D671X Pneumatic Wafer Butterfly Valve

The D671X pneumatic actuated wafer butterfly valve is the automated member of our centerline, resilient seated wafer butterfly valve family: a rubber-lined disc valve driven by a double-acting or spring-return pneumatic actuator for fast, reliable remote shut-off from DN50 to DN500. Full open-to-close in 3–15 seconds, direct PLC/DCS integration via solenoid control, and the same Buna-N (NBR) bi-directional seal as the manual D71X — PN10 / PN16, up to 135°C.

• Pneumatic actuated centerline wafer design — double-acting (DA) or spring-return fail-close / fail-open
• DN50–DN500, six variants: gray cast iron / ductile iron / WCB cast steel bodies at PN10 and PN16
• 0.4–0.7 MPa clean, dry compressed air supply; NAMUR-mount solenoid with 24 VDC / 220 VAC coil options
• Fail-safe spring-return drives the disc to the safe position automatically on air loss
• Pre-machined NAMUR and ISO 5211 interfaces accept solenoid valves, limit switch boxes and 4–20 mA positioners
• Water, steam, petroleum, weak acid and alkali service up to 135°C; zero leakage per GB/T 13927

Product Overview

The D671X is the pneumatic-actuated variant of the D71X wafer butterfly valve family, delivering fast, reliable remote automation for centerline-disc, rubber-seated butterfly valves from DN50 through DN500. A rack-and-pinion or scotch-yoke pneumatic actuator, available in double-acting and spring-return configurations, replaces the manual lever or gearbox, enabling integration into PLC/DCS control systems for water treatment plants, HVAC automation, fire protection, and industrial process lines. The same six body/pressure variants (PN10 and PN16, in gray cast iron, ductile cast iron, or WCB cast steel) and the same Buna-N elastomer seat provide proven bi-directional shutoff performance. Standard solenoid valve, limit switch, and positioner mounting interfaces come pre-machined 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	Pressure	Body Material	Operation
D671X-10	PN10	Gray Cast Iron (HT200)	Pneumatic (DA / SR)
D671X-10Q	PN10	Ductile Cast Iron (QT450)	Pneumatic (DA / SR)
D671X-10C	PN10	WCB Cast Steel	Pneumatic (DA / SR)
D671X-16	PN16	Gray Cast Iron (HT200)	Pneumatic (DA / SR)
D671X-16Q	PN16	Ductile Cast Iron (QT450)	Pneumatic (DA / SR)
D671X-16C	PN16	WCB Cast Steel	Pneumatic (DA / SR)

Key Advantages

Fast Remote 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.

Fail-Safe Spring-Return Option

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

Compact Wafer Design

Short face-to-face length (43–127 mm) minimises pipeline space. Installs between any standard PN10/16 flanges without dedicated lugs or bolts.

Accessory-Ready Mounting

Pre-machined NAMUR interface on the actuator accepts solenoid valves, limit switch boxes, and electro-pneumatic positioners without adapter plates.

Full NBR Elastomer Seal

Buna-N rubber seat ring and O-ring provide zero-leakage bi-directional shutoff across the full rated pressure range, tested per GB/T 13927.

Three Body Materials

Gray cast iron for fresh water economy, ductile iron for impact resistance, WCB cast steel for steam/petrochemical duty — all interchangeable in the same piping envelope.

Pneumatic Actuator Selection

Select the actuator 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 D671X 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.
Spring-Return Fail-Close (FC)	Air opens the valve; spring closes on air loss. Standard for safety-critical shutoff applications.
Spring-Return Fail-Open (FO)	Air closes the valve; spring opens on air loss. For processes where flow must be maintained on air failure.
Solenoid Valve	5/2 or 3/2 NAMUR-mount solenoid pilot valve for remote electrical control. 24VDC / 220VAC coil options.
Limit Switch Box	Mechanical or proximity limit switches for open/closed position feedback to the control room.
Positioner	Electro-pneumatic positioner for 4–20mA modulating control and intermediate disc positioning.

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 loops and ESD service.
• 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.

Air Supply & Control Accessories

• Air supply: 0.4–0.7 MPa clean, dry compressed air; filter to 40 µm with a dew point at least 10°C below ambient. Add a coalescing filter and lubricator if plant air is oily or wet.
• Solenoid valve: 5/2 or 3/2 NAMUR-mount pilot valve with 24 VDC / 220 VAC coil options for remote electrical control.
• Limit switch box: mechanical or proximity switches for open/closed position feedback to the control room.
• Positioner: electro-pneumatic positioner for 4–20 mA modulating control and intermediate disc positioning.
• Mounting: NAMUR interfaces pre-machined on the actuator; ISO 5211 top pad on the valve for actuator interchange.

Technical Specifications

Parameter	PN10 Models	PN16 Models
Nominal Pressure (PN)	10 bar (1.0 MPa)	16 bar (1.6 MPa)
Shell Test Pressure	1.5 MPa	2.4 MPa
Seal Test Pressure	1.1 MPa	1.8 MPa
Working Temperature	≤ 135 °C	≤ 135 °C
Size Range	DN50 – DN500	DN50 – DN500
End Connection	Wafer (between-flange, centerline)	Wafer (between-flange, centerline)
Operation	Pneumatic actuator (DA or spring-return)	Pneumatic actuator (DA or spring-return)
Actuator Air Supply	0.4 – 0.7 MPa compressed air (clean, dry)	0.4 – 0.7 MPa compressed air (clean, dry)
Applicable Medium	Steam, water, petroleum, weak acid, alkali	Steam, water, petroleum, weak acid, alkali
Design Standard	GB/T 13927 (pressure test); GB/T 12238 (face-to-face)	GB/T 13927 (pressure test); GB/T 12238 (face-to-face)

Applicable Media

• Steam (≤135°C)
• Water
• Seawater
• Petroleum
• Fuel Oil
• Weak Acid
• Alkali
• HVAC Water
• Fire Protection

Materials of Construction

Component	D671X-10 / -16	D671X-10Q / -16Q	D671X-10C / -16C
Body	Gray Cast Iron (HT200)	Ductile Cast Iron (QT450)	WCB Cast Steel
Seat Ring	Buna-N Rubber (NBR)	Buna-N Rubber (NBR)	Buna-N Rubber (NBR)
Stem / Worm	2Cr13 Stainless Steel	2Cr13 Stainless Steel	2Cr13 Stainless Steel
Disc	Ductile Cast Iron (QT450)	Ductile Cast Iron (QT450)	Ductile Cast Iron (QT450)
Axis Bushing	Aluminium Bronze	Aluminium Bronze	Aluminium Bronze
O-Ring Seal	Buna-N Rubber (NBR)	Buna-N Rubber (NBR)	Buna-N Rubber (NBR)

Principal Dimensions (mm) — PN10 / PN16

DN	H1	H2	H3	L	L1
DNDN50	68	118	115	43	185
DNDN65	82	140	132	46	240
DNDN80	85	150	132	46	240
DNDN100	105	180	132	52	240
DNDN125	128	200	155	56	285
DNDN150	138	210	190	56	340
DNDN200	175	245	190	60	340
DNDN250	205	280	222	68	445
DNDN300	245	320	265	78	505
DNDN350	265	340	265	78	505
DNDN400	295	380	265	102	505
DNDN450	326	420	265	114	505
DNDN500	345	460	265	127	505

H1 = centerline to top of body; H2 = centerline to top of actuator; H3 = actuator center height; L = face-to-face length; L1 = actuator length (along pipe axis). All values in mm. PN10 and PN16 share identical external dimensions; flange connection dimensions refer to the standard flange dimension table. Air supply: 0.4–0.7 MPa clean, dry compressed air.

Drive Options: Manual Lever vs. Worm Gear vs. Pneumatic

Feature	D71X (Lever)	D371X (Gear)	D671X (Pneumatic)
Drive	Manual lever	Worm gear handwheel	Pneumatic actuator
Size range	DN40 – DN200	DN50 – DN500	DN50 – DN500
Automation	Manual only	Actuator-ready pad	Fully automated (PLC/DCS)
Fail-safe	No	No (gearbox self-locking)	Yes (spring-return option)
Response time	Manual (slow)	Manual (multi-turn)	3–15 sec (adjustable)

Rule of thumb: the lever-operated D71X for small bores and occasional operation, the gear-operated D371X where larger bores are cycled by hand, and the D671X wherever the line must respond to a control signal or a fail-safe position is required. Need electric instead of pneumatic? See the electric actuated D971X.

Butterfly Valve Family at a Glance

Type	Models	Seat	Characteristics	Typical Service
Centerline wafer	D71X / D371X / D671X (this page) / D971X	Rubber (NBR / EPDM)	Lightest & most economical; PN10 / PN16; ≤135°C	Water, HVAC, general service
Double eccentric (high performance)	D342 / D642 / 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 drive options for the same wafer body: D71X (manual lever), D371X (worm gear), D671X (pneumatic) and D971X (electric).

Structure Drawing

Quality Assurance & Testing

Every D671X pneumatic butterfly valve assembly undergoes the following factory acceptance tests:

• Shell Pressure Test — hydrostatic test at 1.5×PN to verify body integrity.
• Seat Leakage Test — air or water test at rated pressure; zero seat leakage per GB/T 13927.
• Actuator Stroke Test — full open-to-close cycling at minimum, nominal, and maximum air supply pressure 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, flange, and actuator mounting dimensions checked against GB/T 12238 and NAMUR standards.
• Visual & NDT — casting and weld surfaces inspected; air piping leak-tested at 0.8 MPa.

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.
• Orientation: D671X valves may be installed in any pipe orientation. Avoid mounting the actuator upside down where condensation may enter the solenoid exhaust port.
• Flange bolts: Use through-bolts to clamp both pipe flanges together through the wafer body. Tighten in a cross pattern to avoid rubber seat distortion.
• Solenoid wiring: Connect solenoid coil to the plant emergency shutdown (ESD) loop if the valve provides a safety function. Verify fail-safe direction before commissioning.
• Stem packing: The stem uses O-ring sealing; no packing adjustment required. Replace O-rings if leakage detected during service.
• Periodic stroke test: Cycle the valve full stroke at least once per month (quarterly for infrequently operated valves) to prevent actuator seal stiction.

International Standards & Certification

The D671X family 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 as standard. On request we quote and certify to EN 593 or API 609 design equivalents, and the ISO 5211 actuator mounting pad is machined as standard.

• 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 conformance documentation on request

Why Buy D671X 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 — every assembly passes shell test, seat leakage test and actuator stroke test before shipment
• Automation-ready — valve, actuator, solenoid and accessories shipped as one calibrated package

Frequently Asked Questions

Ordering Information

Item	Specify When Ordering
Model	D671X-10 / 10Q / 10C / 16 / 16Q / 16C
Nominal Size	DN50 – DN500
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, limit switch, positioner (specify type)
Flange Drilling / Seat / Disc	GB/T 17241 (standard); NBR seat; ductile iron disc

Related Butterfly Valves

D971X Electric Wafer Butterfly Valve — the same wafer body with electric on/off or modulating control. D71X Wafer Butterfly Valve — the manual lever version for small bores. D371X Gear-Operated Wafer Butterfly Valve — worm gear operation. D642 Pneumatic Double Eccentric Butterfly Valve — pneumatic double eccentric pattern for larger mains.

Get a Quote & Technical Support

Gaoshan Valve supplies D671X pneumatic wafer 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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