DEMCO Stem Extension for Butterfly Valves, 2″–24″

The DEMCO stem extension assembly mechanically links the valve's upper stem to a relocated operator (manual handle, gear operator, or pneumatic actuator) up to 16 feet above the valve. Used wherever the operator must be installed at a different elevation than the valve — tank-bottom valves with grade-level operators, buried valves, valves installed inside heavy insulation or cladding, or any inaccessible-installation scenario. Fabricated from carbon-steel or stainless-steel parts contained in a tubular housing, with gaskets and O-rings sealing the stem extension at top and bottom. Lengths from 3″ to 16 ft are fabricated to order; lengths over 16 ft require special design consideration for torsional deflection (special order only).

What it does

Mechanically transmits the rotary motion from a relocated operator down to the valve's upper stem. The tubular housing protects the extension shaft and provides bearing support; the gaskets and O-rings prevent fluid ingress at both ends.

Compatibility

• Compatible valve series: NE-C, NE-I, NE-I Sanitary, NE-D, NEI-T, NF-C (2″–24″; 30″/36″ consult factory)
• Compatible valve sizes: 2″ – 24″ (50 – 600 mm); 30″/36″ require factory consultation
• Mounting standard: DEMCO top-flange standard at both ends — valve flange below, operator flange above

Configuration & trim

Specify the valve series and size, the construction material (carbon steel or stainless steel), and the exact length required in inches (or feet for longer extensions). Lengths over 16 feet require torsional-deflection review at the factory before fabrication. The 14″–24″ NF-C extensions use a different base part number from the 2″–12″ small-valve extensions.

• Actuation method: Mechanical extension between valve top-flange and operator (handle/gear operator/actuator)
• Trim options: Carbon steel or stainless steel construction
• Maximum torque output: Pass-through — does not develop torque; stem material is sized to the valve's rated operating torque
• Supply / input pressure range: N/A (mechanical)
• Weatherproofing / environmental: Tubular housing with gaskets and O-rings sealing the stem extension at top and bottom

Engineered features

• Fabricated to specified length (3″ to 16 ft standard; over 16 ft is special order)
• Carbon-steel or stainless-steel construction
• Tubular housing with sealed gaskets and O-rings at top and bottom
• DEMCO top-flange standard at both ends — accepts any DEMCO operator on the upper end
• Available for 2″–24″ DEMCO valves; 30″ and 36″ NF-C requires factory consultation
• Lengths over 16 ft accommodated with torsional-deflection analysis

Typical applications

• Tank-bottom valves with grade-level manual operators
• Buried-service installations — operator at grade, valve below grade
• Valves installed inside thick insulation or cladding
• Confined-space valves with operators relocated to accessible service points
• High-elevation and below-grade combined installations
• Mezzanine-floor valves with handle-level operators

How to order

For your RFQ, please specify: the DEMCO valve series and size you intend to mount this accessory on, the trim level required (standard, corrosion-resistant or sanitary where applicable), and any environmental requirements (chemical exposure, temperature, IP rating). Indus Hydraulics will return an estimate against the corresponding DEMCO base part number.

Example DEMCO base part numbers in this product family:

• 23318 (2″–4″, carbon steel)
• 23319 (5″–6″, carbon steel)
• 23320 (8″, carbon steel)
• 23321 (10″, carbon steel)
• 23322 (12″, carbon steel)
• 24529 (14″, carbon steel)
• 24532 (24″, carbon steel)

Companion products

This accessory is part of the DEMCO butterfly-valve product family. See the matching valve series in IH-VAL-BFLY-NEC, IH-VAL-BFLY-NEI, IH-VAL-BFLY-NEI-SAN, IH-VAL-BFLY-NED, IH-VAL-BFLY-NEIT and IH-VAL-BFLY-NFC.