Argonaut Kraken #1 getting some service after 5 years and 500 dives

[Luis H]

After five and a half years and about 500 dives I decided that it was probably a good idea to rebuild my number 1 Argonaut (original prototype).

The only indication that service was probably a good idea was some dark coloration on the inlet filter and some minor corrosion.

I was not very concerned about the minor corrosion since this regulator was one of the original prototypes and the chrome plating never covered all the brass. The facility that did the chrome was not familiar with the application and did not plate the threads or most of the internal surfaces. I only use that plating facility once for my prototypes.

The dark coloration on the filter was a much bigger concern since this has been my primary regulator for local diving and a lot of travel diving. I would say that over 2/3rds of my dives in the past 5 years have been using rental tanks in the Caribbean or the Pacific.

The IP was a solid 128 psi. The cracking effort has also been a very consistent at around 0.6 inWC. Based on this data I would not have bothered rebuilding it, but inspecting the corrosion and possible contaminating dirt I decided it was time.

The internal pictures did confirm that it was time for some service and some new O-rings and seat, but it wasn’t too bad, considering a lot of bare brass inside this prototype.

Over all I am very pleased with the reliability of this first Argonaut. About 500 dives without any problems.

It is back together and everything is checking out: the IP solid at 128psi, cracking effort at 0.6 inWC, and it has been pressurized for a week with the tank valve closed and the gauge pressure has not dropped at all.

The chrome plating in this prototype was not very good. I was trying a semi-local facility, but they had no experience plating this type of parts.

There is some evidence that some salty moisture made its way into the regulator at some point. I always insist to all the dive master not to touch my equipment, but sometimes they are just too quick. It could have also happen just from salt spray in the air, no matter how careful I try to be.

Notice there is no chrome on the threads or the tank valve sealing surface. This is not really an issue, but it always show a bit of surface discoloration. The plating facility intentionally masked this area because they didn't want to plate the threads. They were concerned that it would affect the fit.

 

[rhwestfall]

Such a workhorse.....

 

[Couv]

Thanks for this post Luis. I have a few questions.

The plating facility intentionally masked this area because they didn't want to plate the threads. They were concerned that it would affect the fit.

How much does/should plating affect fit? The only time I've had any scuba parts (SP 109) re-chromed I did have to run a tap and die over some of the threads. But the vendor was a custom automotive shop, so I don't know if they just overdid the application. Simply put: Is there an ideal thickness that adequately protects the brass but does not cause issues with the thread fit? Or is it inevitable that a tap/die will have to be used?

it was time for some service and some new O-rings

5 years-nice. Do you remember what material the o-rings were? I'm sure you replaced the diaphragm, but what condition was it in? How about the springs? Was there enough corrosion on any of them that warranted replacement?

Did you see anything that made you think, "hmmm, I think I should add/subtract/change/modify this part or material?"

Thanks,

Couv

 

[Luis H]

Thanks for this post Luis. I have a few questions.

How much does/should plating affect fit? The only time I've had any scuba parts (SP 109) re-chromed I did have to run a tap and die over some of the threads. But the vendor was a custom automotive shop, so I don't know if they just overdid the application. Simply put: Is there an ideal thickness that adequately protects the brass but does not cause issues with the thread fit? Or is it inevitable that a tap/die will have to be used?

5 years-nice. 1) Do you remember what material the o-rings were? 2) I'm sure you replaced the diaphragm, but what condition was it in? 3) How about the springs? 4) Was there enough corrosion on any of them that warranted replacement?

5) Did you see anything that made you think, "hmmm, I think I should add/subtract/change/modify this part or material?"

Thanks,

Couv

Yes... I see some questions.

First, I am not as knowledgeable about plating as I wish I was. Actually, I have minimal working knowledge.

To take care or that, I ended up making my mechanical drawings (including tolerances) with a note saying that dimensions are after plating. To my knowledge the last fabricator that Bryan is using, is also doing the plating, but I will admit that I am not following all the production process.

The production units and the early prototypes are done based on the same drawings, but we have used different machine shops/ fabricators.

The chrome plating doesn’t have to be very thick to provide excellent protection. In theory the plating can be within the allowable tolerances unless the part is at its maximum material condition.

The issue with threads is that due to the valleys, the plating tolerances can be all over the place.


1) I always use Buna-N (Nitrile). They didn’t really need replacing, but I am not going to re-assemble with the original O-rings. Good quality O-rings are cheap and new ones are very rarely defective.

2) If I didn’t have replacement diaphragms on hand, I would have easily reused it. A lot of techs would not approve, but I pulled diaphragms out of Conshelf that were several decades old and they were flexible and didn’t show any cracking or deterioration.

You can see the diaphragm in the pictures. It has some stains that I can probably clean and of course it show some compression from the clamping, but there are no cracks or signs of deterioration. I always replace the HP diaphragms and some I throw away intermediately, but I have many that I have saved thinking that could be re-used if I needed to.

I store my regulator in a dry cool place. Heat, ozone, dirt, etc are killers for the rubber items, so proper cleaning and storage makes a big difference IMO.

3) There was some rust on the springs. That is the primary clue that some salt atmosphere got into the first stage.

4) But, the rust wasn’t bad. I was going to clean them and re-use them, but then I just decided that my time was more valuable doing something else and I just replaced the springs.

5) Not really. I wish the plating on my personal regulator was better, but in a way it is good to see how robust is the basic design. Mechanically the first stage is a well proven design used in many regulator. The only improvements I could do was in the gas flow, but mechanically it is as close to “bullet proof” as it gets.


I should add that I didn’t actually rebuilt the second stage. I just removed the module and flipped the seat over. I re-installed it and it is good to go. Yeah, I can probably say that the second stage is also “bullet proof”. The second stage is my design, but it uses the same principles as most basic demand downstream valves. The dimensions, mechanical advantage of the lever, lever design, and aerodynamics are the only variables that I controlled and adjusted.

 

[Scuba Lawyer]

My AK #21 is 5 years old and still working like a champ! I did replace the main spring a few months ago as I was getting some wonky low IP readings. Fixed it right up. I am very careful with it and opening it up the other day revealed a pristine interior, not a drop of water entry. Looked like the day it was made. I'm a firm believer in the if it ain't broke don't fix it approach, but I may break down and do a preventative o-ring/rubber parts change-out one of these days. I figure every 5 to 10 years to do a reg overhaul can't hurt anything.

Mark

 

[Luis H]

IMHO, I wouldn't take apart just for preventive O-ring/ rubber parts replacement.

If I didn't see the dark coloration on the filter, I probably would have waited a few more years. I think 10 years between service is a nice goal, but the goal is obviously easily shortened by the exposure to to corrosive salt enviroment. That is why I promote somewhat careful handling (to avoid salt intrusion) and most important regular inspection (and IP check).

 

[rsingler]

Hey Luis,
How many times over the five years would you say that you adjusted cracking effort? The gradually increasing indentation of the LP seat would seem to require a tweak every year or two, no?
And did you polish the knife edge of the HP seat before you put it back in? I seem to see sandblasting on a regular basis on the regs I'm asked to service...
Before

After

I'm thinking dust or oxide in the tank air.

 

[Luis H]

I actually haven’t touched the second stage adjustment nut yet. I flipped the seat to use the other side, but did not adjust the nut for the lever height or the volcano orifice.

If I recall correctly, I did replace the seat once in the last 5 years because I have been messing around with second stage venturi upgrades.

This was work related to the new mouthpiece with the flow diverter.

So, if I messed around with the second stage I decided to replace the seat just to make sure there are not two different indents.



I should explain why I don’t feel the need to adjust the seat to compensate for the indent.

With a single hose we all adjust the lever to be touching the diaphragm. That is not the way I adjust or recommend adjusting most double hose and specially the Argonaut.

I adjust the lever height purely based on a guide (I use the same guide that Bryan sells for the vintage Mistral single stage regulator). As an alternate, I can just use a straight edge on the top of the can. The metal part of the lever just below the two plastic beads need to touch my straight edge. The two plastic beads need to show just above the plane of the back can.

This adjustment provides enough clearance between the top of the lever and the diaphragm that the regulator will not free-flow as the seat indents.

The indentation on the LP seat doesn't seem to affect the performance (at least a 2 or 3 years worth of indentation, but probably more).

The diaphragm in a this DH is flexible enough and had enough travel that you don’t need it to be touching the lever at the moment you start to inhale.

The other cool trick that a lot of divers are not aware of is that (if your hose loop has mouthpiece valves) after the first breath the diaphragm stays in contact with the lever, even while you are exhaling. The inlet check valve maintains a slight vacuum in the ambient pressure chamber.

I have measured the pressure (actual vacuum) in the hose just adjacent to the intake horn it would cycle during inhalation to 0.6 inWC, it would go down with the venturi , but when I stop inhaling it would settle to about 0.2 inWC of vacuum and (if the mouthpiece valve is working) it would hold that vacuum until the next inhalation.



That is interesting on that volcano orifice. I don’t think that I have ever noticed that much wear on a volcano orifice. I have seen scratches, but I don’t recall seen that much “sandblasting” looking marks. I have polished some in the past that had a little bit of pitting, but not that bad.

I cleaned the volcano orifice. You can see some discoloration on the flat surface around the orifice. But the edged looked good. Sometimes I use an eraser to polish the orifice edge, but I didn’t bother with it this time.

The Argonaut has a replaceable orifice (as opposed to a Conshelf) so if I saw it bad shape I would just replace it.

 

[Scuba Lawyer]

The other cool trick that a lot of divers are not aware of is that (if your hose loop has mouthpiece valves) after the first breath the diaphragm stays in contact with the lever, even while you are exhaling. The inlet check valve maintains a slight

I did not know that. Very cool actually, explains the workings a bit more fully to me. Thanks for posting that. Mark

 

[rsingler]

Yes, that replaceable orifice is such a great feature! I remember asking Chris Richardson why he didn't put one on the Deep 6, and he just didn't think it was a benefit. But if I'm planning to have my Kraken last as long as I will, it's a great feature.

Thanks for the info about the lever and the hose valve. Fascinating!

When I restore the HP volcano, I'm concerned that a pencil eraser will flatten the edge, increase its surface area, and decrease the crispness of lockup with the seat. So I use Micromesh wrapped around a pencil to burnish it from the inside, using the bunching of the Micromesh cloth around the cone of the pencil end to preserve the round of the volcano edge.