console mounted oxygen breathing regulators.
(See figure 11-1.)
Oxygen system components test stands are
supplied by more than one manufacturer. The
operation, maintenance, and parts are, with a few
minor exceptions, identical. Where there are
differences in applications, or where operational
procedures differ, they will redescribed in the
individual regulator chapters of NAVAIR
Publication 13-1-6.4. Therefore, before you
attempt to test any oxygen component, you should
refer to that manual.
The oxygen system components test stand
consists of a nitrogen pressure source and a
vacuum system. It includes the valving and
instrumentation necessary to measure, test, and
evaluate the performance and operating
characteristics of oxygen system components at
altitudes up to 150,000 feet.
Performance of the test stand is dependent
upon the skill of the operator. You must
be thoroughly familiar with the instruments,
controls, and connections that comprise the
systems that are incorporated within the test stand
There are two ON/OFF valves on the test
stand. These valves are colored red and have two
positionsON and OFF. The first valve is called
the inlet pressure ON/OFF valve (L). This valve
permits a flow of regulated high-or low-pressure
nitrogen to the input connection (18) located in-
side the altitude chamber. The second ON/OFF
valve is called the Leakage ON/OFF valve (G).
This valve permits a flow of regulated low-
pressure nitrogen gas (N2) through the selected
in-system rotameter (7) or (8). You select either
the low-range or the high-range rotameter by
using the leakage selector valve (F). Valve (G),
the leakage ON/OFF valve, also permits a supply
of N2 to go to the input connection (18) inside
the chamber. The only time you will be using
ON/OFF valve (G) is when you are adjusting the
bleed on a miniature oxygen regulator (this is
covered in the NAVAIR 13-1-6.4) and when you
are measuring leakage on oxygen components.
As you look at the Model 1172AS100 test
stand, you may think that with all those different
valves, gauges, rotameters, and connections that
you could never operate it. However, by operating
only four selector valves, you can direct the flow
of N2 to perform the basic functions of the stand.
These valves are M, O, D, and F, shown in figure
The FLOW SELECTOR valve (M) has two
positionsCONTROLLER and REGULATOR.
When this valve is placed in the REGULATOR
position, and you open the OUTPUT valve (C),
the flow is routed directly from the item under
test through the piezometer (26) and OUTPUT
port (23) to the vacuum pump. When the
selector valve is placed in the CONTROLLER
position, the flow is routed through the suit
The REFERENCE PRESSURE SELECTOR
valve (0) is a two-position valve. It references
pressure to either the altitude chamber or
the suit simulator tank from LOW RANGE
The PRESSURE SELECTOR valve (D) has
two positionsH2O (water) and Hg (mercury).
In the Hg position, only mercury pressure can be
read. In the H2O position, either inches of water
pressure (positive pressure) or inches of water
suction (negative pressure) can be read.
The LEAKAGE SELECTOR valve (F) has
two positionsHIGH and LOW. It routes
regulated low pressure through the in-system
rotameters. When the valve is placed in the LOW
position, leakage is indicated on rotameter (7).
The LEAKAGE SELECTOR valve (F) is always
left in the HIGH position unless you are reading
a leak or bleed below 200 cubic centimeters
(CCM). This is done to prevent damage to the
low-range rotameter in the event you develop a
To understand the function of some of the
valves discussed in the following paragraphs, it
is necessary to first understand the function of
the Vol-O-Flo elements installed between certain
control valves and their indicating manometers.
There are three Vol-O-Flo elements installed on
the test stand. The input Vol-O-Flo works in con-
junction with INPUT valve (A) and INPUT
FLOW manometer (2). The output Vol-O-Flo is
used with OUTPUT valve (C) and OUTPUT
FLOW manometer (l). The vent flow Vol-O-Flo
is used with either the VENT PRESSURE valve
(H) or the VENT AMBIENT valve (1) and the
VENT FLOW manometer (3).
The Vol-O-Flo elements have two tapsone
near the inlet end and one near the outlet end.