What precautions should be observed when measuring turbidity with the VN3100 Portable Turbidimeter?

---

1. Avoid measuring under direct sunlight.

2. Avoid diluting the sample as much as possible, as particles may dissolve and other characteristics may change after dilution.

3. Degas the sample to avoid bubble interference.

4. Wipe the tube wall with a soft cloth to eliminate interference from fingerprints or other contaminants.

5. Apply silicone oil to mask defects and surface scratches on the bottle wall.

6. Silicone oil has the same refractive index as the glass sample cell, so it can be applied to the bottle wall to mask defects.

7. Remove the sample cell from the test chamber in a timely manner to avoid damaging the spring plate.

8. Always close the sample cell cover to prevent sample spillage into the instrument.

9. Keep the test chamber cover closed throughout the testing process.

10. Do not leave the sample cell in the test chamber for an extended period after testing.

11. Remove the battery if the instrument is not going to be used for a long time.

12. Use silicone oil regularly.