Butterfly Valve

Double Offset

Double offset butterfly valves offer several advantages over standard butterfly valves, making them a popular choice for industrial applications.

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?

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.