Figure 2-4. Atmospheric Dump Bypass Plumbing - Thermo Scientific 48i Instruction Manual

Installation
Setup Procedure
2-4 Model 48i Trace Level-Enhanced Instruction Manual
SAMPLE
Figure 2–4. Atmospheric Dump Bypass Plumbing
2. Connect the EXHAUST bulkhead to a suitable vent. The exhaust line
should be 1/4-inch OD with a minimum ID of 1/8-inch. The length of
the exhaust line should be less than 10 feet. Verify that there is no
restriction in this line.
3. Connect a source of CO span gas to the SPAN bulkhead. The span gas
should contain CO in balance air, with the CO concentration similar
to that of the sample.
A constant filter wheel purge flow of approximately 140 cc/minute 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" glass capillary, mounted inside the capillary housing on the
rear panel of the instrument will deliver the required 140 cc/minute
purge flow. Flows greater than this are not recommended due to
unstable cooling effects on the IR source.
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.
4. Connect a suitable recording device to the rear panel connector. For
detailed information about connecting to the instrument, refer to:
Instrument Bulkhead
Vent to Exhaust Line at
Atmospheric Pressure
Input Gas Line
Thermo Fisher Scientific