Tech diving with MR 12 first stages???

[Speardoggin]

I bought two of these today for $100 each brand new with warranty (Divers Direct closeout sale). I was wondering if I could use them for deep water tech diving on a set of doubles. I want to get into tech diving and have heard they have been used on doubles, but I am not sure how well they breathe at depth. I want to use different second stages obviously, but not sure which ones work well with the 1st stage. Can an Abyss Second stage be modified to a 3/8 connection? Any input is appreciated. Should I just use them for deco bottles and call it a day?

Jeff

 

[Greg Barlow]

I've used MR12 first stages for my tech diving for nearly 10 years. I find that they offer very good hose routing, and the performance has never been lacking. The MR12 has a gas flow rate of approximately 140scfm. That is more than enough for any diving conditions, especially when you consider that most second stages have a maximum flow capacity between 50-70scfm.

The MR12 is simple to rebuild, and with the new tri-material HP valve installed, is very dependable. I also use MR12 first stages on my deco/stage bottles.

I turn to the MR/V16 and V42 for my single tank diving needs, as they offer superior hose routing for that configuration.

The Abyss second stage can be used on the MR12 without any modifications. I prefer the Proton Metal second stage, as it can be disassembled without any tools. The Abyss requires a phillips head screwdriver. My own doubles use the discontinued Akros second stage. They, too, have served me well on hundreds of dives.

Greg Barlow
Former Science Editor for Rodale's Scuba Diving Magazine

 

[Speardoggin]

I've used MR12 first stages for my tech diving for nearly 10 years. I find that they offer very good hose routing, and the performance has never been lacking. The MR12 has a gas flow rate of approximately 140scfm. That is more than enough for any diving conditions, especially when you consider that most second stages have a maximum flow capacity between 50-70scfm.

The MR12 is simple to rebuild, and with the new tri-material HP valve installed, is very dependable. I also use MR12 first stages on my deco/stage bottles.

I turn to the MR/V16 and V42 for my single tank diving needs, as they offer superior hose routing for that configuration.

The Abyss second stage can be used on the MR12 without any modifications. I prefer the Proton Metal second stage, as it can be disassembled without any tools. The Abyss requires a phillips head screwdriver. My own doubles use the discontinued Akros second stage. They, too, have served me well on hundreds of dives.

Greg Barlow
Former Science Editor for Rodale's Scuba Diving Magazine

I thought the Abyss second stage uses a 1/2" connection to the first stage (correct me if I am wrong).

 

[Greg Barlow]

I thought the Abyss second stage uses a 1/2" connection to the first stage (correct me if I am wrong).

It does, but you can use a standard 3/8" hose on the Abyss as well. The original Abyss hose will only fit the 1/2" fitting, unless you use an adapter. The second stage ends of the hoses are all the same size fitting.

Greg

 

[Speardoggin]

It does, but you can use a standard 3/8" hose on the Abyss as well. The original Abyss hose will only fit the 1/2" fitting, unless you use an adapter. The second stage ends of the hoses are all the same size fitting.

Greg

How does your combo breathe at depth and what depths have you taken them to? Do you think I'm better off just using them for deco and using Abyss 22's for doubles?

 

[Greg Barlow]

How does your combo breathe at depth and what depths have you taken them to? Do you think I'm better off just using them for deco and using Abyss 22's for doubles?

Let's put it this way...The MR12 first stage with a Voltrex (Abyss) second stage met the standards for the USN Class "A" classification at 198'. That means that it had an overall work-of-breathing score of less than 1.4j/l. In simple terms that means that having deep inhalations (2.5 liters) at 25 breaths per minute it still maintained a low work effort.

My own regs have been used with air down to around 140'. I don't make tech dives on air below that depth due to the narcosis factor. Deeper dives have mix running through them, which makes the performance even better.

The MR22 will experience less intermediate pressure drop under such heavy demands, but I doubt if you would even notice.

Greg

 

[LeadTurn_SD]

Just lurking and soaking-up the info on the MR-12, MR-22, Proton, Abyss and Volrex since I have all of these regs. Thanks, great info as always Greg.

 

[BlueDevil]

I have a pair of MR12's that I use on twin tanks. I have used them down to 60m with very good performance (I have the discontinued Akros and Epos first stages). On a 60m dive some years ago I had an Akros MR12 on one tank and an Abyss on the other tank so I was able to make a direct comparison between the two. To be honest the MR12 seemed to breath just as well as the Abyss at this depth.