The core function of a valve is to control the flow state of fluids (liquids, gases, slurries, etc.). Depending on their function and structure, they can be classified into various categories, with common types including:
Stop valve: Used for cutting off or regulating the flow of media, with good tightness when closed.
Gate valve: Suitable for large-diameter pipes, with minimal medium resistance when fully open, often used to cut off fluids.
Ball valve: Quick to open and close (rotation of 90° completes the operation), with low flow resistance, suitable for high-viscosity or particle-containing media.
Butterfly valve: Simple structure, light weight, suitable for flow regulation in large-diameter pipes.
Check valve: Prevents media from flowing backwards, commonly used at the outlet of pumps to avoid water hammer damage to equipment.
Regulating valve: Precisely controls parameters such as pressure, flow, and temperature of the medium.
Safety valve: Automatically opens to release pressure when system pressure exceeds a set value, protecting equipment and pipelines.
Nominal diameter (DN): Indicates the size of the connection between the valve and the pipeline, with common sizes ranging from DN10 (4 inches), DN15 (6 inches), DN20, DN25, to DN100, DN200, DN500, and even larger (such as DN2000), measured in millimeters, corresponding to the nominal diameter of the pipe.
Valve body / Valve cover:
Cast iron: Low cost, suitable for low-pressure, room temperature, non-corrosive media (such as tap water).
Carbon steel (e.g., WCB): Suitable for medium to high-pressure, non-corrosive media (such as oil, steam).
Stainless steel (304, 316, etc.): Strong corrosion resistance, suitable for corrosive media such as acids and alkalis, seawater, etc., with 316 having better corrosion resistance than 304 (contains molybdenum).
Alloy steel: Such as chrome-molybdenum steel, suitable for high-temperature and high-pressure conditions (e.g., power plant steam pipes).
