Pressure On Land
Gauge Pressure
There are times when you are only concerned about pressure beyond atmospheric pressure. For these measurements, we use gauge pressure, which ignores the 14.7 psi of atmospheric pressure that always exists at sea level.
Your submersible pressure gauge is an example of a device that reads gauge pressure. An "empty" cylinder still contains 14.7 psi of pressure at sea level. But your submersible pressure gauge ignores this 14.7 psi of pressure and reads "0" instead.
Your depth gauge is another example. As you'll learn later in this lesson, the pressure you're exposed to while diving is a combination of both atmospheric and water pressure. Your depth gauge is calibrated to read "0" at sea level, therefore ignoring atmospheric pressure and only measuring changes in water pressure.
Your submersible pressure gauge is an example of a device that reads gauge pressure. An "empty" cylinder still contains 14.7 psi of pressure at sea level. But your submersible pressure gauge ignores this 14.7 psi of pressure and reads "0" instead.
Your depth gauge is another example. As you'll learn later in this lesson, the pressure you're exposed to while diving is a combination of both atmospheric and water pressure. Your depth gauge is calibrated to read "0" at sea level, therefore ignoring atmospheric pressure and only measuring changes in water pressure.
