Calibration

Standard Calibration Procedures for  Viscometers

Standard calibration of viscosity measurements instruments is necessary annually but also on regular basic in your laboratory.

Bellow you will find advice on the procedure, oils which should be use and reading you should receive from the instrument.

Procedure

1. Select the appropriate spindle and attach to the Viscometer (refer to table below).
2. Transfer standard oil to clean test vessel.
3. Insert and centre spindle in standard in standard until level is at the immersion groove on the spindle shaft.
4. Ensure that the temperature of the oil is noted. I.e. Note that the oils supplied by QC Labs are calibrated over various temperatures.
5. To take the viscosity reading, turn the viscometer motor on at the recommended speed and wait for the reading to stabilise.

NOTE: With disc type spindles it is sometimes necessary to tilt the spindle slightly while immersing to avoid trapping air bubbles on the disc under surface. You may find it more convenient to immerse the spindle in this fashion before attaching it to the viscometer.

If necessary, calibration can also be checked at other points. Listings of further calibration sets can be given.

Error Limits

Your instruments reading should be within 1% +/- of the full scale reading. Affix new calibration label and date label. Labels are available from QC Labs.

• LV Series L3 60rpm -/+20 cPs
• RV Series R5 50rpm -/+80 cPs
• HV Series R3 50rpm -/+160 cPs

Please also remember that the standard is calibrated to 0.2% of its stated value and you will need to allow for this possible error as well.

NOTE: If your reading is outside these error tolerances then you should check the following:

1. Even a small temperature difference can give large viscosity differences.
2. Spindle / Speed Combination. Check that you are using the correct spindle and speed, as this will affect error values.
3. Check that the viscometer is level (see level indicator).
4. Check that the guard leg is in place if required.
5. Check that the standard is within its recommended expiry date.

If your reading is still outside the error limits then it may need servicing and re-calibration. To arrange please contact:

If you have any problems carrying out your calibration check, or require information on the calibration of any other types of viscometers, please contact us at the above address.

The Calibration oils used in the above procedure are accurate to +/- 0.2% and are certified over 6 temperatures from 20.00 to 27.00 Degrees Cenntigrade.