CA-FIRE Protection · Fujian, China
Stainless Steel Alarm Valve — ZSFZ-Ex Series SS304 / SS316
DN50–DN350 · Explosion-Proof Ex db IIC T5 Gb · Offshore · Coastal · Chemical Plant · NFPA 13
ZSFZ-Ex Series · SS304 / SS316 · Ex db IIC T5 Gb · GB 5135.1 · NFPA 13
Stainless Steel Alarm Valve — ZSFZ-Ex Series
DN50–DN350 · SS304 / SS316 · Explosion-Proof
A stainless steel alarm valve is specified in place of a standard cast iron wet alarm valve when the installation environment exposes the valve body and alarm components to corrosion that would degrade a painted ductile iron valve within its design service life. Salt-laden coastal air, chemical plant atmospheres, outdoor installations, food processing wash-down environments and hazardous area classified locations all demand the inherent corrosion resistance that only a stainless steel alarm valve body can reliably provide — without dependence on coatings that chip, crack and undercut over time.
CA-FIRE's ZSFZ-Ex Series is a flanged wet-pipe alarm check valve manufactured in SS304 or SS316 stainless steel, available in DN50–DN350 across ten nominal sizes. It delivers the same automatic alarm triggering, one-way check function and hydraulic alarm gong output as a standard cast iron wet alarm valve, with the addition of a stainless steel body engineered for 25+ year service life in corrosive environments. The explosion-proof ZSFZ-Ex variant pairs the SS body with Ex-rated accessories certified for Zone 1 and Zone 2 hazardous area installations.
Quick Specifications
ModelZSFZ 50–350-1.6P / ZSFZ-Ex
ConnectionFlanged (ANSI B16.1 / DIN 2501)
SizesDN50 · 65 · 80 · 100 · 125 · 150 · 200 · 250 · 300 · 350
Working Pressure1.6 MPa (16 bar)
Seal Test3.2 MPa
Strength Test6.4 MPa
Hydraulic Loss<0.08 MPa
Body MaterialSS304 (standard) / SS316 (marine)
Clapper FacingEPDM rubber / PTFE
Temperature4°C – 70°C
InstallationUpright (vertical, flow upward)
Ex RatingEx db IIC T5 Gb (ZSFZ-Ex)
IP RatingIP65 (Ex accessories)
StandardGB 5135.1 · NFPA 13 · ISO 9001
Material Grade Selection
Standard Grade
SS304 Stainless Steel
The standard grade — suitable for inland chemical plant atmospheres, food processing, wastewater treatment and general industrial corrosive environments where chloride ion concentration is low. Provides excellent resistance to oxidising acids and most industrial chemicals. Significantly more corrosion resistant than ductile iron in all conditions.
✓ Specify for: inland chemical plants, food processing, wastewater, general corrosive indoor environments
Marine / Chloride Grade
SS316 Stainless Steel
Contains approximately 2% molybdenum, which provides dramatically improved resistance to chloride-induced pitting and crevice corrosion. The correct specification for any installation within 5 km of the coast, offshore or marine environments, or chemical processing environments where chloride compounds are present. The cost difference between SS304 and SS316 is modest relative to the lifecycle cost of replacing a corroded alarm valve — specifying SS316 in any chloride-risk environment is straightforward engineering economy.
✓ Specify for: coastal / offshore, seawater / salt spray, LNG / petrochemical, direct chloride contact
Key Features
Inherent Corrosion Resistance — No Coating Dependence
The fundamental advantage of a stainless steel alarm valve over a coated ductile iron equivalent is that corrosion resistance is inherent in the material, not dependent on an applied coating. Epoxy coatings on cast iron valves are vulnerable to mechanical damage during installation, thermal cycling and chemical attack from vapours that penetrate microscopic coating defects. Once compromised, rapid under-film corrosion begins — often invisibly. A stainless steel body corrodes at a predictable, extremely slow rate regardless of surface damage from installation or maintenance activity.
Widest Size Range — DN50 to DN350, 10 Sizes
The ZSFZ-Ex covers DN50 through DN350 across ten nominal diameters — a significantly wider size range than most equivalent products. This breadth covers every wet-pipe sprinkler system application, from small branch-line installations at DN50 through to large main riser and primary system applications at DN300–DN350, all from a single product family with consistent dimensional standards, accessory interfaces and maintenance procedures.
Explosion-Proof Variant — Zone 1 & Zone 2 Rated
The ZSFZ-Ex variant pairs the stainless steel alarm valve body with a complete suite of Ex-certified electrical accessories — enabling the complete alarm valve station to be installed in Zone 1 and Zone 2 hazardous area classified locations where flammable gas, vapour or combustible dust atmospheres may be present. This combination — SS body for chemical corrosion resistance plus Ex-rated accessories for hazardous area safety — makes the ZSFZ-Ex the correct specification for petrochemical plants, oil refineries, offshore platforms and grain handling facilities.
Compatible with Standard CA-FIRE Alarm Trim
Despite its premium construction, the ZSFZ-Ex uses the same G3/4 alarm port thread and accessory interface dimensions as CA-FIRE's standard cast iron wet alarm valve series. This means it is directly compatible with CA-FIRE's standard water motor alarm gong, retard chamber and pressure switch — and with Ex-rated accessory variants — without requiring custom alarm port adapters or modified trim pipework. Complete stainless trim accessory packages available on request.
ZSFZ-Ex Explosion-Proof Accessories — Complete Hazardous Area Station
All four electrical accessories are Ex-certified and matched to the ZSFZ-Ex stainless steel alarm valve body for Zone 1 / Zone 2 gas and Zone 21 / Zone 22 dust installations.
💡 Explosion-Proof Pressure Switch CT6
Sends electrical alarm signal to fire alarm control panel on valve trip. DC24V / AC220V. IP65.
Ex db IIC T5 Gb / Ex tb IIIC T95°C Db
🔌 Explosion-Proof Solenoid Valves CT4/CT5/CT6
Controls water flow and system actuation in hazardous area installations. IP66/IP68.
Ex db IIC T6 Gb / Ex tb IIIC T80°C Db
🖥️ Explosion-Proof Control Panel
Deluge system control panel for Ex zones. DC24V / AC220V. IP65.
Ex mb IIC T4 Gb / Ex mb IIIC T130°C Db
🔲 Explosion-Proof Junction Box HY-8A-Ex
Field wiring termination box for Ex zone alarm valve trim connections. IP66.
Ex db II B T6 Gb / Ex tb IIIB T80°C Db
Dimensional Data — All 10 Sizes
| DN Size | Body Height (mm) | Working Pressure | Seal Test | Strength Test | Friction Loss |
|---|---|---|---|---|---|
| DN50 | 270 | 1.6 MPa | 3.2 MPa | 6.4 MPa | <0.08 MPa |
| DN65 | 270 | 1.6 MPa | 3.2 MPa | 6.4 MPa | <0.08 MPa |
| DN80 | 330 | 1.6 MPa | 3.2 MPa | 6.4 MPa | <0.08 MPa |
| DN100 | 340 | 1.6 MPa | 3.2 MPa | 6.4 MPa | <0.08 MPa |
| DN125 | 415 | 1.6 MPa | 3.2 MPa | 6.4 MPa | <0.08 MPa |
| DN150 | 435 | 1.6 MPa | 3.2 MPa | 6.4 MPa | <0.08 MPa |
| DN200 | 555 | 1.6 MPa | 3.2 MPa | 6.4 MPa | <0.08 MPa |
| DN250 | 655 | 1.6 MPa | 3.2 MPa | 6.4 MPa | <0.08 MPa |
| DN300 | 800 | 1.6 MPa | 3.2 MPa | 6.4 MPa | <0.08 MPa |
| DN350 | 850 | 1.6 MPa | 3.2 MPa | 6.4 MPa | <0.08 MPa |
Stainless Steel vs Cast Iron Alarm Valve — Selection Guide
| Factor | SS Alarm Valve ZSFZ-Ex (this product) | Cast Iron Wet Alarm Valve |
|---|---|---|
| Body corrosion resistance | ✓ Inherent — no coating required | Depends on epoxy coating integrity |
| Coastal / marine environment | ✓ SS316 specified | ✗ Not recommended |
| Chemical plant atmosphere | ✓ Suitable | Limited — coating vulnerable |
| Indoor climate-controlled room | Suitable (premium cost) | ✓ Standard specification |
| Explosion-proof requirement | ✓ ZSFZ-Ex variant available | ✗ Not available |
| Food / pharma hygiene | ✓ Stainless required | ✗ Not suitable |
| Outdoor / semi-outdoor | ✓ Recommended | ✗ Not recommended |
| Available size range | ✓ DN50–DN350 (10 sizes) | DN65–DN300 (8 sizes) |
| Initial cost | Higher | ✓ Lower |
| 20-year lifecycle cost (corrosive env.) | ✓ Lower — no replacement cycles | Higher — coating maintenance & replacement |
Application Scenarios
🛢️ Petrochemical Plants & Oil Refineries
Process unit areas, pump rooms, tank farm valve stations and loading gantry fire protection systems are subject to hydrocarbon vapour atmospheres, corrosive process chemical contamination and hazardous area classification — often simultaneously. The ZSFZ-Ex addresses all three: SS316 body for chemical resistance, Ex-rated accessories for Zone 1/2 safety. Standard specification for wet-pipe sprinkler systems in classified petrochemical facility areas.
⚓ Coastal & Port Facilities
Port terminal buildings, harbourside warehouses, marine terminal pump rooms and shipyard facilities within 5 km of the coast require SS316 throughout all fire protection valve assemblies exposed to the salt-air marine atmosphere. The ZSFZ-Ex SS316 provides the chloride corrosion resistance needed for 20+ year service life, replacing the frequent re-coating and premature replacement cycles that characterise cast iron valve installations in coastal locations.
🏗️ Offshore Platforms & Marine Vessels
Engine rooms, pump rooms and accommodation module fire protection systems on offshore oil and gas platforms and large vessels require stainless steel alarm valves that can withstand continuous salt spray, high humidity and the mechanical stresses of offshore installation. The ZSFZ-Ex's flanged connections and stainless body meet the material requirements of major offshore classification society standards.
🍺 Food & Beverage Processing
Food processing plants, breweries, beverage production facilities and cold-chain processing environments specify stainless steel for all equipment surfaces to comply with food safety regulations including HACCP. A stainless steel alarm valve body eliminates the corrosion contamination risk associated with painted cast iron valves in regular wash-down environments, and meets the material consistency requirements of food safety certification schemes.
⚗️ Chemical Manufacturing
Chemical plants producing or handling acids, alkalis, solvents, oxidising agents and other corrosive process chemicals need fire protection valves with body materials resistant to the specific chemicals present in each process area. SS304 covers most general chemical plant atmospheres; SS316 is specified for chlorine, chloride compound and strong acid environments. CA-FIRE's technical team can advise on the correct grade for specific chemical compatibility requirements.
🖥️ Data Centres in Humid Tropical Climates
In tropical and high-humidity climates, data centre fire protection systems installed in buildings without consistent climate control can develop corrosion on standard cast iron alarm valves — particularly in the alarm port trim piping. A stainless steel alarm valve with stainless trim accessories eliminates this corrosion risk in humidity-sensitive installations.
Installation Notes
⚠️ Preventing Galvanic Corrosion at Pipe Transitions
Where the stainless steel alarm valve connects to carbon steel or ductile iron sprinkler pipework, a galvanic cell is formed at the bi-metal interface — the less noble metal (carbon steel) corrodes preferentially. Prevent this by installing dielectric flange gaskets or isolation unions at the transition flanges between the stainless steel alarm valve body and the adjacent carbon steel pipework.
🔩 Flange Gasket Specification
In corrosive environments, specify PTFE envelope or full-face PTFE gaskets at all flange connections, or EPDM rubber gaskets in environments not exposed to hydrocarbon fluids. Standard compressed fibre gaskets are not recommended for long-term service in chemical plant or coastal environments.
🔗 Alarm Accessory Material Consistency
For the stainless steel alarm valve installation to provide full corrosion protection, the alarm trim piping — connections between the alarm port, retard chamber, water motor gong and pressure switch — should also be specified in stainless steel or corrosion-resistant materials. Mixing a stainless valve body with standard brass or carbon steel alarm trim in aggressive environments negates part of the benefit. CA-FIRE can supply complete stainless trim accessory packages on request.
Maintenance Schedule — NFPA 25
One practical advantage of the stainless steel alarm valve in corrosive environments is reduced maintenance burden compared to cast iron equivalents — the stainless body requires no re-coating, rust treatment or anti-corrosion touch-up during routine maintenance cycles.
| Frequency | Task |
|---|---|
| Weekly | Visual inspection — pressure gauges, valve exterior, alarm piping for leaks |
| Monthly | Verify upstream gate valve is open and supervised |
| Quarterly | Water flow alarm test via inspector's test connection — verify water motor gong and pressure switch response |
| Annually | Full internal inspection — clapper, seat, retard chamber, alarm port; check all flange connections for corrosion at gasket faces |
| Every 5 years | Replace EPDM clapper facing if hardening or cracking detected. Inspect PTFE components for deformation. CA-FIRE supplies replacement clapper assemblies by model and DN size. |
Frequently Asked Questions
When should I specify SS316 instead of SS304 for a stainless steel alarm valve?
Specify SS316 for any installation within approximately 5 km of the coast, in direct contact with seawater or salt spray, in offshore or marine environments, or in chemical processing environments where chlorides are present in the atmosphere or process water. For all other corrosive environments without significant chloride risk, SS304 provides adequate protection at lower cost.
If in doubt, specify SS316 — the cost difference is modest and the performance margin in chloride environments is substantial. The consequence of specifying SS304 in a high-chloride environment is pitting corrosion that can progress to through-body penetration over a 5–10 year period — a much more costly outcome than the incremental cost of the SS316 upgrade at time of purchase.
If in doubt, specify SS316 — the cost difference is modest and the performance margin in chloride environments is substantial. The consequence of specifying SS304 in a high-chloride environment is pitting corrosion that can progress to through-body penetration over a 5–10 year period — a much more costly outcome than the incremental cost of the SS316 upgrade at time of purchase.
Can the ZSFZ-Ex stainless steel alarm valve be used in a pre-action or dry pipe system?
No — the ZSFZ-Ex is a wet-pipe alarm check valve, designed for wet pipe sprinkler systems where the downstream pipework is continuously filled with pressurised water. For dry pipe systems in freezing environments, specify the dry alarm valve ZSFC. For pre-action systems in sensitive environments requiring both freeze protection and false-discharge prevention, specify the pre-action alarm valve ZSFY.
Is the explosion-proof ZSFZ-Ex variant available in all sizes?
Yes — the ZSFZ-Ex explosion-proof variant is available across the full DN50–DN350 size range. The Ex rating applies to the electrical accessories (pressure switch, solenoid valve, control panel, junction box) rather than the valve body itself, so the body dimensions and specifications are identical to the standard ZSFZ stainless steel alarm valve. The complete Ex-rated station can be supplied pre-assembled and tested, or as individual components for site assembly.
What is the difference between the stainless steel alarm valve and the standard cast iron wet alarm valve?
The operating principle, alarm port interface, accessory compatibility and performance specifications are identical. The difference is entirely in the body material — stainless steel vs. epoxy-coated ductile iron — and the resulting corrosion resistance, service life in aggressive environments, available size range (DN50–DN350 vs DN65–DN300), and accessory options (Ex-rated accessories available for the stainless series only).
For standard indoor building environments with no corrosion risk, the cast iron wet alarm valve ZSFZ is the cost-effective specification. For corrosive, coastal, outdoor or hazardous area installations, the stainless steel alarm valve is the correct engineering choice.
For standard indoor building environments with no corrosion risk, the cast iron wet alarm valve ZSFZ is the cost-effective specification. For corrosive, coastal, outdoor or hazardous area installations, the stainless steel alarm valve is the correct engineering choice.
Does CA-FIRE supply the complete stainless steel alarm valve station assembly?
Yes. CA-FIRE supplies the stainless steel alarm valve body together with the complete alarm trim assembly — retard chamber, water motor alarm gong, pressure switch, alarm test valve and drain valve — as a complete alarm valve station. Ex-rated accessory variants (pressure switch, solenoid valves, control panel, junction box) for hazardous area installations are available as a matched set, pre-certified for Zone 1/2 gas and Zone 21/22 dust locations.
Contact [email protected] with the DN size, material grade (SS304/SS316), flange standard (ANSI/DIN/GB), and whether Ex-rated accessories are required. CA-FIRE responds with a project quotation, dimensional drawings and Ex certification documentation within 24 hours.
Contact [email protected] with the DN size, material grade (SS304/SS316), flange standard (ANSI/DIN/GB), and whether Ex-rated accessories are required. CA-FIRE responds with a project quotation, dimensional drawings and Ex certification documentation within 24 hours.
Related Products
Get a Quote — ZSFZ-Ex Stainless Steel Alarm Valve
DN50–DN350 · 10 Sizes · SS304 / SS316 · 1.6 MPa · Ex db IIC T5 Gb · GB 5135.1 · NFPA 13 · ISO 9001
Standard or explosion-proof variant · Complete station assembly available · ANSI / DIN / GB flanges · Factory direct · 24 hr quote
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Standard or explosion-proof variant · Complete station assembly available · ANSI / DIN / GB flanges · Factory direct · 24 hr quote