Title

13 Chlorine Residual Analyzer Issues

The chlorine residual anaylzers are used to control the amount of sodium bisulfite required to dechlorinate effluent.  The application rate for the sodium bisulfite injection is controlled by a compound loop control system, which includes the chlorine residual analzyers.  If the analyzer is not working properly, the final chlorine residual may nto comply with the permit requirements.

SOP Identification Number
SOP Identification Number:
1301_ChlorineResidualAnalyzerIssues
Purpose and scope
Purpose and scope:

Dechlorination of the effluent is necessary in order to reduce the toxic effects of chlorinated effluent on aquatic life in the receiving water body.

Cautions
Cautions:
Chlorine residuals that suddenly start to climb may be not caused by an actual change in CCC chlorine residuals. Additional potential causes include:
  • Loss of sample flow and/or loss of prime
  • Loss of reagent flow
  • Analyzer(s) is un-calibrated
Potential Interferences
Potential Interferences:
  • The analyzer for System #1 is physically labeled “#3”. 
  • The analyzer for System #2 is physically labeled “#4”.
Personnel Qualifications
Personnel Qualifications:

Operator I, knowledge of disinfection system controls.

Procedure
Procedure:
One chlorine residual sensor is located at the CCC Influent (System #1) and the second chlorine residual sensor is located just before the CCC Weir (System #2). Each sensor has a dedicated analyzer. The analyzers are installed next to each other.
Please note: The analyzer for System #1 {tag nos. 1301AE/AIT3446} is physically labeled “#3”. The analyzer for System #2 {tag nos. 1301AE/AIT3447} is physically labeled “#4”.

Chlorine residuals that suddenly start to climb may be not caused by an actual change in CCC chlorine residuals. Additional potential causes include:
  • Loss of sample flow and/or loss of prime
  • Loss of reagent flow
  • Analyzer(s) is un-calibrated 
1.    Loss of Sample Flow and/or Loss or Prime. Check the sample supply line to make sure the sample pumps {tag nos. 1301PMP/MTR3100 & 1301PMP/MTR3200} are online and sample flows are reaching the analyzers {tag nos. 1303AE/AIT3446 & 1303AE/AIT3447}.
a.    Loosen the sample tubing and check for flow. If flow is visible, skip to Step 2.
b.    Close the isolation valve on the sample piping {tag nos. 1301VLV3673A & 1301VLV3674A}. 
c.    Unscrew and remove the strainer {tag nos. 1301STR3673 & 1301STR3674} and flush any debris. 
d.    Replace the strainer and open the isolation valve.
 
2.    Loss of Reagent Chemical Flow. Check the chemical reagent levels recorded to the Operator’s Log Book. Compare the current level of reagent chemical in the beaker with the recorded level. No change in levels could indicate a loss of prime. If levels have changed and appear normal, skip to Step 3.
a.    Loosen the reagent tubing and verify if there is flow. If not, prime the system by pulling reagent from the tubing with a syringe.
b.    Replace the tubing once flow is reestablished. 
 
3.    Out of Calibration. The influent and pre-weir chlorine residuals display the same value at both analyzers. This could indicate that one or both of the analyzers need to be recalibrated.
a.    Open the sample bypass valve {tag no. 1301VLV3673B} to direct the influent sample flow to the second analyzer (tag no. 1301AE/AIT3446}.  Identical influent samples are now directed to both analyzers, therefore, the chlorine residuals should be identical. If not, recalibrate one or both analyzers. Please note: recalibration requires a Work Order.
b.    Double check calibration by performing a field sample test or by taking a sample to the lab for analysis. Compare the results with the levels displayed at the analyzers.
Data & Records Management, Calculations, Forms, Reports
Data & Records Management, Calculations, Forms, Reports:
  • Record activity to log book.
  • File Work Order (if required)
Limits/Criteria for Data/Results
Limits/Criteria for Data/Results:

Dechlorination chemical injections to the effluent are such that a final chlorine residual of 0.1 mg/l is maintained.

ID
Maintenance Connect