A bung is truncated

Truncation (geometry)

In geometry, a truncation is an operation in any dimension that cuts polytope vertices, creating a new facet in place of each vertex.- Uniform truncation :...

 cylindrical or conical

Cone (geometry)

A cone is an n-dimensional geometric shape that tapers smoothly from a base to a point called the apex or vertex. Formally, it is the solid figure formed by the locus of all straight line segments that join the apex to the base...

 closure to seal

Seal (mechanical)

A mechanical seal is a device which helps join systems or mechanisms together by preventing leakage , containing pressure, or excluding contamination...

 a container

Packaging and labelling

Packaging is the science, art, and technology of enclosing or protecting products for distribution, storage, sale, and use. Packaging also refers to the process of design, evaluation, and production of packages. Packaging can be described as a coordinated system of preparing goods for transport,...

, such as a bottle

Bottle

A bottle is a rigid container with a neck that is narrower than the body and a "mouth". By contrast, a jar has a relatively large mouth or opening. Bottles are often made of glass, clay, plastic, aluminum or other impervious materials, and typically used to store liquids such as water, milk, soft...

, tube or barrel. Unlike a lid

Lid (container)

A lid, also known as a cap, is part of a container, and serves as the cover or seal, usually one that completely closes the object.-History:...

 which encloses a container from the outside without displacing the inner volume

Volume

Volume is the quantity of three-dimensional space enclosed by some closed boundary, for example, the space that a substance or shape occupies or contains....

, a bung is partially inserted inside the container to act as a seal. The lids for safety overpacks for 55 gallon drums sometimes may have a bung built in for access of the contents of the container. These may be referred to as fuel bungs.

A rubber stopper is sometimes called a rubber bung, and a cork stopper is called a cork

Cork (material)

Cork is an impermeable, buoyant material, a prime-subset of bark tissue that is harvested for commercial use primarily from Quercus suber , which is endemic to southwest Europe and northwest Africa...

. Sometimes bung stoppers used for wine bottles are referred to as "corks", even though made from another material.

The most common every-day example of a bung is the stopper of a wine bottle

Wine bottle

A wine bottle is a bottle used for holding wine, generally made of glass. Some wines are fermented in the bottle, others are bottled only after fermentation. They come in a large variety of sizes, several named for Biblical kings and other figures. The standard bottle contains 750 ml,...

. Bungs are used to seal the bunghole

Bunghole

A Bunghole or Bungehole is a hole bored in a liquid-tight barrel to remove contents. The hole is capped with a large cork-like object called a bung. Acceptable usage include other access points that may be capped with alternate materials providing an air or water-tight access to other vessels. For...

 of barrel

Barrel

A barrel or cask is a hollow cylindrical container, traditionally made of vertical wooden staves and bound by wooden or metal hoops. Traditionally, the barrel was a standard size of measure referring to a set capacity or weight of a given commodity. A small barrel is called a keg.For example, a...

s. Other bungs, particularly those used in chemical barrels, may be made of metal and are screwed into place via threading.

Rubber bungs

In chemistry

Chemistry

Chemistry is the science of matter, especially its chemical reactions, but also its composition, structure and properties. Chemistry is concerned with atoms and their interactions with other atoms, and particularly with the properties of chemical bonds....

, bungs are usually made of hardened rubber. Some chemistry bungs may also include one or more holes so a glass tube

Glass tube

Glass tubes or glass tubing are hollow pieces of borosilicate or flint glass used primarily as laboratory glassware. Glass tubing is commercially available in various thicknesses and lengths. Glass tubing is frequently attached to rubber stoppers....

 or laboratory funnel may be inserted through the bung and into the container or another piece of apparatus. The rubber bung may be used to seal a flask because the user may require the contents to be mixed via shaking the flask or may require that the contents be kept inside the flask and prevented from leaking out. In all cases, the bung keeps the experimentation environment completely sealed so that liquids or gases cannot escape.

Apart from self-made glassware, rubber bungs are rarely used now. They have been supplanted by laboratory glassware

Laboratory glassware

Laboratory glassware refers to a variety of equipment, traditionally made of glass, used for scientific experiments and other work in science, especially in chemistry and biology laboratories...

 which come with standard ground glass joint

Ground glass joint

Ground glass joints are used in laboratories to quickly and easily fit leak-tight apparatus together from commonly available parts. For example, a round bottom flask, Liebig condenser, and oil bubbler with ground glass joints may be rapidly fitted together to reflux a reaction mixture...

s which allow the pieces to be fitted together easily. Ground glass joints are also much more resistant to solvents and chemicals used.

Uses

Ground glass stoppers

Ground glass joint

Ground glass joints are used in laboratories to quickly and easily fit leak-tight apparatus together from commonly available parts. For example, a round bottom flask, Liebig condenser, and oil bubbler with ground glass joints may be rapidly fitted together to reflux a reaction mixture...

 and rubber stoppers are commonly used with laboratory glassware, mainly because of their nonreactivity. Some stoppers used in labs have holes in them to allow the insertion of glass or rubber tubing. This is often used when a reaction is taking place in the flask or test tube and the byproduct or result of the reaction is desired to be collected. For instance, if one were to boil water in a test tube and wanted to collect the water vapor, one could seal the test tube with a stopper with holes in it. With tubing inserted into the hole(s), when the tube is heated, water vapor will rise through the hole, make its way through the tubing, and into the collection chamber of choice. The water vapor would not be able to escape into the air, because the stopper and the tubing, if set up correctly, would be airtight.

A phoedelia

Phoedelia

Phoedelia is the ecclesiastical name for one of the stoppers which accompany the cruets used in the liturgical rites of the Anglican and Roman Catholic churches particularly. They are often made of glass and shaped in the form of a cross. They are usually produced in a pair for both the water and...

 is a particular type of stopper, usually made of glass and decorated with a cross, used with ecclesiastical cruets

Cruet

A cruet , also called a caster, is a small flat-bottomed vessel with a narrow neck. Cruets often have an integral lip or spout, and may also have a handle. Unlike a small carafe, a cruet has a stopper, lid, or phoedelia...

.

Plastic bungs are commonly used to stop the air leaking from the lower parts of an air-bed. This type of bung is commonly made in two parts; the plastic outer screw on cap and the inner rubber bung used to seal the hole.