Emerson Clarity II Instruction Manual page 63

MODEL CLARITY II
8.4.3 Analyzer responds too slowly to changes in turbidity
Response time is primarily a function of sample flow rate, distance between the sample point and analyzer, and
the diameter of the sample tubing. Because the debubbler has a flow restrictor on the outlet to increase back pres-
sure, sample flow rate is primarily determined by the inlet pressure.
A. If possible, increase the inlet pressure.
B. If increasing the inlet pressure is not feasible, move the sensor closer to the sample point.
8.4.4 Flow is too low
The debubbler is fitted with a 0.040 inch (1 mm) diameter orifice in the outlet. The orifice puts back pressure on
the debubbler, which helps reduce outgassing. If the inlet pressure is about 3.5 psig (125 kPa abs), the flow
through the debubbler will be about 250 mL/min. The response time to a step change at 250 mL/min is about sss
minutes. If the flow is too low, the response time may become excessive. The only way to improve the response
time is to reduce the back pressure or to increase the inlet pressure.
A. To eliminate back pressure, remove the orifice from the debubbler. See Section 7.3.
B. If removing the orifice causes outgassing — the symptom of outgassing is an upward drift in apparent turbid-
ity — increase the back pressure by a small amount. Use a valve or a valved rotameter (PN 24103-00) in the
debubbler outlet. Do not exceed 30 psig (308 kPa abs).
C. If outgassing continues to persist, increase the back pressure. To maintain flow, use a pump to increase the
inlet pressure.
8.4.5 Readings are lower or higher than expected
A. Is the instrument to which readings are being compared properly calibrated?
B. Are samples being tested immediately after sampling? If samples are allowed to sit too long before testing, the
turbidity may change.
C. Are the measurement chamber and debubbler clean?. Sample flow may be stirring up solids that have previ-
ously settled out in the debubbler and measurement chamber, increasing the apparent turbidity. See Section
7.3.1 for cleaning procedure.
8.4.6 Analog current is too low
Load resistance is too high. Maximum load is 600 Ω.
8.4.7 Alarm relays do not operate when setpoint is exceeded
A. Is the alarm board is in place and properly seated?
B. Is the alarm logic (high/low) and dead band correct?
C. Has the setpoint has been properly entered?
8.4.8 Display is unreadable — too faint or all pixels dark.
While holding down the MENU key, press s s or t t until the display has the correct contrast.
SECTION 8.0
TROUBLESHOOTING
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