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According to DAN, monitoring your turn pressure is simple: “Before the dive, determine your turn pressure based on your starting pressure and your planned dive time/depth. You must return to your beginning point with enough air to make your ascent and do a safety stop.

## What is turn pressure?

Turn pressure is the amount of gas needed to make your way to your exit point expressed in psi, i.e., when I hit 1500 psi I’m going to turn around and head back to the boat. Yield to temptation; it may not pass your way again.

## How is turn pressure calculated diving?

Baseline = cap ÷ working pressure Baseline = 80 ÷ 3000 Baseline = . 0267 Page 7 padi.com A-173 Instructor Guide Appendix ® PADI Assuming your 80 cubic foot cylinder is full (3000 psi), then: Turn pressure = 3000 – (39.2 ÷ . 0257) Turn pressure = 1474 psi.

## What is diving pressure?

The weight of the water above a diver exerts pressure on their body. The deeper a diver descends, the more water they have above them, and the more pressure it exerts on their body. The pressure a diver experiences at a certain depth is the sum of all the pressures above them, both from the water and the air.

## How do you calculate PSI from volume?

If you know some lateral measurement of the tank in addition to the volume, you can calculate the water pressure at the tank’s bottom point. This gives the height. If the height is in feet, then multiply by 0.4333 to get pounds per square inch (PSI). If the height is in meters, multiply by 1.422 to get PSI.

## What is the water pressure at 33 feet?

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.

## Does pressure change underwater?

Pressure increases with ocean depth.

At sea level, the air that surrounds us presses down on our bodies at 14.7 pounds per square inch . … The deeper you go under the sea, the greater the pressure of the water pushing down on you. For every 33 feet (10.06 meters) you go down, the pressure increases by one atmosphere .

## Why do lungs shrink underwater?

As external pressure on the lungs is increased in a breath-holding dive (in which the diver’s only source of air is that held in his lungs), the air inside the lungs is compressed, and the size of the lungs decreases.