PVC Butterfly Valve
This wafer-type plastic butterfly valve isolates or throttles flow in corrosive chemical lines and water treatment infrastructure. Built with an injection-molded UPVC or CPVC body and disc, it replaces metallic valves in low-to-medium pressure applications where acid scaling, rust, or galvanic corrosion causes rapid failure.
Description
Product Overview
This wafer-type plastic butterfly valve isolates or throttles flow in corrosive chemical lines and water treatment infrastructure. Built with an injection-molded UPVC or CPVC body and disc, it replaces metallic valves in low-to-medium pressure applications where acid scaling, rust, or galvanic corrosion causes rapid failure. The full-face EPDM or FKM liner seals the fluid path directly against pipe flanges, eliminating the need for separate flange gaskets.
Key Product Characteristics
Zero-Metal Wetted Surface: The medium contacts only the plastic disc and elastomeric liner, preventing metal leaching and ion contamination in high-purity processes.
Bi-Directional Bubble-Tight Shutoff: Symmetrical disc geometry delivers ANSI Class VI shutoff in both flow directions up to rated working pressure.
Low Operating Torque: Spherical disc edge profiles reduce friction against the liner, enabling manual operation via lever or gear and compatibility with smaller pneumatic or electric actuators.
ISO 5211 Direct-Mount Pad: Top flange accepts standard quarter-turn electric or pneumatic actuators without custom mounting brackets or drive extensions.
Integrated Lockable Lever: Multi-position notched plate allows precise flow throttling and padlocking at specific openings.
Key Specifications
|
Parameter |
Specification Details |
|
Nominal Diameters |
DN50 to DN300 (2 inch to 12 inch) |
|
Pressure Rating (at 20°C / 68°F) |
DN50 to DN150: PN10 (150 PSI) DN200 to DN300: PN6 to PN10 (90 to 150 PSI) |
|
Flange Compatibility |
ANSI B16.5 Class 150, EN 1092-1 PN10, JIS 10K |
|
Face-to-Face Standard |
ISO 5752 short / EN 558 series 20 |
|
Top Flange Mounting |
ISO 5211 (F05 / F07 / F10 depending on size) |
|
Leakage Class |
ISO 5208 Rate A / ANSI B16.104 Class VI (zero visible leakage) |
|
Actuation Options |
Hand lever (DN50 to DN150), Worm gear operator, Pneumatic rack & pinion, Electric |
Materials & Media Compatibility
Body & Disc Materials
UPVC (Unplasticized PVC): Operating range 0°C to 60°C (32°F to 140°F). Resistant to dilute acids, alkalis, salts, and aliphatic hydrocarbons.
CPVC (Chlorinated PVC): Operating range 0°C to 95°C (32°F to 203°F). High resistance to hot corrosive fluids, sodium hypochlorite, and concentrated acids.
Liner & Seal Options
EPDM: Operating range -20°C to 90°C. Ideal for municipal water, seawater, dilute acids, and alkaline solutions. Not suitable for petroleum products or compressed air.
FKM (Viton): Operating range -10°C to 120°C. Exceptional chemical resistance to strong acids, chlorine, aromatic hydrocarbons, and oils.
Stem Material: 410 / 304 / 316 Stainless Steel (fully encapsulated and isolated from process fluid by dual O-ring stem seals).
Connection & Configuration Options
Wafer Style Body
Fits between ANSI 150# or DIN PN10 companion flanges using standard length stud bolts.
Manual Operators
Lever handle with 10-degree position indicator; heavy-duty cast aluminum worm gear drive for DN200 and larger sizes.
Actuator Readiness
Square drive stem end according to DIN 3337 allows direct coupling with quarter-turn actuators.
Application-Specific Design Considerations
Disc Clearance: Plastic disc profile extends beyond the face-to-face dimension when fully open. Ensure pipe ID matches schedule 80 or standard SDR dimensions to prevent disc blade contact with pipe inner walls or adjacent check valves.
Thermal Derating: Maximum allowable operating pressure decreases as media temperature rises. At 60°C, UPVC pressure capacity drops to 30% of its 20°C rating; CPVC retains 40% capacity at 80°C.
Vacuum Limits: Elastomeric full-body liner design prevents liner collapse under suction down to 0.8 bar absolute at ambient temperature.
Applications
Industrial Wastewater Treatment: Neutralization tanks, sludge lines, and chemical dosing stations.
Chlor-Alkali & Chemical Processing: Hydrochloric acid transfer, sodium hydroxide loops, and brine circulation.
Desalination & Marine Systems: Seawater intake, reverse osmosis (RO) membrane rack isolation, and brine discharge.
Commercial Aquaculture & Aquariums: High-volume water circulation where zero metallic ion contamination is required.
Agricultural Irrigation: Liquid fertilizer distribution lines and main filtration manifolds.
Quality & Inspection
Every valve undergoes factory testing before shipment:
Hydrostatic Shell Test
Tested at 1.5x PN rating for body integrity.
Seat Leakage Test
Pneumatic pressure tested at 1.1x PN rating according to ISO 5208 Rate A standards.
Dimensional Verification
Flange bolt circle alignment, face-to-face tolerance, and top flange concentricity checks.
Torque Validation
Operating torque measured before and after cycle testing to ensure actuator sizing consistency.
OEM / ODM & Customization
Custom Tagging & Branding: Laser-etched stainless steel nameplates, custom valve body color molding, and private-label packaging.
Stem Modifications: Extended stems for buried service or insulated lines; custom keyway or double-D stem machining.
Material Customization: Special liner formulations (NBR, PTFE-lined disc options) for specific chemical mixtures.
Actuation Pre-Assembly: Factory mounting, limit switch calibration, and pneumatic solenoid wiring under single-source testing.
FAQ
Q: How do I select between UPVC and CPVC materials for my pipeline?
A: Choose UPVC for ambient water treatment, irrigation, and mild chemical services up to 60°C. Select CPVC when operating temperatures exceed 60°C (up to 95°C) or when handling aggressive oxidizing chemicals such as concentrated nitric acid, sulfuric acid, or hot sodium hypochlorite.
Q: Are separate flange gaskets required when installing this valve?
A: No. The elastomeric body liner extends over the front sealing faces on both sides of the valve body. This full-face liner acts as a built-in gasket when clamped between pipe flanges. Adding extra gaskets causes improper bolt torque distribution and potential seat leaks.
Q: Can this plastic butterfly valve be installed in schedule 80 PVC piping systems?
A: Yes, but verify the internal clearance of thick-wall pipe and fittings (such as stub ends or flange adapters). Ensure the internal diameter allows complete 90-degree disc rotation without the disc outer edge contacting the pipe wall.
Q: What causes high operating torque or binding during manual turning?
A: Torque spikes typically stem from over-torqued flange bolts, which compress the body liner excessively into the disc path. Follow specified cross-pattern bolt torque limits during installation. Media swelling of the liner elastomer due to chemical incompatibility can also increase resistance.
Q: Can I mount an actuator on this valve after initial manual installation?
A: Yes. The valve features an ISO 5211 mounting pad. Remove the top lever or gear operator to expose the standardized drive stem and bolt pattern, allowing direct mounting of compatible pneumatic or electric actuators.
Q: What is the recommended bolt tightening procedure for plastic wafer butterfly valves?
A: Use flat washers on all flange bolt heads and nuts. Hand-tighten all studs first, then use a torque wrench to tighten bolts in a star/crossover pattern in 30% increments until reaching the recommended torque value (typically 25 to 40 Nm depending on valve size). Over-tightening deforms the plastic flanges and damages the internal liner.
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