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5.0
PRINCIPLE OF OPERATION.
5.1
The 737-series pure air generators produce absolutely clean air from pressurized
unclean air by chromatographic techniques. Pressurized air from a compressor or
other source enters either the number 1 or number 2 column system (see Figure
10), depending upon the status of the solenoid valve located at the inlet of the
column. These valves are normally closed, sealing the system against possible
contamination.
5.2
The pressurized air passes through the column where selective absorption takes
place, with a subsequent separation of the various components present in the air.
Only the desired components, which elute first, are permitted to reach the end of
the column system and elute, whereupon, the solenoid valve at the head of the
separation column closes and the solenoid valve at the inlet to the alternate column
system opens.
5.3
Pressurized unclean air now enters the alternate column system where separation
again takes place. The alternation of the two column system produces a steady
flow of purified air.
5.4
During the interval that pressurized unclean air is being separated in one column, a
portion of the clean air passes through the purge valve and back flushes the
alternate column of impurities. This purge valve, Figures 5 and 8(12), has been set
at the factory at optimum flow and must not be altered.
5.5
The back flush flow of air with impurities exits from the instrument through the
swage bulkhead connector labeled "DUMP" at the rear of the instrument, Figure 2
(6). This exit must not be restricted. A back pressure situation must be avoided at
this fitting.
5.6
The timer, Figures 4 and 7 (13), which provides alternate power to the solenoid
valve, has been set to effect the proper residence time of the unclean air in the
column and also the purge time for each size reactor. The timer must not be
altered.
5.7
To prolong the life of the support media within the column, it is mandatory that the
operational directions for the instrument be followed as closely as possible.
Selection of this separation medium, residence time in the column, proper input
pressure, purge flows, and column volumes have been determined to meet the
requirements of the particular 737-series pure air generator being used. These
components are not interchangeable except among units of the same rated output.
5.8
Rapid depletion of the purification reactor can occur if: (a) improperly filtered air is
admitted to the columns as with oil compressors, (b) water is admitted to the
columns, or (c) the unit is operated above its rated capacity.
11
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