Teledyne GFC-7000T - Trace CO2 Analyzer - manual - Manual (Page 203)

Maintenance Model GFC7000TA Carbon Dioxide Analyzer
Teledyne Analytical Instruments 185
8.3.2. Rebuilding the Sample Pump
The diaphragm in the sample pump periodically wears out and must be replaced. A sample rebuild kit is
available – see Appendix B of this manual for the part number of the pump rebuild kit. Instructions and
diagrams are included with the kit.
Always perform a Flow and Leak Check after rebuilding the Sample Pump.
8.3.3. Performing Leak Checks
Leaks are the most common cause of analyzer malfunction; Section 8.3.3.1 presents a simple leak check
procedure. Section 8.3.3.2 details a more thorough procedure.
8.3.3.1. Vacuum Leak Check and Pump Check
This method is easy and fast. It detects, but does not locate most leaks; it also verifies that the sample
pump is in good condition.
1. Turn the analyzer ON, and allow enough time for flows to stabilize.
2. Cap the sample inlet port.
3. After several minutes, when the pressures have stabilized, note the following. In the TEST menu,
note the SAMPLE PRESSURE reading.
4. If the reading is < 10 in-Hg, the pump is in good condition and there are no large leaks.
5. Check the sample gas flow. If the flow is <10 cm 3 /min and stable, there are no large leaks in the
instrument’s pneumatics.
8.3.3.2. Pressure Leak Check
If you can’t locate the leak by the above procedure, use the following procedure. Obtain a leak checker
similar to the Teledyne Instruments part number 01960, which contains a small pump, shut-off valve, and
pressure gauge. Alternatively, a convenient source of low-pressure gas is a tank of span gas, with the
two-stage regulator adjusted to less than 15 psi with a shutoff valve and pressure gauge.
CAUTION
Do not use bubble solution with vacuum applied to the analyzer. The solution may
contaminate the instrument. Do not exceed 15 PSIG pressure.
1. Turn OFF power to the instrument.
2. Install a leak checker or tank of gas as described above on the sample inlet at the rear panel.
3. Remove the instrument cover and locate the inlet side of the sample pump. Remove the flow
assembly from the pump and plug it with the appropriate gas-tight fitting.