Water Curtain Nozzle

Both use open-type heads and a deluge valve, but their purpose and nozzle design are completely different. A standard deluge system uses open spray nozzles (or open sprinkler heads) arranged in a ceiling array to discharge water onto a horizontal protected area below — the goal is to wet fuel surfaces and cool the fire. A water curtain system uses flat-fan or parabolic-deflector nozzles arranged in a line above an opening or surface to form a vertical sheet of water — the goal is to create a fire and heat barrier across a gap in the compartment boundary.

Water curtain nozzles (ZSTMA-T, ZSTMB-T) are not interchangeable with standard deluge spray nozzles. The spray pattern, K-factor, and hydraulic design of the two are calibrated for entirely different functions. Installing deluge nozzles where water curtain nozzles are required (or vice versa) will not achieve the intended protection and may not comply with the relevant code.

No — not in all situations. Water curtain systems are accepted as an equivalent measure for fire separation in specific circumstances defined by GB 50016, GB 50084, and local authority requirements. The key conditions typically include: the water curtain must be activated automatically (not manual only), there must be a reliable water supply capable of sustaining the required flow for a minimum duration (typically 1 hour for fire separation curtains), and the water curtain must cover the full width and height of the unprotected opening with no gaps.

Water curtain systems are generally not accepted as a substitute for fire-rated construction in high-risk areas, areas where a water supply failure could cause catastrophic consequences, or in occupancies where specific fire-rated construction requirements are mandated regardless of suppression systems. Always confirm the acceptability of a water curtain solution with the authority having jurisdiction before including it in a design.

The open-type ZSTMA-T and ZSTMB-T nozzles have no consumable element — the brass orifice and deflector do not change on activation. After a system discharge, the nozzles should be inspected for debris blockage and cleaned, then the system can be restored to service. There is no requirement to replace the heads themselves after activation (unlike closed-head sprinklers, where the glass bulb or fusible link must be replaced after each operation).

The ZSTMB-T80/170-68°C is the exception — it contains a 68°C glass bulb thermal element. If this head has been activated by heat, the bulb has burst and the head must be replaced before the system can be restored, exactly as with a standard closed-head sprinkler.

After any activation, the deluge valve, detection system, and water supply should also be inspected and restored per the system maintenance schedule. Document the activation and notify the relevant authority as required by local regulation.

The choice depends on the function required. If the water curtain is primarily providing fire separation — acting as the fire barrier itself while the shutter descends or when the shutter alone is not sufficient — use ZSTMA-T21.5 (150° wide fan, higher K-factor for denser screen). If the water curtain is providing cooling protection for the shutter face to prevent thermal distortion and edge-seal failure during a fire — use ZSTMB-T18 or ZSTMB-T28 (120° flat fan, positioned close to the shutter face to produce a film-flow effect).

In many fire roller shutter installations, both functions are required simultaneously: a ZSTMA-T line on the fire side of the shutter provides the fire separation screen, while a ZSTMB-T line on the shutter face itself provides structural cooling. This combined approach is common in large-span industrial fire walls. Confirm the specific design requirement with the fire engineer before selecting the head type.

Under GB 50084 (China), the water supply duration for water curtain systems used as fire separation measures is typically 60 minutes (1 hour) for systems substituting for fire-rated walls, and may be reduced for systems providing cooling protection only — confirm the specific requirement with your local fire authority.

Under NFPA 13, deluge systems providing exposure protection are generally designed for a minimum duration determined by the occupancy hazard and the fire scenario being protected against — commonly 30 to 60 minutes. The designer is responsible for justifying the design duration to the authority having jurisdiction.

Water curtain systems typically have significantly higher flow rates than standard sprinkler systems for the same protected area, so the required water tank or reservoir volume can be substantial. Confirm the required duration, flow rate, and storage volume at project inception — these significantly affect tank size and pump selection.