1.Size & Connection:
* Nominal Diameter (DN): Standard size representing the valve's passage diameter (e.g., DN15, DN50, DN200), matching pipeline dimensions for seamless installation.
* Nominal Pipe Size (NPS): Imperial size equivalent to DN (e.g., 1/2", 2", 8"), commonly used in North American markets.
* Connection Type: The way the valve attaches to pipelines, including flanged (ASME B16.5), threaded (NPT/BSP), wafer (for compact spaces), and welded (socket weld/butt weld).
2. Pressure Rating:
* Nominal Pressure (PN): Maximum pressure the valve can withstand at rated temperature (e.g., PN10, PN16, PN40), in bar or MPa.
* Class Rating: Imperial pressure standard (e.g., ANSI Class 150, Class 300, Class 600), corresponding to specific pressure values at different temperatures (e.g., Class 150 ≈ PN20 at 100℃).
* Maximum Working Pressure (MWP): Actual safe pressure limit under the valve's intended operating temperature, not exceeding PN/Class rating.
3. Temperature Range:
* Operating Temperature Range: The minimum and maximum temperature the valve can tolerate (e.g., -40℃~120℃ for EPDM seals, -20℃~538℃ for metal hard seals), determined by material (body, seals) and application media (steam, cryogenic fluids).
4. Material:
* Body Material: Determines corrosion resistance and strength, such as stainless steel (SS304/SS316 for corrosive media), carbon steel (WCB for high pressure), ductile iron (for low-cost industrial use), and PTFE-lined plastic (for acid/alkali fluids).
* Seal Material: Affects sealing performance and temperature resistance, including EPDM (low-temperature water/gas), PTFE (corrosive chemicals), and metal (stainless steel, Stellite alloy for high temperature/pressure).
* Trim Material: Components like valve disc, seat, and spindle, often using stainless steel or hardened alloys to resist wear.
5. Flow & Performance:
* Flow Coefficient (Cv/Kv): Measures the valve's ability to pass media—higher Cv/Kv means lower flow resistance (critical for large-flow pipelines like water supply systems).
* Closing Speed: Time taken to seal against reverse flow, with fast-closing types (e.g., dual-plate, spring-loaded) reducing water hammer (pressure surges) in pipelines.