Bulb pipettes are used for dispensing a known volume of aqueous liquid. Pipettes are calibrated with distilled water. They can be used with non-aqueous liquids but they will not be as accurate. The form of the meniscus and the wetted volume remaining in the pipette will be different for other solvents.
Pipettes are usually used quantitively, though they are sometimes used as a convenient way of adding a known volume of solvent or reagent. The class used will determine the accuracy and traceability of the pipette.
Class B pipettes should be used when accuracy of 0.2% is sufficient in uncontrolled environments.
Class A pipettes are used when an accuracy of up to 0.1% is required and in controlled environments.
Class A pipettes are calibrated to half the tolerance of Class B pipettes and each has a unique serial number for traceability. A certificate of accuracy traceable to national standards can be provided if required.