The JJ-CCR Counter Lungs walk through

It all started from a little hiss that seems to be coming from nowhere…
My unit failed the negative check after only two or three minutes, I checked all the connections, the O-rings but to no avail… I blamed my new BOV, my old regulators but nothing helped, the unit failed time after time.

I was doomed to face the worst… looking inside the counter lungs!
It seems like the hardest part to maintain are the counter lungs, but in hindsight after doing the whole process of disassembling and reassembling the whole thing, it wasn’t that bad.

(To make a long story short, yes I had a puncture in my inhalation CL).

The counter lungs are made of 8 primary components:
Counter lung cover
Two counter lungs
Two T-Pieces
Two flanges
Dump valve

The T-pieces are connected to the CL using a delrin flange by three 15mm 2.5 Alen key screws.
By removing the screws, the T-Piece can be pulled out by holding the base of flange and prey the T-Piece out.
Applying a pressure on the base of the flange is very important, otherwise by pulling the fabric it is easy to damage the CL.

After the T-pieces were removed the CL looks like this:

Pay attention to the O-ring of each t-piece, it accumulates a lot of debris and should be examined, cleaned and lubricated.

There are two slots on the t-piece, the lower one is narrower and should accommodate the O-ring. The upper one is made for the Allen screws and allows it to swivel.

Removing the CL requires a special tool, there is no way to do it without, and you will damage the CL by trying to do so.
The tool is a pin spanner wrench and the right size is 80-90.

The right way to open the flange is to apply a friction to the inner part using two fingers while twisting the outer part to the left, the pin of the spanner should fit perfectly inside the holes of the Allen screws.

After several tries the flange will give up and will start to spin, don’t be tempted to do the rest of the job without the spanner, use it until completely open.

After the flange is open you can remove the CL from the cover and examine it for holes or tears.

The flange (from left to right: inner part, gasket and outer part)

Repairing the CL is very easy, all is needed is the TearAid type A

Just follow the manufacturer’s direction, it works great and the material is very close to the material the CL is made from!

Assembling the CL is pretty much the same but backwards, the only tip I have is to begin by inserting the inner part and the gasket inside the CL, then put it inside the cover and then using both hands twist both parts together for a thread or two and then continue by applying a friction to the inner part and twisting the pin spanner to the right.

This is how i apply friction to the inner part.

In order to seal the outer part against the gasket you should apply some pressure using the spanner but not too much so it will be possible to open it again in the future.


a new BOV at the neighborhood

Divesoft is a Czech company who quickly gained their good reputation as a company who makes high quality, innovative and durable products.
The world of technical diving adopted their Trimix analyzer as the standard for its high speed reading and simplicity.

Divesoft’s iBOV

Golem Gear is a very well known American company for customized technical diving gear, they make their stuff at the Czech republic at iQsub’s factory.
The Shrimp BOV is the go to BOV for rebreathers who doesn’t offer a solution on their own (the JJ-CCR for example) or if ones looking for a better performing BOV then the OEM solution.
Until the iBOV came out, GG were the only major players in the aftermarket BOV  playground.

Golem Gear’s Shrimp BOV

by their specifications, it’s easy to see the Shrimp and the iBOV shares a lot of the same features: both made of machined delrin, embedding Apeks’s second stage pieces, uses the Drager one way flapper valves, can be supplied with connectors to pretty much fit any rebreather available and they even manufactured at the same country!

The comparison

Externally its easy to see how compact is the iBOV is, comparing their weight shows about 35% difference to the iBOV favor.

BOVs weight comparison

Shrimp BOV585g

The Nipples

There is a big difference between the loop nipples of the BOVs, the Shrimp nipples are more rugged and longer then the short and compact nipples of the iBOV.

Connecting the loop with the BOV is very different between the two, Golem Gear really made an amazing system for coupling their nipples to the body of the BOV based on a little white knob loaded by a spring that locks the coupler into place.

The advantages are clear:
a. It’s very easy to connect and disconnect the loop from the BOV
b. There isn’t possibility to get confused, the couplers are mechanically different
c. The flapper valves are more accessible, which makes their inspection easier

The iBOV way to connect the coupler to the body is very simple and is made by a metal wire binds the coupler to the couplers are the same.

While this way of connecting the loop to the BOV is smaller and simpler, there is a need to use a circlip pliers to open this metal wire in case of a need to disconnect the loop (for examining or replacing the one way valves for example).

The Diaphragm (updated…)

Opening the second stage reveals another difference, the iBOV uses the original holder and the diaphragm of the Apeks XTX second stage, while Golem Gear fabricated their custom diaphragm in a way they could ditched the holder.

Both diaphragms are based on the Air 2 (a combination between an inflator and a second stage) idea, the exhaust valve is embedded inside the diaphragm using a plastic adapter.
The Shrimp’s feels like a simple rubber while the Divesoft’s has more silicone touch,  i believe this is one of the main reasons for the CE rating.
The shrimp’s diaphragm seems like a custom made one, while the divisoft’s looks like a modified Apeks with a plastic adapter for the exhaust valve.

The Shrimp has a nice supplemental stainless leaver which helps to bail out when using gloves, the iBOV shorter handle and the lack of any way to extend it makes it a little less convenient to use.

The mouthpiece

The iBOV comes with the same mouthpiece the original JJ-CCR DSV uses, it’s manufactured by Divex sweden and is called ‘model Lars’.
This mouthpiece’s collar is bigger then the standard mouthpieces so it means it’s work of breathing should be better. Other then that it’s a damn good mouthpiece to use with a rebreather.
The Shrimp uses the standard size mouthpieces, if the Divex mouthpiece will be fitted on, it will leak water inside the loop.
This is a big advantage for the iBOV as it can get (with a little effort) any standard mouthpiece and in addition the wider better Divex as well.

Pay attention to the price of this mouthpiece: while N@90 and JJCCR sells it for about 9Eur it is listed on Divesoft’s for about 40Eur.

The HUD holder

To this date the HUD holder for the iBOV is not available yet, so i have very little to write about it.
Divesoft decided to break the conventional way a HUD is placed to the side of the loop and made a bracket on top of their iBOV.

Golem Gear’s HUD holder is pretty straight forward, sometime it moves when handling the loop and needs some readjustments underwater, a thing that shouldn’t happen with the iBOV bracket.


From the gas flow and gas feed direction perspective the BOVs are the same:
Switching the gas flow direction is simple and involves removing the one way valves cages and replacing the positions of the valves or the cages themselves.
Gas feed is assembled in the factory and you cannot change it by yourself.

Divesoft are very proud with the CE approval the iBOV received, it passed the EN250:2014 what means it should breath as good as any second stage who has this marking.

Golem Gear are not required by this standard as they are an American company, but they did make a breathing test for their BOV public.

Assembling the iBOV

Unless you are going to use it with the Liberty CCR, first step would involve removing the metal wires and replacing the couplings.
I am fitting the JJ-CCR nipples.
It seems Divesoft understood the importance of disconnecting the loop so they added a different kind of metal wires so no tools would be needed for the next time.

The corrugated hose is fastened by a ring fastener tightened by an Allen screw.

Overall the process of connecting the loop is super simple and takes about 2 minutes.

The Shrimp BOV is notoriously known for the time and effort it takes to get assembled on the loop hoses, allow at least 30 minutes to an hour if this is your first time doing this.

The Shrimp has a service kit contains about 16 o-rings available in Golem Gear’s web site for 28$.

Using it underwater

I tried to be as fair as possible, even though a lot of the parameters are purely subjective.
I used both BOV’s day after day (the first day I used the iBOV and the second day I took the Shrimp).
For two similar dives of 150 minutes each at maximum depth of 60m. I bailed out several times during the dive, both times I tried to do it in 50 – 60 m.
I am using the JJ-CCR with a radial scrubber the dil mix was the same, standard 15/55.

I will start with the bottom line, I have never expected such a big difference!
The iBOV breath a lot better in both CC and OC, Bailing out breaths exactly like a normal Apeks regulator. The BOV is almost neutrally bouyent and less clumsy.
It seems to me it’s easier to trigger the ADV with the iBOV, but it might be subjective.
The only problem I had is the small leverage the iBOV’s handle gives so it took more effort to bail out. It would have help if the unit was better lubricated from the factory.


I find the iBOV to be like a breath of fresh air (terrible joke I know). It’s a major improvement over what was offered up until now.
There are several things I would change in the design, especially the ease of inspecting the flapper valves and the optional cold water leaver.
Letting the users switch the gas feed direction by themselves would give the iBOV a better value as well.

Second stageApeksApeks
Second stage diaphragmApeksCustom
Loop coupling Metal wireSpring loading system
FitsAny rebreather Any rebreather
One way valvesDragerDrager
Manufactures byDivesoft, Czech republiciQsub, Czech republic
HUDTop bracketSide ratchet
Assembly time2 minutes30 minutes
Cold water knobNoYes
Price (exc. taxes)900$830$