Showing posts with label Pratt. Show all posts
Showing posts with label Pratt. Show all posts

High-performance and Resilient Seated Butterfly Valves for Commercial and Industrial Applications

High-performance and Resilient Seated Butterfly Valves

A butterfly valve has a disc that is in the fluid flow path. In the most common style of butterfly valve, the disc revolves around a central axis, the stem, via a 90-degree arc from parallel to the flow direction (open) to perpendicular to the flow direction (closed).  Butterfly valves have a straightforward design with few moving components, making them simple to repair and maintain. The valve has four main parts: the body, the stem, the disk, and the seat. 

The butterfly disk is always in the flow path, but its thin profile has little effect on flow. Butterfly valves are popular because they provide tight shut-off, are available in various materials and sizes, and may be easily automated using a variety of quarter-turn electric and pneumatic actuators. 

You'll find butterfly valves in a wide range of industrial applications, from managing the flow of water to handling far more hazardous industrial fluids. Many industries use butterfly valves, including water treatment, chemical processing, pulp, paper manufacturing, food processing, power generation, etc. 

There are two primary classifications of butterfly valves:

  1. High-performance butterfly valves (HPBV)
  2. Resilient seated butterfly valves


High-performance butterfly valves include carbon or stainless steel bodies with Teflon seats and can withstand more significant pressures and temperatures.  Resilient seated valves usually feature ductile iron or aluminum bodies and operate at lower pressures and temperatures.

Butterfly valve bodies are available in two mounting styles: lug and wafer. Lug bodies include cast-in lugs with bolt hole designs that match pipe flanges. A wafer body valve does not have a mounting hole pattern, and mounting is facilitated by sandwiching the valve between two pipe flanges, with mounting bolts around the valve body. Wafer-style bodies are less costly. An advantage to lug body valves is their use as a dead-end valve, whereas wafer valves are unsuitable for this service.

The stem is a one or two-piece shaft that keeps the disk in place and provides the rotational torque that allows the disk to open and shut. The stem of resilient seated valves has protection from the process media by packing rings, allowing for a more cost-effective solution to regulate the valve's application to various potentially corrosive media. High-performance butterfly valve stems come into touch with process media and must be media suitable. 

The disk is the valve component that comes into direct contact with the process medium and regulates flow. Disks are available in various materials and optionally come with corrosion-resistant polymer coatings. Some butterfly valves include contoured disks that are carefully aligned with the stem to increase flow control, modify torque needs, or give the valve a longer life. 

A resilient seated valve closes via an "interference fit," which means the disk forces itself into the seat. The seat is the soft substance (polymer elastomer) including Buna-N and Nitrile, and should be specified depending on the process medium involved.

High-performance butterfly valves use an interference fit as well, but with significantly tighter tolerances, but also ensure tight seating with assistance from upstream pressure. PTFE or RTFE are the most often used materials for HPBV seats. Metal seats on HPBVs accommodate more significant pressure and temperature applications. 

Like other valves, butterfly valves have applications in which they outperform. To apply the optimum solution to your flow control applications, combine your process knowledge with your product knowledge with the application skills of a proven valve engineering professional. Contact Piping Specialties, Inc. for more information about industrial valves. Visit or call 800-223-1468.

Considerations for Choosing Industrial Butterfly Valves

Butterfly Valves
High Performance Butterfly Valve
Industrial process control valves are available in uncountable combinations of materials, types, and configurations. An initial step of the selection procedure for a valve application should be choosing the valve type, thus narrowing the selection field to a more manageable level. Valve "types" can generally be classified by the closing mechanism of the valve.

A butterfly valve has a disc that is positioned in the fluid flow path. In the most common form of butterfly valve, the disc rotates around a central axis, the stem, through a 90 degree arc from a position parallel to the flow direction (open) to perpendicular (closed). A variety of materials are used in the valve body construction, and it is common to line the valve with another material to provide special properties accommodating particular process media.

What attributes might make a butterfly valve a beneficial selection over another valve type?
Butterfly Valve
Resilient Seated Butterfly Valve
  • The closure arrangement allows for a comparatively small size and weight. This can reduce the cost, space, and support requirements for the valve assembly.
  • Generally low torque requirements for valve operation allow for manual operation, or automation with an array of electric, pneumatic, or hydraulic actuators.
  • Low pressure drop associated with the closure mechanism. The disc in the flow path is generally thin. In the fully open position, the disc presents its narrow edge to the direction of flow.
  • Quarter turn operation allows for fast valve operation.
  • Some throttling capability is provided at partially open positions.
  • Small parts count, low maintenance requirements.
What may be some reasons to consider alternate valve types?
  • Butterfly valve throttling capability is generally limited to low pressure drop applications.
  • Cavitation can be a concern.
  • Some sources mention the possibility of choked flow as a concern under certain conditions.
Butterfly valves, like other valve types, have applications where they outperform. Careful consideration and consultation with a valve expert is a first step toward making a good selection. Combine your process know-how with the product application expertise of a professional sales engineer to produce the best solutions to your process control challenges.

For more information regarding an type of industrial valve, contact Piping Specialties, Inc. by visiting https://psi-team or by calling 800-223-1468.

Assembling the Pratt Industrial BF Series Resilient Seated Butterfly Valve

Pratt Industrial BF Series butterfly valve
Pratt BF Series
The Pratt Industrial BF Series butterfly valve is recognized for it's quality and durability for use in these industries: Mining, Food/Beverage, Power, OEM’s, Chemical/Pharmaceutical, Desalination, Petroleum/Oilfield, Ultra Pure Water, Transportation, Marine, Irrigation, and HVAC.

The specifications are:
  • Sizes: 2" through 48"
  • Body: Ductile Iron (65-45-12)
  • Disc: Ductile Iron Nickle Plated, Ductile Iron Nylon 11, CF8M Stainless Steel, Aluminum Bronze
  • Stem: 416 S.S. Heat Treated
  • Resilient Seat: EPDM, Buna-N, Viton
  • Actuation Options: Worm Gear, Lever, Pneumatic, Electric
  • Pressure Ratings: 2" – 12" 230psi; 14" – 48" 150psi
  • Innovative 3 point connection, tongue andgroove seat allows for higher pressure rating and full Vacuum service
  • Unique secondary shaft seals prevent leakage from shaft.
  • Two piece shaft design provides maximum strength and a high flow characteristic disc.
Watch video below for assembly instructions:

For more information about the valve, read the BF Series brochure below. The full Pratt BF Series brochure PDF can be downloaded here.