A gas generator is a device for generating gas. A gas generator may create gas by a chemical reaction or from a solid or liquid source, when storing a pressurized gas is undesirable or impractical.
The term often refers to a device that uses a rocket propellant to generate large quantities of gas. The gas is typically used to drive a turbine rather than to provide thrust as in a rocket engine. Gas generators of this type are used to power turbopumps in rocket engines, in a gas-generator cycle.
Another common use of the term is in the industrial gases industry, where gas generators are used to produce gaseous chemicals for sale. For example, the chemical oxygen generator, which delivers breathable oxygen at a controlled rate over a prolonged period.
Other types include the gas generator in an automobile airbag, which is designed to rapidly produce a specific quantity of inert gas.
Hydrazine decomposes to mixtures of nitrogen, hydrogen and ammonia. The reaction is strongly exothermic and produces high volume of hot gas from small volume of liquid.
Many automobile airbags use sodium azide for inflation (as of 2003[update]).[10] A small pyrotechnic charge triggers its decomposition, producing nitrogen gas, which inflates the airbag in around 30 milliseconds. A typical airbag in the US might contain 130 milligrams of sodium azide.[11]
Similar gas generators are used for fire suppression.[12]
Sodium azide decomposes exothermically to sodium and nitrogen.
The resulting sodium is hazardous, so other materials are added, e.g. potassium nitrate and silica, to convert it to a silicate glass.
↑"Main Propulsion System (MPS)"(PDF). Shuttle Press Kit.com. Boeing, NASA & United Space Alliance. October 6, 1998. Archived from the original(PDF) on 2012-02-04. Retrieved December 7, 2011.
↑Betterton, Eric A. (2003). "Environmental Fate of Sodium Azide Derived from Automobile Airbags (Abstract)". Critical Reviews in Environmental Science and Technology. 33 (4): 423–458. doi:10.1080/10643380390245002. S2CID96404307.
![{\displaystyle {2\,\mathrm {H} {\vphantom {A}}_{\smash[{t}]{2}}\mathrm {O} {\vphantom {A}}_{\smash[{t}]{2}}{}\mathrel {\longrightarrow } {}2\,\mathrm {H} {\vphantom {A}}_{\smash[{t}]{2}}\mathrm {O} {}+{}\mathrm {O} {\vphantom {A}}_{\smash[{t}]{2}}}}](https://wikimedia.org/api/rest_v1/media/math/render/svg/a6b31753a4221cf700e7a0f6f056ce5f00fe66ff)
![{\displaystyle {3\,\mathrm {N} {\vphantom {A}}_{\smash[{t}]{2}}\mathrm {H} {\vphantom {A}}_{\smash[{t}]{4}}{}\mathrel {\longrightarrow } {}4\,\mathrm {NH} {\vphantom {A}}_{\smash[{t}]{3}}{}+{}\mathrm {N} {\vphantom {A}}_{\smash[{t}]{2}}}}](https://wikimedia.org/api/rest_v1/media/math/render/svg/c80377ad56d840b857567d385e862badde81ec64)
![{\displaystyle {\mathrm {N} {\vphantom {A}}_{\smash[{t}]{2}}\mathrm {H} {\vphantom {A}}_{\smash[{t}]{4}}{}\mathrel {\longrightarrow } {}\mathrm {N} {\vphantom {A}}_{\smash[{t}]{2}}{}+{}2\,\mathrm {H} {\vphantom {A}}_{\smash[{t}]{2}}}}](https://wikimedia.org/api/rest_v1/media/math/render/svg/ef73bc3476f0676dd82e22a710db61987fa85891)
![{\displaystyle {4\,\mathrm {NH} {\vphantom {A}}_{\smash[{t}]{3}}{}+{}\mathrm {N} {\vphantom {A}}_{\smash[{t}]{2}}\mathrm {H} {\vphantom {A}}_{\smash[{t}]{4}}{}\mathrel {\longrightarrow } {}3\,\mathrm {N} {\vphantom {A}}_{\smash[{t}]{2}}{}+{}8\,\mathrm {H} {\vphantom {A}}_{\smash[{t}]{2}}}}](https://wikimedia.org/api/rest_v1/media/math/render/svg/d558c5be146b7352a005627ddaa04a16c5f3553d)
![{\displaystyle {2\,\mathrm {NaN} {\vphantom {A}}_{\smash[{t}]{3}}{}\mathrel {\longrightarrow } {}2\,\mathrm {Na} {}+{}3\,\mathrm {N} {\vphantom {A}}_{\smash[{t}]{2}}}}](https://wikimedia.org/api/rest_v1/media/math/render/svg/704853713fbeb9f28d5fc0c764fcc75b899cc4e6)