Amron 8225-HP, Instruction Manual

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THEORY OF OPERATION
MECHANICAL 9.1
This section is divided into two parts, the first deals with the mechanical and the second deals with
the electronics.
Refer to the functional block diagram while reading this section.
1. HP-1 and HP-2, high-pressure input has a maximum input pressure limit of 3000 PSI when
using standard CGA850 SCUBA yokes with bleed valves and color coded hose protectors.
Installing the optional 300 Bar DIN Adapter (Amron Part No. SAA5300) will increase the units
maximum input pressure limit to 4500 PSI. Simply remove CGA850 yoke nut and yoke from
bleeder body, screw on 300 Bar DIN adapter, and tighten with a wrench.
The SCUBA yokes can also be removed for connection directly to a high-pressure bank with a
maximum pressure limit of 4500 PSI. The hose fitting is 1/4 inch 37
o
flare, Female swivel.
2.
HP gauges, 0-5000 PSI, 1-1/2% of full-scale accuracy.
3.
HP valves, shut-off type, 4 turns opens to full flow, S/S stem with KEL-F seat for positive
shut off, and Viton O-rings.
4.
HP check valves, 1/3 PSI cracking pressure.
5.
HP filter, inline 50-micron filter element.
6.
HP regulator(s), self-contained, direct acting, spring loaded, diaphragm operated pressure-
reducing regulator. Control pressures are obtained by adjusting the control knob. Pressure
INCREASES are made by a clockwise rotation while pressure DECREASES are made by
a counter-clockwise rotation.
Note: Regulator is a non-venting design and adjustments to decrease the set pressure will not
occur unless there is flow through the regulator. If the diver is not on line adjustment can be made
by opening the pneumo valve slightly while adjusting the regulator. All final adjustments should be
made in the clockwise direction in order to insure the most accurate set point.
When operating in cold weather (40
o
to 45
o
F and below), regulator icing may occur. This is
caused by moisture condensing and freezing, this can and will cause blockage in the regulator.
Increasing the pressure will temporally clear the blockage by lifting the valve seat to allow the ice
to blow through. If this happens terminate the dive immediately. The following information provides
a guide to the causes and procedures that can reduce the possibility of icing.
The cause of icing is moisture in the breathing air combined with a cold temperature, and high flow
rates. Cold air containing moisture is particularly prone to icing. First, air that is cold will support
less moisture before condensing occurs. Second, the colder the air is the closer it is to the
freezing point. Third, when air passes an expansion point (the regulator control valve) it is further
cooled. The combination of these three factors causes the icing.
To reduce the chance of regulator icing, use the following procedures.
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