Mares Abyss Metal (42) cracking pressure adjustment

[LeadTurn_SD]

Leadturn,
Can a metal orifice be retrofit into your Abyss regs? Zeagle has gone back from plastic to a metal (stainless?) orifice in their version of the Apeks second stage.

Hi keyshunter,

I've been looking (online) but have not found metal orifices for the Mares 2nds. It seems they should be out there, but I do not know where to look. My older Voltrex (that my son now uses) has a metal orifice... the newer Abyss 2nds I own (circa 2006 or 2007) have plastic orifices.

I was really happy when Zeagle chose to go back to metal orifices, I quickly bought two for the pair of older ZX 2nd stages I have (they had plastic orifices).

I really do believe metal orifices are the way to go when they are available.

If I ever stumble across a source for new/old Mares metal orifices, I'll post it here and in the DIY section.

Best wishes.

 

[MR12111]

Hi Harro10,

The problem with simply tightening the orifice to "stop the leak" with the Mares Abyss is that you are also lowering the demand lever.

Adjusting this regulator is a balancing act between orifice depth and lever height. Moving the orifice also moves the demand lever.

Properly tuned, your Mares Abyss should be stable (no free flows) but breath very easily.

With this regulator, when it is pressurized, you should be able to gently shake the 2nd stage in a quiet room and hear a light tapping of the lever against the 2nd stage diaphragm, like tapping a finger nail lightly on an aluminum can... this indicates just a slight bit of free play (1 - 2 mm) between the lever and diaphragm.... you should not hear a loud "clacking" like shaking a pebble inside an empty can, that means there is too much free play... and you should never hear anything when you shake an unpressurized Mares 2nd stage (in an unpressurized state, the lever is in full contact with the diaphragm, there is no free play).

A touch-up tuning is sometimes needed, like Scared Silly describes; and in a pinch, yes you can just remove the 2nd stage and use a hex wrench to carefully "stop the leak".... but be aware that more than just a "tweak" will begin to seriously de-tune your 2nd stage since you are not only increasing cracking effort but also lowering the demand lever when you turn the orifice clockwise (and raising the lever when you turn it counter-clockwise).

Lowering the demand lever causes the 2nd stage diaphragm to have to travel further before contacting the lever and open the demand valve; a lever set too low may not fully open the 2nd stage demand valve during inhalation, turning your sweet-breathing Abyss into a "dog".

My quick and dirty pre-dive and between servicing checks for my Mares Abyss's (and other Mares 2nd stages):

1. Vacuum test for leaks (see couv's excellent checklist that is "stickied" at the top of this forum).

2. Pressurize reg... purge a few times, check for freeflows. Also make sure that purge button only travels 1-2mm before air begins to flow. If it travels further than this, the lever may be too low.

3. Shake reg, listen for the slight rattle to make sure lever is not set too high.

4. Breath reg.... with experience, you'll know how the reg should "feel" when it is well tuned.

Finally.... I love my Abyss regs, but simply hate that the newer Abyss regs have plastic orifices. I really think that this causes some tuning issues, i.e. free flows, that I do not see in my older Mares Voltrex 2nd which has a metal orifice.



Best wishes.

Hello , sorry to bug you ..I was reading your post and was Impressed with your knowledge .. I was a reg tech in the 80's after being an auto/truck mechanic for 15 years ..Ended up being a burnt out Instructor/Boat captain here in south Fla .. Anyhow many years later I'm thinking of Diving again ..putting together a reg and your the "lucky" guy I have a question for ...Great Eh ?? .. I used the MR21 -3 all my life but now am thinking of trying the Voltrex as it seems the only difference is the exhaust valve size ? ..I bought 1 and there are a few differences .. It seems .. The question (finally eh?) is does this reg use a different 2nd stage Diaphragm ? The used reg I have , has one that is surely different ..the one from my old mr12 fits also ans "seems" to work better ... Overall what do you think of the Voltrex 2nd stage ...I really liked the vortex effect of the mr12 i could really sip the air ..very good breather and stone dependable ...Except for first stage seats ..sorry for the long question ....

 

[Zef]

Hello , sorry to bug you ..I was reading your post and was Impressed with your knowledge .. I was a reg tech in the 80's after being an auto/truck mechanic for 15 years ..Ended up being a burnt out Instructor/Boat captain here in south Fla .. Anyhow many years later I'm thinking of Diving again ..putting together a reg and your the "lucky" guy I have a question for ...Great Eh ?? .. I used the MR21 -3 all my life but now am thinking of trying the Voltrex as it seems the only difference is the exhaust valve size ? ..I bought 1 and there are a few differences .. It seems .. The question (finally eh?) is does this reg use a different 2nd stage Diaphragm ? The used reg I have , has one that is surely different ..the one from my old mr12 fits also ans "seems" to work better ... Overall what do you think of the Voltrex 2nd stage ...I really liked the vortex effect of the mr12 i could really sip the air ..very good breather and stone dependable ...Except for first stage seats ..sorry for the long question ....

Here is a site with links to all the manuals, diagrams, and parts lists to help you research the answers to your questions:

Mares Regulator Service Information

lowwall.eu5.org

The Voltrex 2nd stage became the Abyss and is an excellent 2nd stage regulator. Mares has updated the design of the cover plate a few times, reshaped the demand lever, and possibly changed the material of the 2nd stage orifice, but other than that nothing much functional has changed over the years, it is a well unbalanced, downstream 2nd stage. You might find that shops are reluctant to work on it as service kits marked Voltrex might no longer be availablebut one should be able to use an Abyss service kit.

The diaphragm for the III and the Voltrex/Abyss have different part numbers. I have no hands-on experience with the III so I can't say whether a Voltrex/Abyss diaphragm will fit, but the clamp ring that secures the faceplate covers on both regulators is the same part number...I imagine that the diameter is the same but the front to back depth is different between the diaphragms for the two 2nd stages which would make them incompatible.

The MR12 is a solid design diaphragm 1st stage, sadly Mares discontinued it a handful of years ago. It is commonly sought after for stage bottles by tech divers, and from my understanding was commonly found in rental fleets due to work horse performance.

The MR12 uses the same 1st stage seat (poppet) as the MR22 and a whole slew of other Mares diaphram design 1st stages. They have made improvements over the years to the face material of the seat as well as the material and coatings used in the rest of this part. I believe I read somewhere awhile ago that very early versions of the Mares 1st stage seat (poppet) had issues with HP air penetrating the along the edges of where the sealing face material meets the metal surounding it, the sealing surface would become compromised and then be blown apart by the HP air in the 1st stage. That issue is long corrected and you should be able to confidently rebuild your MR12 with the current version of the Mares HP seat (poppet) without issue.

-Z

 

[MR12111]

Here is a site with links to all the manuals, diagrams, and parts lists to help you research the answers to your questions:

Mares Regulator Service Information

lowwall.eu5.org

The Voltrex 2nd stage became the Abyss and is an excellent 2nd stage regulator. Mares has updated the design of the cover plate a few times, reshaped the demand lever, and possibly changed the material of the 2nd stage orifice, but other than that nothing much functional has changed over the years, it is a well unbalanced, downstream 2nd stage. You might find that shops are reluctant to work on it as service kits marked Voltrex might no longer be availablebut one should be able to use an Abyss service kit.

The diaphragm for the III and the Voltrex/Abyss have different part numbers. I have no hands-on experience with the III so I can't say whether a Voltrex/Abyss diaphragm will fit, but the clamp ring that secures the faceplate covers on both regulators is the same part number...I imagine that the diameter is the same but the front to back depth is different between the diaphragms for the two 2nd stages which would make them incompatible.

The MR12 is a solid design diaphragm 1st stage, sadly Mares discontinued it a handful of years ago. It is commonly sought after for stage bottles by tech divers, and from my understanding was commonly found in rental fleets due to work horse performance.

The MR12 uses the same 1st stage seat (poppet) as the MR22 and a whole slew of other Mares diaphram design 1st stages. They have made improvements over the years to the face material of the seat as well as the material and coatings used in the rest of this part. I believe I read somewhere awhile ago that very early versions of the Mares 1st stage seat (poppet) had issues with HP air penetrating the along the edges of where the sealing face material meets the metal surounding it, the sealing surface would become compromised and then be blown apart by the HP air in the 1st stage. That issue is long corrected and you should be able to confidently rebuild your MR12 with the current version of the Mares HP seat (poppet) without issue.

-Z

Thank you very much for the reply and the link to Mares service info. I worked on these in the 1980's the diaphragms 2nd stage ...are really soft and thin ..they work good but had some problems getting pin holes in them .. Maybe 1 in 20 I checked had a hole ..The first stages blew out the poppets pretty bad ..same poppet as us divers used and Dacor also ... I set up a sherwood first stage to use with the Mares second stage ..was stone dependable ..That first stage is really obsolete now ..It was the one sherwood used with their posiden side draft second stage .."ultima" I think they called it ... Thanks again for the information ..i will just go with the correct 2nd stage diaphragm and see how it goes ..i noticed that mares now has an adjustable orifice and the vortex tube is larger .. I just wanted it for the larger exhaust valve ...Guess I will see if it's better than the old MR12 or not ..at least to me ....Thanks again ...Don

 

[Zef]

Thank you very much for the reply and the link to Mares service info. I worked on these in the 1980's the diaphragms 2nd stage ...are really soft and thin ..they work good but had some problems getting pin holes in them .. Maybe 1 in 20 I checked had a hole ..The first stages blew out the poppets pretty bad ..same poppet as us divers used and Dacor also ... I set up a sherwood first stage to use with the Mares second stage ..was stone dependable ..That first stage is really obsolete now ..It was the one sherwood used with their posiden side draft second stage .."ultima" I think they called it ... Thanks again for the information ..i will just go with the correct 2nd stage diaphragm and see how it goes ..i noticed that mares now has an adjustable orifice and the vortex tube is larger .. I just wanted it for the larger exhaust valve ...Guess I will see if it's better than the old MR12 or not ..at least to me ....Thanks again ...Don

The Mares 1st stage seat is very similar to what US Divers/Aqualung and Dacor use(d). I believe they were/are dimensionally the same and know from discussions on ScubaBoard that they can be substituted for each other. I also have read that all 3 comapanies had similar issues years ago with the seat face material degrading in a similar fashion and blowing apart. Perhaps they all used a common manufacturer/supplier for this part.

I have no expertise on silicone and can't comment much on pin-holes in 2nd stage diaphragms other than to say that early silicone drysuit wrist seals had problems with being fragile and tearing easily....I think the manufacturing process has improved and those issues have been largly worked out with silicone drysuit seals, and since there is not an abundance of discussion about failed 2nd stage diaphragms, my assumption is improvements have been made over the years on the manufacture of those parts as well.

Mares did add a balanced adjustable 2nd stage to its lineup a few years ago. I think this was mostly a marketing strategy to stay competitive with the other brands than adding much of anything functional to their lineup. There is a fan base and appreciation among some divers for the simplistic workhorse design of Mares unbalanced non-adjustable 2nd stages. Your Voltrex 2nd stage is one of them.

One last note, MR12 is an example of a Mares 1st stage model name, and III (3) is an example of a Mares 2nd stage model name...they were paired together for marketing/sales and Mares has continued this trend throughout its lineup over the years. Folks have a tendency to mix up the names when refering to the different regulator stages in Mares' lineup. For the sake of avoiding confusion it is best to refer to each stage by its proper model name as it will make questions clearer, aid research, and fascilitate responses.

-Z

 

[MR12111]

The Mares 1st stage seat is very similar to what US Divers/Aqualung and Dacor use(d). I believe they were/are dimensionally the same and know from discussions on ScubaBoard that they can be substituted for each other. I also have read that all 3 comapanies had similar issues years ago with the seat face material degrading in a similar fashion and blowing apart. Perhaps they all used a common manufacturer/supplier for this part.

I have no expertise on silicone and can't comment much on pin-holes in 2nd stage diaphragms other than to say that early silicone drysuit wrist seals had problems with being fragile and tearing easily....I think the manufacturing process has improved and those issues have been largly worked out with silicone drysuit seals, and since there is not an abundance of discussion about failed 2nd stage diaphragms, my assumption is improvements have been made over the years on the manufacture of those parts as well.

Mares did add a balanced adjustable 2nd stage to its lineup a few years ago. I think this was mostly a marketing strategy to stay competitive with the other brands than adding much of anything functional to their lineup. There is a fan base and appreciation among some divers for the simplistic workhorse design of Mares unbalanced non-adjustable 2nd stages. Your Voltrex 2nd stage is one of them.

One last note, MR12 is an example of a Mares 1st stage model name, and III (3) is an example of a Mares 2nd stage model name...they were paired together for marketing/sales and Mares has continued this trend throughout its lineup over the years. Folks have a tendency to mix up the names when refering to the different regulator stages in Mares' lineup. For the sake of avoiding confusion it is best to refer to each stage by its proper model name as it will make questions clearer, aid research, and fascilitate responses.

-Z

Thanks for the reply ..I did not know that about the name designation ..so the older metal second stages should be just called III or (3) ? ..Hu ..learn something every day ..perhaps it was because I never saw anything but those 2 stages (MR12 and the III ) together ..It was just after I got out of it that mares started trying different first stage sealing ideas ...glad they go it worked out .. sure you know to gently stretch 2nd stage diaphrams to look for pinholes . And yes I did use different brand poppets sometimes ..didnt like it but they always worked ..This voltrex thing has a couple/few other differences form the III (3) ..the vortex tube is larger ..wonder if it effects "velocity" and the vortex effect ..you'd think the smaller tube opening in the older one the III would create more of a vortex ??? This has an adjustable orifice also ..like a sherwood ..the III did not have this ..not sure how I feel about it ..I only switched to the voltrex for the larger exhaust valve ..oh well ..summer is soon and I will just find out ...

Me working it Islamorada ..mid 80's ..Buddy's Dive Shop ...The "Free and Clear" 34 Crusaider ..

 

[Zef]

Thanks for the reply ..I did not know that about the name designation ..so the older metal second stages should be just called III or (3) ? ..Hu ..learn something every day ..perhaps it was because I never saw anything but those 2 stages (MR12 and the III ) together ..It was just after I got out of it that mares started trying different first stage sealing ideas ...glad they go it worked out .. sure you know to gently stretch 2nd stage diaphrams to look for pinholes . And yes I did use different brand poppets sometimes ..didnt like it but they always worked ..This voltrex thing has a couple/few other differences form the III (3) ..the vortex tube is larger ..wonder if it effects "velocity" and the vortex effect ..you'd think the smaller tube opening in the older one the III would create more of a vortex ??? This has an adjustable orifice also ..like a sherwood ..the III did not have this ..not sure how I feel about it ..I only switched to the voltrex for the larger exhaust valve ..oh well ..summer is soon and I will just find out ...

Me working it Islamorada ..mid 80's ..Buddy's Dive Shop ...The "Free and Clear" 34 Crusaider ..

The adjustable orifice in the 2nd stage works concominantly with the diaphragm lever to regulate cracking pressure. The lever in the body of the 2nd stage should be a couple of milimeters below the diaphram when the regulator is charged. The lever height is adjusted with a small nyloc nut, but is also affected by screwing the orifice in or out. Proper adjustment is made by getting both the lever hieght and orifice in the correct "ballpark" and then fine tuning both. If the lever is too low the 2nd stage will take more effort to crack while underwater and the diaphram may not fully open the valve.

Later models of Mares 2nd stages added a port on the left side of the 2nd stage body for a nut driver to facilitate tuning the lever height without having to take the face plate off.

I know the Vortex tube (VAD tube) has the effect of creating a venturi that is supposed to assist cracking/breathing effort but I don't know the effect of the different sizes of tje VAD tubes....perhaps the larger diameter of the Voltrex's VAD tube provides a larger volume of air that increases the venturi affect.

My understanding, from reading here on ScubaBoard, the Mares MR12 is similar to the US Divers/Aqualung Conshelf 1st stage. The Mares unbalanced 2nd stages are somewhat similar to the Conshelf 2nd stages as well. Your description of the Mares III with a non-adjustable orifice seems identical to the setup of a Conshelf 2nd stage. The Conshelf has a strong following, especially among those that self-service their regulators, and is another tried and true workhorse of a breathing apparatus.

I assume that the larger exhaust valve on the voltrex and later models would translate into slightly less work of breathing (WOB). I hope some other folks who have some expertise on the Mares III chime in, but I don't believe you will find much of a perceptible difference in real diving conditions (as opposed to laboratory conditions) between the III and the Voltrex and subsequent similarly designed 2nd stages in Mares lineup, if the 2nd stage is properly setup.

I look forward to reading a followup once you have a chance to dive your Voltrex.

-Z

 

[Zef]

Here is something intersting that I came across while surfing the web this evening:

A Mares III 2nd stage that is labeled "Mares MR12 III".

I know that Mares often labeled their pre 2008 version of the MR22 as "Mares Abyss DFC"...the Abyss referred to the 2nd stage that was often pared with it:

Eventually Mares removed the "Abyss" label from the 1st stage and began labeling it MR22:

In 2008 Mares changed the outer body style to this with the MR22 label:

Given the 2nd stage marked MR12 III, I can totaly understand why one would refer to the 2nd stage as such. This helps clear up some confusion on my part.

Cheers,
-Z

 

[MR12111]

Here is something intersting that I came across while surfing the web this evening:

A Mares III 2nd stage that is labeled "Mares MR12 III".

View attachment 775685

I know that Mares often labeled their pre 2008 version of the MR22 as "Mares Abyss DFC"...the Abyss referred to the 2nd stage that was often pared with it:

View attachment 775686

Eventually Mares removed the "Abyss" label from the 1st stage and began labeling it MR22:
View attachment 775687

In 2008 Mares changed the outer body style to this with the MR22 label:
View attachment 775688


Given the 2nd stage marked MR12 III, I can totaly understand why one would refer to the 2nd stage as such. This helps clear up some confusion on my part.

Cheers,
-Z

Every ..well almost every mares I worked on in the 80's had that same purge button ..the REAL old ones I think didn't have that ..In fact I think some of them were marked AMF the original? company ...

 

[MR12111]

The adjustable orifice in the 2nd stage works concominantly with the diaphragm lever to regulate cracking pressure. The lever in the body of the 2nd stage should be a couple of milimeters below the diaphram when the regulator is charged. The lever height is adjusted with a small nyloc nut, but is also affected by screwing the orifice in or out. Proper adjustment is made by getting both the lever hieght and orifice in the correct "ballpark" and then fine tuning both. If the lever is too low the 2nd stage will take more effort to crack while underwater and the diaphram may not fully open the valve.

Later models of Mares 2nd stages added a port on the left side of the 2nd stage body for a nut driver to facilitate tuning the lever height without having to take the face plate off.

I know the Vortex tube (VAD tube) has the effect of creating a venturi that is supposed to assist cracking/breathing effort but I don't know the effect of the different sizes of tje VAD tubes....perhaps the larger diameter of the Voltrex's VAD tube provides a larger volume of air that increases the venturi affect.

My understanding, from reading here on ScubaBoard, the Mares MR12 is similar to the US Divers/Aqualung Conshelf 1st stage. The Mares unbalanced 2nd stages are somewhat similar to the Conshelf 2nd stages as well. Your description of the Mares III with a non-adjustable orifice seems identical to the setup of a Conshelf 2nd stage. The Conshelf has a strong following, especially among those that self-service their regulators, and is another tried and true workhorse of a breathing apparatus.

I assume that the larger exhaust valve on the voltrex and later models would translate into slightly less work of breathing (WOB). I hope some other folks who have some expertise on the Mares III chime in, but I don't believe you will find much of a perceptible difference in real diving conditions (as opposed to laboratory conditions) between the III and the Voltrex and subsequent similarly designed 2nd stages in Mares lineup, if the 2nd stage is properly setup.

I look forward to reading a followup once you have a chance to dive your Voltrex.

-Z

Thanks .. I will try to remember to get back to you on this ..It will be summer ...I have dove enough to not care to go when it's cold of rough ..already had my "turn" doing that ..