Graduated pipets have a full graduated scale to their maximum volume and may be used to measure many different volumes of liquid. As with graduated cylinders, the smallest graduated pipet that will hold the desired measured volume should always be used. This maximizes the precision of the measurement. Measured volumes are recorded to one decimal place beyond that which is indicated by the graduations.
Graduated pipets come in three types:
Type 1 - Reverse Graduated - Partial Delivery: These pipets feature the zero mark at the top of the pipet and include a maximum volume (nominal volume) somewhere near the bottom of the pipet. The pipet is first filled to the zero mark, then allowed to drain to the required volume. The pipet is never drained completely during measurement.
Type 2 - Standard Graduated - Full Delivery: These pipets feature the zero mark at the bottom of the pipet with the nominal volume at the top of the pipet. The pipet is filled until the required volume (up to the nominal volume) is achieved, then is allowed to drain completely into the reaction vessel.
Type 3 - Reverse Graduated - Full Delivery: These pipets are similar to Type 1 Pipets except the nominal value can only be achieved by draining the pipet completely.