SPUNDING Fhysics Q wtf atü

[Blue-Frog]

I was looking at some old German books and found mention of Spunding at (some value) atü.
I looked up atü and found it is short for the German word "Atmosphärenüberdruck" which translated by me becomes "above atmospheric pressure" or "over 1 atm"
I looked up atm and found it is given as 14.7 psi

so when we read a pressure or spunding regulator guage and it says 5 psi... is that below 1 atm?
Or, are pressure gauges basically all designed to read above 1 atm?

is 5psi... 5 psi or 19.7 psi ?

 

[bellhp]

yes, you have to account for the one atmosphere at sea level . the 5 psi is "gauge pressure" and the "19.7 is " Atmospheres Absolute"
I'm a deep sea diver so this is correct ... the German translation I'll have to take your word for that.

 

[doug293cz]

yes, you have to account for the one atmosphere at sea level . the 5 psi is "gauge pressure" and the "19.7 is " Atmospheres Absolute"
I'm a deep sea diver so this is correct ... the German translation I'll have to take your word for that.

That would be 19.7 psi absolute (psia), or 1.34 atmospheres (1 atmosphere is 14.7 psia.)

Brew on

 

[bellhp]

But ze Germans use Bar which is 14.5 psi go figure, I stand corrected on the ATA vs. PSIA . I'm tired... been up 18hrs.
But whichever way you go you will have either 1 Atm or 1 Bar in the fermenter when you seal it ... the gauge reads what you add.

 

[Blue-Frog]

So, our gauge pressures (psi) are actually the pressure above 1 atm just as the German atü is.
Funny that one atü = 2 atm
but two atü do not = 4 atm
rather
2 atü = 3 atm
I get it... but one gets so used to being able to simply multiply both sides and still have equality, without taking that last step necessary to comprehend an action's true meaning.