DEMCO Series NE-I Short-Neck Butterfly Valve, 2″–12″

The DEMCO Series NE-I is the short-neck, standard-installation member of the DEMCO butterfly valve family. Designed for installation between ASME Class 125/150 flanges, the NE-I covers the broadest range of body materials of any DEMCO series — including aluminium for low-weight installations and 316 stainless for corrosive-fluid service. Suited to a wide range of applications across many industries, including food and beverage utilities, process flow lines, and general industrial isolation duty. Available in wafer and lug body styles, sizes 2″ through 12″, with three drop-tight shut-off ratings (200 / 285 / 50 psi) plus throttling.

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: Ductile iron, aluminium bronze, carbon steel (WCB), aluminium (wafer only), 316 stainless steel (CF8M), ENC nickel-plated ductile iron, PVF-coated ductile iron
• Stem materials: 416 stainless, 316 stainless (17-4 PH for 8″–12″ upper stem), Monel
• Disc materials: 316 SS, Monel, aluminium, bronze, ductile iron, vented, solid SS, Alloy 20, Hastelloy C, PVF-coated ductile iron, aluminium bronze
• 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

• Short-neck design — installs flush between ASME Class 125/150 flanges without spool-piece adapters
• Broadest body-material range of any DEMCO series — including aluminium (wafer-only) for weight-critical installations
• Hard-backed cartridge seat — field-replaceable with no special tools
• Triple stem seal — integral flange seal + hard-backed seat + dual O-ring ribs
• Dry stem journal eliminates leakage potential behind the seat
• Floating disc with rectangular drive — ensures perfect seat centring and drop-tight closure
• Positive stem retention — blowout-proof stem
• PVF-coated ductile iron disc available for chemically aggressive service at ductile-iron pricing
• MSS SP-25 marking is standard

Typical applications

• Chemical and petrochemical process flow lines
• Food and beverage utility lines (water, steam, cleaning solutions)
• Pharmaceutical and biotech utilities
• Pulp & paper process lines
• Power-plant condensate and cooling water
• Mining slurry and tailings (with appropriate elastomer)
• Marine and shipboard auxiliaries
• General industrial isolation duty

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:

• 22128 (2″, 200 psi)
• 22133 (6″, 200 psi)
• 22136 (12″, 200 psi)
• 22257 (6″, 285 psi)
• 22266 (6″, 50 psi)
• 22275 (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-2P, IH-VAL-BFLY-WGO, IH-VAL-BFLY-DR-DA, IH-VAL-BFLY-DR-SR. For automated installations, also see the position indicator switch, solenoid valve, pneumatic positioner, and seal-repair-kit accessories listed against the corresponding actuator product.