First Stages - Scubapro MK25T Handbuch

5.1

First Stages

Standard Piston
Standard piston fi rst stages are the simplest mechanism with minimum moving parts to
control the pressure drop from a tank to feed the second stage. This translates to high
reliability and durability, combined with minimal maintenance requirements.
Balanced Piston
First stages with air balanced pistons deliver signifi cantly more air to the second stage than any
other fi rst stage, while their performance is totally unaffected by the changing tank pressure.
A balanced system 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 fl ow.
Balanced diaphragm
The inner mechanism in a diaphragm fi rst stage is isolated from the surrounding water. This
feature makes it especially suitable for diving in cold water conditions or murky water. In
this system the air fl ows through a seat & pin assembly, controlled by a loaded diaphragm.
The seat receives equal interstage pressure from both sides, making it react independently
of tank pressure. Balanced diaphragm systems deliver a slightly lower fl ow than piston
regulators, due to the smaller diameter air passageways. However, these differences in
performance are only detectable at great depth.
AF (patented)
This is a fi rst stage device that uses a series of fi ns whose surface acts as an heat dissipater.
By increasing the thermal exchange with the surrounding water, it is possible to use the
regulator in colder waters, surpassing EN norms.
Dry balance chamber
The dry chamber ensures the best performance in especially cold waters by preventing the
entry of water inside the water balancing chamber. In extremely cold water conditions the
formation of ice crystals around the main spring is thus eliminated.
Rotating swivel
With this feature, all inter-stage pressure hoses attached with the swivel have the ability to
rotate in the best possible position to optimize hose distribution and lessen jaw fatigue.
High pressure ports
All fi rst stages are equipped with at least one high pressure port. More sophisticated fi rst
stages are equipped with two high pressure ports, allowing a submersible pressure gauge,
computer hose or transmitter to be positioned on the right or left side of the diver according to
preference and/or correct transmitter orientation.
Intermediate pressure ports
The availability of 4 or 5 intermediate pressure ports enables the connection of equipment such
as an octopus second stage, buoyancy compensator, dry suit hose or other accessories.
HF Ports
High Flow ports have a 15% higher fl ow compared to the standard ports, and thus are
especially suited to connect the second stages. MK 11 & MK 17 have two HF ports each,
MK2 Plus has four and MK19, & 25 have fi ve HF ports each.
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