Valve definition
A device used to either open or close an opening to allow or prevent the flow of a liquid or gas from one place to another. There are many different types. Also see air-valve carburetor , anti-backfire valve , anti-percolation valve , blowoff valve , brake proportioning valve , butterfly valve , bypass valve , cam follower , check valve , compensator valve , economizer valve , exhaust valve , expansion valve , fuel injector nozzle , heat control valve , hydraulic valve lifter , intake valve , lightened valves , manifold heat control valve , overhead valves , PCV valve , petcock , poppet valve , power valve , pressure relief valve , Presta valve , RAVE valve , reed valve , relief valve , safety valve , Schrader valve , sodium-cooled valve , spool balance valve , spool valve , suction throttling valve , throttle valve , tire valve , valve clearance , valve cover , valve duration , valve face , valve float , valve grinding , valve guide , valve-in-head engine , valve keeper , valve key , valve lash , valve lift , valve lifter , valve margin , valve oil seal , valve overlap , valve port , valve rotator , valve seat , valve seat grinding , valve seat insert , valve spring , valve stem , valve tappet , valve timing , valvetrain , valve umbrella , variable valve actuation , and variable valve actuation .