Pre Action Deluge Valve — 2.5MPa Piston Type, Anti-False Discharge (DN50–DN300)
✓ Anti-False Discharge — Dual-Condition Logic✓ Water Hammer Protection✓ Auto Cyclic Reset 自动循环启闭✓ 2.5 MPa Working Pressure✓ Metal Piston + O-Ring Seals✓ DN50–DN300 · 9 Sizes✓ -20°C to +70°C✓ Water + AFFF/AR-AFFF 6%✓ ≥ 15 Year Service Life✓ GB 5135.7 · NFPA 13 / 30 / 409 · ISO 9001
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CA-FIRE's pre action deluge valve (Model ZSFS 50–300-2.5J(Ex)) is a pressurised piston-type fire suppression control valve rated at 2.5 MPa working pressure, with three protective functions not available on standard diaphragm deluge valves: anti-false discharge (dual-condition activation — a single detector fault or transient signal cannot open the valve), water hammer protection (controlled piston opening rate eliminates pressure surge at 2.5 MPa), and automatic cyclic reset (valve opens on fire, closes when detection clears, reopens on reignition — no manual intervention). Available DN50–DN300 in 9 sizes, flanged, with full factory test documentation. For standard 1.6 MPa single-activation applications, see the diaphragm deluge valve. Pre action deluge valve vs pre action alarm valve: This valve controls open-orifice nozzle systems — simultaneous total-zone discharge on activation. The pre-action alarm valve controls closed-head sprinkler systems where individual heads open thermally above a fire. Specify this valve for warehouse, tank farm, hangar, and substation total-zone coverage. Specify the alarm valve for pre-action sprinkler configurations with individual head response.
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Dimensional Data — DN50 to DN300
| DN | DN50 | DN65 | DN80 | DN100 | DN125 | DN150 | DN200 | DN250 | DN300 |
|---|---|---|---|---|---|---|---|---|---|
| Height (mm) | 270 | 270 | 320 | 320 | 365 | 365 | 480 | 610 | 690 |
| Working pressure | 2.5 MPa across all sizes | ||||||||
| Seal test | 5.0 MPa across all sizes | ||||||||
| Strength test | 10.0 MPa across all sizes | ||||||||
Piston-Type Pre Action Valve vs Diaphragm Deluge Valve
Both are normally-closed fire suppression control valves. The piston-type pre action valve adds three critical protective functions that the standard diaphragm design cannot provide — at higher cost. The selection is determined by the consequences of false discharge and the supply pressure of your system.
| Feature | Piston Pre Action Valve ZSFS 2.5J (This Product) |
Diaphragm Deluge Valve ZSFM 1.6 MPa |
|---|---|---|
| Sealing element | ✓ Metal piston + O-ring — no rubber fatigue | EPDM rubber diaphragm — periodic replacement |
| Working pressure | ✓ 2.5 MPa | 1.6 MPa |
| Anti-false discharge | ✓ Dual-condition logic — built in | Not standard — single signal opens valve |
| Water hammer protection | ✓ Controlled opening rate — built in | Not standard |
| Auto cyclic reset | ✓ Automatic — open/close cycles without manual intervention | Manual reset required after each activation |
| Temperature range | ✓ -20°C to +70°C — metal piston, no rubber limit | 4°C to 70°C — EPDM limits low-temp use |
| Maintenance | ✓ O-ring inspection — no scheduled rubber replacement | Periodic diaphragm replacement (every 2–5 yrs) |
| Cost | Higher initial cost | ✓ More economical |
| Specify when | False discharge is catastrophic · Supply > 1.6 MPa · Auto reset required · Warehouse / hangar / substation | Standard single-activation deluge sufficient · Cost is priority |
Three Protective Functions — What Makes This Different
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🛡️ Anti-False Discharge — Dual-Condition Logic False discharge is the most operationally damaging failure mode in a deluge system. A single faulty detector, accidental manual contact, or transient electrical interference can open a standard deluge valve and flood an entire zone — causing water damage to inventory, equipment, or processes that may exceed the value of fire damage the system was installed to prevent. The piston pre action valve eliminates this through dual-condition activation: the piston stays closed until both a confirmed fire detection signal and the required control circuit pressure condition are simultaneously satisfied. Neither condition alone is sufficient. This makes it the mandatory specification for environments where false discharge consequences are severe — aircraft hangars, electrical substations, cold storage, warehouses, museums, and data centres where water discharge causes damage comparable to or exceeding fire loss. |
💧 Water Hammer Protection — Controlled Opening At 2.5 MPa supply pressure, a deluge valve opening instantaneously into empty downstream pipework creates a pressure wave — water hammer — capable of fracturing open-orifice nozzle bodies, displacing pipe supports, causing joint leakage, and damaging instrumentation across the distribution system. This is an engineering consequence of physics, not a product defect, and cannot be resolved by over-specifying pipe wall thickness alone. The piston mechanism controls the rate of valve opening — moving from closed to fully open in a measured sequence rather than snapping open instantly. Downstream pipework pressurises progressively, eliminating the destructive pressure transient. At 2.5 MPa, water hammer protection is an engineering requirement for system integrity, not an optional feature — and it is built into the piston mechanism without additional external components. |
🔄 Auto Cyclic Reset — 自动循环启闭 Standard deluge valves require manual reset after each activation: close the valve, re-pressurise, drain downstream pipework, return to standby. In a fire that partially suppresses and reignites, this manual sequence leaves the protected area unprotected during the reset procedure — a critical gap in active fire events in unmanned facilities. The automatic cyclic reset (自动循环启闭) allows the piston valve to open on confirmed fire detection, close automatically when detection clears, and reopen immediately on reignition — repeating as many times as fire conditions demand, without any manual intervention at the valve station. This maintains continuous suppression capability throughout complex multi-stage fire events — critical for large logistics warehouses, unmanned tank farms, and facilities where access to the valve room during an active fire is hazardous. |
Working Principle — 2.5 MPa Piston Pre Action System
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① Pressurised Standby — Supervised Circuit The piston is held closed against the valve seat by the pressurised control circuit. Downstream pipework and all open nozzles are empty at atmospheric pressure. Loss of control circuit pressure automatically triggers a supervisory alarm — the pressurised circuit itself provides continuous system integrity monitoring without requiring any additional supervision devices. |
② Dual-Condition Confirmation A fire detector signals the control panel. The panel simultaneously verifies the fire detection signal and the control circuit condition. Only when both conditions are confirmed simultaneously does the panel energise the solenoid trim valve. A detection signal alone, or a circuit pressure change alone, cannot open the piston — false discharge from a single fault is physically impossible. |
③ Controlled Piston Opens The solenoid releases control circuit pressure. Supply pressure (up to 2.5 MPa) acts on the piston, which moves from closed to fully open in a controlled rate sequence — not instantaneously. Downstream pipework pressurises progressively, eliminating water hammer. Full bore opens within the response time specification. Water flows at full rate into distribution pipework. |
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④ Simultaneous Total-Zone Discharge Water discharges simultaneously from every open nozzle across the entire protected zone — total-area suppression at 2.5 MPa supply pressure. Water motor gong activates hydraulically; alarm pressure switch sends confirmation to fire panel. At 2.5 MPa, nozzle discharge pressure and density exceed what a 1.6 MPa system can achieve in high-hazard or long-pipe-run applications. |
⑤ Automatic Reset on Detection Clear When fire detectors clear, the control circuit automatically re-pressurises and the piston reseats — valve closes, discharge stops. If detectors reactivate, the valve opens again automatically, without any manual intervention at the valve station. This cycle repeats as many times as fire conditions require, maintaining continuous protection throughout complex multi-stage fire events. |
⑥ Manual Final Reset to Standby After fire event confirmation and approval to return to full standby: isolate upstream supply, drain downstream pipework via drain valve, inspect the distribution system and nozzle array, restore detection circuit, re-pressurise the system and confirm supervisory circuit integrity. Return to supervised pressurised standby. Factory test report and O&M manual cover the full reset procedure. |
Applications — Where the Pre Action Deluge Valve Is Mandatory
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Commodity Warehouses & Logistics Centres Large warehouses storing paper, textiles, electronics, and packaged goods — where water discharge from a false alarm causes product losses comparable to a moderate fire. Anti-false discharge logic prevents single-detector faults from triggering discharge. The 2.5 MPa rating supplies large-area nozzle arrays across long spans without pressure shortfall. Automatic cyclic reset maintains protection during reignition events without requiring personnel to re-enter the building. Compliant with NFPA 13 pre action system requirements. False discharge prevention · 2.5 MPa large area · NFPA 13 |
Electrical Substations & Switchgear Rooms High-voltage equipment where water contact during a false alarm causes short circuits, equipment destruction, and arc flash events far more damaging than a contained electrical fire. Dual-condition activation prevents water from reaching live equipment from anything other than a confirmed fire event. Standard specification for transformer bay, main switchgear, and primary circuit protection in power generation and distribution facilities. Arc flash prevention · Confirmed-fire only · Substation standard |
Aircraft Hangars & Aviation Fuel Facilities Aircraft hangars and aviation fuel tank farms where false discharge onto aircraft causes structural damage, foam contamination, and airside operational shutdown. The 2.5 MPa pressure achieves required discharge density across large unobstructed hangar floor areas without pressure shortfall at the perimeter nozzles. Automatic cyclic reset ensures continued protection if fuel fire reignites after initial suppression. Applicable per NFPA 409 aircraft hangar protection standards. NFPA 409 · Large floor area · Aircraft protection |
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Tank Farms & Chemical Storage Bunds Above-ground storage tank bunds and chemical warehouses where 2.5 MPa supply maintains design discharge density across large protected perimeters with long distribution pipe runs. Automatic cyclic reset is critical during complex multi-stage fire events — flammable liquid fires often reignite from residual vapour after initial suppression, and manual reset would leave the area unprotected during the reset procedure. Per NFPA 30 flammable liquid protection and GB 50151 foam system requirements. NFPA 30 · Tank farm · Cyclic reset for reignition |
Manufacturing Facilities & Process Buildings Production lines and automated manufacturing facilities with high-value machinery — where false discharge causes production shutdown, equipment damage from water ingress into precision machinery, and extended restart downtime. Pre-action dual-condition confirmation ensures suppression water reaches the production floor only on confirmed fire detection, not from detector faults caused by steam, dust, or process vapours that routinely trigger standard detectors in manufacturing environments. Production continuity · Water ingress prevention · Process vapour false alarms |
Airports & Large Public Assembly Buildings Large public facilities where false alarm discharge creates evacuation panic, injury risk in crowded environments, and major operational disruption with significant remediation cost. Airport terminal buildings, convention centres, and sports arenas require the confirmation layer that dual-condition logic provides in high-occupancy environments where evacuation consequences of a false discharge are themselves a significant safety and liability event. 2.5 MPa ensures adequate pressure across long distribution runs in large-footprint buildings. High occupancy · Evacuation risk · Large footprint building |
Factory Quality Control — Test Report with Every Valve
Before shipment, every ZSFS pre action piston deluge valve completes the following factory tests — all results recorded in the test report issued with the valve:
| Test | Specification & What It Confirms |
|---|---|
| Hydrostatic strength test | 10.0 MPa — four times working pressure. Confirms casting integrity and pressure rating under extreme transient conditions. |
| Seal integrity test | 5.0 MPa — twice working pressure, zero leakage confirmed. Validates O-ring and piston seat sealing at twice the maximum operating pressure. |
| Dual-condition logic verification | Single-condition inputs verified non-activating. Confirmed: detection signal alone cannot open piston; circuit change alone cannot open piston. Both required simultaneously. |
| Water hammer test | Controlled piston opening sequence confirmed — downstream pressure rise rate measured and verified against specification. |
| Cyclic reset test | Minimum three consecutive automatic open/close cycles confirmed — reset time, reseat seal integrity, and cycle repeatability all recorded. |
| Dimensional inspection | Flange face geometry and connection dimensions verified against drawing tolerances for all DN sizes. |
Applicable Standards & Certifications
| Standard | Scope |
|---|---|
| GB 5135.7-2019 | 自动喷水灭火系统 第7部分 — Chinese national standard governing deluge valve performance, pressure rating, and type approval. National fire product certification held for ZSFS series. |
| GB 50084 / GB 50151 | Automatic sprinkler system design and foam fire extinguishing system design codes — applicable when the ZSFS valve is integrated into foam-water pre action systems for flammable liquid and warehouse protection. |
| NFPA 13 | Standard for the Installation of Sprinkler Systems — pre action system configuration requirements. Cv hydraulic data available per DN size for NFPA hydraulic calculations on export projects. |
| NFPA 30 | Flammable and Combustible Liquids Code — deluge system requirements for tank farm and bunded storage protection. |
| NFPA 409 | Standard on Aircraft Hangars — deluge system requirements for aircraft hangar foam-water suppression, where pre action confirmation and 2.5 MPa pressure are both commonly required. |
| IEC 60079 series | Ex certification standards — applicable for the Ex-rated solenoid and electrical trim components. Ex-rated model available for Zone 1/2 hazardous area installations requiring both pre-action logic and Ex compliance. |
| ISO 9001:2015 | CA-FIRE QMS certification covering piston machining inspection, pressure testing, dual-condition logic verification, cyclic reset testing, and shipment documentation for all ZSFS products. |
Frequently Asked Questions — Pre Action Deluge Valve
What is the difference between a pre action deluge valve and a standard deluge valve?
A standard deluge valve opens immediately on a single fire signal — fast confirmed-fire response but vulnerable to false discharge from detector faults, accidental manual activation, or transient electrical interference. A pre action deluge valve requires dual-condition confirmation before the piston opens, preventing false discharge while maintaining fast confirmed-fire response.
CA-FIRE's piston-type pre action model adds two further features unavailable on standard diaphragm valves: water hammer protection at 2.5 MPa (controlled opening rate prevents destructive pressure surge in empty downstream pipework) and automatic cyclic reset (valve opens on fire, closes when detection clears, reopens on reignition — without manual intervention). These three protections together make the pre action piston valve the correct specification wherever false discharge would cause damage comparable to or greater than a fire, or where reignition in an unmanned facility is a realistic scenario.
What is the difference between this valve and the pre action alarm valve?
These control fundamentally different fire suppression systems serving different hazard profiles.
This pre action deluge valve controls open-orifice nozzle systems — total-area simultaneous discharge across the entire protected zone on activation. All nozzles discharge together on confirmation. Correct specification for warehouse rack storage, tank farms, aircraft hangars, substations, and industrial process protection where total-zone coverage is required.
The pre-action alarm valve controls closed-head sprinkler systems — individual sprinkler heads respond thermally and open one at a time above the fire. Water is delivered only to the location of the fire, not the entire zone. Correct specification for data centres, archives, cold storage, and library stacks where minimising water discharge area is important and individual head response is acceptable for the hazard.
Why does this valve use a piston instead of a diaphragm?
Three engineering requirements at 2.5 MPa that a rubber diaphragm cannot satisfy. First, controlled opening rate for water hammer prevention: a metal piston can be engineered to move at a controlled speed; a diaphragm snaps open rapidly as soon as control pressure is removed, generating water hammer at 2.5 MPa. Second, operating temperature range: the metal piston with O-ring seals operates from -20°C to +70°C — EPDM diaphragms are limited at low temperatures and can become brittle in cold climates. Third, maintenance profile: O-ring inspection and replacement is simpler and less frequent than periodic full diaphragm replacement, reducing planned maintenance cost over the valve's ≥15 year service life.
Diaphragm valves are the correct and more economical specification for standard 1.6 MPa single-activation deluge applications — see the diaphragm deluge valve. The piston design is the appropriate engineering response to the 2.5 MPa pre-action duty with water hammer and cyclic reset requirements.
How does automatic cyclic reset work — and why does it matter?
When fire detectors in the protected zone clear — because the fire is suppressed below the detection threshold, or the detector itself resets — the control circuit automatically re-pressurises and the piston reseats, closing the valve and stopping discharge. If detectors reactivate (reignition, fire spread to adjacent area), the valve opens again automatically. This cycle repeats without any manual intervention at the valve station, for as many cycles as fire conditions require.
In practice this matters most in three scenarios: (1) large logistics warehouses where a fire in one rack area may suppress partially and reignite from adjacent combustibles — without cyclic reset, the protected area is unprotected during manual reset while the fire is still active; (2) unmanned facilities (unmanned substations, remote tank farms) where there is no personnel on site to perform manual reset during an active fire event; (3) complex industrial fires (flammable liquid spills, transformer fires) where reignition from residual vapour or fuel after initial suppression is a realistic scenario requiring continuous automatic protection response.
Can this valve be used with foam suppression systems?
Yes. The metal piston and valve body are fully compatible with foam-water mixture at up to 6% concentrate — covering AFFF, AR-AFFF, FFFP, and protein foam types. No modification to the valve body or trim is required for foam-water service. The valve connects directly to balanced-pressure proportioner or bladder tank systems upstream.
For aircraft hangar and tank farm foam-water deluge systems, the ZSFS pre action valve with foam-water supply is the standard specified configuration — providing anti-false discharge confirmation before foam-water is committed to the protected area (avoiding both false discharge product loss and foam system resupply downtime). See the foam bladder tank range for compatible proportioning equipment.
What maintenance schedule does the piston-type valve require?
Quarterly: Visual inspection of valve body, trim pipework, and gauge readings. Verify control circuit supervisory pressure against specification — any unscheduled pressure drop triggers alarm investigation before the next inspection. Check all flange bolts for correct torque.
Annually: Functional activation test using test drain — confirm dual-condition logic (verify single-input non-activation), full piston opening, water hammer protection (monitor downstream pressure rise), alarm pressure switch and water motor gong operation, and automatic cyclic reset through minimum two consecutive cycles. Record all response times against factory test baseline.
Biennially: Full O-ring inspection — remove trim and inspect piston O-rings for wear, deformation, or chemical degradation. Replace as scheduled maintenance item if any deterioration is detected, regardless of appearance if operating environment is chemically aggressive. Unlike diaphragm valves, there is no rubber diaphragm requiring scheduled periodic replacement — reducing planned maintenance cost over the valve's ≥15 year service life. CA-FIRE can supply O-ring service kits per DN size — contact sales@ca-fire.com.
Related Products
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Closed-Head · Individual Response · Pre-Action Pre-Action Alarm Valve For pre-action closed-head sprinkler systems — individual thermal head response, water delivered only to the fire location. Data centres, archives, cold storage. Compare before specifying. View Pre-Action Alarm Valve → |
Standard · 1.6 MPa · Single-Activation Diaphragm Deluge Valve The standard cost-effective deluge valve for 1.6 MPa single-activation applications where false discharge risk is acceptable. DN50–DN350. Specify when pre-action protection is not required. View Diaphragm Valve → |
Ex-Rated · Zone 1/2 · 2.5 MPa Explosion-Proof Deluge Valve High-pressure single-activation for Zone 1/2 hazardous areas — 2.5 MPa, Ex db IIC T6 Gb, without pre-action logic. When Ex certification is required but false discharge prevention is not the priority. View Ex Valve → |
Foam Supply · Tank Farm · Hangar Foam Bladder Tank Foam concentrate storage and balanced-pressure proportioning for foam-water pre action deluge systems — aircraft hangars, tank farms, and chemical bunds upstream of the ZSFS valve. View Foam Bladder Tank → |
Get a Quote — Pre Action Deluge Valve
ZSFS 50–300-2.5J(Ex) · Piston Type · 2.5 MPa · DN50–DN300
Anti-False Discharge · Water Hammer Protection · Auto Cyclic Reset · -20°C to +70°C
Water + AFFF 6% | GB 5135.7 · NFPA 13 / 30 / 409 · IEC 60079 · ISO 9001 · Factory Direct