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PTFE lined butterfly valves
Thu 18 Jan 2018

Why choose a butterfly valve?

In this blog, we look at the reasons why you should consider choosing butterfly valves, including the functions, advantages, and disadvantages of these multi-purpose valves. We also look at butterfly valves from trusted butterfly valve manufacturers Unitech and Zwick to give you the lowdown about their unique features and benefits.

BM Engineering can supply a number of butterfly valves from industry experts Unitech and Zwick. Their valves are designed for reliable functionality in many different industries, including energy, chemical and many other fields of engineering.

What is a butterfly valve?

Butterfly valves are quarter-turn valves that are used to regulate flow. A metal disc in the body of the valve is positioned perpendicular to the flow in the closed position, and rotated one quarter of a turn to be parallel to the flow in the fully opened position. Intermediate rotations allow regulation of liquid flow. They are often used in agricultural and water or wastewater treatment applications and are one of the most common and well-known valve types.

Advantages of butterfly valves

There are a number of different advantages to a butterfly valve. Because they are similar to ball valves they’re small and, when they’re actuated they pneumatically, open and close quickly. The actual disc of a butterfly valve is lighter than a ball and does not need as much structural support as a ball valve of comparable diameter. Another advantage of butterfly valves is that they are very precise and reliable in industrial applications.

Disadvantages of butterfly valves

Although butterfly valves do have many advantages, there are also a few disadvantages that are worth mentioning. The first disadvantage is that even when fully opened a portion of the disc is presented to the flow. Because of this, the butterfly valve always results in a pressure switch across the valve, regardless of the setting. Thicker liquids may also stop the movement of the disc.

Zwick TRI-CON Butterfly Valve

The Zwick TRI-CON Butterfly Valve is a high performance triple eccentric design butterfly valve designed for day-to-day maximum performance.

Caption: Zwick TRI-CON Butterfly Valve

Features and benefits

  • Laminated seal and seat made of stainless steel.
  • Metal seating.
  • Friction free opening and closing.
  • Triple eccentric design

Unitech’s split-body PTFE lined butterfly valves

Unitech’s split-body PTFE lined butterfly valves are designed to allow ease of maintenance and their one-piece disc/stem arrangement ensures zero movement between the disc and stem.

Features and benefits

  • Full PTFE liner allows for high temperatures (up to 180°C), chemically toxic and corrosive media.
  • Silicone resilient elastomer backup pad extends around the seat, including the disc hub. This provides uniform force sufficient for bubble-tight shut off.
  • Self-lubricating bearings are SS with PTFE coating.
  • Top and bottom secondary O-ring sealing prevents leaks to atmosphere.

Speak to a BM Engineering adviser today about our complete range of butterfly valves by calling 0141 762 0657 or email sales@bmengineering.co.uk.

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