Hi scientists! My name is Lee-Roy Haarhaus. And I'm Sean Eckley.
We are two of the assistant dive safety officers here at the California Science Center.
It's our job to oversee the day-to-day scuba diving operations that happen in
our exhibit. The ocean environment is full of scientific discovery, amazing animals, and fun!
Many people use scuba as a tool to explore science—from astronauts,
aquarists, and explorers just like you! Come with us and we'll show you how we
use scuba to stimulate curiosity and inspire science learning in everyone.
In today's episode, we're going to learn how to scuba gear work. We're going to learn all
about the equipment that scuba diver needs to breathe underwater and explore the ocean
all aquatic animals have unique adaptations to help them better survive in their underwater
environment. If we want to visit them we'll need some adaptations of our own.
That's where scuba gear comes in. But how exactly does scuba gear allow us to go from here
to here? To live underwater, fish have gills that absorb oxygen directly out of the water.
Unlike a fish, a scuba diver has lungs and must carry their air supply with them on their back.
Now believe it or not, scuba tanks hold a lot of air inside of them.
This here is an 80 cubic foot cylinder, which means it holds 80 cubic feet of air compressed
inside. That is as much air as is in this entire room! Now to get all of that air into this tank,
we use an air compressor. This air compressor here pulls in outside air, compresses it down
in size, and allows us to fill it into our scuba tanks using our fill station.
Now to compress all that air inside, we're dramatically increasing the air pressure.
We're going from zero to now 3,300 pounds per square inch of pressure
inside of here. That is roughly 94 times as much air pressure than is in your car tire.
3,300 psi is too much pressure for us to breathe in at once.
To take this high pressure and to make it breathable, we use a device called a regulator.
The regulator breaks down this tank pressure into two stages. The first stage regulator
takes our 3300 psi tank pressure and reduces it to an intermediate pressure of about 145 psi inside
this hose here. The air inside this hose then travels down to our second stage regulator, which
takes that 145 psi pressure and reduces it to an even more breathable level, or what we call ambient.
Now to access all of my air, a scuba diver breathes off their second stage
regulator. I put this in my mouth. When I take a breath in, a lever gets pushed down, releasing
air from my scuba tank, and it goes through this hose. When I exhale, that lever gets pushed back up,
stopping the flow of air and all of my exhaust air escapes through this vent right here.
Those are all the bubbles that you see coming from a scuba diver. Now it's important for me
to also keep an eye on how much air I have left in my tank, and I do that using my pressure gauge.
You can see I have plenty of air left, so let's go down—let's take a quick dive.
If you look at a rockfish, they are able to float effortlessly in the middle of the water.
You see, most fish have within them is a swim bladder of air that they used to regulate their buoyancy.
Now we know how a scuba diver can breathe underwater. But how are they able to hover
effortlessly just like our fish? In order to explain, let's take a look at a scuba diver's
second piece of equipment—the buoyancy compensating device, or BCD for short. Not only
does it hold the scuba tank in place to the diver, but it also has a much more important role to play.
Let's take a look. Just like a fish's swim bladder, a scuba diver can add or subtract small
amounts of air into their BCD to help regulate their position in the water. When a diver is
neither floating nor sinking but rather hovering effortlessly, they have achieved neutral buoyancy.
In order to move through the water, fish use their fins to push the water in the
opposite direction from which they want to go. The force of this movement propels the fish forward.
As you can see, on our giant sea bass there are many types of fins.
Some fins allow for delicate turns and adjustments in the water, while others allow for great speed.
Our feet are great for walking on land but don't work as well when moving around
underwater, so scuba divers put on fins of their own.
With fins on their feet, our scuba diver now has a much greater surface area
to push more water around, allowing them to move through the water with ease and efficiency.
Wow! So scuba divers really are like fish!
I hope you learned a little bit about how scuba divers are adapted to visit our underwater world.
Join us on our next episode of Diving into Science as we dive into the science of
insulation and how scuba divers stay warm underwater. Until then, see you next time!