360 likes | 657 Vues
NPEG. Valves and Appurtenances. Types of Valves. Air Valves Control Valves Pressure Relief Valves Pressure Reducing Valves. Air Valves. Air valves are needed to control air in and out of pipe lines. Types of Air Valves. Air release valve Vacuum relief valve Air and vacuum valve
E N D
NPEG Valves and Appurtenances
Types of Valves • Air Valves • Control Valves • Pressure Relief Valves • Pressure Reducing Valves
Air Valves • Air valves are needed to control air in and out of pipe lines.
Types of Air Valves • Air release valve • Vacuum relief valve • Air and vacuum valve • Combination air and vacuum relief valve
Air Release Valve • A small orifice, continuous acting valve for air release only. • Used at closed summits to prevent formation of air pockets.
Vacuum Relief Valve • A large orifice valve for vacuum relief only.
Air and Vacuum Valves • Valves with large orifices which allow air to exhaust from the pipeline during filling (not during operation) and allow air to enter the pipeline during emptying. • Generally used at either upper or lower ends of pipeline.
Slide Gate • Used to let water into gravity pipeline, usually from irrigation canal. • Control mechanism is disk or plate sliding over pipe opening.
Check Valves Swing check • In-line back flow prevention valve. • Generally used to prevent surge at pumps and to maintain water column in pipelines. Double swing check Rubber flapper check
Check Valves (cont.) Slanting disk check Automatic control check Silent check (center guided)
Butterfly Valve • In-line distribution valve • Control mechanism is a rotating disk inside of valve housing.
Ball Valve • In-line distribution valve • Control mechanism is a rotating hollow ball inside of valve housing.
Gate Valve • In-line distribution valve • Control mechanism is a sliding plate inside of valve housing.
Globe Valve • In-line distribution valve • Control mechanism is plunger inside of valve housing.
Alfalfa Valve • Outlet distribution valve • Control mechanism is a threaded plate or cap on outside of valve body. • Requires hydrant to open and close.
Pressure Relief Valves • A valve used to relieve excess pressure that develops in the pipeline.
Flow Meter • In-line device used to measure flow. • In NRCS we generally require meters that give both instantaneous flow rates and cumulative volumes.
Air Vent Assembly • Used at at high points to provide combination air and vacuum relief • Outlet of vent must be located above the hydraulic grade line for all flows.
Riser Assembly • Pipe attached to underground pipeline to deliver water to surface outlets or system valves. • A chamber may be required at base for certain installations.
Drain Assembly • Valve and pipe assembly used to empty a pipeline. • Generally either gravity or pump out configurations are used.
Thrust Control • Anchors or thrust blocks used to resist axial thrust in the pipeline at abrupt changes in pipe grade, at changes in pipe alignment, at reductions in pipe diameter, at points of divergence, and at ends of line.
NPRC Project (cont.) 10” Pressure Reducing Valve