WC1 Side-mounted Bailout CCR

WC1 Side-mounted bailout CCR
By Gabriele Paparo



I dive deep and long dives are a regular thing. Because of that fact, I decided to switch from my normal OC bailout bottles to a CCR bailout.

It has been a long time since I bought my Draeger Ray and my Dolphin (These were my first rebreathers). Both of them were waiting to get in the water again. They were lonely because these days I pretty much exclusively dive my Inspiration (since about July 2003).

I decided to build my personal bailout rebreather using parts from the two Draeger Rebreather’s!


Putting together all the parts from the Dolphin breathing loop, the Ray’s canister and some other components, I realized I had created the first version of my CCR mechanically operated/ electronically controlled bailout Rebreather, which I then called called “WC1”. You will understand shortly the reason for the name WC…the number 1 indicates the first prototype; of course…several modifications are going to be done in the near future to build mod.2.

The WC1 Rebreather

I bought a Ø25cm/10inch PVC water pipe and cut it in order to make a cylindrical cover for all the parts. Two cylinders are positioned outside the pipe.


Before every dive I can decide to use any tanks available at the moment (oxygen and diluent) because no special size/shape is needed and normal DIN valves are used.

Of course you probably would prefer to use neutrally buoyant aluminium cylinders, especially diving in fresh water…any size you need (A 2lt/200bar for both oxygen and diluent works fine for me).

You can also plan to attach one or both cylinders on the side of your main Rebreather… (connecting it/them to the bailout RB using the right length LP hose).

I suggest that you do not connect the bailout Rebreather to the same cylinders of your main RB… if a failure is due to a cylinder problem it will fail both rebreathers!

At the moment I am using the standard 3lt steel cylinders from Inspiration as bottles while a standard Oxygauge from Draeger is used to control the Oxygen Pp in the loop (it is connected to one of the two p-ports available on the inhalation counter-lung).


Actually I own 2 Oxygauges (one from my Dolphin, one from my Ray) so shortly I will use both of them to check the Pp in the loop.

I started a series of dives that will have me testing the Rebreather up to 40/45m (maximum working depth for the Oxygauge). After that, if I decide to dive it deeper I will need to switch to a different Pp controller, rated to at least 120m/400ft depth at which I sometimes dive.

To feed oxygen inside the loop I am using a very rude way (but it is cheap and it works for the first prototype): I connected a normal hose and inflator from my old BCD to a L-shaped piece of the Ray’s breathing hose; thus allowing me to connect the L piece to the second p-port of the inhalation counter-lung and to add oxygen in the same way you add gas inside your BC. The LP hose, in fact, is connected to the oxygen first stage. No other method for oxygen addition is used at the moment but I am thinking about modifying the system in order to build in a KISS-style valve (0,3 – 0,7lt/min of oxygen addition). I am going to evaluate this option in the future.


Diluent is added in 2 different ways

1. Manually depressing the diaphragm of the Dolphin diluent valve (using one finger) or
2. Automatically during the descent and/or when more gas is needed for the diver breathing

The features of the WC1 are listed here:

1. Sidemounted, totally independent, bailout Closed Circuit Rebreather
2. ADV (the standard, original valve from the Dolphin)
3. Draeger Ray 1.25kg chemical scrubber (enough to complete a 2hr decompression)
4. Possibility of using a constant flow for oxygen (using an 0,5lt/min orifice or similar)
5. Manual addition for both Diluent & Oxygen
6. Up-gradable to 2 electronic Pp controllers (Oxygauge)
7. PVC rigid case for all the components but the tanks

Diving Comments

Comments here come from just 2 solo-dives that I have done, one in the pool (4m depth) and one in open water (Lake Garda, 19m-30minutes). More comments (and improvements of the unit) will be added after every test dive.

Before the dive a check list is completed and a very good negative pressure test is performed.

General impressions are very good; the unit is light, easy to be carried on surface and underwater.

Swimming is perfect; very low drag, pretty good buoyancy. I wonder how much fun it would be to scooter with this!).

The unit (equipped with the inspiration 3lt/232bar steel cylinders) is slightly negative when in use (full counter-lungs, about 4/5lt in volume) and pretty negative if staged with emptied counter-lungs. If staged with full counter-lungs it stays in vertical position, slightly negative (about 2/3 kilos). – remember we are talking about fresh water behaviour.


Breathing resistance is not too bad: pretty good in normal horizontal position. Just a little harder if you turn up side down. The unit can be easily moved into different positions (up/down / in the front) as well as be completely removed (for example to be attached to a decompression line). You can really optimize the breathing resistance for every condition).

It can be “no-mounted” to overcome tiny restrictions or it can be completely removed to be passed to a dive buddy or to the guys on the boat at the end of the dive.

This feature is very important if you dive from a boat, especially in rough seas. Do not consider it if you dive only from the real comfortable ground-level entries of Florida caves!

Oxygen partial pressure is easy to control and maintain. The small breathing loop (about 4/5lt) allows you a very good control using little oxygen. At the same time it is imperative to have a very good practice in manual Pp control of a system because is easy to make mistakes with so small amount of breathing volume (as I said 4/5lt).


Instrument reading is very easy, since they are almost in the front of the diver’s vision. The Oxygauge has acoustic and visual alarms to inform you about critical parameters during the dive (High PpO2, Low PpO2, Low Battery and more). It also has a backlit display.

It is very easy to keep visual control on the overpressure valve as well as operate/rotate it.

It is also very easy to reach and operate cylinder valves, the oxygen manual addition valve and diluent addition valve. It is possible (in this version of the unit) to very quickly disconnect the Oxygen LP hose from the BCD-style inflator (for example for a problem due to a oxygen free flow in the loop); It is also possible to connect oxygen LP hoses from other cylinders (it is enough to have a BCD LP hose to connect to the Rebreather set-up).


I have not made any check to evaluate the ability of a partial and/or complete flood recovery. Honestly, due to the design of the unit, I do not think it is easily possible although there is a way that I could check…. I’ll let you know…

After the dive I noticed a very small amount of condensation inside the inhalation bag (it is bad to have large amount of water in this section because there are sensors…). I have to check what happens after, let’s say, a 1 hour 30 minute dive.


The ADV – Manual DV – Oxygen injection is connected directly to the Ray’s scrubber.

Note the solid position: it allows you to press the manual diluent valve easily…because it is not going to move anywhere while you are depressing the valve (and also you will find it always in the same exactly place).


This is the front part, the lid from which the breathing loop hoses are exiting, together with the overpressure valve. These are original parts from Draeger Dolphin. Note the PVC rigid pipe lid used as a cover.


Gabriele Paparo
March 2006


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