Exclusive: How do Aqualungs used by Divers work?

Hey friends, Happy Wednesday!

50 Days of my Newsletter - Thank you!

Today is the 50th day since I started the Newsletter. So, I wanted to celebrate the small wins of being consistent. I was originally planning to write a blog post on the Fall Detection algorithm. But instead, I decided to write an exclusive issue where I explain a gadget in the newsletter itself, with something short to explain.

I spend 3x time finding a gadget to write about, distilling information, and analyzing how it works as compared to the time spent on writing the Newsletter and blog post itself. Finally, I review and handle the logistics of posting, scheduling, and publicizing by myself so far. So thank you for reading my emails and engaging with them, it means a lot to me!

Future of the Newsletter Survey

I’d like to learn more about how you feel about the newsletter. It takes me hours to write the newsletter, but only 15 seconds to answer these 4 questions. So, it would be of great help if you could fill out this Survey. I’ll share the results with you next week. Thank you in advance!

Let's jump in!

What are Aqualungs and why do Divers use them?

What are Aqualungs? ”A container of air that a person carries on his or her back when swimming under the surface of the sea, a lake etc. (diving) and which provides air through a tube for the person to breathe.”

But, why are they needed? Water pressure increases rapidly with depth and therefore, divers need to survive such conditions by maintaining the same pressure within their lungs. Imagine if we inhale air at atmospheric pressure underwater when the water body is at a higher pressure - then, the lungs should expand and withstand the high pressure (Not possible as lungs are not powerful). Hence we need aqualungs which supply air from a cylinder maintained at high pressure. This gadget makes the divers sustain underwater.

Working Mechanism

The cylinder worn by the diver has air at a pressure much higher than the water pressure, initially. The mouthpiece worn by the diver has an assembly that helps them breathe air that is regulated at the same pressure as the surrounding water. Let’s see how.

Inhalation

Figure 1: Aqualung with mouthpiece during Inhalation

The valve (pink) is initially closed. As the diver (marked in brown) inhales air from the air chamber (white), the flexible diaphragm (red) expands downward due to pressure decrease inside the chamber (Lesser volume of air in the chamber due to some inhalation, so less pressure). This diaphragm presses against the lever (yellow) in the chamber, causing it to open a valve (pink) to let in air from the cylinder carried by the diver. The high-pressure air from the air cylinder drops to the surrounding water pressure right when it comes into the air chamber. This is achieved by having the water inlet on the other side of the diaphragm (dark blue). Water is drawn in through this opening automatically from the sea, lake, etc. (as seen in the figure) to balance the pressure. Thus, we achieved the same pressure for the surrounding water and the air chamber using a flexible diaphragm in-between and a water inlet. The diver inhales the air that comes in from the cylinder.

Exhalation

Figure 2: Aqualung with mouthpiece during Exhalation

When the diver finishes inhaling, the increased volume of air (there is continuous air intake from the cylinder as long as the valve is open) in the air chamber pushes back the diaphragm which then pulls the lever to shut the valve, and thereby, cutting the airflow. The air chamber has an exhaust valve through which the exhaled air by the diver is released into the waterbody (These are the trail of bubbles that we see typically in a documentary or a movie from a diver). There is a button to clear the water from the flooded mouthpiece in such cases. This process then repeats. This is how an Aqualung works making it possible for divers to do their job.

Answer to the question I posed last week

Last week, I posed a question asking about other ways in which water is filtered and purified apart from using UVC light. Activated Carbon Filter is one of the prominent ways for water treatment. Pollutants in the fluid to be treated are trapped inside the pore structure of a carbon substrate in this methodology.

Blog posts

I’m thinking of writing about fall detection which was originally planned for this week, for the next episode S1E7. Also, let me know if you’d like to read about a specific gadget/device. Thank you for reading.

Have a nice rest of the week, and take care!
Until next Wednesday,
Chendur