cylinder pressure with the boost pump. During aircraft
a large area reciprocating air drive piston directly
oxygen servicing, the oxygen module is grounded to
coupled by a connecting rod to a small area gas piston.
the nitrogen module and trailer grounding reel. The
The gas piston operates in a high-pressure gas barrel
following components are contained on or within the
section. Each gas barrel end cap contains
oxygen module (refer to figure 10-16 to locate the
high-pressure inlet and outlet check valves. (The boost
components on the module, and to figure 10-13 to trace
pump serves the same purpose as the pump and motor
oxygen flow):
assembly on the nitrogen servicing unit covered in
chapter 9. The internal design and operation of the
NOTE: The number in parentheses following a
oxygen boost pump are quite similar to those of the
component name refers to figure 10-13.
nitrogen servicing unit's pump and motor assembly.)
Oxygen Supply Pressure Gauge.--The oxygen
Figure 10-17 shows various features of the boost
supply pressure gauge (19) indicates the amount of
pump. The boost pump is physically located inside the
pressure in the oxygen cylinder (2). The gauge is
oxygen module. (See figure 10-16, rear view.)
located on the left corner of the oxygen module panel.
NOTE: The number in parentheses following a
(See figure 10-16, front view.) The oxygen cylinder
valve (4) must be open to read cylinder pressure.
component name refers to figure 10-13.
Selector Valve.--The selector valve (20) is a
P i l o t Va l ve s . -- Two b o o s t p u m p p r e s s u r e -
t h r e e - p o s i t i o n ( O F F / B O O S T / B Y PA S S ) , h a n d -
operated pilot valves (23) and (24), are located within
operated valve that controls oxygen flow to the boost
the oxygen module. (See figure 10-16, rear view.) The
pump (21), or it allows the oxygen to bypass the boost
pressure operated pilot valve (23) is a normally closed
pump. It also provides a means of shutting off the
(NC) oxygen module safety device, which prevents the
oxygen supply to the servicing system. The selector
boost pump (21) from operating with a high
valve is located on the left side of the oxygen module
compression ratio (in excess of 25:1). When the
panel. (See figure 10-16, front view.)
gaseous oxygen supply to the boost pump (21) inlet
port falls below 200 psi, the pilot valve (23) closes,
Boost Pump.--The boost pump (21) increases
shutting off the boost pump drive (nitrogen or
(boosts) the pressure of the gas leaving the oxygen
compressed air). The pilot valve (23) opens when the
cylinder for high-pressure servicing operations. It has
oxygen supply pressure to the boost pump (20) exceeds
a compression ratio of 25:1 to 36:1, depending on
300 psi.
oxygen cylinder pressure. The boost pump consists of
INTERCOOLER
BREATHER
DASH 30X
GAS
DASH 15X
AIR
BARREL
GAS
DRIVE
BARREL
VIEW A
GASEOUS NITROGEN INLET
AIR
LOWER
UPPER
DRIVE
CAP
CAP
HIGH
PRESSURE
OXYGEN
OUTLET
LOW
PRESSURE
OXYGEN
INLET
DASH 30X
DASH 15X
GAS
GAS
MOUNTING
BARREL
BARREL
BRACKET
ASf10017
VIEW B
Figure 10-17.--Oxygen boost pump.
10-30
