In laboratory equipment, a beaker is generally a cylindrical container with a flat bottom. Most also have a small spout to aid pouring, as shown in the picture. Beakers are available in a wide range of sizes, from one millilitre up to several litres. A beaker is distinguished from a flask by having straight rather than sloping sides. The exception to this definition is a slightly conical-sided beaker called a Philips beaker. The beaker shape in general drinkware is similar. Beakers are commonly made of glass, but can also be in metal or certain plastics. A common use for polypropylenebeakers is gamma spectral analysis of liquid and solid samples.
Construction and use
Standard or "low-form" beakers typically have a height about 1.4 times the diameter. The common low form with a spout was devised by John Joseph Griffin and is therefore sometimes called a Griffin beaker. These are the most universal character and are used for various purposes—from preparing solutions and decanting supernatant fluids to holding waste fluids prior to disposal to performing simplereactions. Low form beakers are likely to be used in some way when performing a chemical experiment. "Tall-form" beakers have a height about twice their diameter. These are sometimes called Berzelius beakers and are mostly used for titration. Flat beakers are often called "crystallizers" because most are used to perform crystallization, but they are also often used as a vessel for use in hot-bath heating. These beakers usually do not have a flat scale. The presence of a spout means that the beaker cannot have a lid. However, when in use, beakers may be covered by a watch glass to prevent contamination or loss of the contents, but allowing venting via the spout. Alternatively, a beaker may be covered with another larger beaker that has been inverted, though a watch glass is preferable. Beakers are often graduated, that is, marked on the side with lines indicating the volume contained. For instance, a 250mL beaker might be marked with lines to indicate 50, 100, 150, 200, and 250 mL of volume. These marks are not intended for obtaining a precise measurement of volume, but rather an estimation. Most beakers are accurate to within ~10%.
Standards
DIN EN ISO 3819:2015-12 defines the following types and sizes:
