R-100
BALANCED PISTON FIRST STAGE REGULATOR
DESCRIPTION AND OPERATION
SECTION II
2.0
TERMINOLOGY AND DESCRIPTION OF OPERATION
The following discussion will introduce the proper terminology to be used through
the manual. To help establish efficient communications when reporting problems
to the factory or discussions with the customer we recommend that you utilize
these terms. Terms will be introduced in full text followed by the acronym or
abbreviation in brackets.
The regulator reduces high-pressure air from the scuba cylinder (supply
pressure) to ambient pressure suitable breathing, through the operation of first
and second stage regulators. The first stage regulator reduces incoming high
pressure (HP) air, to an intermediate pressure (IP) of approximately 130 to 145
pounds per square inch (psi). The second stage regulator is a diaphragm
operated downstream demand valve and functions to reduce air from
intermediate pressure to ambient pressure permitting normal breathing at depth.
A low-pressure (LP) hose connects the first and second stages of the regulator. A
yoke on the first stage body secures the regulator to the cylinder valve, while an
o-ring surrounding the outlet orifice on the cylinder valve ensures an airtight
connection to the first stage. During servicing and overhaul, the term supply
pressure is used to denote an air supply of high pressure between 2750 to 3000
psi.
2.1
BALANCED PISTON FIRST STAGE
Refer to
Figure 2-a
and
2-b
for the following discussion. High-pressure air
entering the yoke retainer inlet port of the first stage regulator passes through a
sintered filter which helps prevent the entry of any foreign particles. This airflow
continues through the regulator body passages to the HP seat chamber where it
flows across the annular gap between the HP seat and the need of the HP piston
stem. Here the air expands resulting in a reduction of pressure. Airflow continues
past the HP seat, as long as the piston remains in an OPEN position, and passes
through the internal section of the HP piston stem. The term “flow through piston”
describes this operation. Air merges form the HP piston stem and enters the
intermediate pressure chamber inside the upper portion of the cap and swivel.
The LP hoses are attached to the swivel and guide airflow to the second stage
regulator or buoyancy compensator inflator device.
The forces which tend to maintain the HP piston in the OPEN position are (1) the
force of the HP spring and (2) the force produced by ambient water pressure
acting on the back surface of the HP piston head. The force, which tends to move
the piston to the CLOSED position is the pneumatic force produced by the
intermediate pressure acting on the front of the piston head. The regulator is
designed so that the piston remains in the open position until the intermediate
pressure approaches approximately 135 psi. When this intermediate pressure is
achieved the force becomes great enough to overcome the force of the HP
spring and the ambient water pressure allowing the piston to move into the
CLOSED position sealing against the HP seat.
Revised v1.0-2000
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