High-Quality WRAS Butterfly Valve Lever Operated Manufacturers & Factories

A certified WRAS butterfly valve has undergone destructive and migration laboratory verification under BS 6920: Suitability of non-metallic materials for use in contact with water intended for human consumption. Standard commercial EPDM often utilizes carbon black, plasticizers, and vulcanization accelerators containing toxic metallic catalysts or sulfur residues that leech offensive odors, toxic substances, or sustain coliform bacterial growth. A WRAS approved model utilizes peroxide-cured, ultra-pure synthetic EPDM compounds and WRAS-approved epoxy coatings applied to the body interior. Furthermore, the complete valve assembly is audited for mechanical durability and seal retention without water taint.

While lever actuators allow rapid 90-degree shut-off, rapid manual closure on large diameters (DN200 and above) induces severe hydraulic shockwaves known as water hammer ($ΔP = ρ \cdot a \cdot Δv$). Furthermore, the hydrodynamic torque exerted by moving water columns on a disc exceeding 200mm at 16 bar differential can overcome human operator grip, posing safety hazards. Consequently, international standards recommend manual hand levers from DN40 through DN150, while DN200 and above are paired with worm gear operators or electric/pneumatic actuators equipped with slow-closure dampers.

Grey Cast Iron (EN-GJL-250 / GG25) contains flake graphite, giving it high brittleness and negligible elongation under tensile stress (less than 1%). Under cold weather, water hammer pulses, or mechanical pipe alignment stresses, grey iron can fracture catastrophically. In contrast, Ductile Iron (EN-GJS-400-15 / GGG40 / ASTM A536) features nodular (spherical) graphite produced via magnesium inoculation in our foundry. It delivers tensile strength ≥ 400 MPa and elongation ≥ 15%, providing high mechanical resilience against pipeline expansion, ground settling, and transient pressure spikes.

Traditional butterfly valve discs rely on taper pins or through-pins passing through both the disc hub and the drive shaft. Over years of cyclic duty, vibration causes localized fretting wear around pinholes. Furthermore, corrosive chlorinated fluid can migrate past the pin seals, inducing galvanic corrosion between dissimilar metals and causing catastrophic shaft disconnection. A pinless disc architecture utilizes precision internal broached hexagonal, double-D, or splined shaft interfaces enclosed entirely within the disc hub, leaving zero leak pathways to the internal shaft and ensuring uninterrupted torque transmission.

Yes, when specified with a Full Lug (threaded lug) body or a Double Flanged body. Wafer type valves cannot be used for dead-end terminal isolation because they rely on compressive clamp force between two companion flanges. Lug type valves feature threaded holes drilled to EN 1092-2 PN10/PN16 or ASME Class 150 specifications, allowing the valve to be securely bolted to the terminal flange while holding full rated working pressure (up to 16 bar) without leaking, even when downstream piping is unbolted for pump maintenance or cleaning.