Optional Equipment
Teflon Particulate Filter
Thermo Fisher Scientific
Model 48
i
Instruction Manual
9-5
The stability of the purge gas is very important. Since this gas is in the same
optical path as the sample, changes in the composition of the purge gas can
change the calibration of the instrument. Therefore, either zero air or a
non-toxic dry inert gas, such as nitrogen, is recommended for use in this
option. Other than the effect of the purge gas, operation and calibration of
the instrument is not affected by the addition of the purge housing.
A constant purge flow of approximately 140cc/min is recommended for
optimum performance. This is produced by feeding a purge gas to the rear
panel bulkhead at a constant pressure of 15 psig. A 0.006-inch glass
capillary (green) will deliver the required 140cc/min purge flow. Flows
greater than this are not recommended due to unstable cooling effects on
the IR source. Lower flows are acceptable as long as the purge housing is
adequately purged for the application.
A 5-10 micron pore size, two-inch diameter Teflon® element is available for
the Model 48
i
. This filter should be installed just prior to the
SAMPLE
bulkhead. When using a filter, all calibrations and span checks must be
performed through the filter.
The I/O expansion board provides six analog current output channels (0-
20 mA or 4-20 mA) and eight analog voltage inputs (0-10V). The DB25
connector on the rear panel provides the interface for these inputs and
outputs.
The 25-pin terminal board assembly is included with the optional I/O
expansion board. Refer to “Terminal Board PCB Assemblies” on page
2-5
for information on attaching the cable to the connector board. For
associated part numbers, refer to “
External Device Connection
Components
” on page
7-6
.
The optional terminal block and cable kits provide a convenient way to
connect devices to the instrument. These kits break out the signals on the
rear panel connector to individual numbered terminals.
Two types of terminal block and cable kits are available. One kit is for the
DB37 connectors and can be used for either the analog output connector
or the relay output connector. The other kit is for the DB25 connector and
can be used for the optional I/O expansion board. For associated part
numbers, refer “
External Device Connection Components
” on page
7-6
.
Calibration Note
Teflon Particulate
Filter
I/O Expansion Board
Assembly
25-Pin Terminal
Board Assembly
Terminal Block and
Cable Kits
