Hello folks, this article is going to be straightforward about Butterfly Valve Offset. Here I assume that you are aware of the Butterfly Valve. If you don’t let me tell you that The Butterfly Valve is a quarter-turn Valve that contains a central disc that rotates on its axis and creates a barrier to stop the fluid flow. It can be detrimental to your operation to choose the wrong type of valve. There are three types of butterfly valves available on the market: zero offsets, double offsets, and triple offsets.
Zero Offset
Known as a concentric design, this is common in general-service ‘resilient seat’ or ‘rubber seat’ butterfly valves. The stem and disc are centered in the seat of the valve, both of which are center in the body of the valve. In constant contact with the seat is the disc.
It is an advantage of this valve that the media will not contact the body since the seat is construct as a sleeve or cartridge inside the body.
In basic and specialty liquid and gas applications, zero offset butterfly valves can handle up to 200 PSI and 400°F. Chemicals, coatings, food, some solids, and abrasives can all handle by the zero offset butterfly valve.
Butterfly valves with zero offset are available in epoxy-coated cast iron and stainless steel. Seat materials include Buna, EPDM, VITON, Teflon, natural rubber, and others.
Double Offset Butterfly Valve
High-performance butterfly valves are another name for this popular valve. The stems of this valve are offset from the center. This results in a cam action during application.
- 1st offset: The axis of the shaft is behind the centerline of the sealing point between the disc and the seat.
- 2nd offset: The axis of the shaft is eccentric to the center of the valve or pipeline.
Double offset butterfly valves are commonly use in:
- Power generation
- Pulp and paper
- HVAC
- Chemical
- Oil and gas
- Water and wastewater treatment
- Shipbuilding
Double offset butterfly valves are available in higher pressures than zero offset valves. Carbon steel, stainless steel, Hastelloy, and other body materials are available along with Teflon seats and Fire Safe designs with metal backup seats.
Triple Offset Butterfly Valve
The triple offset butterfly valve has three offsets. A triple offset valve has two offsets in the same position as a double offset butterfly valve, while the third offset is the geometry of the seating surface, creating a cone-shaped disc. Together with the two eccentric shaft offsets, this cone angle allows the disc to seal against the seat without friction.
In a metal seat, this design also allows for uniform sealing, and thus a tight shutoff. The design is a low-cost, low torque option (easier to automate) than alternative metal-seated valves.
These valves are generally use in applications that require a metal seat, tight shutoff, and quarter-turn actuation, such as gate valves. It is suitable for high-pressure steam (over 150 PSI), superheated steam, high-temperature gasses, oils, and high-temperature applications since a metal seat is require over a soft seat.
Triple offset butterfly valves are use in industries similar to double offset butterfly valves but in more demanding applications.
Aira Euro Automation is one of the Reputed industrial valve manufacturers in India. We have huge varieties of Butterfly valves. We are API 609 – 0055 certified Triple Offset butterfly valve manufacturer in India.
Also, read Why a Union Ball Valve May Be the Right Choice for Your Home’s Plumbing
