My first Tanks

On Mon, 24 Jul 2006 21:34:29 GMT, mag3 wrote:
> Hi All.
>
> Just purchased my first set of tanks (Worthington X7-120)'s Steels, rated
> at 230bar/3442psi as part of my new RAS setup (also purchased an AL30
> Pony). They came from the LDS charged at 3500 PSI. But upon filling at
> Dutch, the gas blender indicated he would fill them to 4000 PSI and they'd
> cool down to 3500 PSI or thereabouts (actually, there down to 3100 PSI now
> so perhaps I got rooked for a high pressure fill).

Typical. At Dutch, they can't afford to fill slowly enough to avoid a large
temperature rise. To keep the temperature rise to a minimum, they'd have to
fill at 60-80 psi per minute. That means it would take 45 minutes to fill your
cylinder. Imagine them doing that on a busy day!

At 3100 psi, you still have around 100 cubic feet of gas in that cylinder.
Don't think you'll use that up on a single dive at Dutch, do you?

> Question being, for a steel 120 rated at 230bar/3442 PSI, is there any
> margin for "overfilling" and what would be the max to which it could be
> filled without any danger to the tank or the 1st stage (which in the case
> of my 2 regs, are rated to 3500PSI each as well)?

Those cylinders, new or in like-new condition, should be able to handle an
occasional overfill to 4000 psi without a problem.

> 2nd Question - The LDS recommended converting the regs to DIN for these
> tanks but I hear from other shops that it is not necessary. Thoughts?

The 300 bar DIN fitting is nominally rated to handle higher pressures (there
is also a 200 bar DIN - both ratings are very conservative). Modern "A-Clamp"
or "yoke" fittings should be able to withstand 3500 psi without problem.

To a large degree, this is a matter of personal preference. I prefer 300 bar
DIN, even on low-pressure cylinders. I do have a few with 200 bar DIN on them.
I don't like the clamp knob of the yoke sticking out behind me, where it is
subject to snagging or entanglement in a place I can't see or reach well to
clear it.

> BTW, doing much better on buoyancy. THe steel 120's actually help.

Why? Were you underweighted before? You don't need big cylinders to fix that.

--
Art Greenberg
artg at eclipse dot net

On Mon, 24 Jul 2006 21:34:29 GMT, mag3 wrote:
> Hi All.
>
> Just purchased my first set of tanks (Worthington X7-120)'s Steels, rated
> at 230bar/3442psi as part of my new RAS setup (also purchased an AL30
> Pony). They came from the LDS charged at 3500 PSI. But upon filling at
> Dutch, the gas blender indicated he would fill them to 4000 PSI and they'd
> cool down to 3500 PSI or thereabouts (actually, there down to 3100 PSI now
> so perhaps I got rooked for a high pressure fill).

Typical. At Dutch, they can't afford to fill slowly enough to avoid a large
temperature rise. To keep the temperature rise to a minimum, they'd have to
fill at 60-80 psi per minute. That means it would take 45 minutes to fill your
cylinder. Imagine them doing that on a busy day!

At 3100 psi, you still have around 100 cubic feet of gas in that cylinder.
Don't think you'll use that up on a single dive at Dutch, do you?

> Question being, for a steel 120 rated at 230bar/3442 PSI, is there any
> margin for "overfilling" and what would be the max to which it could be
> filled without any danger to the tank or the 1st stage (which in the case
> of my 2 regs, are rated to 3500PSI each as well)?

Those cylinders, new or in like-new condition, should be able to handle an
occasional overfill to 4000 psi without a problem.

> 2nd Question - The LDS recommended converting the regs to DIN for these
> tanks but I hear from other shops that it is not necessary. Thoughts?

The 300 bar DIN fitting is nominally rated to handle higher pressures (there
is also a 200 bar DIN - both ratings are very conservative). Modern "A-Clamp"
or "yoke" fittings should be able to withstand 3500 psi without problem.

To a large degree, this is a matter of personal preference. I prefer 300 bar
DIN, even on low-pressure cylinders. I do have a few with 200 bar DIN on them.
I don't like the clamp knob of the yoke sticking out behind me, where it is
subject to snagging or entanglement in a place I can't see or reach well to
clear it.

> BTW, doing much better on buoyancy. THe steel 120's actually help.

Why? Were you underweighted before? You don't need big cylinders to fix that.

--
Art Greenberg
artg at eclipse dot net

Art Greenberg wrote

> The 300 bar DIN fitting is nominally rated to handle higher pressures
> (there
> is also a 200 bar DIN - both ratings are very conservative). Modern
> "A-Clamp"
> or "yoke" fittings should be able to withstand 3500 psi without problem.

There seems to be three DIN valves available in the US, 300 BAR, 232 BAR and
200 BAR. The rating does not indicate the valve's ability to handle high
pressure. Instead, it refers to the ability of the regulators it will
attached to to withstand pressure. You can hook a 300 BAR regulator to any
of the three, but can not hook a regulator rated for 200 or 232 BAR to a 300
BAR valve.

The tanks he has most likely have the 232 BAR valves, the newer ones that
come with slugs to convert to an A clamp system. If he had anything else,
he would not be asking about whether to convert, he'd be asking how. The
slugs, by the way, won't work in the 300 BAR valves either.

>> BTW, doing much better on buoyancy. THe steel 120's actually help.
>
> Why? Were you underweighted before? You don't need big cylinders to fix
> that.

I'll take that a step further. The 120's can't help buoyancy. The
increased weight shift during the dive increases the amount of adjustment
required during the dive. As Art suggests, if your buoyancy is better with
the 120s, there was something wrong with your weighting to begin with.

Lee

Art Greenberg wrote

> The 300 bar DIN fitting is nominally rated to handle higher pressures
> (there
> is also a 200 bar DIN - both ratings are very conservative). Modern
> "A-Clamp"
> or "yoke" fittings should be able to withstand 3500 psi without problem.

There seems to be three DIN valves available in the US, 300 BAR, 232 BAR and
200 BAR. The rating does not indicate the valve's ability to handle high
pressure. Instead, it refers to the ability of the regulators it will
attached to to withstand pressure. You can hook a 300 BAR regulator to any
of the three, but can not hook a regulator rated for 200 or 232 BAR to a 300
BAR valve.

The tanks he has most likely have the 232 BAR valves, the newer ones that
come with slugs to convert to an A clamp system. If he had anything else,
he would not be asking about whether to convert, he'd be asking how. The
slugs, by the way, won't work in the 300 BAR valves either.

>> BTW, doing much better on buoyancy. THe steel 120's actually help.
>
> Why? Were you underweighted before? You don't need big cylinders to fix
> that.

I'll take that a step further. The 120's can't help buoyancy. The
increased weight shift during the dive increases the amount of adjustment
required during the dive. As Art suggests, if your buoyancy is better with
the 120s, there was something wrong with your weighting to begin with.

Lee

Lee Bell wrote:

> I'll take that a step further. The 120's can't help buoyancy. The
> increased weight shift during the dive increases the amount of adjustment
> required during the dive. As Art suggests, if your buoyancy is better with
> the 120s, there was something wrong with your weighting to begin with.

It gets weight off your hips and onto your back, which can improve
trim, which Arnold might be confusing with buoyancy.

Lee Bell wrote:

> I'll take that a step further. The 120's can't help buoyancy. The
> increased weight shift during the dive increases the amount of adjustment
> required during the dive. As Art suggests, if your buoyancy is better with
> the 120s, there was something wrong with your weighting to begin with.

It gets weight off your hips and onto your back, which can improve
trim, which Arnold might be confusing with buoyancy.

Al Wells wrote

>> I'll take that a step further. The 120's can't help buoyancy. The
>> increased weight shift during the dive increases the amount of adjustment
>> required during the dive. As Art suggests, if your buoyancy is better
>> with
>> the 120s, there was something wrong with your weighting to begin with.

> It gets weight off your hips and onto your back, which can improve
> trim, which Arnold might be confusing with buoyancy.

Good point.

Lee

Al Wells wrote

>> I'll take that a step further. The 120's can't help buoyancy. The
>> increased weight shift during the dive increases the amount of adjustment
>> required during the dive. As Art suggests, if your buoyancy is better
>> with
>> the 120s, there was something wrong with your weighting to begin with.

> It gets weight off your hips and onto your back, which can improve
> trim, which Arnold might be confusing with buoyancy.

Good point.

Lee

On 25 Jul 2006 07:11:13 -0700, "Al Wells" <al.wells@gmail.com> wrote:

>Lee Bell wrote:
>
>> I'll take that a step further. The 120's can't help buoyancy. The
>> increased weight shift during the dive increases the amount of adjustment
>> required during the dive. As Art suggests, if your buoyancy is better with
>> the 120s, there was something wrong with your weighting to begin with.
>
>It gets weight off your hips and onto your back, which can improve
>trim, which Arnold might be confusing with buoyancy.

Perhaps so. Let's put it this way. Prior to the 120's, I could not begin to submerge
properly without at least 22lbs in fresh water with a 7.0mm. With the 120's (and
with dumping my ankle weights) I'm now down to 16-18lbs, leaning toward 16.
Dumping the ankle weights helped a lot with trim in fresh water, but I need to see
if they might be required in salt water. I recall some issues with salt water this past
January in Bradenton Beach Fl.

Next salt water opportunity is back in Bora Bora in another month where I'll be taking
Rescue Diver as well as some other "enjoyment" dives, and practicing with the Ikelite
housing. After that, back to the NJ Shore for the two ocean dives I need to do for my
Wreck/Deep Diver specialties.

BTW, Lee, I'll be back in Bradenton Beach in mid-January for a week visiting Dad. If
you want to set something up, perhaps I can hook up with some of you FL. folks.




____________________________________________
Regards,

Arnold

On 25 Jul 2006 07:11:13 -0700, "Al Wells" <al.wells@gmail.com> wrote:

>Lee Bell wrote:
>
>> I'll take that a step further. The 120's can't help buoyancy. The
>> increased weight shift during the dive increases the amount of adjustment
>> required during the dive. As Art suggests, if your buoyancy is better with
>> the 120s, there was something wrong with your weighting to begin with.
>
>It gets weight off your hips and onto your back, which can improve
>trim, which Arnold might be confusing with buoyancy.

Perhaps so. Let's put it this way. Prior to the 120's, I could not begin to submerge
properly without at least 22lbs in fresh water with a 7.0mm. With the 120's (and
with dumping my ankle weights) I'm now down to 16-18lbs, leaning toward 16.
Dumping the ankle weights helped a lot with trim in fresh water, but I need to see
if they might be required in salt water. I recall some issues with salt water this past
January in Bradenton Beach Fl.

Next salt water opportunity is back in Bora Bora in another month where I'll be taking
Rescue Diver as well as some other "enjoyment" dives, and practicing with the Ikelite
housing. After that, back to the NJ Shore for the two ocean dives I need to do for my
Wreck/Deep Diver specialties.

BTW, Lee, I'll be back in Bradenton Beach in mid-January for a week visiting Dad. If
you want to set something up, perhaps I can hook up with some of you FL. folks.




____________________________________________
Regards,

Arnold