Graduated cylinders are pieces of scientific equipment which are used for volume measurements of liquids. In addition to being used to measure liquid volume, they can also be used in density measurements for certain types of objects, which can be lowered into a graduated cylinder filled with water or another fluid to see how much fluid is displaced by the object. Many manufacturers of scientific equipment make graduated cylinders, and they are readily available at science supply stores, through catalogs, and at online merchants who sell lab equipment.
The design of a graduated cylinder includes a flat base which is designed to keep the cylinder stable, and a series of markings on the cylinder which indicate volume measurements. Some graduated cylinders give measurements using several different systems, while others provide measurements in only one. Many also have a ring near the neck of the cylinder which is designed to absorb the impact if the cylinder falls so that it does not shatter.
There are a number of qualities which need to be present in a graduated cylinder. Chemical resistance is important, to avoid clouding the cylinder or causing accidents with materials which may eat through a cylinder made from reactive material. Heat resistance can also be valuable, as people may want to be able to heat graduated cylinders or to pour hot liquids into them. The ability to be sterilized is also important, to avoid cross-contamination. Shatter resistance may also be important, to prevent accidents.
The graduated cylinder is designed as a measurement device. For other activities in the lab, there are more suitable pieces of scientific equipment available. To measure liquids in a graduated cylinder, people read the lowest point of the meniscus, the curved shape formed by the top of the fluid in the cylinder. It is important to have the cylinder on a flat surface to avoid accidentally shifting the low point of the meniscus, and it can take some practice to learn to read the measurement well.
Like other pieces of scientific equipment, graduated cylinders work best when they are well cared for. It is important to make sure that they are properly cleaned after use, and people should try to avoid dropping filled or empty cylinders, even if they are shatterproof. They should also be stored in conditions where they will not be exposed to chemicals which could contaminate them, skewing measurements made and potentially posing a safety risk.