DEMCO Series NE-C General-Purpose Butterfly Valve, 2″–12″

The DEMCO Series NE-C is the long-neck, general-purpose member of the DEMCO resilient-seated butterfly valve family. The longer neck length is engineered to provide full clearance of the valve top over two inches of insulation on ASME Class 150 pipe flanges, making it the default selection for insulated process lines, steam-jacketed systems, and any installation where the valve top must clear lagging or cladding. Available in both wafer and lug body styles, in sizes 2″ through 12″, with the full DEMCO range of body / stem / disc materials and seat elastomers. Bi-directional sealing at full rated pressure, with three drop-tight shut-off ratings (200 / 285 / 50 psi) and a throttling option for control-valve service.

Construction

• Body configurations: Wafer and Lug
• Size range: 2″ – 12″ (50 – 300 mm)
• End connections: ASME Class 125/150 flanges (raised- or flat-face)
• Body materials: Cast iron (wafer), ductile iron (lug), aluminium bronze, carbon steel (WCB), aluminium, ENC nickel-plated ductile iron, 316 stainless steel (CF8M), PVF-coated ductile iron
• Stem materials: 416 stainless, 316 stainless, Monel — utility-top option for actuator interchangeability
• Disc materials: 316 SS (CF8M), Monel (M30C), aluminium, bronze, ductile iron, ENC nickel-plated ductile iron, vented, solid SS, Alloy 20 (CN-7M), Hastelloy C (CW-2M), aluminium bronze, PVF-coated ductile iron
• Seat elastomers: Buna-N, Black Neoprene, Hypalon, Viton, EPDM (peroxide-cured), Natural Rubber, White Neoprene, ETM-30230, Fluorosteam, Peroxide-Cured Buna-N
• Bearings: Bronze (standard); throttling discs include 4 stem O-rings for stem sealing.

Performance

• Pressure class: ASME Class 150 (285 psi non-shock body rating).
• Drop-tight shut-off ratings: 200 psi (standard), 285 psi (high-pressure), 50 psi (low-torque), Throttling.
• Vacuum: Sealed against 10 microns of vacuum (29.9 in Hg).
• Temperature range: −30°F to +300°F (−34°C to +149°C) — depends on selected elastomer.
• Bi-directional sealing: Identical drop-tight closure from either flow direction.
• End-of-line service: Lug body suitable for end-of-line service with downstream piping removed (weld-neck or socket flanges only).
• Flow coefficient (Cv at 90° open): 145 (2″) → 7,500 (12″).

Engineered features

• Long neck clears 2″ of insulation on ASME Class 150 flanges — eliminates handle/actuator clearance issues on lagged piping
• One-piece body for minimum weight and maximum strength
• Hard-backed cartridge seat — bonds resilient elastomer to a rigid backing ring; field-replaceable with no special tools
• Triple stem seal: integral flange seal + hard-backed seat + dual O-ring ribs in stem bore (eliminates stem leakage path that is common to "boot-seat" competitive designs)
• Dry stem journal — continuous annular raised land around stem hole prevents fluid behind the seat
• Floating disc — perfectly centres in seat for prolonged service life and drop-tight closure
• Positive stem retention — blowout-proof stem
• Flatted "double-D" upper stem with large flange top — accepts the full DEMCO actuation range
• MSS SP-25 marking is standard

Typical applications

• Chemical and petrochemical process lines (insulated)
• Oil and gas drilling and production utilities
• Steam-jacketed and steam-traced piping
• Cooling towers and HVAC chilled-water service
• Power generation auxiliary systems
• Mining and minerals processing
• Water and waste-water treatment
• Marine and government service

How to order

DEMCO uses an 11-character part number to specify each unique configuration. Build the part number from the base number plus six selection digits:

Example DEMCO base part numbers in this series:

• 22119 (2″, 200 psi)
• 22124 (6″, 200 psi)
• 22127 (12″, 200 psi)
• 22230 (6″, 285 psi)
• 22239 (6″, 50 psi)
• 22248 (6″, throttling)

For your RFQ, please specify: required size, pressure rating, body configuration (wafer or lug), body / stem / disc materials, seat elastomer, and required actuation. Indus Hydraulics will return an estimate against the corresponding DEMCO base part number.

Compliance & marking

• MSS SP-25 marking standard on every valve.
• Body rating to ASME Class 150 (285 psi non-shock).
• Wafer body diameters self-centre in ASME Class 150 flange patterns.
• Triple stem seal: hard-backed cartridge seat + integral flange seal + dual O-ring stem ribs in the seat bore.

Companion products

Manual handles, weatherproof worm-gear operators, and Series DR pneumatic actuators all interchange on this valve via the DEMCO top-flange standard. Compatible Indus SKUs include IH-VAL-BFLY-HDL-10P, IH-VAL-BFLY-HDL-MEM, IH-VAL-BFLY-WGO, IH-VAL-BFLY-DR-DA, IH-VAL-BFLY-STMX. For automated installations, also see the position indicator switch, solenoid valve, pneumatic positioner, and seal-repair-kit accessories listed against the corresponding actuator product.