Foam Fire Fighting Systems

Our company handles the design, installation and maintenance of low-, medium- and high-expansion foam fire extinguishing systems. Such systems are broadly used in contexts in which it is necessary to protect hazardous environments such as petrochemical plants, tyre depots, waste deposits, refineries, pharmaceutical industries, airports, helipads, offshore platforms and naval contexts in general.

HOW FIRE SUPPRESSION FOAM WORKS

Foam System uses a mixture of water and foam as an extinguishing agent that works on the fire by creating a barrier that separates the fuel from the oxygen in the air and cools the fuel itself (wetting power).

TYPES AND FIELDS OF USE

Our company utilises different types of foaming agents, with concentrations of use (Mixing Ratios) varying from between 0.5% and 6% of the volume of water. Some examples can be low-expansion Protein (P), low-expansion Fluoroprotein (FP), synthetic-based film-formers (AFFF) or low-expansion protein (FFFP), low-expansion alcohol-resistant film-formers (AFFFAR or FFFPAR) and medium-/high-expansion synthetics (HI-EX).

One specific case concerns Class A foaming agents – also called wetting agents – that, when added to the water in the necessary proportion (typically 0.1%–1%), reduce the surface tension and increase the impregnating capacity to improve operational water efficiency. However, it must be taken into consideration that these are suitable only for Class A fires such as of wood, paper, plastic or rubber. These Class A foams are, amongst other uses, widely utilised in the fire-fighting vehicles used by Fire Brigades.

When it comes to foam, it is necessary to make a distinction on the basis of the Expansion Ratio, which represents the volume of foam generated in m³ by each m³ of water-liquid foaming mixture (hence, a ratio of 1:200 indicates that 1 m³ of the mixture will generate 200 m³ of foam).

• Low-expansion foam (1:5–1:20) is used for fuel depots, warehouses, process areas, where rapid intervention would be required and the fuel load is low;
• Medium-expansion foam (1:20 - 1:200) is for large oil spills, containment basins and processing areas;
• High-expansion foam (1:200–1:1000) is used for safeguarding large volumes by total saturation, hence submerging the entire volume of foam, used for deposits of LPG, LNG and tyres as well as cable tunnels.

COMPONENTS 

The main components of a foam plant are:

• A water reserve for ensuring the system has access to water;
• A reservoir for concentrated foam liquid;
• A water-liquid foaming mixer/premixer, for different types;
• Pumping unit (if foreseen);
• Pipes and valves, which carry the water-foaming liquid mixture to the point of use;
• Foam generators, lances, nozzles, monitors and cannons that facilitate erogation of the mixture in the environment to be protected.

When the need arises, water and the foaming liquid are mixed according to the predetermined ratios, then the mixture formed is piped to the foam generators, where it comes into contact with air and expands to create the foam.

ADVANTAGES AND DISADVANTAGES

Advantages

• Foam is ideal for extinguishing fires of flammable liquids, often representing the only viable solution;
• Wetting agents, or Aqueous Film-Forming Foam Concentrates (AFFFs), offer a marked reduction in the volume of water necessary to extinguish a fire, already having very low concentrations of the agent (0.1%–0.5%).

Disadvantages

• Leaves a filming residue that necessitates intense cleaning operations;
• It is a complex system in proportion to the number of components.

The extinguishing agents utilised in foam fire-fighting systems can be distributed in various ways. In some cases, to ensure the highest level of safety and efficiency, they can be combined with smoke-detection systems and be subject to the numerous maintenance operations covered by our Service.