D642 Pneumatic Double Eccentric Butterfly Valve

The D642 pneumatic double eccentric butterfly valve — a pneumatic high performance butterfly valve (HPBV) — pairs the cam-lift, double-offset disc of the D342 with a double-acting or spring-return pneumatic actuator for fast remote shut-off from DN50 to DN500. PN6 / PN10 / PN16 flanged ratings, six soft seat materials from −268 to +250°C, 0.4–0.7 MPa air supply and NAMUR-mounted solenoid, limit switch and positioner options for PLC/DCS control.

• Pneumatic double eccentric (high performance) design — cam-lift disc, low actuator torque, long seat life
• DN50–DN500, PN6 / PN10 / PN16, flanged raised-face ends per GB/T 17241 / ISO 7005
• Double-acting (DA) or spring-return fail-close / fail-open actuators; full open-to-close in 3–30 seconds
• 0.4–0.7 MPa clean, dry compressed air; NAMUR solenoid with 24VDC / 220VAC coil options, Ex d IIC T6 on request
• Six soft seats: PTFE, NBR, EPDM, FKM, Silicone, FEP — service from cryogenic to 250°C
• Bi-directional Class VI zero leakage per GB/T 13927; actuator stroke-tested at 0.4 / 0.55 / 0.7 MPa

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.

As a factory-direct manufacturer since 1975, Gaoshan Valve supplies CE-marked, API 6D certified quality at competitive factory pricing, with standard configurations ready for fast global shipment.

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

Why Double Eccentric Means High Performance

“Double eccentric” and “high performance butterfly valve” (HPBV) name the same pattern: two offsets between shaft, disc and seat turn the disc into a cam that lifts cleanly off the seat as it opens. For a pneumatic valve that matters twice over — the actuator sees far less seat friction to overcome, so a smaller actuator sizes the valve, and the seat survives many more cycles at rated pressure.

Low Torque, Smaller Actuator

The disc only contacts the seat at the moment of closure, so breakaway torque stays low even after long idle periods. Lower torque means a smaller, cheaper rack-and-pinion actuator, faster stroking and less air consumption per cycle.

Large Bore, Flanged Rigidity

Double eccentric geometry scales to large diameters with rigid cast-in flanges — the D642 covers DN50–DN500 for automated duty, and the same body pattern continues to DN2000 on the gear-operated D342. That is why the family sits on water transmission mains, cooling loops and plant headers.

Pneumatic vs. Worm Gear in the Same 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

Key Advantages

Fast Pneumatic Automation

Double-acting or spring-return pneumatic actuators deliver full open-to-close in seconds, with speed control via exhaust flow regulators. Direct PLC/DCS integration via solenoid control and NAMUR-standard mounting.

Fail-Safe Spring-Return Option

Configure fail-close (FC) or fail-open (FO) spring-return mode for safety-critical loops — the actuator automatically drives the disc to the safe position on air loss.

Double Eccentric Cam Action

The dual-offset shaft design generates a cam-like wiping motion as the disc opens: the disc lifts cleanly from the seat face with minimal sliding friction, reducing wear and lowering actuator torque requirements.

6 Seat Materials, −268 to +250 °C

Choose from PTFE, NBR, EPDM, FKM, Silicone, or FEP to match any process media and temperature: from cryogenic liquefied gases through to saturated steam and hot oils.

Replaceable Seat Ring

The seat is retained as a serviceable insert: when the elastomer ages or the application changes, the seat can be replaced in-situ by the user without removing the valve body from the pipeline.

Bi-Directional Bubble-Tight Seal

The double eccentric geometry + soft seal achieves zero-leakage performance in both flow directions at rated pressure, meeting Class VI shutoff per GB/T 13927.

Pneumatic Actuator Selection

Select the actuator package from three linked decisions: the action mode (double-acting or spring-return), the fail-safe position the valve must take on air loss, and the control accessories. Every D642 is delivered as a fully assembled and tested package — valve, actuator, solenoid and accessories calibrated and ready to install.

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.

Choosing the Action Mode & Fail-Safe Position

• Double-acting (DA): air pressure opens and closes the valve; on air loss the disc holds its last position. Choose DA for general automation where no defined fail position is required.
• Spring-return fail-close (FC): air opens the valve and the spring closes it on air loss — the standard choice for safety-critical shutoff, fire protection and emergency isolation.
• Spring-return fail-open (FO): air closes the valve and the spring opens it on air loss, for processes where flow must be maintained on air failure (cooling water, ventilation bypass).

Air Supply & Control Accessories

• Air supply: 0.4–0.7 MPa clean, dry compressed air, filtered to 40 µm with a dew point at least 10°C below ambient; add a coalescing filter if plant air is oily or wet.
• Solenoid valve: 5/2 or 3/2 NAMUR-mount pilot valve with 24VDC / 220VAC coil options; explosion-proof Ex d IIC T6 version available.
• Limit switch box: mechanical or proximity switches in weatherproof IP67 or explosion-proof enclosures for open/closed feedback to PLC/DCS.
• Positioner: electro-pneumatic positioner for 4–20mA modulating control and intermediate disc positioning in flow and pressure loops.

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

Applicable Media by Seat Type

• Water / Seawater
• 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)

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	0.6 MPa	0.6 MPa
Size Range	DN50 – DN500 (2″ – 20″)	DN50 – DN500 (2″ – 20″)	DN50 – DN500 (2″ – 20″)
End Connection	Flanged, Raised Face (RF) per GB/T 17241 / ISO 7005	Flanged, Raised Face (RF) per GB/T 17241 / ISO 7005	Flanged, Raised Face (RF) per GB/T 17241 / ISO 7005
Disc Type	Double eccentric (double-offset) disc	Double eccentric (double-offset) disc	Double eccentric (double-offset) disc
Operation	Pneumatic actuator — double-acting or spring-return (FC/FO)	Pneumatic actuator — double-acting or spring-return (FC/FO)	Pneumatic actuator — double-acting or spring-return (FC/FO)
Actuator Air Supply	0.4 – 0.7 MPa compressed air (clean, dry, filtered)	0.4 – 0.7 MPa compressed air (clean, dry, filtered)	0.4 – 0.7 MPa compressed air (clean, dry, filtered)
Seat Type	Soft-seal: PTFE, NBR, EPDM, FKM, Silicone, or FEP	Soft-seal: PTFE, NBR, EPDM, FKM, Silicone, or FEP	Soft-seal: PTFE, NBR, EPDM, FKM, Silicone, or FEP
Applicable Medium	Air, water, sewage, steam, gas, oil, weak acid, alkali	Air, water, sewage, steam, gas, oil, weak acid, alkali	Air, water, sewage, steam, gas, oil, weak acid, alkali
Design Standard	GB/T 12238; GB/T 13927 (pressure test)	GB/T 12238; GB/T 13927 (pressure test)	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)	PTFE / NBR / EPDM / FKM / Silicone / FEP (as selected)	PTFE / NBR / EPDM / FKM / Silicone / FEP (as selected)
Stem / Shaft	2Cr13 Stainless Steel / SS304 / SS316 (on request)	2Cr13 Stainless Steel / SS304 / SS316 (on request)	2Cr13 Stainless Steel / SS304 / SS316 (on request)
Stem Packing	O-Ring (NBR/FKM) / Flexible Graphite	O-Ring (NBR/FKM) / Flexible Graphite	O-Ring (NBR/FKM) / Flexible Graphite
Actuator Body	Extruded Aluminium Alloy (hard anodised)	Extruded Aluminium Alloy (hard anodised)	Extruded Aluminium Alloy (hard anodised)
Actuator Seals	NBR (standard); FKM (high-temp option)	NBR (standard); FKM (high-temp option)	NBR (standard); FKM (high-temp option)
Fasteners	Carbon Steel / Stainless Steel (as specified)	Carbon Steel / Stainless Steel (as specified)	Carbon Steel / Stainless Steel (as specified)

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. Actuator dimensions (H, L1) are 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.

Butterfly Valve Family at a Glance

Type	Models	Seat	Characteristics	Typical Service
Centerline wafer	D71X / D371X / D671X / D971X	Rubber (NBR / EPDM)	Lightest & most economical; PN10 / PN16; ≤135°C	Water, HVAC, general service
Double eccentric (high performance)	D342 / D642 (this page) / D942	Rubber / PTFE	Large bores, PN6–PN16, low operating torque	Water mains, large pipelines
Triple offset (metal seated)	D343H / D363H	Laminated metal	High temperature & high pressure service	Steam, hot oil, petroleum

Browse the whole butterfly valve series or compare the double eccentric drive options: D342 (worm gear), D642 (pneumatic) and D942 (electric).

Structure Drawing

Quality Assurance & Testing

Every D642 pneumatic butterfly valve assembly undergoes the following factory acceptance tests:

• 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.

International Standards & Certification

The D642 is manufactured and tested to Chinese national standards with international equivalents available on request: face-to-face dimensions to GB/T 12238, pressure testing to GB/T 13927, and flange drilling to GB/T 17241 / ISO 7005 as standard. On request we quote and certify to EN 593 or API 609 design equivalents, and an ISO 5211 actuator mounting pad can be machined for actuated versions.

• CE-marked (EU PED) and holding API 6D plus ISO 9001 / ISO 14001 / ISO 45001 management system certification
• China pressure-pipeline valve manufacturing license held by the factory
• Every valve passes shell and seat leakage tests before shipment; factory inspection report included
• EN 593 / API 609 / ISO 5211 conformance documentation on request

Why Buy D642 from Gaoshan Valve

Gaoshan Valve has manufactured industrial valves since 1975 and is CE-marked with API 6D and ISO 9001/14001/45001 certification. We are an approved supplier to Sinopec, CNPC and State Grid, exporting to more than 30 countries.

• 50-year factory — manufacturing industrial valves since 1975
• Certified quality — CE (EU PED), API 6D, ISO 9001/14001/45001, China pressure-pipeline valve manufacturing license
• Trusted by majors — approved supplier to Sinopec, CNPC and State Grid; exports to 30+ countries
• 100% tested — shell test at 1.5×PN, seat test at 1.1×PN, actuator stroke test at 0.4 / 0.55 / 0.7 MPa
• Automation-ready — valve, actuator, solenoid and accessories shipped as one calibrated package

Frequently Asked Questions

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

Related Butterfly Valves

D342 Double Eccentric Butterfly Valve — the same double eccentric body with worm gear drive to DN2000. D942 Electric Double Eccentric Butterfly Valve — electric actuated double eccentric. D343H Triple Eccentric Hard-Seal Butterfly Valve — triple offset metal-seated valve for high-temperature service. D671X Pneumatic Wafer Butterfly Valve — pneumatic centerline wafer valve for small-bore automation.

Get a Quote & 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, and control schematics — reply within 24 hours.

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