SOP for OPERATION & CALIBRATION OF CONDUCTIVITY METER (Toshcon Industries Ltd., Model : TCM15+)

1.0                    OBJECTIVE:

To provide guideline for operation and calibration of conductivity/TDS Meter.

2.0                    SCOPE:

This SOP covers operation and calibration of  Conductivity/TDS Meter. (Make : Toshcon Industries Ltd., Model : TCM15+ )

3.0                    RESPONSIBILITY:

               QC Officer: Responsible for operation, daily calibration and maintenance of the    conductivity meter as per procedure.

               QC Manager/QC Executive: Review the records and governing the document.

4.0                    PROCEDURE:

4.1                OPERATION:

4.1.1           Ensure that instrument is clean and free from dust.

4.1.2           Connect the conductivity probe to the instrument. Then switch ON the instrument.

4.1.3           Conductivity/TDS mode is selected by pressing the switch given on rear side of instrument

4.1.4           Set the temperature by rotating the knob provided at back side of instrument.

4.1.5           Rinse the electrode and submerse the electrode into the sample solution, which has to be measured.

4.1.6           The sleeve holes must be completely submersed. Tap the probe repeatedly to remove any air bubbles that may be trapped inside the sleeve.

4.1.7           The conductivity/TDS value will be displayed on the display.

4.1.8           Depending on the concentration of solution, instrument will display the conductivity value in different unit (e.g. millisiemens, microsiemens).

4.1.9           After completion of measurement, rinse the conductivity cell and keep it at dry place.

4.1.10       Note down the activities performed in instrument usage log book. (Refer Annexure-I)

4.2                 CALIBRATION:

4.2.1           Rinse the electrode with distilled water then after calibration solution.

4.2.2           The sleeve holes must be completely submersed.

4.2.3           Tap the probe repeatedly to remove any air bubbles that may be trapped inside the sleeve.

4.2.4           For calibration prepare KCL solution (0.7455 gm / 1 kg in CO2 free water), using AR/GR grade KCL dried at 180°C for 1 hour. Maintain preparation record in Annexure-III.

4.2.5           Cool the solution at 20°C and measure its conductivity.

4.2.6           Also the following table gives the conductivity in mhos per centimeter of KCL solutions for standardization.

Gm KCL / kg of solution	Conductivity µS/cm at
	20°C
0.7455	1330
0.0746	133.0
0.0149	26.6

4.2.7           After completion of measurement, wash the cell with distilled water and restore it in same.

4.2.8           Record the calibration detail in calibration record format. (Refer Annexure – II).

4.2.9           Note : CO2 free water is prepared by boiling distilled water for 10 minutes & cooling it in CO2 free atmosphere. ( Desiccators containing NaOH flakes in bowl).

   Acceptance Criteria :

                The observed conductivity should 1.330 ± 1% at ms/cm at 20 °C.      

4.3                CELL RECALIBRATION PROCEDURE:

4.3.1           After continuous use in chemical solution residue gets accumulated on platinum plates of conductivity cell. To overcome this problem cell needs cleaning & re-calibration.

4.3.2           The conductivity cells are thoroughly cleaned by a solution of Potassium dichromate in conc. Sulphuric acid and after that clean it with distilled water.

4.3.3           Dip cell 24 hrs before calibration in distilled water. Put cell into standard solution of KCL (0.01 molar). Connect cell terminals to 1.409 millimho at 25°C by varying cell  constant preset without pressing CELL K READ key. Then press CELL K READ key & get new cell constant to the cell.

4.4                CALIBRATION FREQUENCY : Daily