Butterfly Valve FAQ: Installation, Selection and Maintenance Guide
Welcome to the Laux Valve FAQ page. We have compiled the most common questions we receive from customers worldwide about butterfly valves - from product selection and installation to maintenance and custom orders. If you have a question not listed here, please contact our team and we will respond within 12 hours.
Product Selection and Types
Q：What is the difference between a wafer and lug butterfly valve?
A :The main difference is that wafer butterfly valves are designed to be clamped between two pipe flanges and rely on flange bolts for alignment, while lug butterfly valves have threaded inserts (lugs) on the valve body that allow them to be bolted directly to the flanges. Lug valves can also serve dead-end applications, meaning one side of the pipeline can be removed without the valve falling out.
Q:Can a lug butterfly valve be used for dead-end service?
A:Yes, one of the key advantages of lug butterfly valves is their ability to provide dead-end service. The threaded lugs allow the valve to be bolted directly to a flange on one side, so downstream piping can be removed for maintenance without shutting down the entire system. This makes lug valves ideal for terminal isolation applications.
Q:What is a PTFE lined butterfly valve used for?
A:PTFE lined butterfly valves are designed for highly corrosive media applications. The PTFE lining provides excellent chemical resistance, making these valves ideal for the chemical processing, pharmaceutical, petrochemical, and food processing industries.
How do I select the right butterfly valve for my application?
Consider: (1) Media type. (2) Pressure and temperature. (3) Pipe size and connection. (4) Material compatibility. (5) Actuation method. (6) Industry standard (ISO, API, AWWA, EN). Contact our engineers for help.
Q:What pressure ratings are available?
A:Common ratings: PN6, PN10, PN16, PN25 (DIN) and Class 125, 150, 250 (ANSI). Higher pressures need eccentric designs.
What materials are butterfly valve discs made from?
Ductile Iron (ASTM A536), Stainless Steel (CF8M/SS316, CF8/SS304), Cast Steel (WCB), Nickel-Aluminum Bronze, and specialty alloys. Discs can be coated with Nylon, Halar, PTFE, or PFA.
Materials and Technical Specifications
Q:What materials are butterfly valve discs made from?
A:Ductile Iron (ASTM A536), Stainless Steel (CF8M/SS316, CF8/SS304), Cast Steel (WCB), Nickel-Aluminum Bronze,Duplex stainless steeland specialty alloys. Discs can be coated with Nylon, Halar, PTFE, or PFA.
What is the difference between concentric and eccentric butterfly valves?
Concentric (zero offset) = most common and economical. Double offset = reduced seat wear for higher pressure/temp. Triple offset = metal-to-metal bubble-tight seal for critical high-pressure applications.
Q:What seat materials are available?
A:EPDM (water up to 120℃), NBR/Nitrile (oil/fuel), PTFE (chemicals), PFA, Viton/FKM (high temp), Silicone (food/pharma), metal seats (high temp/pressure).
Q:How do I install a wafer butterfly valve correctly?
A:(1) Valve fully open before insertion. (2) Center between flanges. (3) Insert bolts through both flanges and valve body. (4) Partially open/close to check disc clearance. (5) Tighten evenly in crisscross pattern. (6) Never close valve to align flange holes.
Q:What is the AWWA C504 standard?
AWWA C504 is the standard for rubber-seated butterfly valves in water supply systems. Covers valves 3" to 72" with pressure classes 150B, 250B, 300B.
Q：Can butterfly valves be used for throttling?
A:Yes but with limits. Concentric valves have limited throttling performance. Use eccentric valves with positioner for better control. Extended partial throttling reduces seat life.
What actuators can be used?
Manual levers (up to 4"), gearboxes (larger valves), pneumatic (on/off or modulating), electric (remote/automation), hydraulic (high-torque). ISO 5211 mounting standard.
Installation and Maintenance
Q：What actuators can be used?
A：Manual levers (up to 14"), gearboxes (larger valves), pneumatic (on/off or modulating), electric (remote/automation), hydraulic (high-torque). ISO 5211 mounting standard.
Q：What causes butterfly valve leakage?
A：Seat wear, misalignment, improper torque, exceeding pressure/temp rating, corrosion, debris. Quarterly inspection helps prevent issues.
Q:How do I maintain a butterfly valve?
A：Inspect quarterly. Full open/close cycle twice yearly. Lubricate stem/gearbox. Check flange bolts. Inspect actuator seals. Replace seat/seals every 3-5 years.
Actuation and Automation
Q：How do I maintain a butterfly valve?
A：Inspect quarterly. Full open/close cycle twice yearly. Lubricate stem/gearbox. Check flange bolts. Inspect actuator seals. Replace seat/seals every 3-5 years.
What is reduced bore vs full bore?
Full bore = disc matches pipe ID for unobstructed flow. Reduced bore = smaller disc for lighter/economical option with slight flow restriction.
Ordering, Customization and Shipping
Q：Does Laux Valve offer custom OEM manufacturing?
A：Yes! Custom materials, seat compounds, flange drilling, coatings, actuation packages, private labeling, branded packaging. ISO 9001 certified.
Q：What is the minimum order quantity?
A :1 pc is the minimum order .Samples and trial orders welcome.
Q:What certifications does Laux Valve hold?
A:ISO 9001:2015, CE, WRAS (UK), NSF 61 (drinking water), API 598. Every valve tested.
Q:What is the typical lead time?
A:Standard: 15-25 days. Custom/OEM: 30-45 days. Expedited available.
Q:What temperature ranges can butterfly valves handle?
A:EPDM: -40C to 120C. NBR: -20C to 100C. PTFE/PFA: -60C to 200C. Viton: -20C to 200C. Metal: up to 450C (842F).
Q:Can butterfly valves be used for high-pressure?
A:Standard rubber-seated: up to Class 300/PN25. For Class 600+, triple offset metal-seated valves recommended.
Q:Does Laux Valve ship internationally?
A:Yes, worldwide from Tianjin, China. FOB, CIF, CFR, DDP, EXW. DHL/FedEx/UPS/TNT for small orders.
Still Have Questions?
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