GAS-BASED FIRE SUPPRESSION SYSTEMS


GAS-BASED FIRE SUPPRESSION SYSTEMS

Various gases are available as extinguishing agents. Their choice depends on the design of the fire suppression system, which in turn is a function of the risk to be protected, the characteristics of the facilities, as well as people's exposure to the gas as it is discharged.

Gases are better suited to protect electrical equipment, computer rooms, telephony switches, electrical power generators, rotary printing presses, paint rooms, and data and paper archives.

They may provide total flooding or localized protection, as the case may be, also depending on the extinguishing agent used.

Localized protection refers to those cases where the risk to be protected is in an open space. In such scenario, hypothetical volumes and additional discharges are considered, together with the risk-targeted discharge, so as to swiftly suppress the fire.

Total flooding is the concept used to protect closed spaces. Here, we need to achieve certain concentrations and discharge times which are standardized depending on the risk to be protected and the extinguishing agent used.

Main extinguishing agents are:

  • INERT GASES
  • CO2
  • CLEAN GASES - HFC- 227ea (FM-200)

  • INERT GASES

    Gases such as nitrogen or argon are used. They are stored in highly pressurized cylinders, thus reducing to a minimum the amount of oxygen used during application. They are suitable for small volume equipment items such as ducts, small power generators, and inside transformers. They are not used for total flooding.


    CO2

    Its extinguishing action is achieved through oxygen displacement. Each risk and system require specific design concentrations and discharge times. It is stored in high-pressure cylinders in liquid form. Hence, distribution pipes and discharge nozzle orifices should be designed so that carbon dioxide remains in a liquid state until reaching the discharge nozzle, where it turns into gas.

    Considering that concentrations are high, large amounts of gas are usually needed for extinction; therefore, equipment costs are high despite the low cost of gas. Special care should be taken regarding the presence of people in the facilities to be flooded, as C02 concentrations are lethal. Pre-alarms, interlocking devices or other systems should therefore be in place to ensure people are evacuated before the system becomes activated.


    CLEAN GASES – HFC 227 EA (COMMERCIAL NAME: FM-200)

    They act by interrupting the fire chain reaction, suppressing the thermal energy generated by combustion.

    Discharge time is 10 seconds maximum, so the fire is immediately suppressed. In addition, they are not harmful to people or electronic equipment, so they are the method of choice for this kind of risk.


    MELISAM designs, supplies and installs gas-based systems in compliance with international standards, with equipment which has been previously approved by recognized agencies.