Foam Concentrate does not extinguish a fire in its original form. Instead, it is a specially formulated liquid that must be proportioned with water and discharged through suitable firefighting equipment to produce finished firefighting foam.

The entire firefighting process can be divided into the following stages.

Step 1 – Foam Concentrate Storage

Foam Concentrate is stored in dedicated containers or tanks until it is required during a fire emergency.

Depending on the fire protection system design, the concentrate may be stored in:

• Bladder Tanks
• Atmospheric Storage Tanks
• Foam Pump Skids
• Portable Foam Containers
• Intermediate Bulk Containers (IBCs)
• Drums or Pails

The storage system must protect the concentrate from contamination, excessive temperatures, and prolonged exposure to sunlight.

Step 2 – Foam Proportioning

When the fire protection system is activated, the foam concentrate is introduced into the fire water supply through a foam proportioning device.

Common proportioning methods include:

• Bladder Tank Proportioners
• Balanced Pressure Proportioners
• Inline Foam Inductors
• Around-the-Pump Proportioners
• Foam Pump Systems

The proportioner accurately injects the required amount of foam concentrate into the water stream.

Typical mixing ratios include:

• 1%
• 3%
• 6%

Accurate proportioning is essential because insufficient concentrate may result in poor extinguishing performance, while excessive concentrate increases operating costs without improving fire suppression effectiveness.

Step 3 – Formation of Foam Solution

After proportioning, the water and foam concentrate combine to create a homogeneous mixture known as Foam Solution.

At this stage, the solution does not yet possess the characteristics of finished firefighting foam.

Instead, it serves as the intermediate fluid that will later be transformed into foam through air aspiration.

Maintaining the correct concentration throughout the system is critical to ensure consistent firefighting performance.

Step 4 – Air Aspiration

The foam solution then passes through a discharge device designed to entrain atmospheric air into the liquid stream.

Typical discharge devices include:

• Foam Chambers
• Foam Makers
• Foam Monitors
• Foam Nozzles
• Foam Pourers
• Foam-Water Sprinklers

As air mixes with the foam solution, millions of stable bubbles are generated, creating finished firefighting foam.

The foam expansion ratio depends on both the foam concentrate formulation and the discharge device used.

Step 5 – Foam Application

The finished foam is applied directly onto the burning fuel surface or protected hazard.

Rather than mixing with the fuel, the foam spreads gently across the liquid surface, forming a continuous blanket.

This blanket performs several critical firefighting functions simultaneously.
It:

• Separates oxygen from the fuel.
• Suppresses the release of flammable vapors.
• Cools the fuel surface.
• Reduces radiant heat.
• Prevents reignition after extinguishment.

The effectiveness of the foam blanket depends on proper application techniques and maintaining adequate foam coverage until the fuel has cooled sufficiently.

Step 6 – Fire Extinguishment

Once a continuous foam blanket has been established, the fire gradually loses access to oxygen while vapor production is significantly reduced.

Without sufficient oxygen and flammable vapor, combustion ceases.

Unlike water alone, which may spread certain fuel fires, properly applied firefighting foam provides both extinguishment and long-term protection against re-ignition.

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Chemical Composition

Foam Concentrates are carefully engineered chemical formulations consisting of several ingredients, each serving a specific purpose in foam generation, stability, and fire suppression performance.

Although the exact formulation varies among manufacturers and foam types, most modern Foam Concentrates contain the following components.

1. Water

Water acts as the primary carrier for the chemical ingredients during manufacturing.

It provides the liquid medium necessary for maintaining solution stability and facilitating proportioning within the fire protection system.

2. Surfactants

Surfactants are the most important active ingredients in Foam Concentrates.

They reduce the surface tension of water, allowing it to spread rapidly over burning fuel surfaces and generate stable foam bubbles.

Surfactants are responsible for:

• Rapid foam generation
• Improved fuel coverage
• Vapor suppression
• Enhanced wetting characteristics
• Increased extinguishing efficiency

3. Foam Stabilizers

Foam stabilizers strengthen the foam blanket and increase its resistance to heat and mechanical breakdown.

These additives improve:

• Foam drainage time
• Bubble stability
• Burn-back resistance
• Foam blanket durability

4. Solvents

Solvents help dissolve and evenly distribute the chemical ingredients within the concentrate.

They also improve low-temperature performance and maintain consistent viscosity during storage.

5. Corrosion Inhibitors

Because Foam Concentrates remain in storage for extended periods, corrosion inhibitors are added to protect:

• Storage tanks
• Piping
• Pumps
• Valves
• Foam proportioning equipment

These additives help extend the service life of the fire protection system.

6. Preservatives

Preservatives prevent biological growth, bacterial contamination, and chemical degradation during long-term storage.

Proper preservation helps maintain foam performance throughout the product's service life.

7. Performance Additives

Depending on the foam type, manufacturers may include specialized additives to enhance:

• Fuel resistance
• Alcohol compatibility
• Freeze protection
• Environmental performance
• Foam expansion
• Burn-back resistance
• Drainage characteristics

These additives are one of the primary differences between various types of Foam Concentrates.

Engineering Insight

Many people assume that all Foam Concentrates are interchangeable, but this is not the case.

A foam concentrate designed for hydrocarbon fuels (such as gasoline or diesel) may perform poorly—or even fail—when used on polar solvent fuels like ethanol or methanol. Polar solvents can rapidly destroy conventional foam blankets by absorbing water from the foam.

For this reason, selecting the correct foam concentrate based on the fuel type, hazard classification, and applicable standards is one of the most important engineering decisions in any foam fire suppression system.