Phoenix DIN question

Rusty Shackleford · Mar 6, 2020

If I get a Phoenix first stage from VDH, is there anyways to convert it to DIN as all my tanks are DIN. Would the Kraken DIN piece work?

rsingler · Mar 6, 2020

@herman ?

Rusty Shackleford · Mar 6, 2020

I was gifted three DA Aquamasters. I re-gifted one and am going to upgrade the other two as best possible. The Phoenix and other internal upgrades are no-brainers.

herman · Mar 6, 2020

I was not involved in the DIN and am not sure. I know there are 2 versions of the AK threads and I heard rumors that the Phoenix may also have 2 different thread patterns. Bryan is the best one to ask.
Personally, I never understood the fascination with DIN.

Rusty Shackleford · Mar 6, 2020

All my tanks are DIN.

tbone1004 · Mar 6, 2020

@Luis H will have to answer definitively. The "old" version uses a really annoying DIN fitting that is essentially unobtanium. I believe the new one uses a standard DIN set but Luis or @Bryan@Vintage Double Hose would have to clarify. They're various versions of the Aqualung Titan din kits, but I can't remember when they switched to the new design.

Angelo Farina · Mar 7, 2020

herman:
Personally, I never understood the fascination with DIN.

It is just a bit more safe... O-ring explosion is relatively frequent on rented yoke tanks to poorly-maintained O-rings.
Usually it happens on boat, when pressurizing the reg. But sometimes it happens underwater, and it empties the tank quite quickly. If you have two regs on two valves, and you are quick enough, you can close the valve of the exploded O-ring. But if you, as many, only rely on a single first stage, then the situation becomes quite bad.
On DIN fitting the O-ring is much more protected, and it stays on the reg, not on the tank, so it is usually much better maintained. O-ring explosions are very rare. And when they occur, the air loss is not so dramatic, giving you time to act.
In conclusion, in my opinion, DIN is safer than Yoke. Even using two Yoke regs on two separate valves is not entirely safe, as the procedure of closing one valve is something not usual for most rec divers.

To @Rusty Shackleford
If you unscrew your yoke nut and post a photo of the threaded part and O-ring I can see if I have something compatible in my storage...

Luis H · Mar 7, 2020

When I originally designed the Phoenix (about 15 years ago)I wanted to use as many available parts as possible, such as the yokes from the Conshelf.

The yoke threads and yoke nut retainer threads that US Divers (now Aqua Lung) has been using started around 1955 with the yoke nut for the original Mistral (or the Overpressure regulator).

I measure the treads as 0.78” by 20 TPI (Threads Per Inch). This is not a standard threads, but that is what it is.

Since this is not a standard thread, I felt the need to specify the following ranges for minor, pitch and major diameters:

Minor dia. 0.726” to 0.737”
Pitch dia.: 0.748” to 0.753”
Major dia.: 0.780” to 0.786”

Years later I was able to locate a drawing (thanks to Ryan Spence) for the original 1955 yoke nut from US Divers and sure enough the threads are 25/32” – 20TPI.

25/32” = 0.7813”

These are male threads on the body of the regulator. Aqua Lung and many other manufactures have switched to using female thread on the body of the regulator because it seems to be easier to design the regulator with a conversion from yoke to DIN. The newer yoke retainers now use male threads instead of a yoke nut.

I am not exactly sure why US Divers picked that unique thread size, but it may have something to do with the CGA valve interface size. IMO, they should have picked the next standard size up, but they were manufacturing both parts, so they controlled the interface between their parts.

Below is a copy of the 1955 yoke nut drawing.

Designing the original Argonaut Kraken (about 8 years ago), I again followed the philosophy of forwards and backwards parts compatibility. At the time Aqua Lung was still making the original Titan. Yokes and DIN fittings were available for both the early Titan and the Conshelf. VDH was going to supply the Argonaut with the yoke fitting, but at the time it made sense to be compatible with parts available by probably the biggest manufacturer of Scuba regulator.

About 5 years ago we decided to change the male threads in the Argonaut to a standard male Metric thread used by several manufacturers (including Mares and some of the manufacturers in Asia).

The new threads are M20 x 1mm pitch. So the new threads are in inches approximately 0.7874 inches in diameter and the 1 mm pitch is 0.03937”, or about 25.4 threads per inch. So the new threads are just a little bit finer threads, but about the same diameter.

In appearance the threads look similar unless you compare them side by side.

The old yokes and yoke nut are not compatible with the new threads and you do not want to try to force them together. It will not happen.

I believe that @Bryan@Vintage Double Hose also converted the new Phoenix to the new metric threads a few years ago. I provided him with new drawings, but I do not keep track of his production. I do not know when or if he switched. I am pretty sure he did, but you should check with him.

Bryan was selling DIN adapters for the new threads. Contact him about it.

Be aware that the regulator will stick-out even further with the DIN adapter. It will guaranty to touch your back. With the correct back-plate and cylinder, this can be a very good thing.

Luis H · Mar 7, 2020

Angelo Farina:
It is just a bit more safe... O-ring explosion is relatively frequent on rented yoke tanks to poorly-maintained O-rings.
Usually it happens on boat, when pressurizing the reg. But sometimes it happens underwater, and it empties the tank quite quickly. If you have two regs on two valves, and you are quick enough, you can close the valve of the exploded O-ring. But if you, as many, only rely on a single first stage, then the situation becomes quite bad.
On DIN fitting the O-ring is much more protected, and it stays on the reg, not on the tank, so it is usually much better maintained. O-ring explosions are very rare. And when they occur, the air loss is not so dramatic, giving you time to act.
In conclusion, in my opinion, DIN is safer than Yoke. Even using two Yoke regs on two separate valves is not entirely safe, as the procedure of closing one valve is something not usual for most rec divers.

To @Rusty Shackleford
If you unscrew your yoke nut and post a photo of the threaded part and O-ring I can see if I have something compatible in my storage...

Hi Angelo,

First, I hope you and your family are doing well. I hope you and your family are not affected by the virus.

I will suggest not to use rental tanks with DIN valves. Rental tanks and valves receive a lot of abuse and the last thing you want to do is screw your nice regulator into a rental valve. Think of it as having unprotected sex with a rental… never mind, you get the picture.

The only exception would be if you are renting from a high end tech-friendly dive operator that takes extremely good care of their gear AND replaces their tank valves with new ones on a regular basis.

If the valve doesn’t look brand-new from the outside, the female DIN threads are going to look much worse. But you can’t really inspect the loaded side of the threads. The side of the threads that receive wear are not visible from the outside.

DIN fittings are fine if you own both the regulator and the cylinders. They are even better if you only use them in fresh water.

There are a number of reasons why most large rental tank fleets use only yoke (not even convertible valves). They can tolerate the abuse much better and they will not damage the regulator interface. Yes, sometimes damaged yoke valves or due to operator error will blow an O-ring, but the few times I have seen in happen it was easily traced to some damage or more often operator error.

I was talking to Augusto (the dive operator manager at Buddy Dive in Bonaire)and he was telling me that he replaced all his DIN convertible valves with basic yoke valves because they would get damaged too easily. Shore diving, even a small bump on the back of the pick-up truck would slightly deform the top of the valve. Just a slight amount of deformation and a regulator would go in hard, but after pressurizing it, after the dive it can be very hard to remove the regulator.

I stated using DIN fitting in the mid 70’s (before they were call DIN fittings and long before they were commonly available in the US). I have had to replace several Poseidon and Drager tank valves because the chrome on the female threads would wear and more than once I have had to use a wrench to unscrew a regulator after a dive. Diving from a sandy beach was always the worst. If anything get in the threads, you may not notice it while screwing the regulator, but after the dive (after removing all the pressure) the regulator was often very hard to unscrew (if the threads were not brand new).

I was talking to a dive resort owner in the Philippines (flying out of Dumaguete) that caters to a German clientele. I ask her if they used DIN valves on their rental tanks. She said yes, they are no problem; she just has to replace all of them every 5 years. I thought, that is nice if you catch it when the valves are new. I am not sure if I still want to screw my regulator into a 5 year old valve.

I still have my Poseidon and Drager double cylinders that I bought from a “merchant mariner” in Puerto Rico (45 years ago). I used to love those cylinders and the DIN connections, but I have had too many issues with both. A lot of little issues, but it adds up. They are still fun to dive, but it is too much trouble.

This is one of my old Phoenix with a DIN fitting and my Poseidon tanks.