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Soft-Seated Butterfly Valve vs. Eccentric Butterfly Valve — Ultimate Comparison

2025-05-26 16:08:52

Soft-Seated Butterfly Valve vs. Eccentric Butterfly Valve

 

Comparison Dimension

Soft-Seated Butterfly Valve (Centerline Soft-Seated)

Eccentric Butterfly Valve (Double/Triple Offset Metal-Seated)

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.

Sealing Type

Elastic sealing (rubber, PTFE, etc.)

Metal-to-metal sealing (stainless steel + Stellite, tungsten carbide, etc.)

Sealing Performance

Good (zero leakage, suitable for low-pressure systems)

Excellent (bubble-tight sealing Class VI, suitable for high-pressure and harsh conditions)

Temperature Resistance

Moderate: -20°C to 120°C (depends on sealing material)

Superior: Up to 600°C (depends on structure and sealing materials)

Pressure Rating

Typically PN10–PN16

Up to PN25–PN100 or higher

Opening/Closing Torque

Low torque, easy operation

Medium torque (eccentric design reduces friction), compatible with automated drives

Abrasion Resistance

Poor (seal rings prone to wear and aging)

High (metal sealing pairs resist wear and erosion)

Suitable Media

Water, air, mildly corrosive media, food-grade fluids

High-temperature steam, acids/alkalis, powders, oil/gas, particulate-laden media

Installation & Maintenance

Simple installation, low maintenance costs

High installation requirements (alignment and pre-commissioning), longer maintenance intervals

Service Life

Moderate (seal lifespan: 2–5 years)

Long (triple-offset design minimizes friction, lifespan exceeds 10 years)

Initial Cost

Low, cost-effective

High (precision materials and machining required)

Actuator Compatibility

Optional: Manual (lever, gear), electric, pneumatic

Typically paired with electric, pneumatic, or hydraulic actuators for automation

Typical Applications

Municipal water supply, HVAC, fire protection, water treatment

Petrochemical, power generation, metallurgy, marine, natural gas, nuclear industries

Hard seal eccentric butterfly valve

Structural & Sealing Principle Comparison

 

Comparison Item

Centerline Soft-Seated Butterfly Valve

Eccentric Butterfly Valve (Double/Triple Offset)

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).

Opening/Closing Method

90° rotation of the disc; sealing ring contacts the seat.

Eccentric design achieves “separation before sealing” for frictionless operation.

Sealing Pair Type

Elastic material (EPDM/NBR/PTFE) soft seal.

Metal-to-metal (stainless steel + hard alloy) or metal-to-composite layer sealing.

Sealing Principle

Elastic deformation ensures sealing.

Eccentricity creates compression on metal conical surfaces during closure for tight sealing.

 

Performance & Applicability Comparison

 

Comparison Dimension

Centerline Soft-Seated Butterfly Valve

Eccentric Butterfly Valve (Hard-Seated)

Pressure Rating

Typically PN1.0–1.6 MPa

Up to PN2.5–6.4 MPa or higher

Temperature Range

-20°C to +120°C (depends on sealing material)

-29°C to +600°C (varies with metal materials)

Sealing Class

Generally Class IV–V

Optimized designs achieve Class VI (zero leakage)

Suitable Media

Water, gases, weak acids/alkalis

High-temperature steam, corrosive gases, particulate media, oils, etc.

Opening/Closing Torque

Low torque, easy operation

Medium torque (eccentricity reduces friction)

Installation Space

Compact wafer-style design saves space

Flanged/wafer styles available; triple-offset suits large diameters.

Cost Efficiency

Low cost, ideal for bulk systems

Higher cost, suitable for demanding conditions

 

Pros & Cons Summary

 

Comparison Item

Centerline Soft-Seated Butterfly Valve

Eccentric Butterfly Valve (Double/Triple Offset)

Advantages

– Simple structure, compact, lightweight
– Low torque, easy operation
– Cost-effective for bulk procurement
– Good sealing (zero leakage in clean media)

– Frictionless opening/closing, longer seal life
– Withstands high temperature/pressure and harsh conditions
– Metal seals resist wear/corrosion
– High sealing class (Class VI)

Disadvantages

– Limited temperature resistance (standard EPDM/NBR <130°C)
– Vulnerable to corrosion, aging, and wear
– Unsuitable for abrasive/corrosive media
– Seal friction reduces lifespan with frequent cycling

– Complex structure, high cost, precision machining required
– High torque for large diameters, needs heavy actuators
– Challenging sealing surface machining/alignment
– Leakage risk if misaligned

Pressure Range

≤PN16

Up to PN25–PN100 (model-dependent)

Temperature Range

-20°C to +120°C (common rubber materials)

-29°C to +600°C (metal seals)

Suitable Media

Water, air, sewage, HVAC fluids

Steam, oils, acid/alkali gases, particulate fluids, corrosive media

Service Life

Moderate (seals wear with frequent cycling)

Long (minimal friction in eccentric design), extended maintenance intervals

Sealing Reliability

Relies on elastomer elasticity; susceptible to aging and permanent deformation

Precision-machined metal conical sealing ensures zero leakage (Class VI)

Cost Efficiency

Low cost, high cost-performance

High cost, suited for critical or extreme conditions

butterfly valve

Typical Application Scenarios

 

Industry/Condition

Recommended Valve Type

Reason

Water supply/drainage systems

Centerline soft-seated butterfly valve

Low pressure/temperature, cost-sensitive requirements

HVAC systems

Centerline soft-seated butterfly valve

Moderate temperature, frequent operation

High-temperature steam pipelines

Triple-offset metal-seated butterfly valve

Metal seals withstand high temperatures and minimize friction

Petrochemical high-pressure lines

Eccentric metal-seated butterfly valve

Resists corrosion, particulates, and pressure fluctuations

Powder/gas/slurry transport

Eccentric valve + special coating/structure

Enhanced sealing, reduced wear and clogging

Food/pharma pure water systems

Centerline soft-seated valve (food-grade)

Hygienic, easy disassembly

 

Summary Recommendations

 

Operating Conditions

Recommended Valve Type

Ambient temperature/pressure, clean water

Centerline soft-seated butterfly valve

High temperature/pressure, oil/gas, particulates

Triple-offset metal-seated butterfly valve

Frequent cycling/actuation

Eccentric butterfly valve (low friction)

Cost-sensitive, bulk procurement

Centerline soft-seated butterfly valve

soft seal butterfly valve

✅ Is a Soft-Seated Butterfly Valve Right for You?

 

✔ 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.

 

Is the Eccentric Metal-Seated Butterfly Valve Your Best Choice?

 

✔ 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.

 

Final Recommendations

 

Application Scenario

Recommended Valve Type

Municipal water/HVAC/AC networks

Centerline soft-seated butterfly valve

Food, beverage, water treatment

✅ Food-grade soft-seated butterfly valve

High-temperature steam, acid/gas/oil systems

Eccentric metal-seated butterfly valve

Large-diameter networks/frequent cycling/automation

✅ Eccentric valve + electric/pneumatic actuator

soft seal butterfly valve

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