The high pressure in the scuba tank must be delivered
to the diver at the same pressure as the surrounding water. The regulator
does this. It makes little difference what brand is being used. They are
all reliable, efficient, and have an extremely low failure rate. Law suits
would abound if this were not true.
In the modern single-hose regulator there are two stages.
The first stage is that part that attaches to the tank. The primary second
stage has the mouthpiece that goes in the diver's mouth. The air entering
the first stage from the tank might be 3000 psi. The air leaving the first
stage through the hose to the second stage will be about 140 psi. The air
entering the diver's mouth from the mouthpiece will be at the ambient pressure.
(Note: "ambient" means surrounding.)
Once the regulator is attached to the tank, and the tank
is turned on, there is no noticeable air flow. Air is not wasted when the
diver isn't breathing in. When the diver inhales on the mouthpiece the pressure
is lowered inside the second stage. Water on the outside pushes a diaphragm
in. That is connected to a lever that opens the valve to the air in the hose
coming from the first stage. As the 140 psi air pressure is lowered, another
valve opens in the first stage and the air from the tank enters. When the
diver exhales the process reverses and the air flow is shut off.
Sometimes a regulator, that is not in a diver's mouth,
is put in the water with the mouthpiece facing up. The water pushes
the diaphragm in and the regulator starts to quickly release air by itself.
To stop the air flow it is necessary to turn it over so the mouthpiece is
pointing toward the bottom. After the flow stops the regulator may be released
with no further "bleeding."
Although there should be no leaks with most regulators,
a minor leak is not something that should cause grave concern. (Some regulators
are designed to leak small amounts of air in order to keep water from entering
the regulator's interior.) A leak that is a barely audible hiss, although
it should be repaired, will not subtract much from the dive time. To illustrate
this: If you let the air that is leaking flow into a water-filled cubic foot
box, so that as the air went in water would come out, the time it took to
fill the box would roughly amount to about 1 minute of dive time.
Breathing underwater is about the same as breathing in
the atmosphere. The inhale should be slightly deeper, followed by the exhale.
There should be no pause between the two. It is important to keep the lungs
well ventilated without risking lung injury by holding the breath and ascending.
If the regulator is put in the mouth underwater it will
be necessary to blow the water out of it prior to breathing in. A simple
exhale will accomplish that. A regulator should never
be placed in the mouth upside down. When that happens the exhaust
port is above the mouthpiece making it impossible to get the water out of
the interior. The inhale will contain mostly water resulting in a possible
drowning! This is especially important to remember when a regulator is handed
to a buddy!
On the rare occasion some water may leak into the second
stage. There are three main reasons for this. 1. The mouthpiece may have
a hole or tear in it; 2. The exhaust port valve is not lying flat against
the housing; and 3. The diver is not making a good seal with the mouth. There
are rare instances where a leak is the result of a unseated diaphragm or
cracked housing. Having a regulator serviced at least once per year should
prevent all of the above except for the mouth seal.
Throwing up underwater is rare. That is fortunate. Thinking
about the process leads one to many questions. Should you throw up into the
regulator? Should you take the regulator out and risk drowning on the inhalation?
Will the diver remain under control during the process? Don't dive if there
is a feeling of nausea. If the diver feels they are about to throw up try
to move safety to the surface. If it has to be done under water, I think
the best procedure would be to throw up into the regulator, replace the regulator
with the alternate air and resume breathing. Clean out the primary second
stage by shaking and pressing the purge button, and then return that to the
mouth. Be aware: This author has never put this to the test nor is aware
of anyone else successfully doing it!
The proper procedure to remove a regulator from the tank
Shut off the air from the tank.
Purge the air from the regulator by pushing the secondary purge button. This
will prevent the loud and damaging pop to the tank's O ring, and will make
removal of the regulator easier.
Remove the hoses from the BCD.
Carefully remove the regulator from the tank - before doing this be sure
the pressure has been removed!
Turn the tank on slowly so a stream of air is flowing and then hold the dust
cover (yolk cap) in it. This will dry the water from the dust cover. Prevent
the spraying water from entering the sintered filter.
Place the dust cover on the opening to the regulator and turn the tank knob
to hold it in place.
If the regulator has been used in salt or contaminated water it should be
rinsed with fresh water. During the rinse the purge buttons must not be depressed
or water may get into the regulator's interior.
Afetr rinsing, if there is a method to keep the the purge button(s) depressed
it should be done to keep pressure off the low-pressure seat(s).
Hang the regulator up to dry.
There are high and low-pressure ports on the first stage
of the regulator. The high-pressure ports are usually stamped, "HP." The
high-pressure port threads are larger than the low-pressure port threads.
That has not always been the case. Many years ago regulators had the same
threads on both ports and some divers accidentally put a low-pressure hose
on a high-pressure port. When the pressure in the hose exceeded 400 psi it
would explode! The spg is put on the high-pressure port. The BCD hose, the
alternate air hose, the dry suit hose, and the secondary regulator hose are
all attached to low-pressure ports.
How often should a regulator be overhauled? It really
depends on how it is used. If it is frequently used in salt water the service
should be done at least once per year. A less heavily used regulator in fresh
water might require servicing after two years. If the period is much longer
certain parts of the regulator may permanently seal due to corrosion. Servicing
involves the complete disassembly and cleaning of the regulator, lubrication
of the O rings, replacement of worn parts, and function testing. An unserviced
regulator may begin to destroy itself due to moving parts scoring other