What is Discharge Time in Fire Suppression System?

Fire suppression system is a system designed to detect and extinguish fires automatically or manually in various types of environments, such as commercial, industrial, or critical facilities. One of the important elements in the operation of this system is the discharge time. So, what is discharge time and why is it important?

Definition of Discharge Time

Discharge time is the duration of time required by the extinguishing media (such as gas, liquid, or other chemicals) to be fully released from the fire extinguishing system to the intended area. This duration is usually measured from system activation until all the extinguishing media is discharged from nozzles or other distribution devices.

Factors that Affect Discharge Time

1. Type of Extinguishing Media
   • Media such as carbon dioxide (CO2), FM-200 gas, or water-based liquids have different physical characteristics and discharge mechanisms.
   • Gas-based media usually have a faster discharge time than liquid-based media.
     
2. System Pressure
   • Systems with high pressure allow media to be released faster.
   • Inadequate pressure can prolong the release time and reduce the effectiveness of the system.
     
3. Size and Design of Protected Area
   • Larger or complex areas take longer to distribute media evenly.
   • Optimal system design can minimize the release time.
     
4. System Configuration
   • Pipe length and diameter, number of nozzles, and distribution orientation affect the flow of extinguishing media.
     

Importance of Discharge Time

1. Extinguishing Effectiveness
   • Discharge times that are too slow can increase the risk of the fire spreading before the extinguishing media has successfully covered the entire area.
   • A standardized discharge time ensures that the fire is extinguished quickly before causing further damage.
     
2. Compliance with Standards
   • Many international standards such as NFPA (National Fire Protection Association) set maximum limits for discharge time.
   • Compliance with these standards is part of ensuring occupant safety and asset protection.
     
3. Effect on Ventilation System and Environment
   • The discharge time also affects the interaction between the extinguishing media and ventilation in the protected area. Discharging too soon or too late can reduce the effectiveness of the extinguishment.

Example of Discharge Time Standards

• Inert Gas Systems: Typically requires a discharge time of approximately 60-120 seconds, depending on system specifications.
• FM-200 Systems: These media are often designed to discharge in less than 10 seconds to ensure rapid response to fires.
• Foam systems: The nominal discharge time for foam fire suppression systems on mine vehicles is 50 seconds. The average discharge rate must be at least 4.1 liters per minute per square meter over the fire risk area.