Specification

10 Inch Dn250 Centerline Pneumatic Flange Soft Seal Ductile Iron Sewage butterfly Valve

I. Product Technical Overview

The Nwv pneumatic flanged soft-seal concentric butterfly valve is specially designed for industrial fluid automation control. It adopts a concentric central line structure (with the stem axis, disc center, and pipeline centerline coaxial), covering DN50-DN400 (2″-16″) in diameter, suitable for PN16 (1.6MPa) pressure class. The applicable medium temperature ranges from -18℃ to 80℃ (with short-term resistance up to 120℃). The body uses QT450 ductile iron (tensile strength ≥450MPa, elongation ≥10%), the sealing seat adopts EPDM rubber, and it is matched with single-acting/double-acting pneumatic actuators, enabling precise shut-off and flow regulation for media such as water, sewage, oil, and gas. It is widely applied in municipal pipelines, sewage treatment, industrial water supply/drainage, and HVAC systems.

II. Core Product Features

(A) Concentric Central Line Structure Design

The NWV concentric butterfly valve achieves three technical advantages through its concentric layout:

Optimized Flow Path Efficiency

Geometric Coaxial Principle: The stem, disc, and pipeline centerline are completely concentric. When fully open, the disc aligns parallel to the fluid direction, with the flow coefficient Cv increased by 15% compared to eccentric structures (pressure loss of DN200 valve ≤0.3m water column), ideal for high-flow transportation (e.g., urban water main lines).

90° Precise On-Off: The disc completes opening/closing within a 90° rotation around the axis. A mechanical limit device ensures an angle error ≤1°, with the handle position directly corresponding to the opening degree for visual on-site monitoring.

Low Maintenance Cost

No Eccentric Friction: The sealing seat directly fits the disc edge without eccentric displacement, eliminating wear. The seat is fixed by a dovetail groove for online replacement (no pipeline disassembly needed), reducing maintenance time by 40%.

Simple Structure: 20% fewer mechanical components than double-eccentric designs reduce processing complexity and failure points, suitable for 24/7 continuous operation (e.g., sewage treatment plants).

Installation Compatibility

Standardized Flange Connection: Complies with GB/T 9113, ANSI B16.5, and other flange standards. Flange surface roughness Ra≤12.5μm, bolt hole spacing deviation ≤±0.3mm, adapting to global pipeline systems.

(B) High-Performance Material System

Component	Material	Performance Indicators
Body	Ductile Iron QT450	Tensile strength ≥450MPa, impact energy ≥27J at -20℃, epoxy coating (thickness ≥200μm)
Disc	Ductile Iron Nickel-plated/304 SS	Surface roughness Ra≤3.2μm, nickel plating thickness ≥25μm, 30% improved anti-erosion
Sealing Seat	EPDM Rubber (food-grade optional)	Compression set ≤8% (80℃×72h), chloride-resistant (≤2000ppm), WRAS certified for drinking water
Stem	2Cr13 Stainless Steel	Trapezoidal thread accuracy 6g, quenched & tempered (HB220-250), V-type PTFE packing for anti-leakage

(C) Integrated Pneumatic Drive System

Actuator Configuration

Standard IP65-protected pneumatic actuator, optional single-acting (spring return)/double-acting, air source pressure 0.4-0.7MPa. Full stroke time for DN200 valve ≤8s, supporting 4-20mA position feedback.

Anodized aluminum cylinder with dual-piston rack-and-pinion mechanism ensures stable torque output (error ≤5%), compatible with DCS/PLC remote control.

Safety Redundancy Design

Optional manual handwheel (for DN≥150) enables manual operation during air source failure, complying with ISO 13849-1 safety standards.

Integrated limit switches and solenoid valves support 3-position control (“open-closed-stop”), meeting ESD system response time ≤3s.

Environmental Adaptability

Actuator built-in anti-freeze grease (-18℃~60℃ applicable). Stainless steel fasteners optional for coastal areas, resisting salt spray (GB/T 10125≥1000 hours).

Product Overview

III. Key Technical Attributes

Parameter Category	Technical Indicators	Expansion Options
Size Range	DN50-DN400 (2″-16″)	Customized DN500-DN800 (subject to engineering mechanics verification)
Pressure Rating	PN16 (1.6MPa)	High-pressure types PN25/PN40 (2.5/4.0MPa, requires material upgrade)
Connection Type	Flanged (GB/T 9113/ANSI B16.5)	Wafer-type (ISO 5752), Butt Weld
Execution Standards	GB/T 12238, ISO 5281, API 609	CE, NSF61 (drinking water), ACS (French food-grade) certifications
Testing Standards	API 598 (1.5x hydrostatic test), EN12266	Fire test (API 607, metal seal redundancy), vibration test (ISO 10816)
Applicable Media	Water, sewage, air, oil, neutral gases	Acid-base media (requires NBR/FKM seal replacement)

IV. Manufacturing Processes and Quality Control

(A) Precision Processing Flow

Valve Body Casting and Treatment

Ductile iron uses lost foam casting, annealed at 900℃ to relieve stress, with graphite spheroidization rate ≥90%. Flange surfaces are machined by CNC gantry milling, flatness error ≤0.05mm.

Epoxy coating applied in two layers (primer + topcoat), tested by cross-cut (ISO 2409, adhesion grade 0).

Seal System Assembly

EPDM seal seat formed by compression molding (pressure ≥5MPa), interference fit clearance with body ≤0.02mm. Disc edge rounded (R≥3mm) to reduce seal wear during operation.

Each valve undergoes 1.5x nominal pressure hydrostatic test (30-min hold), leakage rate ≤5×10⁻⁸m³/s (EN12266 Class A).

Drive System Debugging

Pneumatic actuator undergoes 100 no-load cycles, positioning accuracy ±1%, torque decay ≤10%. Stability tested under simulated air source fluctuations (±10% pressure).

(B) Quality Certification System

Material Traceability: Key components with heat numbers, chemical reports (CMA certified), supporting third-party PMI testing.

Performance Certifications: Drinking water valves certified by WRAS, NSF61; marine models available with LR/DNV-GL classification.

After-Sales Guarantee: 18-month warranty, free replacement for seal failure, lifelong technical support (including seal replacement guidance videos).