Soft-Seated Butterfly Valve vs. Eccentric Butterfly Valve
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Comparison Dimension |
Eccentric Butterfly Valve (Double/Triple Offset Metal-Seated) |
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Structural Design |
Centerline structure: Valve stem, disc, and valve body centerline are aligned. |
Eccentric structure: Valve stem, disc, and sealing surfaces are not on the same centerline, typically double or triple offset. |
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Sealing Type |
Elastic sealing (rubber, PTFE, etc.) |
Metal-to-metal sealing (stainless steel + Stellite, tungsten carbide, etc.) |
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Sealing Performance |
Good (zero leakage, suitable for low-pressure systems) |
Excellent (bubble-tight sealing Class VI, suitable for high-pressure and harsh conditions) |
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Temperature Resistance |
Moderate: -20°C to 120°C (depends on sealing material) |
Superior: Up to 600°C (depends on structure and sealing materials) |
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Pressure Rating |
Typically PN10–PN16 |
Up to PN25–PN100 or higher |
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Opening/Closing Torque |
Low torque, easy operation |
Medium torque (eccentric design reduces friction), compatible with automated drives |
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Abrasion Resistance |
Poor (seal rings prone to wear and aging) |
High (metal sealing pairs resist wear and erosion) |
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Suitable Media |
Water, air, mildly corrosive media, food-grade fluids |
High-temperature steam, acids/alkalis, powders, oil/gas, particulate-laden media |
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Installation & Maintenance |
Simple installation, low maintenance costs |
High installation requirements (alignment and pre-commissioning), longer maintenance intervals |
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Service Life |
Moderate (seal lifespan: 2–5 years) |
Long (triple-offset design minimizes friction, lifespan exceeds 10 years) |
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Initial Cost |
Low, cost-effective |
High (precision materials and machining required) |
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Actuator Compatibility |
Optional: Manual (lever, gear), electric, pneumatic |
Typically paired with electric, pneumatic, or hydraulic actuators for automation |
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Typical Applications |
Municipal water supply, HVAC, fire protection, water treatment |
Petrochemical, power generation, metallurgy, marine, natural gas, nuclear industries |
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Comparison Item |
Eccentric Butterfly Valve (Double/Triple Offset) |
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Structural Features |
Valve axis, disc center, and valve body centerline are collinear. |
Disc axis deviates from the valve body centerline (single/double/triple offset structure). |
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Opening/Closing Method |
90° rotation of the disc; sealing ring contacts the seat. |
Eccentric design achieves “separation before sealing” for frictionless operation. |
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Sealing Pair Type |
Elastic material (EPDM/NBR/PTFE) soft seal. |
Metal-to-metal (stainless steel + hard alloy) or metal-to-composite layer sealing. |
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Sealing Principle |
Elastic deformation ensures sealing. |
Eccentricity creates compression on metal conical surfaces during closure for tight sealing. |
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Comparison Dimension |
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Pressure Rating |
Typically PN1.0–1.6 MPa |
Up to PN2.5–6.4 MPa or higher |
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Temperature Range |
-20°C to +120°C (depends on sealing material) |
-29°C to +600°C (varies with metal materials) |
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Sealing Class |
Generally Class IV–V |
Optimized designs achieve Class VI (zero leakage) |
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Suitable Media |
Water, gases, weak acids/alkalis |
High-temperature steam, corrosive gases, particulate media, oils, etc. |
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Opening/Closing Torque |
Low torque, easy operation |
Medium torque (eccentricity reduces friction) |
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Installation Space |
Compact wafer-style design saves space |
Flanged/wafer styles available; triple-offset suits large diameters. |
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Cost Efficiency |
Low cost, ideal for bulk systems |
Higher cost, suitable for demanding conditions |
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Comparison Item |
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Advantages |
– Simple structure, compact, lightweight |
– Frictionless opening/closing, longer seal life |
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Disadvantages |
– Limited temperature resistance (standard EPDM/NBR <130°C) |
– Complex structure, high cost, precision machining required |
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Pressure Range |
≤PN16 |
Up to PN25–PN100 (model-dependent) |
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Temperature Range |
-20°C to +120°C (common rubber materials) |
-29°C to +600°C (metal seals) |
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Suitable Media |
Water, air, sewage, HVAC fluids |
Steam, oils, acid/alkali gases, particulate fluids, corrosive media |
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Service Life |
Moderate (seals wear with frequent cycling) |
Long (minimal friction in eccentric design), extended maintenance intervals |
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Sealing Reliability |
Relies on elastomer elasticity; susceptible to aging and permanent deformation |
Precision-machined metal conical sealing ensures zero leakage (Class VI) |
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Cost Efficiency |
Low cost, high cost-performance |
High cost, suited for critical or extreme conditions |
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Industry/Condition |
Recommended Valve Type |
Reason |
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Water supply/drainage systems |
Centerline soft-seated butterfly valve |
Low pressure/temperature, cost-sensitive requirements |
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HVAC systems |
Centerline soft-seated butterfly valve |
Moderate temperature, frequent operation |
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High-temperature steam pipelines |
Triple-offset metal-seated butterfly valve |
Metal seals withstand high temperatures and minimize friction |
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Petrochemical high-pressure lines |
Eccentric metal-seated butterfly valve |
Resists corrosion, particulates, and pressure fluctuations |
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Powder/gas/slurry transport |
Eccentric valve + special coating/structure |
Enhanced sealing, reduced wear and clogging |
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Food/pharma pure water systems |
Centerline soft-seated valve (food-grade) |
Hygienic, easy disassembly |
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Operating Conditions |
Recommended Valve Type |
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Ambient temperature/pressure, clean water |
Centerline soft-seated butterfly valve |
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High temperature/pressure, oil/gas, particulates |
Triple-offset metal-seated butterfly valve |
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Frequent cycling/actuation |
Eccentric butterfly valve (low friction) |
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Cost-sensitive, bulk procurement |
Centerline soft-seated butterfly valve |
✔ Cost-effective choice — Low initial investment and reduced maintenance costs, ideal for budget-sensitive projects.
✔ Excellent performance in standard conditions — Suitable for clean water, HVAC, fire protection, and low-pressure pipelines.
✔ Quick and easy to install — Lightweight, compact design with simple operation.
❌ Not recommended for harsh environments — Avoid use in high-temperature (>120°C), high-pressure (>PN16), frequent cycling, or corrosive/particulate-laden media.
Ideal for: Municipal, commercial, and light industrial applications prioritizing reliability and affordability.
✔ Engineered for critical service — Designed for extreme conditions: high temperature (up to 600°C), high pressure (up to PN100+), and aggressive media.
✔ Superior durability and sealing — Triple-offset metal-to-metal sealing ensures long service life and bubble-tight shutoff (Class VI).
✔ Ideal for automation — Compatible with electric, pneumatic, or hydraulic actuators for precise remote control.
❌ Higher complexity and cost — Requires precise selection, alignment during installation, and upfront investment.
Best suited for: Oil & gas, petrochemical, power generation, metallurgy, and other demanding industrial sectors.
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Application Scenario |
Recommended Valve Type |
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Municipal water/HVAC/AC networks |
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Food, beverage, water treatment |
✅ Food-grade soft-seated butterfly valve |
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High-temperature steam, acid/gas/oil systems |
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Large-diameter networks/frequent cycling/automation |
✅ Eccentric valve + electric/pneumatic actuator |
