Intro into Gas page.

[Drewskey]

Intro to Scuba Gas Laws

Larry,

Please read what I copied off of the above link. It is the second paragraph. Is the bold wording correct?

"Water weighs considerably more than air does, so it can exert much more pressure. It only takes a 1 inch column of sea water 33 feet tall to weigh 14.7 pounds. This means that at a depth of 33 feet deep in the ocean, there is a total pressure of 29.4 pounds per square inch (psi). This would be 2 ATMs of pressure. One ATM from the water, + one ATM from the water(Do you mean air?). We call this the ambient pressure or absolute pressure. "

Also, your atmosphere multipliers are not consistent.

"Let's then find out the absolute pressure for a depth of 50 feet of sea water. To solve this, we multiply the depth, 50, times the pressure per foot, .445. This gives us an answer of 22.25. This however would be the gauge pressure at a depth of 50 feet. To find the absolute pressure, we must add in the 14.7 psi of atmospheric pressure. 22.25 + 14.7 = 36.95 Thus the pressure for a depth of 50 feet in sea water is 36.95 pounds per square inch absolute. It is common to refer to this as "PSIA", pounds per square inch absolute.

Try to figure out the gauge pressure for a depth of 75 feet in fresh water. To solve this we multiply .432 by 75 to get 32.4 psi. Since we wanted gauge pressure in this example, we do not add in the atmospheric pressure and show the pressure using psi, not psia."

Just checking. I am no expert.

[DMWiz]

The multipliers for fresh water and salt water are different because salt water is more dense. .432 for fresh water is correct.

[Drewskey]

Gotcha. Good to know. I did not read into the fresh water vs. salt water part. I'm landlocked and the only salt water near me is when I have a sore throat!

[BouzoukiJoe A.K.A. wrecker130 AKA Chuck Norris AKA joeforbroke (banned)]

It's horrible to be landlocked. You seem to be reading carefully and asking questions. That's a great attitude!