Editing Injector (section)

{{short description|Type of pump using high pressure fluid to entrain a lower pressure fluid}}
{{About||the system that adds fuel to an internal combustion engine|fuel injection|other uses|Injector (disambiguation)}}
[[Image:Boiler Feed Injector Diagram.svg|thumb|right|350px|Injector used in steam locomotives]]
[[Image:Injector Giffard-02.jpg|thumb|right|400px|A- Steam from boiler, B- Needle valve, C- Needle valve handle, D- Steam and water combine, E- Water feed, F- Combining cone, G- Delivery nozzle and cone, H- delivery chamber and pipe, K- Check valve, L- Overflow]]

An '''injector''' is a system of ducting and nozzles used to direct the flow of a high-pressure fluid in such a way that a lower pressure fluid is [[Entrainment (hydrodynamics)|entrained]] in the jet and carried through a duct to a region of higher pressure. It is a fluid-dynamic pump with no moving parts except a valve to control inlet flow.

Depending on the application, an injector can also take the form of an ''eductor-jet pump'', a ''[[water eductor]]'' or an ''aspirator''. An ''[[Vacuum ejector|ejector]]'' operates on similar principles to create a vacuum feed connection for braking systems etc.

The motive fluid may be a liquid, steam or any other gas. The entrained suction fluid may be a gas, a liquid, a slurry, or a dust-laden gas stream.<ref>{{cite book|editor1=Perry, R. H. |editor2=Green, D. W.|title=Perry's Chemical Engineers' Handbook|edition=8th|publisher=McGraw Hill|year=2007|isbn=978-0-07-142294-9|title-link=Perry's Chemical Engineers' Handbook}}</ref><ref>{{cite book|author=Power, Robert B.|title=Steam Jet Ejectors For The Process Industries|edition=First|publisher=McGraw-Hill|year=1993|isbn=978-0-07-050618-3}}</ref><ref>{{cite journal |title=Analysis of the adiabatic process by using the thermodynamic property diagram of water vapor |date=2021 |doi=10.1051/e3sconf/202125203055 |last1=Yarong |first1=Wang |last2=Peirong |first2=Wang |journal=E3S Web of Conferences |volume=252 |page=03055 |bibcode=2021E3SWC.25203055Y |s2cid=238022926 |doi-access=free }}</ref>