1. OBJECTIVE
To lay down the procedure for operation, Cleaning and Calibration of Refractometer
2. SCOPE
This procedure is applicable to Quality Control Department
3. RESPONSIBILITY
• Officer QC
• Manager QC
4. SAFETY INSTRUCTIONS
• Proper handling the instrument.
• Temperature should be carefully adjusted and maintained since refractive index varies significantly with temperature.
5. PROCEDURE
5.1 OPERATION
5.1.1 Switch “ON” the mains.
5.1.2 Ensure that instrument is free from dust.
5.1.3 Ensure that all the parts including eye lens, prism and mirror are cleaned before the operation.
5.1.4 Place the instrument on the table where adequate light can be refracted through the mirror.
5.1.5 Open the prism lock and place the few drops of liquid testing sample.
5.1.6 Allow the liquid to smear on the lower prism surface quickly close the prism lock.
5.1.7 Adjust the eye piece cross wire with the knob by rotating it in a clockwise direction so that the sharp demarcation line pass through its center.
5.1.8 Sharp demarcation is produce in the form of circle having half-light and half dark portion.
5.1.9 Note down the reading from the scale with the help of magnifier lens of instrument.
5.2 CLEANING
5.2.1 After completion of testing, Switch “OFF” the instrument.
5.2.2 Switch “OFF” the mains.
5.2.3 Clean the prism with xylene and wipe with tissue paper
5.2.4 Clean the mirror and eye-piece with isopropyl alcohol and then wipe with tissue paper
5.2.5 Clean the instrument with lint free cotton cloth
5.2.6 Record in the cleaning activity log.
5.3 CALIBRATION
Frequency: Monthly or after any maintenance
5.3.1 Switch “ON” the mains.
5.3.2 The calibration of rafractometer is must to achieve the accuracy.
5.3.3 The instrument should be calibrated against distilled water.
5.3.4 The refractive index of distilled water is 1.3325 at 25◦C
5.3.5 Check it using distilled water against the reference liquid given below:
Carbon tetrachloride: 1.4603
Toluene: 1.4969
Water: 1.3325
5.3.6 Record the activity in the calibration Log
6. RELATED DOCUMENTS
Operational Log Book Format – Annex. I
Cleaning Log Book Format – Annex. II
Calibration Report Format – Annex. III
7. DISTRIBUTION INDEX
Original Copy will be retained by Quality Assurance Department.
| DISTRIBUTION INDEX | ||
|---|---|---|
| Distributed To | Copy No. | Received By/Date |
| Quality Control Department | 01 | , |
8. ABBREVIATIONS
Q.C Quality Control Department
SOP Standard Operating Procedure
9. REVISION HISTORY
| Revision No. | Issue Date | Supersedes | Reason of Change / Description |
| Revision No. Dated | |||
| 00 | 14/09/2022 | 00 N/A | First Version |