Lug butterfly valve

Lug butterfly valve introduction

Lug butterfly valve is available in pressure rating of PN 10, PN 16, Class 150 for soft seated structure,PN10 to PN64,Class 150 to Class 900 for metal seated structure.Lug Butterfly Valve is available in body and disc material of cast Iron, ductile iron, carbon steel (WCB), SS 304 (CF8), SS 316 (CF8M) or other material. Lug butterfly valve comes with wide range of rubber liner options like Black Nitrile, EPDM, Viton, Hypalon, Silicon and metal seated structure for sever working condition.

Lug butterfly valve operation options include lever, gear unit, motorized, electrical actuator,pneumatic actuator (double / single acting).Flanged butterfly valve can also be supplied with special arrangement of long neck, extended stem, locking arrangement, limit switch and chain wheel operator.

Lug butterfly valve feature

1. Fully rubber lined,fully teflon lined,metal seated body is optional according to different working condition
2. Ideal valve for installation with lined pipes, since the disc chord interference with pipe ID is negligible.
3. Controlled compression of the gasket face offers optimum sealing and prevents gasket face crushing.
4. Unique triple sealing system,for shaft sealing to ensure zero secondary leakage.
5. Self lubricated bearings, for both drive end and non-drive end shafts, ensures minimum bearing friction.
6. Soft seated structure lug butterfly valve is Bi-directional tight shut off sealing from vacuum to rated pressure.Metal seated structure lug butterfly valve is single directional tight shut off sealing for high pressure and high temperature medium.
7. Excellent adaptability for actuated operation through standardized ISO top flange.
8. Choice of seat and disc materials to suit media and operating conditions.
9. Enables installation close to other pipe fittings, without disc interference.
10. Preferred design for desalination plants, municipal water supply and Effluent plants.

Concentric lug butterfly valve

This is the most basic kind of butterfly valve.Sometimes called the centric valve or the zero offset butterfly valve, the stem passes through the centerline of the disc and through the center of the pipe.Also known as the resilient-seated butterfly valve, sealing depends on how efficient the seat is during closing. This kind of butterfly valve is used for low-pressure applications.
 

Eccentric lug butterfly valve

The stem of the eccentric type does not pass through the centerline of the valve.Rather, it is placed behind the face of the disc which is opposite of the flow direction. 
1 Single Offset lug butterfly valve
The single offset only has the stem attached at the back of the disc. This enables lesser disc-to-seal contact before full closure. This is to ensure a better and longer life service of the disc.
2 Double Offset lug butterfly valve
A double offset type has the stem located at the back of the disc. There is an offset present on the other side of the disc. This further limits the contact of the disc and the seat to about 1-3 degrees. The double offset butterfly valve is suitable for high-pressure applications that need a bubble-tight sealing.
3 Triple Offset lug butterfly valve
The triple offset lugbutterfly valve has an additional offset located at the axis of the disc and seat, apart from the ones already mentioned in the double offset design. This creates a valve with a slightly tilting disc and seat. TOVs are often used for highly critical applications. It often has a metal-to-metal seat design.

Lug butterfly valve actuation

Hand Lever: Is common for small butterfly valves and is capable of being locked into a position of open, partially open, or closed.
Gear: These are designed for slightly larger butterfly valve and utilize a gearbox to increase torque at the expense of decreased speed of opening/closing. Gear operated butterly valves are also self-locking (cannot be back driven) and can be equipped with position indicators.
Electric: Use an electric motor to turn the butterfly valve stem
Pneumatic: Requires compressed air to move a piston or diaphragm to open/close the butterfly valve.
Hydraulic: Requires a hydraulic pressure to move a piston or diaphragm to open/close the butterfly valve.