Fire sprinkler systems are the core components of automatic fire suppression systems. They are primarily categorized into the following types based on different fire risks, environmental requirements, and design principles. Below is a detailed introduction and a comparative analysis of their advantages and disadvantages:
A. Wet Pipe Sprinkler System
Main Components: Sprinkler Heads: Glass bulb type (68°C/93°C), fusible alloy type. Pipes: Galvanized steel, CPVC (for corrosive environments). Valves: Alarm valve, flow switch. Auxiliary Equipment: Pressure switch, water motor gong, inspector’s test valve.
Working Principle: The pipes are constantly filled with pressurized water. When the thermal element of the sprinkler head (typically activated at 68°C) ruptures, water is immediately discharged.
Advantages: Fastest response time and high efficiency. Simple structure and low maintenance costs. Suitable for most environments (above 4°C).
Disadvantages: Risk of pipe freezing; not suitable for environments. Accidental discharge may cause water damage.
B. Dry Pipe Sprinkler System
Main Components: Sprinkler Heads: Dry-type sprinklers (freeze-resistant design). Pipes: Galvanized steel (sloped for drainage). Valves: Dry pipe valve, quick-opening device. Air Supply Equipment: Air compressor, pressure monitoring device.
Working Principle: The pipes are filled with compressed air/nitrogen. When a sprinkler head opens, the air is released, and water then fills the pipes.
Advantages: Freeze-proof, suitable for environments (e.g., cold storage, parking garages).
Disadvantages: Delayed response (air must be released first), slower. Complex system with higher maintenance costs (requires regular air pressure checks). Higher risk of pipe corrosion compared to wet systems.
C. Pre-Action Sprinkler System
Main Components: Sprinkler Heads: Standard closed-type sprinklers. Control Valve: Pre-action valve. Detection System: Smoke/heat detectors, fire alarm control panel (FACP). Activation Components: Solenoid valve, manual emergency release station.
Working Principle: Combines fire detection with dry pipes. Water is released only when both the detector (e.g., smoke alarm) and sprinkler head are activated.
Advantages: Dual safeguards, significantly reducing false discharges (ideal for data centers, archives). Can be used in environments (pipes filled with air or dry).
Disadvantages: Highest cost, complex installation and maintenance. Response time depends on detector performance.
D. Deluge System
Main Components: Sprinkler Heads: Open-type sprinklers (no thermal element). Control Valve: Deluge valve. Triggering Devices: Fire detectors (IR/UV flame detectors), manual pull station. Pipes: Large-diameter steel pipes (corrosion-resistant).
Working Principle: All sprinkler heads are open. Upon fire detection, the control valve releases water across the entire protected area.
Advantages: Full-coverage suppression, suitable for high-risk fires (e.g., chemical plants, aircraft hangars).
Disadvantages: Extremely high water demand, may cause secondary damage. Requires an independent detection system for activation.
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E. Water Curtain System
Main Components: Sprinkler Heads: Water curtain nozzles (fan/mist type). Control Valve: Deluge valve or dedicated control valve. Pipes: Stainless steel/galvanized steel. Pump: High-pressure centrifugal pump (to maintain water curtain pressure).
Working Principle: Creates a water barrier to (not for direct).
Advantages: Effective for fire compartmentation (e.g., theater stages).
Disadvantages: Does not directly extinguish fires; must be used with other systems.
F. Foam-Water Sprinkler System
Main Components: Sprinkler Heads: Foam-specific sprinklers (low/high-expansion). Mixing Device: Proportioner (pressure-balanced). Foam Tank: Corrosion-resistant (PE/stainless steel). Valves: Foam control valve, check valve.
Working Principle: Mixes foam concentrate with water to suppress flammable liquid fires (e.g., oil depots, hangars).
Advantages: Effective for liquid fires (cools and smothers flames).
Disadvantages: Requires regular foam replenishment, higher operational costs.
G. Comparative Analysis Table
| System Type | Response Speed | Suitable Environment | False Discharge Risk | Maintenance Cost | Typical Applications |
| Wet Pipe | Fastest | Above 4°C | High | Low | Offices, malls |
| Dry Pipe | Slower | Below 4°C | Medium | Medium-High | Cold storage, parking garages |
| Pre-Action | Moderate | Sensitive/Low-temp areas | Low | High | Data centers, museums |
| Deluge | Fast | Fast-spreading fires | High | Medium-High | Chemical plants, aircraft hangars |
| Water Curtain | – | Fire barriers | – | Medium | Building fire compartments |
| Foam-Water | Moderate | Flammable liquid fires | High | High | Oil depots, industrial plants |
H. Common Components of Fire Systems
Piping Materials: Steel (galvanized/stainless), CPVC (corrosive areas).
Pumps: Fire pumps (centrifugal/vertical), jockey pumps.
Monitoring Devices: Pressure gauges, flow meters, water quality sensors.
Testing Equipment: Inspector’s test valve, air pressure tester.
I. Selection Guidelines and Recommendations
General Areas: Prioritize wet pipe systems (cost-effective).
Environments: Dry pipe or pre-action systems.
High-Value Sensitive Areas: Pre-action systems (to minimize accidental damage).
Rapid-Spreading Fires: Deluge or foam systems.
Sprinkler Head Selection: Choose based on ambient temperature (e.g., 93°C for high-heat areas) and corrosion resistance (stainless steel heads).
Valve Certifications: Must comply with UL/FM/EN standards.
Special Requirements: Data centers may use ESFR (Early Suppression Fast Response) sprinklers.
Cleanrooms may require concealed sprinklers.
Different systems can be customized (e.g., pre-action + foam systems). Designs should follow NFPA 13 standards.