Graduated cylinder

Two graduated cylinders

A graduated cylinder, measuring cylinder or mixing cylinder is a piece of laboratory equipment used to measure the volume of a liquid. Graduated cylinders are generally more accurate and precise than laboratory flasks and beakers. However, they are less accurate and precise than volumetric glassware, such as a volumetric flask or volumetric pipette. For these reasons, graduated cylinders should not be used to perform volumetric analysis.^[1] Graduated cylinders are sometimes used to indirectly measure the volume of a solid by measuring the displacement of a liquid.

Often, the largest graduated cylinders are made of polypropylene for its excellent chemical resistance or polymethylpentene for its transparency, making them lighter and less fragile than glass. Polypropylene (PP) is easy to repeatedly autoclave; however, autoclaving in excess of about 130 °C (266 °F) (depending on the chemical formulation: typical commercial grade polypropylene melts in excess of 160 °C (320 °F)),can warp or damage polypropylene graduated cylinders, affecting accuracy.

A traditional graduated cylinder (A in the image) is usually narrow and high (so as to increase the accuracy and precision of volume measurement) and has a plastic or glass bottom and a "spout" for easy pouring from the measured liquid. An additional version is wide and low. Other type of cylinders (B in the picture) have ground glass joints instead of a "spout", so that they can be closed with a stopper or connect directly with other elements of a manifold; they are also known as mixing cylinders. ^[2] With this kind of cylinder, the metered liquid does not pour directly, but is often removed using a cannula. A graduated cylinder is meant to be read with the surface of the liquid at eye level, where the center of the meniscus shows the measurement line. Typical capacities of graduated cylinders are between 5 ml and 2000 ml.

References

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