DEMCO Series NF-C Large-Bore Butterfly Valve, 14″–36″

The DEMCO Series NF-C extends the DEMCO butterfly-valve product line into large-bore service: 14″ through 36″ (350 mm through 900 mm). Wafer and lug bodies are available across the full range, and the 14″–24″ sizes carry the same hard-backed cartridge seat, dry-stem-journal and triple-stem-seal architecture as the 2″–12″ DEMCO product line. Sizes 30″ and 36″ use a robust upper-and-lower bronze bearing arrangement plus thrust collar to handle the dynamic loads of large-bore service. All sizes are supplied with a worm-gear operator as standard (recommended for 14″ and larger), with Series DR pneumatic actuation available for automated installations. Drop-tight shut-off at 150 psi standard, with 50 psi and throttling-rated options for low-torque service.

Construction

• Body configurations: Wafer and Lug
• Size range: 14″ – 36″ (350 – 900 mm)
• End connections: ASME Class 125/150 flanges (14″–24″); ASME Class 150 Series A and MSS SP-44 (30″–36″)
• Body materials: Ductile iron lug, cast iron wafer, carbon steel lug, 316 stainless steel lug, ENC nickel-plated, PVC-coated ductile iron
• Stem materials: 416 stainless, 316 stainless, Monel
• Disc materials: 316 SS, Monel, aluminium bronze, ductile iron (nickel-plated), PVF-coated ductile iron, bronze (30″–36″ option)
• Seat elastomers: Buna-N, Black Neoprene, Hypalon, Viton, EPDM
• 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: 150 psi (standard) and 50 psi (low-torque) for 14″–36″; Throttling for 14″–24″.
• 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 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): 10,000 (14″) → 70,000 (36″).

Engineered features

• Sizes 14″–36″ (350–900 mm) — the large-bore companion to the NE-C/NE-I/NE-D/NEI-T 2″–12″ product lines
• Same hard-backed cartridge seat and triple stem seal as the small-size DEMCO valves on 14″–24″
• Upper-and-lower bronze bearings plus thrust collar on 30″ and 36″ for large-bore stability
• 30″ and 36″ flanged pattern conforms to ASME Class 150 Series A and MSS SP-44
• Worm-gear operator standard on every 14″ and larger valve (manual lever not practical at this size)
• Series DR pneumatic actuators (EDA350 → PSA4004) cover the torque range for full automation
• Lug-body variant supports end-of-line liquid service to 150 psi with downstream piping removed
• MSS SP-25 marking is standard

Typical applications

• Power-plant cooling-water mains
• Water- and waste-water treatment plants
• Mining tailings and concentrate handling
• Petroleum and petrochemical low-pressure mains
• HVAC chilled-water and condenser-water mains
• Pulp and paper mill stock and white-water lines
• Marine ballast and bilge mains

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:

• 23820 (14″, 150 psi)
• 23822 (18″, 150 psi)
• 23824 (24″, 150 psi)
• 24141 (30″, 150 psi)
• 24357 (36″, 150 psi)
• 24446 (16″, 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-WGO, IH-VAL-BFLY-DR-DA, IH-VAL-BFLY-DR-SR, 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.