3 and the others were dual rEvodreams like myself.

The unit was very easy to use to maintain my selected PPO2 using the voting logic in my skull, the rEvodreams gave me all the cell values and worked flawlessly.

Diluent flushing on the unit brought the PPO2 down remarkably quickly, and like the Ouroboros, the small bore plumbing on this unit means that manual control of the O2 given an orifice failure would be easily achievable.

Everything is compact and reachable by hand, you can even get your hand to touch the OPV which is situated at the base of the unit on the inhale lung.

Just a point here, this is a unit that demands the correct use of a minimum loop volume policy, due to the siting of the OPV if you are not diving the unit in this fashion, manually added gas will just blow out of the OPV.

However rest assured that this unit is easy to feel when lungs are overfull.

I also tested the ADV a number of times and was more than pleased with its use and flow properties.

HUDs were very easy to read and well positioned.

Post-dive verification of the cells showed they were bone-dry, this is no mean feat given the amount of gas I was flushing through the unit whilst going through my drills.

Unfortunately I forgot my camera!! Doofus!

Paul Raymaekers will be presenting this unit at the Dive Shows in Paris, Germany and at LIDS where he will share a stand with Greenforce.

I cannot recommend highly enough that you should pay him a visit.

Finally many thanks to Paul and Johann for your welcome, explanation and guidance during my try-dive.

As soon as Paul accepts orders I am hoping to be high on the list.

This is a unit to watch, I am very impressed.

Cheers,

Dave Cooper


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