advice on pony bottles

[TechBlue]

Mixing measurement system had nothing to do with the Hubble fiasco. The problem was an instrument in the lab was assembled wrong.

I think maybe you are thinking of a Mars lander issue which was traced to a software flaw. While the code flaw did have something to with mixing units, they real problem was they did not design proper test for the software and the stupid mistake was undetected. You can't trust this dam s/w engineers, I know cause I is one <sic>.

You SW guys get away with murder but as I recall they used metric and imperial calculations for the mirror alignment which was why they had to send the shuttle out to fix it, regardless it is so much easier to count in units of ten.

As a simple carpenter I was very unimpressed to see that in the union they actually used building blocks to help apprentices learn imperial and 16th's rather than saying 20 feet 7 inches and "one little mark"

 

[DandyDon]

imperial vs metric blah blah blah, whatever

I am on Roatan. On previous trips, I never saw a thermometer - but I like to see one at times so I brought one to hand outside the dive shop. It reads metric and Fahrenheit both and today got to 94F. :cool2:

Hahaha! Ten fingers???

Don't you mean 15??

I think you're speaking of Arkansad, Apalacia and the NJ Pine Barrons where family trees intertwine a lot. :shocked2:

 

[GrumpyOldGuy]

You SW guys get away with murder but as I recall they used metric and imperial calculations for the mirror alignment which was why they had to send the shuttle out to fix it, regardless it is so much easier to count in units of ten.

As a simple carpenter I was very unimpressed to see that in the union they actually used building blocks to help apprentices learn imperial and 16th's rather than saying 20 feet 7 inches and "one little mark"

It fun playing blame the s/w, I work with a bunch of mechanical engineers that like the same game. Lucky, I don't have to rely on a faulty human memory (which are less reliable than Windoze on a bad day) and can use the search button. See below. I enjoy popcorn, want to share. All I know about carpentry is the old adage, measure once and beat in to place.

Side note: Since I am a geek, I think in hex, not 10ths. So thinking in 10th does not help me.


Do a search for hubble teescope problems, borrowed from From Wikipedia...

A commission headed by Lew Allen, director of the Jet Propulsion Laboratory, was established to determine how the error could have arisen. The Allen Commission found that the main null corrector, a device used to measure the exact shape of the mirror, had been incorrectly assembled&#8212;one lens was wrongly spaced by 1.3 mm.[49] During the polishing of the mirror, Perkin-Elmer had analyzed its surface with two other null correctors, both of which correctly indicated that the mirror was suffering from spherical aberration. The company ignored these test results as it believed that the two null correctors were less accurate than the primary device that was reporting that the mirror was perfectly figured.[50]

 

[Divedaily]

I used to carry a spare air unit with me on deep dives as a secondary option to my alternate air supply for my students. I stopped doing that the first time a student grabbed it at 85' and sucked every thing out of it in a single breath.

:laughing:

 

[elmer fudd]

To put things into a little perspective. A fully charged 3cf SpareAir contains 85 liters of air. The average adult has a lung capacity of 4-6 liters and at 85' will use up air at 3.6 times the normal rate. Let's say though that the distressed diver is Lance Armstrong and has a lung capacity of 8 liters. He's still not capable of using more than 28.8 liters in a single breath.

In reality, he wouldn't even be capable of that, because you can't exhale all of the air in your lungs. There's generally about 1 liter of air left in your lungs at a full exhale.

In normal breathing, we inhale about 1/2 liter per breath.

 

[DandyDon]

To put things into a little perspective. A fully charged 3cf SpareAir contains 85 liters of air. The average adult has a lung capacity of 4-6 liters and at 85' will use up air at 3.6 times the normal rate. Let's say though that the distressed diver is Lance Armstrong and has a lung capacity of 8 liters. He's still not capable of using more than 28.8 liters in a single breath.

In reality, he wouldn't even be capable of that, because you can't exhale all of the air in your lungs. There's generally about 1 liter of air left in your lungs at a full exhale.

In normal breathing, we inhale about 1/2 liter per breath.

How much air in a 1.7 cf filled to 2,000 psi bleeding off of a tank? 32?

Ain't it cute - a paperweight tank

Down at 3.5 atmospheres, I can see flow stopping quickly...

 

[elmer fudd]

I can't really see much point to a 1.7 cf tank myself, although they do make an even smaller 1 cf model.

To my way of thinking, a 3 cf is an absolute minimum and then only for dives of 50' or less.

At 85' I'm going to be packing a 19 cf pony.

One neat thing about SpareAir's though is they share the same thread pitch as paintball tanks. So if you buy a cheap 48" paintball tank you can easily go to 5.7 cf and 48 ci paintball tanks are dirt cheap. There's also a 72", (8.5 cf), paintball tank out there. Not very common, but still quite reasonably priced.

 

[DandyDon]

I can't really see much point to a 1.7 cf tank myself, although they do make an even smaller 1 cf model.

They're all lame, but they'll make whatever divers will buy.

They have a Nitrox model. You can put blended Nx in any scuba tank.

 

[elmer fudd]

They're all lame, but they'll make whatever divers will buy.

They have a Nitrox model. You can put blended Nx in any scuba tank.

I think they're just more of a special purpose item than anything else. I picked one up cheap the other day, ($55), primarily for use with vintage equipment, (DH reg and no octo). For me it will be used in shallow water and I've tested it on an ascent. I started breathing on it at 20' at the beginning of a three minute stop and then gradually swam up along the bottom. Total time was perhaps 4 minutes and the air was mostly gone when I got to the surface. That's good enough for what I intend on using it for.

If I'm doing a deep dive it's sure not going to be with a double hose reg and a spare air.

 

[palmm]

i would get a al40 if i was going to get a bail out bottle why not have more air than try to cut it close.