Anhui Rongda Valve Co., Ltd. specializes in valve manufacturing.
A valve is a device used in fluid systems to control the direction, pressure and flow rate of fluids. It enables or stops the flow of media (liquids, gases, powders) inside pipelines and equipment and regulates flow capacity.
As a control component in piping fluid‑transport systems, a valve changes flow passage cross‑section and medium flow direction. It performs functions such as flow diversion, shut‑off, throttling, non‑return, flow splitting and overflow pressure relief.
Valves for fluid control cover a wide variety of types and specifications, ranging from simple globe valves to various valves used in highly complex automatic control systems. Their nominal diameters vary from miniature instrument valves up to industrial pipeline valves with a nominal diameter of 10 m.
Valves can control the flow of water, steam, oil products, gases, slurry, various corrosive media, liquid metals, radioactive fluids and other fluids. Their operating pressure ranges from 0.0013 MPa up to ultra‑high pressure of 1000 MPa, and operating temperature ranges from ultra‑low temperature of ‑270 °C up to high temperature of 1430 °C.
Multiple actuation modes are available for valves: manual, electric, hydraulic, pneumatic, worm‑gear, solenoid, solenoid‑hydraulic, electro‑hydraulic, pneumo‑hydraulic, spur‑gear, bevel‑gear drive and so forth. Valves can act according to preset requirements under pressure, temperature or other sensor signals, or simply open and close without sensor signals. Driven by actuators or automatic mechanisms, the closure member performs lifting, sliding, swinging or rotary motion, changing the flow‑passage area to realize control functions.
Classification by Function and Application
(1) Shut‑off Valves
Examples include gate valves, globe valves, plug valves, ball valves, butterfly valves, needle valves, diaphragm valves, etc. Also known as stop valves, they connect or cut off media in pipelines.
Check valves, also called one‑way valves or non‑return valves, are automatic valves. They prevent medium backflow in pipelines, avoid reverse rotation of pumps and driving motors, and stop medium leakage from vessels. Foot valves at pump suction ends also belong to check valves.
Safety valves such as explosion‑proof valves and emergency valves prevent medium pressure in pipelines or equipment from exceeding specified values for safety protection purposes.
Control valves, throttle valves and pressure reducing valves adjust parameters such as medium pressure and flow rate.
(2) Vacuum Valves
Examples: vacuum ball valves, vacuum baffle valves, vacuum gas‑charging valves, pneumatic vacuum valves, etc. As components of vacuum systems, they change gas‑flow direction, adjust gas flow rate, and cut off or connect vacuum pipelines.
(3) Special‑purpose Valves
Examples: pigging valves, vent valves, blow‑down valves, air vent valves, strainers, etc.
Air vent valves are indispensable auxiliary components in piping systems, widely used in boilers, air‑conditioning systems, oil & gas, water supply and drainage pipelines. Usually installed at high‑points or elbows, they remove excess gas inside pipelines, improve pipeline efficiency and reduce energy consumption.
Classification by Main Parameters
By Nominal Pressure
(1) Vacuum valve: valve whose operating pressure is lower than standard atmospheric pressure.
(2) Low‑pressure valve: nominal pressure PN ≤ 1.6 MPa.
(3) Medium‑pressure valve: nominal pressure PN 2.5 MPa, 4.0 MPa, 6.4 MPa.
(4) High‑pressure valve: nominal pressure PN 10.0 MPa ~ 80.0 MPa.
(5) Ultra‑high‑pressure valve: nominal pressure PN ≥ 100.0 MPa.
(6) Strainer: nominal pressure PN 1.0 MPa, 1.6 MPa.
By Operating Temperature
(1) Cryogenic valve: for medium operating temperature t < ‑101 °C.
(2) Normal‑temperature valve: for medium operating temperature ‑29 °C < t < 120 °C.
(3) Medium‑temperature valve: for medium operating temperature 120 °C < t < 425 °C.
(4) High‑temperature valve: for medium operating temperature t > 425 °C.