122 Maintenance and Service 083730300A DCN8101
5.7.9.1 FLOW IS ZERO
The unit displays a SAMPLE FLOW warning message on the front panel display or the
SAMPLE FLOW test function reports a zero or very low flow rate.
Confirm that the sample pump is operating (turning). If not, use an AC voltmeter to
make sure that power is being supplied to the pump if no power is present at the electrical
leads of the pump.
1. If AC power is being supplied to the pump, but it is not turning, replace the pump.
2. If the pump is operating but the unit reports no gas flow, perform a flow check as
described in Section 5.6.4.
3. If no independent flow meter is available:
• Disconnect the gas lines from both the sample inlet and the exhaust
outlet on the rear panel of the instrument.
• Make sure that the unit is in basic SAMPLE Mode.
• Place a finger over an Exhaust outlet on the rear panel of the instrument.
• If gas is flowing through the analyzer, you will feel pulses of air being
expelled from the Exhaust outlet.
4. If gas flows through the instrument when it is disconnected from its sources of zero
air, span gas or sample gas, the flow problem is most likely not internal to the
analyzer. Check to make sure that:
• All calibrators/generators are turned on and working correctly.
• Gas bottles are not empty or low.
• Valves, regulators and gas lines are not clogged or dirty.
5.7.9.2 LOW FLOW
1. Check if the pump diaphragm is in good condition. If not, rebuild the pump (see
Section 5.6.2). Check the Spare Parts List for information on pump rebuild kits.
2. Check for leaks as described in Section 5.6.3. Repair the leaking fitting, line or
valve and re-check.
3. Check for the sample filter and the orifice filter for dirt. Replace filters (see 5.6.1).
4. Check for partially plugged pneumatic lines, or valves. Clean or replace them.
5. Check for plugged or dirty critical flow orifices. Replace them.
6. If an IZS option is installed in the instrument, press CALZ and CALS. If the flow
increases then suspect a bad sample/cal valve.
5.7.9.3 HIGH FLOW
The most common cause of high flow is a leak in the sample flow control assembly or
between there and the pump. If no leaks or loose connections are found in the fittings or
the gas line between the orifice and the pump, replace the critical flow orifice(s) inside
the sample flow control assembly.
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