Physical testing
Turbidity meter
Measures how cloudy a liquid is by shining light through it and measuring the light scattered by tiny particles. Results are given in NTU or FNU and are used for clarity and opalescence tests.
- Pharmaceutical
- Biotech
- Water treatment
- Food & beverage
- Brewing
- Environmental testing
TROUBLESHOOTING
Common problems, causes and fixes
Reading high and unstable
Likely causes
- • Air bubbles in the sample
- • Particles settling or rising
What to do
- • Let the sample stand, invert gently or degas
- • Read promptly after gentle mixing
Blank (low-turbidity water) reads too high
Likely causes
- • Scratched or dirty cuvette
- • Fingerprints or condensation
- • Contaminated water
What to do
- • Clean or replace the cuvette
- • Wipe and handle only by the top
- • Use freshly filtered water
Results differ when the cuvette is turned
Likely causes
- • Cuvette not uniform or scratched
- • Orientation mark not aligned
What to do
- • Index the cuvette (find the lowest reading position) and always use that position
- • Replace the cuvette
Verification standard out of limit
Likely causes
- • Standard expired or contaminated
- • Lamp ageing
- • Calibration drift
What to do
- • Use a new standard
- • Replace the lamp
- • Recalibrate with formazin
Coloured sample reads lower than expected
Likely causes
- • Colour absorbs the scattered light
What to do
- • Use ratio mode if available, or follow the monograph's visual method
In LimsPulse · Calibration Management
Keep every Turbidity meter in control: usage logs, calibration and maintenance schedules, and automatic blocking of overdue instruments.