Corresponding to Boyle's law: For an ideal gas, when the temperature remains constant, pressure and volume are inversely proportional.

Think of the lungs as a balloon. We can inhale to blow it up, or exhale to deflate the air inside it.

When we dive, the pressure rises. Every time we take a breath, the air inside the lungs is compressed, but the space in the lungs is filled again after inhaling.

The deeper you dive, the higher the pressure, and more air is needed to fill it, so air consumption increases.

The pressure on a diver's lungs at depth causes them to require more energy to expand their lungs.

When breathing regularly, the "balloon" never inflates too much.

The same is true for the next two laws.

The reason why deep diving is called technical diving is because it contains too many technical methods.

This is a way to balance the lungs and qi.

Coincidentally, Bi Fang is well versed in this.

These abyssal worlds seem to be completely separated from the rest of the earth. They have been waiting there quietly for millions of years until Bifang's flashlight cast the first ray of light there.

A pressure-resistant infrared detector was installed at a distance of forty meters.

This is military equipment and cannot be taken out of the country under normal circumstances. It was only approved after Bi Fang made an application. Through infrared rays, it can better detect the activities of dolphins.

Above thirty meters, the sun can barely shine. Below thirty meters, it will be completely dark even during the day. Therefore, further down, Bi Fang and others need to install not cameras but detection devices.

Most of these devices may be useless, but they must exist, just like there are a lot of discarded lenses in movie shooting. Not every device can capture just the right shot, but it must exist.

After loading, Bi Fang did not dive rashly, but took out his flashlight and gave Mandy a series of flash signals.

When Mandy finished answering, he also flashed the light, and Bifang answered.

After confirming that both of them were fine, Bi Fang adjusted the gas in the oxygen bottle and continued to dive.

People usually define diving within a depth of 40 meters as recreational diving.

Why choose the number 40 meters?

Two reasons.

First, when diving at this depth, you can rise directly to the surface in an emergency without worrying about serious safety issues.

Second, the partial pressure of air at sea level is one bar, so under the partial pressure of oxygen of 1.4 bar, the toxicity of oxygen will become more and more serious. Oxygen poisoning may affect the diver's central nervous system and cause divers to have underwater nerve convulsions.

This directly affects the diver's ability to bite the regulator.

Similarly, when the partial pressure of nitrogen is around 30 meters and exceeds about 3 bar, some divers will feel anesthetized, and this feeling becomes worse as the partial pressure increases.

This is Henry's Law, which relates the solubility of a gas in a liquid to the surrounding pressure.

As the diving depth increases, more and more nitrogen will accumulate in the human body.

This nitrogen can cause the human body to enter a state similar to drunkenness, commonly known as "nitrogen drunkenness".

At depths below 40 meters, the effect of nitrogen narcosis will be so strong that people lose their ability to judge and react, leading to safety accidents.

Many people don't even realize that they are nitrogen intoxicated. They feel very awake and even very high, but they can't even do the basic math problem that one plus one equals two correctly.

Just now, Bifang and Mandy were confirming each other's sobriety and asked each other a two-digit addition and subtraction math problem.

Because of this, people set the depth limit of recreational diving at 40 meters, and diving beyond 40 meters enters the fields of technical diving and industrial diving.

Decompression sickness, nitrogen drunkenness and other troubles are all caused by nitrogen, but it can't be done without nitrogen because breathing pure oxygen directly is toxic.

Astronauts can breathe pure oxygen for several hours before a spacewalk and will not be affected by decompression sickness. However, this is because the air pressure inside the spacesuit is lower than that inside the space station, which is equivalent to a decompression environment.

Pure oxygen poisoning is conditional - when the partial pressure of inhaled oxygen exceeds 0.3 bar (30 kPa), oxygen will be toxic to cells.

Things that astronauts can do in space are not possible underwater. Inhaling pure oxygen in an underwater high-pressure environment can cause oxygen poisoning.

The human body is so fragile.

Even more accurately, at a depth of more than 55 meters, even breathing air will cause oxygen poisoning, let alone breathing pure oxygen.

At this time, the oxygen bottles behind Bifang and Mandy had three types of gases: helium, oxygen, and nitrogen.

This is the so-called three-phase gas. The addition of helium reduces the content of oxygen and nitrogen. Just how to mix the content is enough to give amateurs a headache.

Not only is diving down, but coming up is even more troublesome. You need to stay at different depths for enough time to gradually discharge excess nitrogen from the body.

The world record for technical diving was set by a man named Ahmed Gabr in 2014 - he dived to a depth of 332 meters.

It only took Gabr 14 minutes to dive to 332 meters, but it took 14 hours to surface.

Even though Bi Fang can now dive into an area of ​​70 meters with bare hands, this is based on the fact that he does not have to stay for a long time, and the changes in his body are not too drastic.

If he stays too long, he also needs to obey the laws of physics.

50 meters underwater.

Bi Fang's body entered the second stage, and the capillaries in his lungs began to become congested and hardened to protect his chest from water pressure.

The pressure is getting bigger and bigger. If ordinary people don't make any preparations and enter such a stressful environment in an instant, they will definitely die.

A long time passed until we were 80 meters underwater.

Eighty meters is a number that makes people feel suffocated, but the more they struggle, the more dangerous it becomes.

Here, you can only rely on spiritual and psychological strength to overcome it, tell yourself, follow nature, and only by completely relaxing can you turn harm into protection.

In the dark world, far away from light and humans, with only coldness and loneliness for company, Bi Fang seemed to have turned into a small drop of water, floating quietly in the ocean.

As the last piece of equipment was installed, Mandy and Bifang breathed a sigh of relief.

Plan completed!

－－－－－－Digression－－－－－

Please give me a monthly ticket. Is it possible to get two thousand...
Chapter completed!