How to Use an Air Tank in Scuba Diving

This nifty cylinder holds the compressed air you'll be breathing underwater. Do take care of it.

Things You'll Need

  • Scuba Gear
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Instructions

  1. Learn the Basics

    • 1

      Jettison the most common (and most frustrating) fallacy that a scuba tank holds pure oxygen. It is filled with compressed air, which is roughly 21 percent oxygen and 79 percent nitrogen ' the same mixture we breathe (almost) every second on land. Pure oxygen can be toxic when breathed at relatively shallow depths. Compressed air, however, can be toxic at depths greater than 200 feet (far beyond the reaches of recreational diving).

    • 2

      Note that the most common recreational scuba tank is made of aluminum and holds 80 cubic feet of air, compressed into an area 2 feet high and half a foot in diameter.

    • 3

      Know that "an 80" is usually filled from 2000 to 3000 psi ' pounds per square inch ' of air pressure.

    • 4

      Understand that scuba tanks are regulated by the U.S. Department of Transportation and other similar foreign agencies. Regulations require that tanks undergo periodic visual inspections and pressure tests.

    Using the Tank

    • 5

      Fill or rent your tank from a reputable dive shop.

    • 6

      Ask where the shop compressor's air intake pipe is. If you find it sticking out of the shop's back wall, into an alley where cars idle their engines, go somewhere else.

    • 7

      Remember that air expands when heated ' never leave a filled tank in a hot car.

    • 8

      Store tanks in the back of a car during transport, always with the tank valve facing passengers. If the valve is damaged in transit, the tank will propel the other way.

    • 9

      Remove the rubber valve protection cap and inspect the O-ring.

    • 10

      Replace the ring if it is missing or damaged.

    • 11

      Attach the buoyancy compensator to the tank body.

    • 12

      Secure the regulator's first stage in place on the tank valve.

    • 13

      Open the valve by turning the knob counterclockwise until it stops, then twist it back one-half turn.

    • 14

      Check your gauges and note the psi.

    • 15

      Scuba dive to your heart's content, always keeping an eye on the remaining air pressure.

    • 16

      Stop diving with air still remaining.

    • 17

      Remove the attachments after diving and store the tank in a cool place.