Quiz - 26 - Diving Knowledge Workbook - Diving Physiology

[spoolin01]

No doubt because in German the more common term is Eigenschaftsgrößeerhöhungoderabnahme .

Here the term apparently was first more commonly used for describing the rise or fall of the land such as for roads or railbeds. That's a pretty intuitive basis for its generalization into other areas of physical world or metaphoric use, even to color space and occasionally social science.

I found an interesting site purporting to catalog frequency of English usage of 60,000 common words. Gradient ranks #14,853 but usage is predominately in academics (760/959 cites), and even many of the other cites are clearly in a physical science context.

Looking at a few similarly ranked words with similar academic contribution to frequency of use, it scores on a rough par with oscillation, leakage, coded, inversion, and externally. Not sure that means anything other than probable flaws in that site's methodology, but at least gradient seems not wholly esoteric.

Words and phrases: frequency, genres, collocates, concordances, synonyms, and WordNet

 

[elmo]

I'm Australian, and in my experience gradient is commonly used to refer to the steepness of a slope. This is both technical and non-technical language.

In technical language it could also refer to a difference in temperature or pressure per distance. A difference in pressure in itself is called "head" in hydrodynamics (and perhaps other disciplines).

 

[Protondecay123]

I'm Australian, and in my experience gradient is commonly used to refer to the steepness of a slope. This is both technical and non-technical language.

In technical language it could also refer to a difference in temperature or pressure per distance. A difference in pressure in itself is called "head" in hydrodynamics (and perhaps other disciplines).

Gradient is a somewhat technical term, but certainly not limited to it's use in differential equations such as Maxwell's equations, etc. It's common parlance in Civil Engineering. Conceptually along a specific direction, i.e. alveoli to capillaries, etc. Here's an example. What is Vertical Alignment of Highways? Gradients and Vertical Curves
and physiology. A-a gradient • LITFL • CCC Ventilation

 

[Bob DBF]

Bringing technical/scientific terms into laymans language is always fun, in that one usually have to use imprecise language in order to make a simplified concept understandable to the new student. In a quiz like this, someone who a precise understanding of the terms may find themselves at a disadvantage.

Bring in different disciplines, languages, and cultures and it becomes quire interesting.

Thanks guys.

 

[DiverDaniel2485]

Hello, for the maths experts out there, I have done my EANx and Gas Blender and there is one thing I still cannot find. A formula for filling EANx tanks with a pre-existing pressure and oxygen concentration.

I know there are calculators available on computer/phone, but with where and how I work I often have only paper and pen handy.

Can anyone help me out with a formula? It must exist as that's what the gary kessler calculator (and similar ones) are using.

For example, I have a 20.9%O2 tank at 80 bar, I want to make it a EANx32 tank at 220 bar, how do I calculate this?

Thanks in advance.

 

[Angelo Farina]

Hello, for the maths experts out there, I have done my EANx and Gas Blender and there is one thing I still cannot find. A formula for filling EANx tanks with a pre-existing pressure and oxygen concentration.

I know there are calculators available on computer/phone, but with where and how I work I often have only paper and pen handy.

Can anyone help me out with a formula? It must exist as that's what the gary kessler calculator (and similar ones) are using.

For example, I have a 20.9%O2 tank at 80 bar, I want to make it a EANx32 tank at 220 bar, how do I calculate this?

Thanks in advance.

This case is simple, as the tank contains normal air.
The recipe for EAN32 is that the unknown pressure of pure oxygen, px, summed with 20.9% of the remaining pressure of air, pa, must be equal to 32% of 230 bar.
It is irrelevant if a fraction of pa is already in the tank, and another fraction needs to be added after the oxygen...
What matters is to find px and to be sure to add exactly this to tank, which will go from 80 to 80+px while pumping pure oxygen in it.
Hence the formula is:
px+0.209*(230-px)=0.32*230.
You solve the equation and find px=230*(0.32-0.209)/(1-0.209)=32.27 bar of pure oxygen.
Of course the calculation would be more complex if the gas already in the tank was not standard air...

 

[DiverDaniel2485]

This case is simple, as the tank contains normal air.
The recipe for EAN32 is that the unknown pressure of pure oxygen, px, summed with 20.9% of the remaining pressure of air, pa, must be equal to 32% of 230 bar.
It is irrelevant if a fraction of pa is already in the tank, and another fraction needs to be added after the oxygen...
What matters is to find px and to be sure to add exactly this to tank, which will go from 80 to 80+px while pumping pure oxygen in it.
Hence the formula is:
px+0.209*(230-px)=0.32*230.
You solve the equation and find px=230*(0.32-0.209)/(1-0.209)=32.27 bar of pure oxygen.
Of course the calculation would be more complex if the gas already in the tank was not standard air...

Thank you mate! You are an absolute legend!

This has driven me nuts for days. Out of interest, do you know the formula for if the content is Say EANx32 at 80 bar and I wish to make it into 40% (typical 230)?

But I think air is the only pre-existing gas I am likely to encounter

 

[Angelo Farina]

Thank you mate! You are an absolute legend!

This has driven me nuts for days. Out of interest, do you know the formula for if the content is Say EANx32 at 80 bar and I wish to make it into 40% (typical 230)?

But I think air is the only pre-existing gas I am likely to encounter

We are going severely off topic, it had been better if you did start a new thread in the proper section of this forum...
Now let's try to solve the case the existing gas in your tank is already Nitrox, at a certain percentage of Oxygen, say 32% at 80 bar, and you want a tank full at 230 bar with EAN 40%.
The equation is similar, but you must account separately the p.p. of the oxygen already in the tank:
0.32*80+px+0.209*pa = 0.4*230
In this case, pa=230-80-px = 150-px
Hence the solution of the equation becomes:
0.32*80+px+0.209*(150-px) = 0.4*230
px = (0.4*230-0.32*80-0.209*150)/(1-0.209) = 44.31 bar of pure oxygen
Please note, however, that in some cases there is no solution, and you must release at least partially the gas contained in the tank. This occurs easily if the tank has an high percentage of oxygen and is at an high pressure.
In this case, there is already too much oxygen, and the formula above yields a negative result, which is nonsense.