ABB Aztec 600 User Manual page 84

Aztec 600 aluminium, ammonia, color, iron, manganese, phosphate
Single- and multi-stream colorimetric analyzers
Check
Check valves/valve
manifold for blockages
External Influences
IM/AZT6CR–EN Rev. J
Action
Blockages in the valves or the valve manifold result in incorrect dosage of reagent or sample that cause
erratic or incorrect readings. Check reagent usage. Excessive or reduced usage of one reagent can
indicate a blocked or partially restricted valve.
1. Disconnect the tubing from the valve block assembly.
2. Remove the valve block assembly from the analyzer.
3. Starting with the waste valve, remove the valve and check the diaphragm for particulate build-up
– clean or replace if necessary.
4. With the valve removed check that there are no blockages in the valve manifold:
a. Attach a syringe filled with de-ionised water, with a length of tubing, to the centre barb on the
valve manifold.
b. Depress the syringe plunger and ensure that the deionised water flows freely.
c. Remove the syringe from the centre barbed connector and attach to the outer barbed
connector of the valve position being tested. Depress the syringe plunger and ensure that the
deionised water flows freely.
d. Replace the valve, ensuring that the face gasket is located correctly.
e. Repeat for each of the remaining valves.
5. Prior to refitting the valve block to the analyzer, test for an air-tight seal by attaching the syringe to
the centre barbed connector, drawing back the plunger and releasing it. Check the syringe
plunger returns to the start position.
6. Replace the valve block, connect the tubing and prime/calibrate the analyzer.
There are a number of external influences that cause erratic or unstable results, such as inconsistent
dosage of chemicals within the process, dirty sample lines leading to the analyzer or changes in water
quality.
1. Check sample line(s) feeding the analyzer have sufficient flow to ensure that there is no settling of
particles – adjust the flow and backwash the sample line(s) if necessary.
2. Check the side sample pot is clean and that no particles have built up – clean the side sample
pot if necessary.
3. Check that particles outside the specification of the analyzer are not entering the side sample
pot, such as coagulant breakthrough – install a pre-filter or settling pot if necessary.
4. If a pre-filter or settling pot is used, check that this is functioning correctly – clean if necessary.
5. Check the historical log of the analyzer and compare period of erratic readings against
conditions.
Appendix B – Troubleshooting
81