Calibration Services

Mass and Related Quantities: Volume Measurements

General

The Mass and related quantities Laboratory of SCL provide calibration services for various kind of volume vessels, such as measuring tanks, measuring cylinders, single channel and multiple channel pipettes and etc.

There are two methods employed by Mass and related quantities Laboratory for volumetric determination. The gravimetric method determines the mass of water either contained or delivered from a test measure. From the measured mass, the volume can be determined with a knowledge of water density and corrections for air buoyancy and thermal expansion of the vessel. The volumetric method requires a measurement standard (calibrated) volumetric measure. The volume of the test volumetric vessel is determined from the number of "dumps" of the measurement standard measure required to fill the test measure. Normally gravimetric method will be used for volumetric determination at the capacity of 20 L or below, whilst volumetric method will be used for measurements above 20 L.

To optimize the calibration results, the submitted vessels should be in a clean condition.

Measuring tanks, Measuring Cylinders

Calibration of a water tank

The contained volume (capacity) or the delivered volume of a vessel can be calibrated. The contained volume is the volume of water required to fill the vessel at 20°C, whilst the delivered volume is the volume of water which may be poured from the vessel at 20°C under specified conditions (e.g. with a fixed drainage time of 30 seconds after cessation of main flow). The delivered volume is always less than the contained volume, due to the film of liquid left on the walls of the vessel after delivery. The difference between the contained and delivered volume for glassware may be of the order of 0.1% of the capacity for a 1 L flask increasing to 0.25% for a 50 mL flask, using water as the working medium. Hence, customers are reminded to specify whether the contained volume or the delivered volume is required during calibration request.

Single channel / Multi-channel pipette

Calibration of single channel pipettes

Calibration of multi-channel pipettes

Unless or otherwise specified, the delivered volume of a single channel / multi-channel pipette would be determined by using the gravimetric methods in accordance with ISO8655-6 "Piston-operated volumetric apparatus – Part 6: Gravimetric methods for the determination of measurement error".