SOP for Operation & Maintenance of Automatic Digital Refractometer (Model: DG-NXT)

To provide guidelines for the Operation & Maintenance of an Automatic Digital Refractometer.

To establish a procedure for an operation of an Automatic Digital Refractometer.

It is the responsibility of QC Executives to follow the procedure without deviation.

Assistant Manager – Quality Control
Manager – Quality Assurance

  • Open the Flap cover of the prism and ensure the prism surface is free from dust, or any other particle. In case not then clean the prism surface gently with distilled water and wipe the same with Cotton or Tissue paper.
  • Switch on the instrument by pressing the ON / OFF switch. The current power level of the 9V battery fitted is shown in the top right corner of the LCD screen.

  • Select the desired scale (Refractive Index, nD / Brix) by pressing the scale key & keep it pressed till the scale indication points on the desired scale shown at the bottom of the screen for P&G Blue Hawaii select the refractive index option.
  • Calibrate the instrument by using DI water. Place approx 1 ml of DI Water on the prism surface. Close the flap cover, and wait for 30 seconds. Calibrate the instrument by pressing the Zero key until CAL is displayed on the screen. Then release the calibration reading is displayed on the screen, the RI of water is 1.3333. Then press the zero key. The display will be ……
  • In case of Temperature, compensated reading is required then the automatic Temperature compensation function needs to be switched ON (Indicated by the symbol “ATC” on the LCD screen). In case “ATC” is not appearing on the screen press the FUNCTION key thrice. Then “ATC.Y” will appear on the screen. Select option Y by pressing the scale key. Then press Read/Enter key to confirm your setting. Now recheck whether ATC appearing on screen. If this function needs to be switched off, the same procedure needs to be followed wherein after pressing the Function key thrice. Then “ATC.N” will appear on the screen which needs to be selected.
  • Take a small amount of sample (approx 1ml) to be measured with the help of a dropper and put it on the prism surface gently. Close the flap cover. Press the READ key. The value will instantly be displayed on the LCD screen. After the measurement is done gently clean, and wipe the prism with distilled water and tissue paper after use.

As and when required.



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