The LOX converter (fig. 7-8) consists of an inner
and outer shell of stainless steel separated by a vacuum.
A blowout disc provides a margin of safety from
explosion if a leak occurs in the inner shell.
The filler valve is a combination filler, vent, and
buildup valve. The filler portion of the valve is
essentially a spring-loaded check valve (fig. 7-9).
When the servicing hose of the LOX cart is coupled to
the filler connection, the poppet is displaced. This seals
Figure 7-9.--Filler valve.
the supply port and allows container pressure to be
relieved through the vent port. At the same time,
oxygen flows through the filler connection and fill port
Pressure Control Valve
to the container. When the container is full, the liquid
flows from the container through the gas port and then
The pressure control valve used on most converters
through the vent port. In the normal position, the spring
is a combination opening and closing valve (two
in the filler connection holds the poppet in place,
valves contained within one housing). These valves
forming a gastight seal. There is a check valve in the fill
are controlled by spring-loaded bellows. The
port that acts as a backup seal in the event the filler
pressure-closing valve is spring-loaded open and the
connection develops a leak. The vent port also is sealed
pressure-opening valve is spring-loaded closed. The
in this position, allowing the gaseous boil-off (from the
pressure-opening valve controls the flow of gaseous
top of the container) to flow through the gas port to the
oxygen into the supply line. If the pilot's demand for
supply port and into the oxygen system.
oxygen becomes greater than the capability of the
pressure opening valve to deliver, there is a differential
check valve that opens and allows liquid oxygen to flow
directly into the supply line. It is transformed into
gaseous oxygen during its passage through the oxygen
system supply lines.
A relief valve is provided in the converter to relieve
excessive pressure buildup in the event of a malfunction
in the pressure control valves. It also relieves normal
pressure buildup when the system is not in use. This
normal buildup pressure is caused by heat entering the
system, and will cause a loss of 10 percent of the
system's capacity every 24 hours; for example,
approximately 1 liter of loss will be experienced from a
Liquid oxygen systems are designed for the rapid
removal of the LOX converter for ease of servicing and
maintenance. This is accomplished by the use of supply
and vent quick-disconnect couplings, a single
point converter retainer wing nut hold down, and
Figure 7-8.--Liquid oxygen converter assembly.