How many shots till empty using 70CI/4500 PSI Nitrogen ?

[tatfree]

I have been on Hubbs tank calculator and wanted to double check my figures on the forum here. Seems it's to good to be true to me.


http://www.spudfiles.com/spud_wiki/inde ... bb_Library




Nitrogen tank filled to 4500PSI and it's 70 Cu In
Elevation 0


Chamber volume 42.39 Cu In
@ 200 PSI = 38 shots
@ 18 PSI = 2270 shots

Chamber volume 21.195 Cu In
@ 200 PSI = 77 shots
@ 18 PSI = 4539 shots

Chamber volume 4.71 Cu In
@ 200 PSI = 345 shots
@ 18 PSI = 20,427 shots

Are these figures correct ?
Anything else I should take into consideration ?

[DR]

p¹ x v¹ = p² x v² ???


4500 x 70 = 3150000

315000 / (200 x 42.39) = 37
315000 / (18 x 42.39) = 412

315000 / (200 x 21.95) = 71
315000 / (18 x 21.95) = 825

315000 / (200 x 4.71) = 334
315000 / (18 x 4.71) = 3715

[tatfree]

p¹ x v¹ = p² x v² ???


4500 x 70 = 3150000

315000 / (200 x 42.39) = 37
315000 / (18 x 42.39) = 412

315000 / (200 x 21.95) = 71
315000 / (18 x 21.95) = 825

315000 / (200 x 4.71) = 334
315000 / (18 x 4.71) = 3715

Thanks Dr.
So that's how that works.......
Wonder why Hubbs tank calculater has the 18PSI figures so far off ? Never the less I'm still happy with how many shots I can get out of a single tank. Kinda knew it was to good to be true on those figures when checking it out.

[DR]

... Hope that formula is the right one? Ha!

[Hubb]

I have no idea how the errors ended up like that. Thanks for pointing it out.

... Hope that formula is the right one? Ha!

It is.