Flasks are a type of clear glass or plastic laboratory equipment used to measure, mix or hold fluids or chemicals. Laboratory flasks are available in a number of shapes, sizes and with a various number of openings as determined by their intended uses. Along with test tubes, Erlenmeyer flasks — also known as E Spot or conical flasks — are among the most familiar pieces of laboratory glassware recognized by the general public. Named after their inventor, Erlenmeyer flasks are clear conical flasks topped with long narrow necks that include a small, convenient pour spout within the lip at the top of the glassware. The design of these flasks has proven to be particularly useful in a laboratory setting for a number of reasons, including safety and filling a variety of experimental needs.
Erlenmeyer flasks are frequently marked with white dashes of volumetric measures — i.e., graduations — along one edge of the vessel to aid in measuring fluids. The large, round bottom of the flask allows the vessel to sit solidly and securely on a lab table without overturning if lightly bumped or jarred by the chemist. The long, columnar necks of Erlenmeyer flasks serve several purposes. They provide an easy area to move or transport the flasks with hands or tongs, if necessary, and allow the flasks to be easily secured by metal clamps over a heat source, for example. Fluids are easily mixed in these vessels — swirled together by rotating the bottom of the flask — without significant splash risk.
Although they may be stoppered with rubber tops, the long necks of the Erlenmeyer flasks also decrease fluid loss by evaporation. This advantage is particularly helpful in maintaining proper concentrations when the chemist is working with volatile fluids. The columnar necks also allow titration or distillation fluids to be heated within Erlenmeyer flasks, without the usual risk of over-boiling the fluid, into attached distillation coils or tubes attached to the top of the flask.
Most Erlenmeyer flasks are made of glass, although some plastic vessels are available. Although they are breakable, glass flasks are more useful in the commercial laboratory. Glass flasks can be heated without risk of contaminating the contained substance with volatile substances potentially released by a plastic flask. Sterilizing glass flasks by heat is also an easier process than disinfecting and cleaning plastic flasks. Erlenmeyer flasks are available in a wide variety of sizes, although they are most commonly available in 250 and 500 ml (cc) sizes.