Butterfly valves are commonly used in a wide range of industrial processes to control the flow of liquids and gases. A triple offset butterfly valve is a specific type of butterfly valve that offers improved sealing and reduced leakage compared to standard butterfly valves.
How Triple Offset Butterfly Valves Work
A triple offset butterfly valve consists of a circular disc mounted on a rod. The disc rotates within a cylindrical valve body between open and closed positions. When the disc is aligned with the flow, the valve is open and process fluid can pass through. When the disc is perpendicular to the flow, the valve is closed and no fluid passes.
The “triple offset” refers to the design of the disc and seats. Instead of a single seal point between the disc and seat like a standard butterfly valve, there are three offset sealing points:
- The disc edge seals against the inner surface of the body.
- The disc face seals against the seat on the valve body.
- An extension of the disc seals against the seat on the valve body.
- This triple offset design creates two dynamic seal points and one static seal point, improving the sealing performance and reducing leakage rates.
Benefits Of Triple Offset Butterfly Valves
The main benefits of triple offset butterfly valves compared to standard butterfly valves include:
• Lower leakage – The triple offset design provides multiple seal points for improved leakage rates, especially at low differential pressures.
• Bi-directional sealing – Triple offset valves can seal effectively in both flow directions.
• Rising stem – The valve stem rises with the disc as it opens, allowing for visual confirmation that the valve is fully open.
• Bubble-tight shutoff – Triple offset butterfly valves can achieve zero-leakage shutoff when requested.
• Compact design – The disc and stem rotate within the valve body, providing a space-saving design.
• Easy maintenance – The valve parts have simple designs and are easy to access for maintenance.
Typical Applications Of Butterfly Valves Triple Offset Types
Triple offset butterfly valves are specified for applications that require:
• Low leakage rates – Processes with strict containment specifications favor triple offset valves.
• Infrequent operation – Valves that remain closed for long periods benefit from the triple offset design’s superior shut-off.
• Alternating flow directions – Bi-directional fluids are well suited for triple offset valves.
• High cycle life – The design ensures long service life, suitable for frequent opening and closing.
• Simplicity – Their fewer moving parts make triple offset valves easy to maintain.