Valves yog ib qho tseem ceeb ntawm kev lag luam pipeline accessories hauv lub teb chaws kev lag luam. Lawv yog dav siv nyob rau hauv pipelines ntawm ntau yam kua engineering systems. Nws tuaj yeem hais tias xav tau li qub nyob qhov twg muaj cov kav dej muaj kev lag luam. Hais txog lub ntsiab lus ntawm "valve", muaj cov lus piav qhia sib txawv hauv cov phau ntawv sib txawv. GB/T21465-2008 "Valve Terminology" hais tias "valve yog hais txog lub npe dav dav ntawm cov khoom siv tshuab uas siv los tswj cov nruab nrab hauv cov kav dej thiab muaj cov txheej txheem txav tau."
Qhov "tswj" kev ua haujlwm ntawm lub valve hauv cov ntsiab lus saum toj no feem ntau yog hais txog kev ua haujlwm ntawm lub valve ntsia ntawm lub raj xa dej kom txiav tawm, coj kev khiav, tiv thaiv kev thim rov qab, kho kev hloov pauv lossis dhau lub siab nyem, thiab lwm yam "nruab nrab" hauv qhov txhais tau hais txog ntau yam kua, gases, granular solids thiab lawv ua ke.
Nyob rau tib lub sijhawm, feem ntau cov khoom siv valve siv nyob rau hauv cov kav raj xa dej poob nyob rau hauv cov peev txheej ntawm cov raj xa dej siab hauv lub teb chaws "Cov Khoom Siv Tshwj Xeeb", thiab lawv cov txheej txheem tsim khoom yuav tsum ua raws li "Kev Tswj Xyuas Khoom Tshwj Xeeb Kev Nyab Xeeb" thiab TSG.
Cov kev cai tsim nyog nyob rau hauv D2001 "Kev Tsim Cov Cai Lij Choj rau Cov Khoom Siv Hluav Taws Xob".
