First Stages
(I would like to give a special thanks to my friends at SCUBAPRO for providing the illustrations...it is good to have friends!)
FIRST
STAGES
The task of a first stage regulator is quite simple: reduce high pressure air coming from the tank to a consistent intermediate pressure. They are generally divided into PISTON and DIAPHRAGM categories, depending on the mechanism used to control the valve allowing air to flow to the second stage. Due to their design and their particular advantages, each of them has become the favorites of different groups in the diving community. First stages can be further classified between CLASSIC DOWNSTREAM and BALANCED, affecting function and performance of the first stage related to pressure changes in the tank.
The task of a first stage regulator is quite simple: reduce high pressure air coming from the tank to a consistent intermediate pressure. They are generally divided into PISTON and DIAPHRAGM categories, depending on the mechanism used to control the valve allowing air to flow to the second stage. Due to their design and their particular advantages, each of them has become the favorites of different groups in the diving community. First stages can be further classified between CLASSIC DOWNSTREAM and BALANCED, affecting function and performance of the first stage related to pressure changes in the tank.
THE PISTON TECHNOLOGY
The general advantage of a piston-based first stage lays in its reliability and reduced maintenance requirements, due to an effective but simpler mechanism with less moving parts. More importantly, no other design can reach the high air delivery rate of a balanced piston controlled first stage.
Balanced-piston
first stages are the first choice of demanding deep sport divers and
professionals. First stages with air balanced pistons deliver significantly
more air to the second stage than any other first stage, while their
performance is totally unaffected by changing tank pressure and depth.
AIR BALANCED FLOW THROUGH PISTON
First stages with air balanced pistons deliver significantly more air to the second stage than any other first stage, while their performance is totally unaffected by the changing tank pressure. A balanced piston allows the use of lighter and more sensitive components, resulting in ultra fast breathing response, instant delivery of air on demand and extra high air flow, especially in low tank pressure ranges. The tired diver benefits from of a smoother breathing regulator during the ascent or deco stop. Balanced piston first stages are the first choice of demanding sport divers and professionals. A balanced piston performs equally in both warm and cold water environments.
First stages with air balanced pistons deliver significantly more air to the second stage than any other first stage, while their performance is totally unaffected by the changing tank pressure. A balanced piston allows the use of lighter and more sensitive components, resulting in ultra fast breathing response, instant delivery of air on demand and extra high air flow, especially in low tank pressure ranges. The tired diver benefits from of a smoother breathing regulator during the ascent or deco stop. Balanced piston first stages are the first choice of demanding sport divers and professionals. A balanced piston performs equally in both warm and cold water environments.
CLASSIC DOWNSTREAM PISTON
This is the best example of bulletproof reliability and trouble-free, minimal maintenance regulators. The conventional downstream piston configuration is the simplest mechanism that exists to control the pressure drop from a tank to feed the 2nd stage. The classic downstream valve is the first choice of diving centers and rental facilities worldwide for warm and moderate water temperatures.
This is the best example of bulletproof reliability and
trouble-free, minimal maintenance regulators. A classic downstream piston does
not compensate for the minor changes in pressure delivered to the second stage
as tank air is consumed, but still guarantees solid performance.
DIAPHRAGM TECHNOLOGY
Diaphragm based first stages are environmentally sealed so that water cannot enter the inner mechanism. Bearing in mind that regulators generate temperatures up to minus 30 °C due to the incredibly fast moving air and the high pressures involved, it is imperative that sensitive moving metal parts avoid contact with extremely cold water.
Therefore, diaphragm first stages have been the favored choice of cold-water divers and those working in contaminated or muddy water.
All SCUBAPRO diaphragm first stages feature a balanced technology and are packed with patented features resulting in ultra fast flow to the second stage upon request and a fantastic overall performance and are my personal favorite of the diaphragms. The balanced diaphragm technology provides consistent performance at all cylinder pressures, at any depth and optimizes the second stage performance, thus allowing for effortless breathing.
Diaphragm based first stages are environmentally sealed so that water cannot enter the inner mechanism. Bearing in mind that regulators generate temperatures up to minus 30 °C due to the incredibly fast moving air and the high pressures involved, it is imperative that sensitive moving metal parts avoid contact with extremely cold water.
Therefore, diaphragm first stages have been the favored choice of cold-water divers and those working in contaminated or muddy water.
All SCUBAPRO diaphragm first stages feature a balanced technology and are packed with patented features resulting in ultra fast flow to the second stage upon request and a fantastic overall performance and are my personal favorite of the diaphragms. The balanced diaphragm technology provides consistent performance at all cylinder pressures, at any depth and optimizes the second stage performance, thus allowing for effortless breathing.
Diaphragm first stages featuring a dry balancing
chamber so that the water cannot enter the first stage, means it's resistance
to freezing is unmatched even in extremely cold waters.
Diaphragm first stages with the same structure but
without a dry chamber are the perfect choice for the recreational diver who
wants the advantage of a diaphragm first stage for use in temperate waters.
~More details
below~
BALANCED DIAPHRAGM (Dry Chamber)
Diaphragm based first stages
are more complex and have more moving parts than piston first stages. With a
dry chamber, they have an environmentally sealed design so that water cannot
enter the inner mechanism.
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Diaphragm first stages
have been the favored choice of cold-water divers because of their better
resistance to freezing. They are also recommended for divers working in water
containing a high degree of suspended particles, silt, or other contaminating
materials.
BALANCED
DIAPHRAGM
Diaphragm first stages have been the favored choice of cold-water
divers because of their better resistance to freezing.
Diaphragm first stages
are also recommended for those working in water containing a high degree of
suspended particles, silt, or other contaminating materials.
Second Stages
A
second stage regulator must translate natural breathing behavior into
mechanical reality. A high quality second stage can significantly reduce stress
and enhance diver safety by providing smooth, low-effort breathing response,
resulting in ample yet controllable quantities of air. The designation
"balanced" and "classic downstream" are also distinguishing
marks for second stages and imply the same general attributes like first
stages, i.e. ultimate flow performance and incredible inter-stage pressure
stability in addition to reliability, simplicity and solid performance
AIR BALANCED VALVE TECHNOLOGY
The air balanced valve technology of SCUBAPRO second stages features a balancing chamber in the second stage mechanism, slightly offsetting the force of the downstream air entering from the first stage. This allows reduced spring tension and decreases the inhalation resistance to the lowest possible level. The result is an ultra-high airflow that remains exceptionally stable under all breathing conditions. The air-balanced valve technology is featured in our A700 and S600 second stages. For optimum results they should be combined with balanced first stages, like the MK25 or the MK17. These are the combonations Coleen and I dive.
The air balanced valve technology of SCUBAPRO second stages features a balancing chamber in the second stage mechanism, slightly offsetting the force of the downstream air entering from the first stage. This allows reduced spring tension and decreases the inhalation resistance to the lowest possible level. The result is an ultra-high airflow that remains exceptionally stable under all breathing conditions. The air-balanced valve technology is featured in our A700 and S600 second stages. For optimum results they should be combined with balanced first stages, like the MK25 or the MK17. These are the combonations Coleen and I dive.
OPTIMAL FLOW DESIGN TECHNOLOGY (OFD)
The Optimal Flow Design valve is the ultimate evolution of the
classic downstream technology. Unlike this one the OFD valve features a full
length piston shaped to obtain the optimal aerodynamic performance. The gas
flows freely over the piston surface and provides the diver with the best
breathing experience. No regulator part slows down the airflow, and even the
valve spring is shifted to the back side of the piston so that the air doesn't
have to flow through the spring coils. The airflow is huge and rich but always
under control. This is an intermediate worry free regulator with high end
performance.
CLASSIC DOWNSTREAM
TECHNOLOGY
Classic downstream valves are particularly noted for their legendary safety and reliability. When in use, the downstream valve opens in the same direction as the incoming airflow. To close the valve and stop the airflow, a spring counteracts the force of the incoming air. Therefore, a certain inhalation effort is always required to overcome the spring tension and open the valve. The classic downstream valve is a popular design for alternate air sources such as an octopus or AIR 2. Technical divers will often use a Classic downstream for stage bottles.
Classic downstream valves are particularly noted for their legendary safety and reliability. When in use, the downstream valve opens in the same direction as the incoming airflow. To close the valve and stop the airflow, a spring counteracts the force of the incoming air. Therefore, a certain inhalation effort is always required to overcome the spring tension and open the valve. The classic downstream valve is a popular design for alternate air sources such as an octopus or AIR 2. Technical divers will often use a Classic downstream for stage bottles.
