Gas fire suppression

There are various gases available as extinguishing agents. The choice depends on the design of the fire suppression system according to the following factors: the risk to be protected, the characteristics of the facilities, and the 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 files.

They may provide total flooding or localized protection, depending on the case and the extinguishing agent used.
Localized protection refers to those cases in which the risk to be protected is in an open space. In such scenario, hypothetical volumes and additional discharges of gas are considered, together with the risk-targeted discharge, so as to swiftly suppress the fire.

Total flooding is the method used to protect closed spaces. Certain concentrations and discharge times, which are standardized depending on the risk to be protected and the extinguishing agent used, should be achieved.

The main extinguishing agents are:

  • INERT GASES
  • CARBON DIOXIDE 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. Therefore, they are appropriate for small volume equipment items such as ducts, small power generators, and inside transformers. They are not used for total flooding.

CARBON DIOXIDE 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 be in place to ensure people are evacuated before the system discharges gas.

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 it is the ideal method to protect this kind of risks.

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