Diaphragm Deluge Valve — ZSFM Series, Cast Iron Flanged (DN50–DN350)

Deluge Valve Parts Name — ZSFM Series

Diaphragm Deluge Valve Working Principle — Step by Step

① Standby Condition

Control-chamber water pressure — supplied via the priming line ball valve from the supply side — acts on the upper face of the EPDM diaphragm, pressing it firmly against the valve seat. The downward closing force exceeds the upward supply pressure due to the larger area of the diaphragm top face. The valve is positively closed with leakage ≤ 0.1 L/min. All downstream open nozzle pipework is dry and at atmospheric pressure.

② Fire Detection → Solenoid Trip

A fire detector (heat, smoke, UV/IR, or flame) sends a signal to the fire alarm control panel. The panel energises the solenoid trip valve on the control chamber vent line. The solenoid opens and vents control-chamber pressure to drain in under 1 second. Alternatively: a pilot sprinkler operates (wet pilot) or pilot line pressure drops (dry pilot), or an operator activates the manual release handle — all three produce the same result.

③ Valve Opens — Full-Zone Discharge

With control pressure removed, supply water pressure acting on the underside of the diaphragm lifts it fully into the bonnet cavity within ≤ 3 seconds of signal receipt. The complete bore is exposed — hydraulic resistance drops to below 0.08 MPa. Water floods the downstream distribution pipework at full design flow rate and simultaneously discharges from every open spray nozzle or open sprinkler head across the entire protected zone.

④ Alarm Activation

Simultaneously with zone discharge, water flows through the alarm port into the alarm line. The water motor alarm gong activates (hydraulic bell — no electrical supply required). The alarm pressure switch closes and sends an electrical supervisory signal to the fire alarm control panel and building monitoring system. Total time from detection signal to alarm activation: ≤ 3 seconds.

⑤ Reset & Restoration to Standby

After suppression: (1) close upstream OS&Y gate valve; (2) de-energise solenoid; (3) drain downstream pipework via main drain; (4) re-pressurise control chamber via priming line ball valve; (5) confirm diaphragm has reseated — zero flow at drain; (6) restore detection and solenoid circuit; (7) open upstream supply to full standby. Total time: 15–30 minutes. No special tools required.

💧 EPDM Diaphragm — Full-Bore Flow, Zero Obstruction

The EPDM rubber diaphragm (fabric-reinforced for dimensional stability) is the sealing element and actuating mechanism in one. When closed, it provides a positive, leak-free seal maintained by water pressure alone — no springs, latches, or mechanical catches that can corrode, seize, or fatigue over the valve's service life. When open, the diaphragm retracts fully into the bonnet cavity, exposing the complete bore with hydraulic resistance below 0.08 MPa — consistently lower than clapper-type equivalents (0.08–0.12 MPa). This reduces the hydraulic calculation margin required in system design and can allow slightly smaller pipe sizing in flow-critical systems. The EPDM compound is compatible with chlorinated municipal water, foam-water mixtures at up to 6% concentrate (AFFF, AR-AFFF, FFFP, protein foam), and moderate chemical contamination from impure supply sources. Diaphragm replacement takes 45–90 minutes without removing the valve body from the pipeline — the bonnet unbolts directly, the worn diaphragm lifts out, and a new one drops in.

⚡ Three Actuation Modes — Solenoid, Pilot, Manual

Electric solenoid (most common): DC24V or AC220V signal from the fire alarm control panel energises the solenoid trip valve on the control chamber vent line. Valve opens within ≤ 3 seconds. Standard for all modern automatic deluge systems. The solenoid can be combined with a manual release for dual-mode installations.

Wet pilot: a pressurised water pilot line connects to a closed-type detection sprinkler or rate-of-rise detector. When pilot sprinkler operates, pilot line pressure vents and the main valve trips hydraulically — no electrical power required for activation. Used where supply power reliability is uncertain.

Dry pilot: a pressurised air or nitrogen pilot line replaces the water pilot. The correct choice for freezing environments where a water pilot line would be at risk of ice formation and blockage.

Manual release: a mechanical handle at the valve station trips the valve directly — fully independent of detection and power. Provides a last-resort activation path regardless of system faults. All three modes can be installed simultaneously for maximum redundancy.

🏗️ Cast Iron Body — Proven Strength, Competitive Cost

The valve body, bonnet, and end connections are cast from high-quality grey cast iron, CNC-machined for consistent flange face geometry and sealing surface finish. Grey cast iron provides the structural integrity required for a 1.6 MPa working pressure valve — strength-tested to 6.4 MPa, seal-tested to 3.2 MPa — at a significantly lower material cost than ductile iron or stainless steel alternatives. For the majority of standard industrial and commercial installations (indoor or weatherproof-enclosure, non-corrosive water supply, ambient temperature environment), cast iron provides decades of reliable service and is the globally dominant body material for deluge valves. For corrosive, marine, or offshore environments where cast iron is not appropriate, the same diaphragm mechanism is available in the stainless steel deluge valve (SS304/SS316 body).

📋 Assembly Drawing & Cv Data — Available on Request

A full dimensional drawing for the ZSFM series — including the complete deluge valve trim assembly drawing showing solenoid valve, manual release, priming circuit, pressure gauges, alarm port, water motor gong connection, main drain, and upstream isolation valve positions — is available as PDF and AutoCAD DWG file for all 10 DN sizes. Drawings are provided free of charge with all project enquiries. Hydraulic Cv values for each DN size are available for NFPA 13/15 hydraulic calculations. For NFPA project submissions, CA-FIRE can provide hydraulic performance data in the format required by the responsible hydraulic calculator.

Contact sales@ca-fire.com with your required DN size and drawing format. Response within 24 hours. All technical data provided free of charge to specifying engineers and EPC contractors.

Replacement diaphragm kits for DN50–DN350 are available from CA-FIRE — contact sales@ca-fire.com with model ZSFM and DN size. Same-week despatch available for stocked sizes.

Dimensional drawings, Cv data, and material certifications are provided free of charge with all project enquiries.