re-valve tanks OR convert my reg?!?

[Byte Me]

Originally Posted by CompuDude

You should be ashamed of yourself, awap. You should know better than to give advice like that. You're going to get someone seriously hurt... and yourself sued... one of these days with comments like that. It's one thing to joke among friends during your SI, it's another to present it as a seriously viable option in a public online forum where who knows who may be taking you seriously.

OP: Do NOT start hacking pieces off your valve. These are "true" high pressure tanks, 3500psi, which are required to be used with DIN only. (No, no one enforces this as "law", but there is good reason nontheless.)

Convert your regs to DIN, or pick up a second (DIN) first stage, if you want to use these tanks. DIN first stages can be had for $60 (new), less if yo buy used, so this is NOT a huge expense.

No worries, this was never an option. As learned in rescue - modifying equipment to perform in a manner other than what was intended or engineered for it is one of the best ways to end up in need of rescue or worse, recovery.

I'm going to convert to DIN and get an adapter for warm water dives where yoke is status quo.

[Jack Hammer]

Try calling Northeast Scuba, they carry a lot of used/rebuilt valves. See if they have a 3/4" 200 bar din valve then spend $15 and add the convertable yoke piece to it. I believe there were 200bar din valves made in 3/4" at some point. That'd be cheaper and give you more options than just changing your reg.

Jack

[awap]

Originally Posted by CompuDude

You should be ashamed of yourself, awap. You should know better than to give advice like that. You're going to get someone seriously hurt... and yourself sued... one of these days with comments like that. It's one thing to joke among friends during your SI, it's another to present it as a seriously viable option in a public online forum where who knows who may be taking you seriously.

OP: Do NOT start hacking pieces off your valve. These are "true" high pressure tanks, 3500psi, which are required to be used with DIN only. (No, no one enforces this as "law", but there is good reason nontheless.)

Convert your regs to DIN, or pick up a second (DIN) first stage, if you want to use these tanks. DIN first stages can be had for $60 (new), less if yo buy used, so this is NOT a huge expense.

I'm not joking. It may be a viable, affordable option which would allow this older valve design to be used with modern yoke regulators. I was hoping to see someone come along with some regulatory reason this is not doable. Or perhaps you could add some meat to your claim that there is "good reason nonetherless".

Exactly where do you think that magic catastrophic value is between 3442 psi and 3500 psi? And how is it that you think someone would be hurt? When you mount a yoke regulator on a tank with more pressure than the yoke can handle, you can expect the o-ring to extrude and leak or, perhaps the yoke to distort enough to result in a leak.

Here is a related discussion on Scubaboard: Using 232 bar yoke on HP 130 steel tank - ScubaBoard

[BSea]

Originally Posted by Jack Hammer

Try calling Northeast Scuba, they carry a lot of used/rebuilt valves. See if they have a 3/4" 200 bar din valve then spend $15 and add the convertable yoke piece to it. I believe there were 200bar din valves made in 3/4" at some point. That'd be cheaper and give you more options than just changing your reg.

Jack

As mentioned earlier by Indydiver. The threads on those tanks are 7/8 USF not the 3/4 NPS that are the norm for most all scuba tanks today. Switching to the convertible valve is not an option.

Originally Posted by awap

I'm not joking. It may be a viable, affordable option which would allow this older valve design to be used with modern yoke regulators. I was hoping to see someone come along with some regulatory reason this is not doable. Or perhaps you could add some meat to your claim that there is "good reason nonetherless".

Exactly where do you think that magic catastrophic value is between 3442 psi and 3500 psi? And how is it that you think someone would be hurt? When you mount a yoke regulator on a tank with more pressure than the yoke can handle, you can expect the o-ring to extrude and leak or, perhaps the yoke to distort enough to result in a leak.

Here is a related discussion on Scubaboard: Using 232 bar yoke on HP 130 steel tank - ScubaBoard

I see where you were going with cutting down the valve. And I agree that the pressure difference between the 2 is virtually non-existant. I know I've had just over 3500 in my hp120 that's rated for 3442. Most gages I've seen are + or - 2% or higher. So that gives more than a 68 psi high low range when filling a 3442 tank, or just over 3500 PSI when taking in the error factor.

And I agree that if done right, that cutting down the valve doesn't really expose the diver to any additional risk. But I also agree with Compudude (although I think the "Shame On You" was a little harsh). I wouldn't ever tell someone to do that in any public forum. 1st off, how many divers actually know the difference between a 200 bar valve & a 300 bar valve? My guess would be less than 10%.

Actually, since I know that those valves are hard to replace, I'd be afraid that the machine shop might ruin the valve. Then I'd have to find another one. As you and almost everyone esle pointed out, and the OP agrees. Converting the reg to yoke is the best, and arguably the only option.

[IndyDiver]

Originally Posted by awap

I'm not joking. It may be a viable, affordable option which would allow this older valve design to be used with modern yoke regulators. I was hoping to see someone come along with some regulatory reason this is not doable. Or perhaps you could add some meat to your claim that there is "good reason nonetherless".

I see two issues here: 1. is it OK from an engineering point of view? 2. is it OK from a practical point of view.

1. It is fine from an engineering point of view. It is an easy thing to do with a good milling machine. Putting 3500 lbs of pressure on a 5 thread DIN valve is no problem at all, it is well below the rated working pressure of the 5 thread DIN standard. Yoke valves are used on 3442 tanks all the time and there is no real difference between 3442 and 3500 psi. If you are going to worry about things like that, start worrying that a yoke fitting is rated at 232 bar, which is only 3365 psi, and people are putting them on 3442 psi tanks with the manufacturers blessing.

2. It has problems from the practical side. Many shops will know that a conversion valve was never made in 7/8 thread, especially with the Genesis brand stamped on it. When they ask about it and you tell them, "I just milled 5mm off the front", they will not fill the tank for you. If the machine shop messes up the valve, you are out one hard/costly to replace valve. Finally, depending on your reg, the Yoke/DIN conversion may not be a big deal and may not need a converter when traveling. I have a Zeagle reg and to convert it from DIN to Yoke or vice versa, all I have to do is screw out one bolt that holds the fitting. It is no harder than screwing the converter on and off. If you start with a Zeagle yoke reg, the DIN fitting is $45. I don't think you can beat $45 by milling the valve and doing a new viz on the tank.

Finally, I would not recommend it on an open internet forum because I wouldn't have control of the machining operation. Given my low opinion of my fellow man's ability not to screw up even simple directions, I would not want to assume they wouldn't find some way to kill themselves doing the mods. (Leaving all the metal filings from the machining operation in the valve comes to mind)

All rebuttals are welcome

[Jack Hammer]

Originally Posted by BSea

As mentioned earlier by Indydiver. The threads on those tanks are 7/8 USF not the 3/4 NPS that are the norm for most all scuba tanks today. Switching to the convertible valve is not an option.

...

Brain fart. I actually read the post regarding thread size and somehow confused the two. Good catch.

On a similar note, anyone know how difficult/costly/realistic it would be to have a 300 bar screw in din to yoke adapter made by a machine shop?

Jack

EDIT: I'm on a roll today, 2nd brain fart. Doesn't matter if they can make the adapter as most yoke regulators aren't large enough to fit over a 300 Bar din valve.

[northfrisian]

Originally Posted by Jack Hammer

EDIT: I'm on a roll today, 2nd brain fart. Doesn't matter if they can make the adapter as most yoke regulators aren't large enough to fit over a 300 Bar din valve.

And even if it did, the valve does not have the dimple on the back that the yoke needs

[Daddy Diver]

There is a style of adapter that would work. Rather than the insert type which works on the convertable valves, a simple nipple design, with din threads on one side and a yoke on the other would work great. I've seen them for sale on ebay, cheaper than covnerting your reg and you can still do yoke

[CompuDude]

Originally Posted by Daddy Diver

There is a style of adapter that would work. Rather than the insert type which works on the convertable valves, a simple nipple design, with din threads on one side and a yoke on the other would work great. I've seen them for sale on ebay, cheaper than covnerting your reg and you can still do yoke

If you're referring to these, they're are only for filling... not intended for underwater use. (And strongly recommended against.)

[beperkins]

The scuba gods were truly smiling upon you. You got a whole basement full of steel tanks, buying a DIN reg is a price I would pay gladly.