英文阅读：潜水时水中呼吸器坏了怎么办
潜水是很多人都喜欢的运动。在神秘的大洋海底，绚烂多彩的世界让人着迷。可要是这时水中呼吸器发生故障可就麻烦了。下面这篇文章就教您如何应对这种事情。Diving equipment failure, yikes! While we all agree this would be a
frightening experience, it's usually not as dire as it sounds. When you hear
about a diving incident, it most often involves a malfunctioning regulator or a
tank low on air. There are two things you need to worry about if your equipment
fails:
Your lungs
The bends
Typical recreational SCUBA divers breathe either compressed air (78 percent
nitrogen(氮), 21 percent oxygen) or an oxygen-enriched, nitrogen-oxygen
combination called Nitrox (64 to 68 percent nitrogen, 32 to 36 percent oxygen).
The gas is contained in a cylinder that you carry on your back. You can't
breathe directly out of the tank because the high pressure would damage your
lungs. Therefore, the cylinder is fitted with a regulator. The regulator does
two things: It reduces the pressure from the tank to a safe level for you to
inhale, and it supplies air on demand.
To accomplish these tasks, regulators have two stages:
First stage attaches to the cylinder. It reduces the pressure from the tank
(3000 psi(磅/平方尺) or 204 atmospheres) to an intermediate pressure (140 psi or 9.5
atmospheres).
Second stage is connected to the first stage by a hose. It reduces the
pressure from the intermediate pressure to ambient water pressure (such as one
to five atmospheres, depending upon depth). The second stage also supplies air,
either only when you inhale (typical operation) or continuously (emergency
operation).
So what would happen if your regulator were to malfunction or your tank ran
out of air? Obviously, when the air stops, your first instinct will be to head
straight for the surface. But before you do, there are two things to keep in
mind.
As you ascend back to the surface, the air in your lungs will expand. In
order to keep your lungs from expanding too quickly or too much, you need to
exhale as you float to the surface. Think about a balloon. Say you take a
blown-up balloon with you as you dive 30 feet below the ocean's surface. The
balloon will deflate to about half its capacity by the time you reach your
destination because of the pressure of all that water pushing down on it. As you
go back to the surface, it will expand. Now let's say you took an empty balloon
down 30 feet and somehow inflated it to normal size down there. Then you brought
it back to the surface with you. What happens? It expands beyond its capacity
and bursts. The same thing would happen to your lungs if you don't exhale
constantly. If you exhale and rise no faster than the bubbles do, you should be
OK.
The other thing you have to worry about, depending on how deep you are when
you run out of air, is the "bends."
The air we breathe is a mixture of mostly nitrogen (78 percent) and oxygen
(21 percent). When you inhale air, your body consumes the oxygen, replaces some
of it with carbon dioxide and does nothing with the nitrogen. At normal
atmospheric pressure, some nitrogen and oxygen is dissolved in the fluid
portions of your blood and tissues.
As you descend under the water, the pressure on your body increases, so
more nitrogen and oxygen dissolve in your blood. Your tissues consume most of
the oxygen, but the nitrogen remains dissolved. All this dissolved nitrogen is
where the bends come from.
If you ascend rapidly, the nitrogen comes out of your blood quickly,
forming bubbles. It's like opening a can of soda: You hear the hiss of the
high-pressure gas and you see the bubbles caused by the gas rapidly coming out.
This is what happens in your blood and tissues if you come up too fast. You get
the bends (which is also called decompression sickness) when nitrogen bubbles
form in your system and block tiny blood vessels. This can lead to heart
attacks, strokes, ruptured blood vessels in the lungs and joint pain (one of the
first symptoms of decompression sickness is a tingling sensation in your
limbs).
The best way to avoid decompression sickness is to follow the no
decompression depths and bottom times provided by dive tables. If you violate
the no decompression limits, you have to stay underwater longer, for various
times at pre-set depths (determined by dive tables), to allow the nitrogen to
come out of your system slowly. This obviously presents problems because you're
out of air. So what do you do? The only thing you may be able to do is come up,
get another tank, and then immediately dive back down to a safe depth. But if
you're near shore, you may be able to go to a decompression chamber instead,
which is much safer.
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