Resilient-seated butterfly valve

Concentric butterfly valve / Resilient seated butterfly valve / Rubber lined butterfly valve

All names where usually the same type of butterfly valve design is meant. The shaft is in the middle of the disc and is the center of the rotation of the disc. It’s also in the middle of the valve body and in line with the sealing area.​
The disc seals to the rubber liner which is “on” the valve body. It actually presses into the liner.​
This “on” needs to be explained as it can be loose, which means it can be replaced when damaged, but it also means it can get off in under pressure (usually called vacuum but it isn’t) applications. I can be vulcanized to the valve body which is understood as high quality and applicable in under pressure applications but there is also the “glued” version.​

Typically class 150 (PN16/20) rated, this does not always mean the complete valve can handle this pressure but it’s the body rating.​
Usually available in wafer, wafer/lug and lugged.​
EPDM, NBR are the usual liner materials.​
The body can be Iron or steel and the disc is typically Stainless Steel or (epoxy) coated steel. ​

A lined (PTFE) butterfly valve is a high corrosion resistant version of the above.​

Temperature is limited by the liner material.

Our brand: Demco


Demco, part of the Cameron valve division was established in 1947. Demco is manufacturer of one of the most durable of all resilient-seated butterfly valves in the industry and the premier designed Gate Valve in the oil and gas drilling market, specifically engineered for the rigorous requirements of oilfield applications.

Butterfly valves, concentric resilient seated

  • Model : NE-CNE-INE-D & NF-C
  • Size range : 2 – 36”​
  • Rating : #150 (suits #125 & #150 flanges)​
  • Style : wafer & lug​
  • Neck : long & short

Gate valves for drilling applications

  • Model : DB, DM & DT ​
  • Size range : 2 – 8”​
  • Rating : # 600, 900, 1500 and 5000 & 7500 psi​
  • End connection : flanged, weld ends & hammer union​

BT1 Standard features

As one of the most durable resilient-seated butterfly valves in the industry, the Cameron butterfly-style DEMCO valve excels in a variety of applications.
Cast in both wafer and tapped lug patterns in a variety of material choices, butterfly-style DEMCO valves feature a one-piece body for reduced weight and increased strength.
The unique stem hole design in the disc ensures a dry stem journal. The hard-backed seat enables ease of installation, reliable operation, and infield repairability without special tools. Butterfly-style DEMCO valves are available in sizes 2 to 36 in [50 to 900 mm].
Engineered for long-term, reduced-maintenance performance, butterflystyle DEMCO valves are commonly selected for a variety of applications in the following industries:

  • chemical and petrochemical
  • agriculture
  • oil and gas drilling and production
  • food and beverage
  • water and wastewater
  • cooling towers (HVAC)
  • power
  • mining and materials
  • dry bulk handling
  • marine and government.

Bidirectional sealing

The butterfly-style DEMCO valve provides bidirectional sealing at full-rated pressure with identical flow from either direction.

Integral flange seal

An integral flange seal molded into the edge of the seat accommodates ASME weld neck, slip-on, threaded, socket, and stub-end type C flanges.

ASME Class 150 rating

With a body rating of American Society of Mechanical Engineers (ASME) Class 150 (285-psi nonshock), the wafer body diameters are designed to self-center in the ASME Class 150 flange pattern.

Need to let it flow? Call on Wegman!