Teledyne GFC-7000T - Trace CO2 Analyzer - manual - Manual (Page 204)

Maintenance Model GFC7000TA Carbon Dioxide Analyzer
Teledyne Analytical Instruments 186
4. Pressurize the instrument with the leak checker, allowing enough time to fully pressurize the
instrument through the critical flow orifice. Check each fitting with soap bubble solution, looking
for bubbles. Once the fittings have been wetted with soap solution, do not re-apply vacuum, as it
will suck soap solution into the instrument and contaminate it. Do not exceed 15 psi pressure.
5. If the instrument has one of the zero and span valve options, the normally closed ports on each
valve should also be separately checked. Connect the leak checker to the normally closed ports
and check with soap bubble solution.
6. Once the leak has been located and repaired, the leak-down rate should be < 1 in-Hg (0.4 psi) in
5 minutes after the pressure is shut off.
8.3.4. Performing a Sample Flow Check
CAUTION
Always use a separate calibrated flow meter capable of measuring flows in the 0 – 1000
cc/min range to measure the gas flow rate though the analyzer.
DO NOT use the built in flow measurement viewable from the Front Panel of the
instrument. This measurement is only for detecting major flow interruptions such as
clogged or plugged gas lines.
See Figure 3-4 for SAMPLE port location.
1. Attach the Flow Meter to the sample inlet port on the rear panel. Ensure that the inlet to the Flow
Meter is at atmospheric f.
2. Sample flow should be 800 cc/min  10%.
3. Once an accurate measurement has been recorded by the method described above, adjust the
analyzer’s internal flow sensors (See Section 6.13.8)
Low flows indicate blockage somewhere in the pneumatic pathway, typically a plugged sintered filter or
critical flow orifice in one of the analyzer’s flow control assemblies. High flows indicate leaks downstream
of the Flow Control Assembly.
8.3.5. Cleaning the Optical Bench
The GFC 7000TA sensor assembly and optical bench is complex and delicate. Disassembly and
cleaning is not recommended. Please check with the factory before disassembling the optical bench.
8.3.6. Cleaning Exterior Surfaces of the GFC 7000TA
If necessary, the exterior surfaces of the GFC 7000TA can be cleaned with a clean damp cloth. Do not
submerge any part of the instrument in water or cleaning solution.