What is a single eccentric butterfly valve?
Single-eccentric butterfly valve, also known as a single-eccentric bearing butterfly valve, has a simple structure consisting primarily of a valve body, valve disc, bearing, and compression bolts. The bearing is offset from the center of the valve disc by a certain distance relative to the valve stem, hence the name. When the valve is closed, the contact area between the valve disc and the valve seat is large, resulting in a better sealing performance. Single-eccentric butterfly valves are suitable for low-pressure, medium-temperature, and medium-viscosity fluids and are primarily used in the tap water, industrial water treatment, and water supply and drainage industries.
What is a double eccentric butterfly valve?
Double-eccentric butterfly valves, also known as double-eccentric bearing butterfly valves, are more complex than single-eccentric butterfly valves but offer a wider range of applications. Their valve body and disc are larger than those of single-eccentric butterfly valves, and the eccentricity of the valve stem is greater. This reduces friction between the disc and seat during opening and closing, improving the valve's sealing performance. Double-eccentric butterfly valves are suitable for pipelines carrying high-temperature, high-pressure, high-viscosity, and scaling media, primarily in the chemical, petroleum, and power industries.
What is a triple eccentric butterfly valve?
A triple-eccentric butterfly valve is one in which the valve stem axis is offset from both the disc and body centers, and the valve seat's rotational axis is at a certain angle to the valve body's channel axis. Triple-eccentric butterfly valves are widely used in industrial pipelines, such as metallurgy, electric power, petrochemicals, water supply and drainage, and municipal construction, for flow regulation and flow control, with media temperatures ≤425°C. They are available in cast iron, cast steel, and stainless steel.
What is the difference between single, double, and triple offset butterfly valves?
| Features | Single Offset Butterfly Valves | Double Offset Butterfly Valves | Triple Offset Butterfly Valves |
|---|---|---|---|
| Sealing Type | Soft Seal(Rubber/PTFE) | Soft / Metal Seal(Line contact) | Metal hard seal (face contact, zero leakage) |
| Pressure resistance | ≤PN16(Medium and low pressure) | ≤PN25(Medium pressure),Some reach PN40 | ≤PN420(High pressure, such as 2500 psi) |
| Temperature range | -29°C to 180°C(Soft seal limit) | -29°C to 425°C(Metal seal adapter) | -29°C to 650°C(ultra high temperature) |
| Opening and closing friction | Medium (scratch residue) | Low(Quick escape) | Zero friction (millisecond disengagement) |
| Typical Applications | Municipal water supply and drainage, ventilation systems | HVAC, city water supply | Refinery and power plant steam pipelines |
