ZSXDF7 / ZSXDF8 Series — Hazardous Area Fire Isolation Valve
Explosion Proof
Butterfly Valve
for Fire Suppression
CA-FIRE ZSXDF series — dual-certified Ex db IIC T6 Gb / Ex tb IIIC T80°C Db explosion-proof butterfly valve for Zone 1 / Zone 2 hazardous area fire suppression systems. NEPSI certified to GB 3836 (IEC 60079 equivalent; ATEX-equivalent protection levels). Wafer and grooved versions, DN50–DN300, IP66.
Product Overview
ZSXDF Series —
Ex-Certified Fire Isolation
Designed for petrochemical, offshore, and hazardous-area fire suppression installations where standard valves cannot be used.
The CA-FIRE explosion proof butterfly valve (ZSXDF7 / ZSXDF8) is a certified fire protection isolation valve for fire suppression systems operating in Zone 1/2 flammable gas and Zone 21/22 combustible dust classified areas. It integrates a butterfly disc valve body with a supervisory tamper switch inside an IEC 60079-1 flameproof enclosure — delivering real-time valve position monitoring to the fire alarm control panel.
Available in two connection types — wafer (ZSXDF7) installed between pipe flanges, and grooved Victaulic-compatible (ZSXDF8) for mechanical coupling systems. Both share identical Ex db IIC T6 Gb / Ex tb IIIC T80°C Db dual certification, 1.6 MPa working pressure, and DC24V tamper switch output.
At a Glance
| Models | ZSXDF7 / ZSXDF8 |
| Connection | Wafer / Grooved |
| Size Range | DN50 – DN300 |
| Working Pressure | 1.6 MPa |
| Tamper Switch | DC24V 0.5A |
| Body Material | SS316 / GGG40 |
| Media | Water, Foam-water |
| Media Temp. | 4–70°C (0–80°C) |
Key Features
What Sets the ZSXDF Apart
Ex db IIC T6 Gb + Ex tb IIIC T80°C Db
Dual gas and dust explosion-proof certification. IIC covers the most demanding gas group including hydrogen and acetylene. Suitable for Zone 1/2 and Zone 21/22 classified areas — LNG, petrochemical, offshore, paint facilities.
IP66 Outdoor Rating
Complete dust-tight and powerful water jet protection. Suitable for outdoor petrochemical plants, offshore topsides, coastal tank farms, and installations exposed to tropical rain, hose-down, and salt spray.
Integrated Tamper Switch
DC24V 0.5A supervisory switch monitors valve position in real time. Outputs "OPEN", "TAMPER", and "CLOSED" signals directly to the FACP — satisfying NFPA 72 Chapter 17 supervisory signal requirements without additional components.
Wafer (ZSXDF7) + Grooved (ZSXDF8)
Both models share identical Ex certification, pressure rating, and signal output. ZSXDF7 installs between flanges (ANSI 150, DIN PN16, GB PN16). ZSXDF8 uses Victaulic-compatible grooved couplings for faster installation in modular fire systems.
SS316 or GGG40 Body
Stainless steel SS316 recommended for foam concentrate, offshore seawater, and corrosive environments. Cast iron GGG40 for standard onshore fresh-water systems. Both carry the same Ex db IIC T6 Gb certification and 1.6 MPa pressure rating.
AFFF / AR-AFFF / Protein Foam
Rated for water and all major foam-water mixture types at full system operating pressure. EPDM seat resists foam concentrate degradation. Used extensively on tank farm and offshore platform foam suppression headers.
Technical Data
Full Technical Specifications
ZSXDF7 (wafer) and ZSXDF8 (grooved) share identical performance parameters. Connection type is the only difference.
| Parameter | Wafer — ZSXDF7 | Grooved — ZSXDF8 |
|---|---|---|
| Model Number | ZSXDF7-Q-50-300-16-Ex | ZSXDF8-Q-50-300-16-Ex |
| Nominal Diameter | DN50 / DN65 / DN80 / DN100 / DN125 / DN150 / DN200 / DN250 / DN300 | DN50 / DN65 / DN80 / DN100 / DN125 / DN150 / DN200 / DN250 / DN300 |
| Working Pressure | 1.6 MPa | 1.6 MPa |
| Strength Test Pressure | 6.4 MPa | 6.4 MPa |
| Seal Test Pressure | 3.2 MPa | 3.2 MPa |
| Applicable Media | Water, foam-water mixture | Water, foam-water mixture |
| Explosion-Proof Mark | Ex db IIC T6 Gb / Ex tb IIIC T80°C Db | Ex db IIC T6 Gb / Ex tb IIIC T80°C Db |
| Switch Electrical Rating | DC24V 1.5A | DC24V 1.5A |
| Signal Output | DC24V 0.5A (open / closed position) | DC24V 0.5A (open / closed position) |
| Protection Rating | IP66 | IP66 |
| Rated Voltage | AC250V / AC220V / AC125V / DC250V / DC220V / DC125V / DC24V | AC250V / AC220V / AC125V / DC250V / DC220V / DC125V / DC24V |
| Rated Current | ≤ 16A | ≤ 16A |
| Media Temperature | 4–70°C (signal switch version: 0–80°C) | 4–70°C (signal switch version: 0–80°C) |
| Body Material | SS316 / GGG40 (ductile iron) | SS316 / GGG40 (ductile iron) |
| Seat Material | EPDM | EPDM |
| Connection Type | Wafer — between pipe flanges | Grooved — Victaulic-compatible |
| Cable Entry | M20 × 1.5 thread | M20 × 1.5 thread |
Structural Dimensions
Face-to-Face Lengths
ZSXDF7 — Wafer Type (mm)
| DN | 50 | 65 | 80 | 100 | 125 | 150 | 200 | 250 | 300 |
|---|---|---|---|---|---|---|---|---|---|
| L (mm) | 45 | 50 | 50 | 55 | 60 | 60 | 65 | 70 | 80 |
ZSXDF8 — Grooved Type (mm)
| DN | 50 | 65 | 80 | 100 | 125 | 150 | 200 | 250 | 300 |
|---|---|---|---|---|---|---|---|---|---|
| L (mm) | 80 | 80 | 80 | 95 | 102 | 110 | 120 | 160 | 165 |
Operating Principle
How the ZSXDF Explosion Proof Valve Works
Five-stage working principle — from normal supervision to hazardous atmosphere protection.
Normal Open Position — Tamper Supervision
Disc sits parallel to the bore. Minimal flow resistance. The supervisory switch outputs a continuous DC24V "OPEN" signal to the FACP, confirming the water supply path is unobstructed in real time.
Tamper Detection — Partial Movement
If the disc rotates — even slightly — the switch changes state after 1–2 turns and transmits a "TAMPER" supervisory alarm to the FACP per NFPA 72 Chapter 17. Impaired water supply is flagged before any fire event occurs.
Emergency Closure — Full Isolation
The worm gear or lever rotates the disc 90° to the fully closed position. The switch outputs a "CLOSED" signal and the FACP logs the valve status change. Seal test pressure is 3.2 MPa — zero leakage at working pressure.
Hazardous Atmosphere Protection
The IEC 60079-1 flameproof "db" housing contains any internal arc entirely within the enclosure. Surface temperatures do not exceed T6 class (85°C) — well below the ignition temperature of IIC group hydrogen (500°C AIT). Dust "tb" enclosure limits surface temperature to T80°C.
Signal Wiring — FACP Integration
The tamper switch connects to the FACP via a 2-wire supervised circuit through the Ex-rated M20×1.5 cable entry. DC24V 0.5A rating is compatible with Siemens, Notifier, Hochiki, EST, and all major fire alarm panel brands.
ZSXDF vs Standard Signal Butterfly Valve
| Feature | ZSXDF Ex Proof |
ZSXDF7-S Standard |
|---|---|---|
| Working Pressure | 1.6 MPa | 1.6 MPa |
| Tamper Switch | ✓ | ✓ |
| IP Rating | IP66 | IP54 |
| Ex db IIC T6 Gb | ✓ | — |
| Ex tb IIIC T80°C | ✓ | — |
| Zone 1/2 Use | ✓ | — |
| IEC 60079 | ✓ | — |
When You Need This Valve
Specify the ZSXDF series when any part of the fire suppression system passes through a hazardous classified area — Zone 1/2 gas or Zone 21/22 dust. If your project does not involve classified zones, the standard non-Ex signal butterfly valve offers the same tamper switch supervision at lower cost.
Selection Guide
Wafer or Grooved — Which to Choose?
Both models deliver identical explosion-proof performance. Connection type is the only selection criterion.
Wafer Type
Explosion Proof BFV
- Installed between pipe flanges — ANSI 150, DIN PN16, or GB PN16
- Shorter face-to-face length (45–80 mm vs 80–165 mm for grooved)
- Lower hardware cost — requires only flange through-bolts
- Specify when project calls for "wafer butterfly valve, between flanges"
- Ideal where face-to-face envelope is tight
Best for: Flanged pipe systems, onshore fire mains, petrochemical process areas
Grooved Type
Explosion Proof BFV
- Victaulic-compatible grooved mechanical couplings — no flange bolt circle
- Up to 40% faster field installation vs flanged joints
- Allows angular pipe deflection — better on platforms subject to movement
- Easy disassembly for maintenance — no hot work required
- Standard in offshore platform fire mains and modular suppression skids
Best for: Grooved pipe systems, offshore platforms, modular foam suppression skids
Applications
Where the ZSXDF Is Specified
Wherever fire suppression pipework passes through or serves a hazardous classified area.
Petroleum Refineries & Petrochemical Plants
Zone 1/2 classified process areas. Fire water ring mains and foam suppression headers requiring Ex-certified isolation with FACP supervision.
Offshore Oil & Gas Platforms
Topsides fire water main isolation. IP66 protection against salt spray and wash-down. SS316 body for all offshore applications. Grooved ZSXDF8 common on platform topsides.
Tank Farms & Flammable Liquid Terminals
Foam-water suppression systems on above-ground storage tanks per NFPA 30. Grooved ZSXDF8 commonly used on modular tank farm suppression skids.
Paint Spray Booths & Solvent Facilities
Zone 21/22 combustible dust environments. Ex tb IIIC T80°C Db rating covers the highest combustible dust category including metal dusts.
LNG Terminals & Gas Compressor Stations
IIC gas group environments (hydrogen, acetylene) requiring the highest explosion-proof classification. Ex db IIC rating is the most stringent classification available.
Aircraft Hangars & Fuel Systems
IIA/IIB gas group environments. Suitable for foam suppression systems protecting jet fuel storage and dispensing areas per NFPA 409 and IFC.
Chemical & Pharmaceutical API Plants
Hazardous atmosphere isolation on foam suppression and water mist systems. Process vapors creating classified zones require Ex-certified valves with supervisory signal capability.
Underground Mining Operations
Methane (IIA gas group) environments. Fire suppression valve supervision mandated by mining safety regulations. The ZSXDF IIA rating satisfies most mining jurisdictions.
Frequently Asked Questions
Technical Questions Answered
Standards & Compliance
Design, Manufacturing & Test Standards
The ZSXDF series is designed, manufactured, and tested to the following international and Chinese national standards. Chinese NEPSI Ex certification (GB 3836) is equivalent to IEC 60079 and achieves the same protection levels as ATEX and IECEx.
NFPA 13
Installation of Sprinkler Systems
Section 8.16 — water supply control valve supervision requirements. ZSXDF tamper switch satisfies electrical supervision per this section.
NFPA 72
National Fire Alarm & Signaling Code
Chapter 17 — supervisory signal initiating device requirements. ZSXDF switch output meets supervisory signal definition and wiring requirements.
NFPA 30
Flammable and Combustible Liquids Code
Tank farm foam suppression valve specifications. ZSXDF Ex IIC rating covers Zone 1 areas around Class I flammable liquid storage.
IEC 60079 / ATEX Equivalent
Explosive Atmospheres — International Standards
NEPSI certification to GB 3836 (IEC 60079 harmonised) covers Ex db IIC T6 Gb and Ex tb IIIC T80°C Db. This achieves the same protection level as ATEX Category 2G/2D and IECEx certification. For EU ATEX or IECEx project requirements, contact CA-FIRE for third-party verification options.
GB 5135.13
Fire Protection Signal Butterfly Valves
Chinese national standard governing fire protection butterfly valve construction, testing, and marking. Factory hydrostatic test certificate supplied with each unit.
GB 50116
Fire Alarm System Design Code
Chinese design code requiring valve position supervision. ZSXDF tamper switch output satisfies the supervisory signal requirements of this code.
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