D642 Pneumatic Double Eccentric Butterfly Valve
• D642F (PTFE seat) and D642X (rubber seat) pneumatic double eccentric soft-seal butterfly valve, PN6/10/16
• Six seat materials: PTFE, NBR, EPDM, FKM, Silicone, FEP — wide temp range
• Size range DN50–DN500, flanged ends, short and long body variants
• Double-acting or spring-return pneumatic actuator with NAMUR accessory interface
• Suitable for air, water, sewage, steam, gas, oil, and corrosive media
Model: D642F / D642X Series | Pressure: PN6 / PN10 / PN16 | Connection: Flanged (Pneumatic) | Medium: Water, Air, Oil, Gas, Acid
Gaoshan Valve — D642 Pneumatic Double Eccentric Soft-Seal Butterfly Valve
Pneumatic-actuated double-offset (double eccentric) flanged butterfly valve, available with PTFE (F) or rubber (X) seat and 6 seat material options for sizes DN50–DN500 across PN6, PN10, and PN16 pressure ratings. Double-acting and spring-return actuator configurations with NAMUR accessory mounting.
Product Overview
The D642F/D642X is the pneumatic-actuated variant of the D342 double eccentric soft-seal butterfly valve family, delivering fast, reliable remote automation for flanged, double-offset butterfly valves from DN50 through DN500. A rack-and-pinion or scotch-yoke pneumatic actuator — available in double-acting and spring-return (fail-close / fail-open) configurations — replaces the manual worm gear, enabling direct integration into PLC/DCS control systems for water treatment plants, chemical processing, HVAC automation, fire protection, and industrial process lines. The same proven double eccentric cam-lift disc geometry minimises seat friction and extends service life, while the full selection of six seat materials (PTFE, NBR, EPDM, FKM, Silicone, FEP) covers cryogenic to high-temperature applications. Solenoid valve, limit switch, and positioner mounting interfaces are pre-machined via NAMUR standard for rapid field wiring.
Model Designation Guide
| Model Code | Pressure | Body Material | Seat Designation | Operation |
|---|---|---|---|---|
| D642F-6/10/16 | PN6 / 10 / 16 | Specify: —, Q, or C | F = PTFE (polytetrafluoroethylene) | Pneumatic (DA / SR) |
| D642X-6/10/16 | PN6 / 10 / 16 | Specify: —, Q, or C | X = Rubber (NBR / EPDM / FKM / Silicone) | Pneumatic (DA / SR) |
| Body: — | — | Gray Cast Iron / Ductile Iron | Standard body (omitted in code) | General water & low-pressure service |
| Body: Q | — | Ductile Cast Iron (QT450-10) | Example: D642F-10Q | Elevated impact / pressure shock duty |
| Body: C | — | WCB Cast Steel / Stainless Steel | Example: D642X-16C | High pressure, steam, petrochemical |
Seat Material Selection Guide
| Material Code | Seat Material | Max Temp | Min Temp | Working Temp | Best For |
|---|---|---|---|---|---|
| X (FKM) | Fluorine Rubber (Viton) | 82 °C | −40 °C | ≤65 °C | Oils, fuels, chemical media at moderate temp |
| J (NBR) | Nitrile Rubber (Buna-N) | 93 °C | −40 °C | ≤80 °C | Water, petroleum, oil, general industrial |
| YBX (EPDM) | Ethylene Propylene Diene Monomer | 150 °C | −40 °C | ≤120 °C | Steam, hot water, polar fluids, HVAC |
| F (PTFE) | Polytetrafluoroethylene (Teflon) | 232 °C | −268 °C | ≤200 °C | Strong acids, oxidisers, cryogenic, high-temp dry |
| GX (VMQ) | Silicone Rubber | 250 °C | −70 °C | ≤200 °C | Food processing, pharmaceuticals, high-temp air |
| FJ (FEP) | Fluorine Plastic (Fluorinated Polyethylene) | 204 °C | −23 °C | ≤180 °C | Chemical processing, semi-corrosive, high temp |
Key Advantages
Technical Specifications
| Parameter | PN6 | PN10 | PN16 |
|---|---|---|---|
| Nominal Pressure | 6 bar (0.6 MPa) | 10 bar (1.0 MPa) | 16 bar (1.6 MPa) |
| Shell Test Pressure | 0.9 MPa | 1.5 MPa | 2.4 MPa |
| Seal Test Pressure | 0.66 MPa | 1.1 MPa | 1.76 MPa |
| Air Tightness Test | 0.6 MPa | ||
| Size Range | DN50 – DN500 (2″ – 20″) | ||
| End Connection | Flanged, Raised Face (RF) per GB/T 17241 / ISO 7005 | ||
| Disc Type | Double eccentric (double-offset) disc | ||
| Operation | Pneumatic actuator — double-acting or spring-return (FC/FO) | ||
| Actuator Air Supply | 0.4 – 0.7 MPa compressed air (clean, dry, filtered) | ||
| Seat Type | Soft-seal: PTFE, NBR, EPDM, FKM, Silicone, or FEP | ||
| Applicable Medium | Air, water, sewage, steam, gas, oil, weak acid, alkali | ||
| Design Standard | GB/T 12238; GB/T 13927 (pressure test) | ||
Materials of Main Parts
| Component | Standard (—) | Q Body | C Body |
|---|---|---|---|
| Body | Gray Cast Iron / Ductile Iron | Ductile Cast Iron (QT450-10) | WCB Cast Steel / SS |
| Disc | Gray Cast Iron / Ductile Iron | Ductile Cast Iron | Cast Steel / Stainless Steel |
| Seat Ring | PTFE / NBR / EPDM / FKM / Silicone / FEP (as selected) | ||
| Stem / Shaft | 2Cr13 Stainless Steel / SS304 / SS316 (on request) | ||
| Stem Packing | O-Ring (NBR/FKM) / Flexible Graphite | ||
| Actuator Body | Extruded Aluminium Alloy (hard anodised) | ||
| Actuator Seals | NBR (standard); FKM (high-temp option) | ||
| Fasteners | Carbon Steel / Stainless Steel (as specified) | ||
Applicable Media by Seat Type
Sewage / Wastewater
Steam (≤250 °C)
Compressed Air
Natural Gas / Coal Gas
Petroleum / Fuel Oil
Weak Acid
Alkali / Caustic
Food / Beverage
HVAC Hot/Chilled Water
Fire Protection
Cryogenic (LNG / LOX)
Principal Dimensions (mm) — All Pressure Classes
| DN | in. | L (Short) | L (Long) | H1 | H | L1 |
|---|---|---|---|---|---|---|
| 50 | 2 | 108 | 150 | 82 | 320 | 160 |
| 65 | 2½ | 112 | 170 | 92 | 355 | 160 |
| 80 | 3 | 114 | 180 | 102 | 410 | 200 |
| 100 | 4 | 127 | 190 | 112 | 450 | 200 |
| 125 | 5 | 140 | 200 | 128 | 505 | 240 |
| 150 | 6 | 140 | 210 | 145 | 540 | 240 |
| 200 | 8 | 152 | 230 | 185 | 690 | 285 |
| 250 | 10 | 155 | 250 | 220 | 750 | 340 |
| 300 | 12 | 178 | 270 | 250 | 820 | 445 |
| 350 | 14 | 190 | 290 | 280 | 880 | 445 |
| 400 | 16 | 216 | 310 | 316 | 1040 | 505 |
| 450 | 18 | 222 | 330 | 344 | 1100 | 505 |
| 500 | 20 | 229 | 350 | 370 | 1180 | 505 |
L (Short) = compact face-to-face, L (Long) = standard face-to-face; H1 = centerline to top of valve body; H = overall height to top of actuator; L1 = actuator length along pipe axis. All values in mm. PN6 / PN10 / PN16 share identical face-to-face dimensions. L and H1 dimensions verified from D342 body standard. Actuator dimensions (H, L1) are estimated for rack-and-pinion type; consult factory for scotch-yoke or large actuator applications. Flange bolt-circle dimensions refer to GB/T 17241 standard tables.
Pneumatic Actuator Configuration Options
| Option | Description |
|---|---|
| Double-Acting (DA) | Air pressure opens and closes the valve. No fail-safe position on air loss; last position is held. Suitable for general process automation where safety position is not critical. |
| Spring-Return Fail-Close (FC) | Air opens the valve; spring closes on air loss. Standard configuration for safety-critical shutoff applications in process, fire protection, and emergency isolation. |
| Spring-Return Fail-Open (FO) | Air closes the valve; spring opens on air loss. For processes where flow must be maintained on air failure (cooling water, ventilation bypass, etc.). |
| Solenoid Valve | 5/2 or 3/2 NAMUR-mount solenoid pilot valve for remote electrical control. 24VDC / 220VAC coil options. Explosion-proof (Ex d IIC T6) available. |
| Limit Switch Box | Mechanical or proximity (inductive / P+F NAMUR) limit switches for open/closed position feedback to PLC/DCS. Weatherproof IP67 or explosion-proof enclosures. |
| Positioner | Electro-pneumatic positioner for 4–20mA modulating control and intermediate disc positioning. Suitable for flow control, pressure regulation, and cascade loops. |
D642 Pneumatic vs. D342 Worm Gear — Double Eccentric Family
| Feature | D642 Pneumatic | D342 Worm Gear |
|---|---|---|
| Operation | Pneumatic actuator (DA / SR) | Manual worm gear handwheel |
| Automation | Fully automated (PLC/DCS ready) | Manual (actuator pad optional) |
| Fail-safe | Yes (spring-return FC / FO) | Self-locking (stays in position) |
| Response time | 3–30 sec (size dependent) | Manual multi-turn |
| Max size | DN500 | DN2000 |
| Seat materials | 6 materials (same as D342) | 6 materials |
| Best for | Remote automation, safety loops, frequent cycling | Large bore, infrequent operation, cost-sensitive |
Product Structure Diagram
Quality Assurance & Testing
Every D642 pneumatic butterfly valve assembly undergoes the following factory acceptance tests before shipment:
- Shell Pressure Test — hydrostatic test at 1.5×PN to verify body and flange integrity.
- Seat Leakage Test — bi-directional water or air test at 1.1×PN; Class VI zero leakage per GB/T 13927.
- Air Tightness Test — pneumatic seat test at 0.6 MPa to confirm bubble-tight shutoff in gas service.
- Actuator Stroke Test — full open-to-close cycling at minimum, nominal, and maximum air supply pressure (0.4, 0.55, 0.7 MPa) to verify smooth operation and stroke time.
- Accessory Function Test — solenoid valve operation, limit switch signalling, and positioner feedback calibration verified as a complete assembly.
- Dimensional Inspection — face-to-face (short & long), flange bolt-circle, actuator mounting, and NAMUR interface dimensions per GB/T 12238 and VDI/VDE 3845.
- Seat Material Verification — each seat lot is hardness-tested and thermally qualified against the selected material specification.
- Air Piping Leak Test — actuator air circuit pressure-tested at 0.9 MPa; no pressure decay over 3 minutes.
Installation & Maintenance Notes
- Air supply quality: Use compressed air filtered to 40 μm and dew point at least 10 °C below ambient. Install a coalescing filter and lubricator if plant air is oily or wet. For FKM actuator seals, use oil-free dry air.
- Orientation: Install with the shaft horizontal or vertical (preferred for DN300+). Avoid mounting the actuator upside down where condensation may enter the solenoid exhaust port.
- Flange alignment: Align pipe flanges precisely before inserting the valve. Use full-face or spiral-wound gaskets compatible with the media and temperature.
- Disc position during installation: Leave the disc slightly open (5°–10°) to protect the seat edge from flange face damage during bolt tightening.
- Solenoid wiring: Connect solenoid coil to the plant emergency shutdown (ESD) loop if the valve provides a safety function. Verify fail-safe direction (FC/FO) before commissioning.
- Seat replacement: The soft seat is a field-replaceable insert. No special tools required — remove retaining ring, swap seat, re-torque evenly.
- Periodic stroke test: Cycle the valve full stroke at least once per month (quarterly for infrequently operated valves) to prevent actuator seal stiction and verify travel time.
- Actuator lubrication: Rack-and-pinion actuators are factory-lubricated for life. For scotch-yoke types, replenish EP2 grease every 5,000 cycles or annually.
Ordering Information
| Item | Specify When Ordering |
|---|---|
| Model | D642F or D642X — plus pressure class (6 / 10 / 16) and body designation (, Q, or C) |
| Nominal Size | DN50 – DN500 |
| Face-to-Face Length | Short (compact) or Long (standard) |
| Actuator Type | Double-acting (DA) or spring-return (FC / FO) |
| Air Supply Pressure | 0.4 – 0.7 MPa (standard); other on request |
| Accessories | Solenoid valve (24VDC / 220VAC), limit switch box, electro-pneumatic positioner (specify type and enclosure class) |
| Seat Material | FKM (X) / NBR (J) / EPDM (YBX) / PTFE (F) / Silicone (GX) / FEP (FJ) |
| Disc Material | Ductile Iron (standard); SS304 / SS316 / Special alloy on request |
| Shaft Material | 2Cr13 (standard); SS304 / SS316 / Duplex on request |
| Flange Standard | GB/T 17241 (standard); ANSI B16.5 / DIN EN 1092 on request |
Request a Quote or Technical Support
Gaoshan Valve supplies D642 pneumatic double eccentric butterfly valves as fully assembled and tested packages — valve, actuator, solenoid, and accessories calibrated and ready to install. Contact our automation team for actuator sizing, torque calculations, control schematics, and CAD drawings for your specific application.