All turbidity guides
Start with timing
Compare the time of the change with plant events, taking sample travel time into account.
Check flow and air
Look for interrupted flow, air ingress and recent changes to the sample or drain line. Record what you find before making adjustments.
Verify the instrument
Check the instrument against the applicable verification procedure and record the result alongside the trend.
Compare the same water at the same time
Where a grab sample is useful, match it to the process sample point and account for transit time. Record the reference instrument and optical method alongside the result.
Document the outcome
Keep the trend, operating events, verification result and any work on the sample line together. If the change recurs, that record helps the next operator pick up the investigation.
