Butterfly Valve
Double Offset
Double offset butterfly valves offer several advantages over standard butterfly valves, making them a popular choice for industrial applications.
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Specifications
Butterfly Valve – Double Offset Size Range
2 – 24 NPS, DN50 – DN600
Body Materials
Cast Iron, Ductile Iron
Temperature Range
-20°F to 250°F (-29°C to 121°C)
Stem Materials
Stainless Steel
Maximum Allowable Operating Pressure
Maximum 250 psi (17.2 Bar)
Seat Materials
EPDM, BUNA-N
Shutoff Rating
Bidirectional Bubble-tight
Disc Materials
Nylon 11 Coated Ductile Iron, Stainless Steel
Body Style
Wafer 3W, Lug 3L
Design Standard
API 609, Category A, EN 593, MSS SP-67
Flange Drilling
API 609, Category A, ASME B16.1 Class 125, ASME B16.5 Class 150, AS 2129 Table D & E, EN 1092 PN6, PN10, PN16, JIS 10K
Testing Standard
API 598, ISO 5208, EN 12266-1, MSS SP-61
Certifications
ABS Type Approval, CE/PED, CRN, FDA, ANSI/NSF 372, ANSI/NSF-61
Face To Face
API 609 Category A, EN 558 Series 20
Applications
Potable Water, Wastewater, Seawater, HVAC, Data Centers, Sugar & Ethanol
Features:
- Double Offset Design: The core feature involves two intentional offsets in the valve body. These offsets position the disc so it shifts away from the seat during operation . This minimizes contact between the sealing surfaces, reducing wear and tear.
- Variety of Sealing Options: Double offset valves can utilize various sealing materials, including elastomers or metal seats, depending on the application’s pressure and temperature requirements.
- Compact Design: Similar to standard butterfly valves, they offer a space-saving design due to their quarter-turn operation.
Benefits:
- Tight Sealing: The offset design allows for a more secure seal compared to standard butterfly valves, reducing leakage and making them suitable for higher-pressure applications.
- Lower Operating Torque: Reduced friction due to the offset design translates to lower torque required to open and close the valve. This simplifies automation and reduces actuator size and power needs.
- Extended Service Life: Minimized wear on the sealing surfaces leads to a significantly longer lifespan compared to standard butterfly valves.
- Broad Pressure and Temperature Range: Double offset valves can handle a wider range of pressures and temperatures than standard butterfly valves due to their design and available sealing materials.
- Versatility: They are suitable for various applications involving liquids, gases, slurries, and even some viscous fluids depending on the chosen seat material.
- Reduced Maintenance: The simpler design and lower wear rates contribute to less frequent maintenance needs compared to standard butterfly valves.
double offset butterfly valves provide a good balance between performance, reliability, and cost-effectiveness. They offer improved sealing, longer lifespan, and wider applicability compared to standard butterfly valves, making them a valuable choice for many industrial processes. However, they may not be ideal for applications requiring precise flow control.
FAQs:
A. What are the advantages of double offset butterfly valves?
- Tighter Sealing: Compared to standard butterfly valves, the offset design minimizes contact between the disc and seat, leading to a more secure seal and reduced leakage.
- Lower Operating Torque: The offset design reduces friction, requiring less force to open and close the valve, simplifying automation needs.
- Extended Service Life: Less wear on sealing surfaces translates to a longer operational lifespan.
- Wider Pressure and Temperature Range: They can handle a broader range of pressures and temperatures than standard butterfly valves.
- Versatility: Suitable for various applications with liquids, gases, slurries, and even some viscous fluids (depending on seat material).
- Reduced Maintenance: Simpler design and lower wear rates contribute to less frequent maintenance.
C. When to use a double offset butterfly valve?
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These valves are a good choice for applications that require:
- Improved sealing performance: Such as chemical processing, water treatment plants, or higher-pressure pipelines.
- Longer lifespan: Industrial settings aiming to minimize downtime and maintenance costs.
- Broader operating range: Handling a wider range of pressures and temperatures than standard butterfly valves can accommodate.
D. How does a double offset butterfly valve differ from a triple offset butterfly valve?
- Triple offset valves have an additional offset in the seating surface compared to double offset valves. This extra offset creates a camming action that eliminates disc-to-seat contact during most of the opening and closing cycle, leading to even lower friction and potentially a longer lifespan. However, triple offset valves tend to be more expensive.
E. What are some things to consider when selecting a double offset butterfly valve?
- Pressure and temperature rating: Choose a valve exceeding your application’s requirements.
- Pipe size and flange type: Ensure compatibility with your existing piping system.
- Material selection: Select appropriate body, disc, and seat materials for the fluid being handled.
- Actuation type: Decide on manual, pneumatic, or electric actuation based on automation needs.