Figuring out PSI at depth...

[cwkline]

I've always used 2.5 ft per pound to calculate head pressure and lift requirements for pumps. Seems to work for diving. 100ft/33 +1 = 25 psi, or 2.5 ft/lb.

 

[ruready7]

Yes metric easier all because of the base 10.....lol

 

[sschlesi]

100ft/33 +1 = 25 psi, or 2.5 ft/lb.

This must be that new math I've heard so much about.

 

[cwkline]

This must be that new math I've heard so much about.

Yeah, my equation is wrong, but on a guage (psig) at 100ft would be a little over 40 psi. You can look here Converting Pump Head to Pressure to see what I mean.
Sorry my math was a little screwy, I work nights and was a bit tired.

 

[AXL72]

Here ya go:

Seawater Density = 64 pcf = 64 pounds per cubic foot

To calculate pressure at depth, x in feet

use:

64 pcf * x / (144 square inches per square foot) = pressure, P, in psi (gauge)


Example:

P(x=33ft) = 64 pcf * 33 ft/144 in^2/ft2 = 14.7 psi @ 33 ft...gauge of course

and so on and so on...................just substitute whatever you want for x



so...at x = 100 ft

P(x=100ft) = 64*100/144 = 44.4 psi....gauge of course

 

[AXL72]

In Imperial-

Surface- 14.7 psi
33'- 29.4 psi
66'- 44.1 psi
99'- 58.8 psi
132'- 73.5 psi
165'- 88.2 psi


Edit- that's PSIA- absolute

TC is tabularizing "absolute pressure", which you will never see on an external pressure gauge that marked off in psi.