other tanks

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Posted by Chris on March 07, 2001 at 12:01:00:

In Reply to: Answers... posted by R Bear on March 07, 2001 at 11:00:54:

I noticed you did not include HP tanks in your list.
I used a set of double PST HP120's for about three years.
With a Sherwood manifold at 300 psi they were neutral.
I know because I measure the buoyancy of all my tanks instead of relying on charts.
Using my Dive-Rite ABS back plate I needed 20 lbs. of lead to maintain my last safety stop.

To check tank buoyancy I fill a large trash can with water, put the tanks in, and weigh them full and at 300 psi.
If they are buoyant, I add fixed weights to them, to make them negative.
This procedure does not account for the slight buoyancy difference between fresh and salt water, but it is close enough to adjust my weights.

When I dive I adjust my weights for the various tanks so that I have the same total buoyancy at 300 psi, regardless of tank size, material, or volume.

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