Ejection charge, also called expelling charge, is a pyrotechnic composition

Pyrotechnic composition

A pyrotechnic composition is a substance or mixture of substances designed to produce an effect by heat, light, sound, gas or smoke or a combination of these, as a result of non-detonative self-sustaining exothermic chemical reactions...

, a type of a pyrotechnic gas generator

Gas generator

A gas generator usually refers to a device, often similar to a solid rocket or a liquid rocket that burns to produce large volumes of relatively cool gas, instead of maximizing the temperature and specific impulse. The low temperature allows the gas to be put to use more easily in many...

 designed to produce a small short-term amount of thrust to burst open a container and eject its content.

In model rocketry, ejection charges are used to deploy a recovery system (usually parachute

Parachute

A parachute is a device used to slow the motion of an object through an atmosphere by creating drag, or in the case of ram-air parachutes, aerodynamic lift. Parachutes are usually made out of light, strong cloth, originally silk, now most commonly nylon...

 or streamer). The ejection charge is ignited through a layer of delay composition

Delay composition

Delay composition, also called delay charge or delay train, is a pyrotechnic composition, a sort of pyrotechnic initiator, a mixture of oxidizer and fuel that burns in a slow, constant rate that should not be significantly dependent on temperature and pressure. Delay compositions are used to...

, to fire shortly after the main engine burns out. Ejection charges can be also triggered by a timer or an altimeter

Altimeter

An altimeter is an instrument used to measure the altitude of an object above a fixed level. The measurement of altitude is called altimetry, which is related to the term bathymetry, the measurement of depth underwater.-Pressure altimeter:...

. A small amount of black powder is usually used, but smokeless powder

Smokeless powder

Smokeless powder is the name given to a number of propellants used in firearms and artillery which produce negligible smoke when fired, unlike the older gunpowder which they replaced...

 and other compositions are possible.

Ejection charges are also used in some flares

Flare (pyrotechnic)

A flare, also sometimes called a fusee, is a type of pyrotechnic that produces a brilliant light or intense heat without an explosion. Flares are used for signalling, illumination, or defensive countermeasures in civilian and military applications...

 to eject the light or smoke producing components out of the flare casing. In countermeasure flares

Flare (countermeasure)

A flare is an aerial infrared countermeasure to counter an infrared homing surface-to-air missile or air-to-air missile. Flares are commonly composed of a pyrotechnic composition based on magnesium or another hot-burning metal, with burning temperature equal to or hotter than engine exhaust...

, ejection charges are used to propel the flares out of their casing, or to eject pyrophoric fluids from their containers.

In cluster bomb

Cluster bomb

A cluster munition is a form of air-dropped or ground-launched explosive weapon that releases or ejects smaller sub-munitions. Commonly, this is a cluster bomb that ejects explosive bomblets that are designed to kill enemy personnel and destroy vehicles...

s, ejection charges are used to disperse the submunitions.

Burst charges are also used to dispense leaflets from leaflet bombs.

In chemical weapons, ejection charges are used to disperse the chemical agent from the bomb, submunition, grenade, or warhead.