Firefighting Foam Concentrate for Oil and Chemical Tankers

Firefighting foam concentrate is a key component of the FFE systems installed on oil tankers and chemical carriers, designed to isolate the fire source, cut off oxygen, and prevent the spread of flames across flammable liquid surfaces.

However, selecting the right type of foam concentrate today faces two major challenges:

Compliance with international environmental regulations, particularly the PFOS ban under SOLAS; and

Ensuring firefighting effectiveness across various cargo types – from non-polar fuels such as petroleum products to polar solvents used in chemical cargoes.

Firefighting Foam on Board

Onboard ships, firefighting foam is one of the primary agents for combating Class B fires – those involving flammable and volatile liquids such as oil, gasoline, or chemical solvents.

Unlike water, which cannot smother or blanket fuel surfaces, foam forms a stable foam layer that seals off flammable vapors from oxygen in the air, while simultaneously cooling the burning surface and preventing re-ignition.

For oil and chemical tankers, where a wide range of fuels and solvents are stored, foam concentrate systems play a critical role in liquid fire control. When activated, the system mixes the foam concentrate with water at a specified ratio (typically 3% or 6%) to produce a uniform, stable foam blanket that spreads over the burning surface, effectively suppressing the fire.

Common types of Firefighting Foam Concentrates

Each foam type offers specific performance characteristics depending on the fuel involved and the operating environment. Selecting the right foam is essential to ensure compatibility with existing systems, optimal extinguishing performance, and compliance with environmental and SOLAS requirements.

What Does the Foam Concentrate Induction Rate (1%, 3%, 6%) Mean?

The induction rate refers to the percentage of foam concentrate mixed with water to form the firefighting foam solution.
For example, a 3% induction rate means 3 liters of foam concentrate are mixed with 97 liters of water.

Different foam concentrates are designed for specific mixing ratios, typically 1% (common for some AFFF types), 3%, or 6% (especially for AR-AFFF, where a higher ratio improves performance on polar solvent fires).

Selecting the correct induction rate directly affects foam stability, film-forming capability, and burn-back resistance. When changing the foam type on board, it is essential to verify system compatibility (e.g., proportioner and pump settings), as foam concentrates with different induction rates must not be mixed.

New Regulation: Ban on Firefighting Foam Containing PFOS Onboard Ships

According to the latest amendments to SOLAS Chapter II-2, Regulation 10.11 (adopted under IMO Resolution MSC.532(107) and corresponding amendments to the HSC Code), the use and carriage of firefighting foam containing Perfluorooctane Sulfonic Acid (PFOS) on board ships will be prohibited effective 1 January 2026.

Specifically:

• New ships delivered on or after 1 January 2026 must comply upon delivery.

• Existing ships must comply at the first scheduled survey after 1 January 2026.

This requirement applies to both FFE systems and portable foam equipment carried on board.

The acceptable PFOS concentration limit is defined as not exceeding 10 mg/kg (0.001% by weight) to be considered “PFOS-free” under the IMO guidance.

Shipowners must therefore ensure that all foam concentrates used on board meet this requirement, as non-compliance may result in PSC detention or deficiency reports during inspection.

Challenges in Replacing Firefighting Foam for Oil and Chemical Tankers

In the maritime industry—particularly on oil tankers and chemical carriers—the stored cargo often includes petroleum fuels, polar fuels, or polar solvents. When selecting firefighting foam concentrates for these areas, two major technical challenges arise:

Standard AFFF Is Ineffective Against Polar Solvent Fires

Certain polar solvents or water-miscible flammable liquids can destroy the foam blanket generated by standard AFFF (Aqueous Film Forming Foam).

As stated in industry guidance:

“Polar solvent/alcohol liquids destroy any foam blanket that has been generated using standard AFFF or fluoroprotein type concentrates.”

This means that if the vessel carries polar cargoes such as alcohols, ketones, or gasoline/oxygenate blends, the use of standard AFFF alone may lead to foam breakdown, loss of fuel coverage, and increased risk of fire spread or re-ignition.

Therefore, for oil and chemical tankers, the foam concentrate must be resistant to polar solvents, such as AR-AFFF (Alcohol-Resistant AFFF) or other specialized foam types designed for such environments.

Balancing Regulatory Compliance and Firefighting Performance

Shipowners must now choose a foam concentrate that both:

• Complies with the new PFOS ban under SOLAS and IMO Resolution MSC.532(107), and
• Delivers proven firefighting performance under real onboard conditions.

In practice, this means:

The foam must be PFOS-free or below the maximum limit of 10 mg/kg (0.001% by weight) to ensure regulatory compliance.

It must provide stable foam formation, effective burn-back resistance, and protection against polar fuels, while withstanding vibration, corrosion, and marine conditions.

The ship’s firefighting system must be compatible with the chosen foam type (induction rate, proportioner, pump, storage, and piping) to achieve full system efficiency.

Selecting foam solely for regulatory compliance (e.g., fluorine-free foam) without considering fuel compatibility may result in poor fire suppression performance. Conversely, choosing a high-performance foam that exceeds PFOS limits will lead to non-compliance with SOLAS and potential prohibition or mandatory replacement.

Replacement Solutions for Firefighting Foam on Oil and Chemical Tankers

Selecting the appropriate firefighting foam concentrate for marine applications must be a technically justified decision—not only to comply with regulatory requirements but also to ensure effective response in real-life emergency situations.

From general cargo vessels to oil and chemical tankers, the foam selection process must consider:

• Fire performance against specific fuel types,
• Compatibility with existing proportioning systems and onboard equipment, and
• Transparent technical documentation for classification society inspection and approval.

Common Replacement Foam Types in the Maritime Industry

Depending on cargo characteristics and environmental requirements, three main groups of foam concentrates are widely adopted in the maritime sector:

F3 Foam (Fluorine-Free Foam)

Formulated without PFOS/PFAS, this foam type meets international environmental standards and is recommended as a sustainable alternative to traditional fluorinated foams.

However, its fire performance should be validated against specific fuel types to ensure system compatibility and reliable extinguishing efficiency.

AR-AFFF (Alcohol-Resistant Aqueous Film Forming Foam)

This foam contains a polymer barrier layer that resists fuel absorption, maintaining foam stability when in contact with polar solvents such as ethanol, acetone, or isopropanol.

When selecting AR-AFFF for tankers, it is important to ensure the latest PFOS-free or PFOA-free formulation to comply with current environmental regulations.

AR-F3 (Alcohol-Resistant Fluorine-Free Foam)

Considered the “gold standard” solution, AR-F3 combines environmental compliance (PFOS-free) with effective performance on both polar and non-polar fuels.

This foam type is increasingly recommended by the IMO and recognized by classification societies as the optimal replacement option for oil and chemical tankers.

Selection Criteria (Technical & Regulatory)

When evaluating and selecting firefighting foam concentrate for vessels, the following requirements must be ensured:

• Certified in accordance with IMO/SOLAS or approved by IACS/Class societies.
• PFOS content ≤ 10 mg/liter as per international environmental regulations.
• Foam must be Alcohol Resistant (AR) if the vessel carries polar chemical cargoes.
• Ensure the correct mixing ratio (3% or 6%), compatible with the existing foam proportioner and piping system.

Required Technical Documentation

• MSDS (Material Safety Data Sheet)
• COA (Certificate of Analysis) or Test Report
• Declaration of Conformity to support PSC/VR/Class inspections

Transition and System Verification Process

To ensure an effective transition and compliance with SOLAS, shipowners should:

1. Conduct a risk assessment and classify hazardous zones on board.
2. Test current foam samples at an accredited laboratory to determine PFOS/PFAS content.
3. Flush and clean the system thoroughly before introducing a new foam type.
4. Recalibrate the proportioning system according to the manufacturer’s guidance.
5. Maintain complete technical records and test results for PSC/VR/Class verification.

MARICO’s Solution – Full Compliance with SOLAS & Performance Assurance

Selecting the right firefighting foam concentrate and foam extinguishers is not merely a matter of compliance — it is a strategic step to safeguard life, property, and the marine environment.

As PFOS and PFAS compounds are being phased out globally, transitioning to next-generation, fluorine-free foams has become an inevitable trend.

With over 20 years of expertise in marine safety equipment supply, MARICO is committed to supporting shipowners and operators in the replacement process — providing IMO/SOLAS–USCG approved fire-fighting foams and extinguishers, along with complete technical documentation and certifications to ensure smooth PSC/VR/Class inspections.

Our team delivers end-to-end support, from system compatibility checks and transition guidance to certification management, helping vessels achieve full compliance with SOLAS 2026 — safely, efficiently, and sustainably.