Compressed Air Foam Systems (CAFS)
Compressed Air Foam Systems (CAFS)
RML AU provides engineered Compressed Air Foam Systems (CAFS) for high-risk fire suppression applications across Australia.
CAFS combines water, a selected foam concentrate and compressed air to produce an aerated suppression medium designed to provide rapid flame knockdown, sustained cooling and efficient use of firefighting water.
RML AU CAFS applications include Battery Energy Storage Systems (BESS), lithium-ion batteries, electric vehicles, transformers and electrical infrastructure, waste and recycling, underground mining, data centres, wind energy and other high-risk industrial environments.
Our approach is evidence-based: understand the fire risk, select the appropriate detection and suppression strategy, control flaming combustion, remove heat and use water efficiently.
What Is CAFS?
CAFS stands for Compressed Air Foam System.
CAFS is a compressed air foam system that combines water, foam concentrate and compressed air to create a controlled aerated firefighting medium
Unlike conventional aspirated foam systems, where air is introduced primarily as the foam solution leaves the nozzle or discharge device, CAFS introduces compressed air into the water and foam solution within the system.
The resulting finished foam is then transported through the hose or pipework to the point of application.
A CAFS system typically combines three components:
Water — provides cooling and heat absorption.
Foam concentrate — reduces surface tension and assists wetting, coverage and foam formation.
Compressed air — creates and controls the aerated foam structure.
The interaction between these components produces a finished foam whose characteristics can be engineered for the intended application.
How Does CAFS Work?
A CAFS system proportionally combines water and foam concentrate before introducing compressed air under controlled conditions.
The process can be represented simply as:
Water + Foam Concentrate + Compressed Air → Finished Compressed Air Foam
The foam is generated within the CAFS system rather than relying solely on aspiration at the discharge nozzle.
This allows the system to control important characteristics including foam consistency, expansion, bubble structure, flow and application behaviour.
The resulting foam can provide:
rapid flame knockdown;
effective surface coverage;
cooling and heat removal;
improved wetting;
adhesion to vertical and irregular surfaces;
vapour suppression in appropriate applications; and
more efficient use of available firefighting water.
The required CAFS configuration depends on the fire hazard, fuel, application method, discharge arrangement and engineering objectives.
CAFS Expansion Ratio and Foam Quality
Expansion ratio describes the relationship between the volume of finished foam and the volume of foam solution used to produce it.
However, expansion ratio alone does not determine whether a foam is a true compressed air foam or whether it is suitable for a particular fire hazard.
In a CAFS system, compressed air is mechanically introduced and mixed with the foam solution before discharge. The relationship between water, foam solution, compressed air, system pressure and resulting bubble structure influences the characteristics of the finished foam.
RML AU/EZCAFS systems can therefore be configured to produce CAF with characteristics appropriate to the intended application rather than relying solely on nozzle aspiration.
For lithium-ion battery applications, the objective is not simply to create the greatest possible foam expansion. The required foam must support effective application, flame control, heat removal and cooling.
CAFS Compared with Water-Only Suppression
Water remains one of the most important firefighting media available.
Its ability to absorb heat makes it particularly valuable where cooling is a primary fire-control objective.
CAFS does not eliminate water from the suppression process. Instead, it is designed to use water more effectively by combining it with a selected foam concentrate and compressed air.
Depending on the fire hazard and system configuration, CAFS can provide advantages including:
rapid flame knockdown;
sustained surface coverage;
improved wetting;
continued cooling;
reduced runoff from excessive water application;
reduced water-storage requirements; and
potentially smaller associated pumps, pipework, drainage and containment infrastructure.
The appropriate comparison between CAFS and water-only suppression must always consider the specific fire hazard, application rate, test configuration and engineering objective.
CAFS and Lithium-Ion Battery Fires
Lithium-ion battery incidents present particular challenges because extinguishing visible flame does not necessarily end the underlying hazard.
A cell experiencing thermal runaway can generate substantial heat and expose neighbouring cells or modules to sufficient thermal energy to initiate further failures.
For lithium-ion applications, the RML AU CAFS strategy is therefore focused on:
rapid flame control → sustained cooling → heat removal → reduced thermal energy transfer → propagation management.
CAFS should not be described as preventing the initiating cell from entering thermal runaway.
The engineering objective is to control the resulting fire, remove heat and reduce the transfer of sufficient thermal energy to neighbouring cells and modules, helping limit wider propagation.
Reducing Firefighting-Water Demand
One of the important potential advantages of CAFS is more efficient use of firefighting water.
RML AU/EZCAFS test data has demonstrated water reductions of approximately 85% under defined test configurations compared with the conventional water application used as the test benchmark.
These results should not be interpreted as a universal water reduction applicable to every fire or CAFS installation.
Actual project requirements depend on the hazard, fuel, fire scenario, application method, system configuration, cooling requirements and duration of suppression.
For high-risk infrastructure, lower design water demand can have implications beyond water consumption.
Depending on the project, it may reduce requirements associated with:
water storage;
fire pumps;
pipework;
drainage;
containment;
contaminated firewater management; and
associated fire-protection infrastructure.
The objective is not simply less water.
The objective is effective fire control and cooling using the water available as efficiently as possible.
Firewater Runoff and Environmental Management
Water used during firefighting can become contaminated by combustion products and materials released from the fire.
Depending on the incident, contaminated firewater may require containment, testing, treatment and appropriate disposal.
Reducing the volume of water required for effective fire suppression can therefore reduce the volume of potentially contaminated runoff requiring management.
This does not eliminate the requirement for appropriate firewater containment or environmental planning.
RML AU considers water demand, drainage and contaminated firewater management as part of the broader fire-protection discussion for high-risk applications.
Fixed CAFS Systems
Fixed CAFS can be engineered for automatic or manually activated fire protection of high-risk assets and facilities.
Applications can include:
BESS installations;
transformers and substations;
electrical infrastructure;
data centres and battery rooms;
waste and recycling facilities;
industrial processing;
charging infrastructure;
wind-energy assets; and
other high-risk fixed installations.
System design can incorporate appropriate detection, controls, discharge devices, water supply, foam concentrate and compressed-air generation according to the particular fire protection strategy.
Mobile CAFS Systems
Mobile CAFS provides a flexible suppression capability where permanent fixed infrastructure is not appropriate or where additional emergency-response capability is required.
Applications can include:
emergency response;
electric vehicles;
battery incidents;
mining and heavy equipment;
waste and recycling facilities;
industrial sites;
ports and transport infrastructure; and
remote or water-constrained locations.
Mobile systems can be configured for different flow requirements, water capacities and operational applications.
CAFS Applications
Battery Energy Storage Systems
CAFS can form part of an engineered BESS fire protection strategy focused on rapid fire control, sustained cooling, propagation management and reduced firefighting-water demand.
Explore BESS Fire Suppression →
Electric Vehicles
EV battery fires can involve difficult battery access, thermal runaway, high heat release, re-ignition and prolonged cooling requirements.
RML AU CAFS applications include approaches designed to deliver suppression and cooling to the affected vehicle and battery area.
Explore EV Fire Suppression →
Electrification and Transformers
Transformers, substations and electrical infrastructure can require significant firewater infrastructure when protected using conventional high-flow systems.
CAFS provides an alternative engineering approach combining flame control, cooling, surface coverage and potentially substantially reduced water demand.
Explore Transformer & Electrical Fire Protection →
Waste and Recycling
Lithium-ion batteries entering waste and recycling streams can initiate fires in conveyors, shredders, processing equipment, bunkers and stockpiles.
Early detection combined with rapid targeted suppression can reduce escalation and business interruption.
Explore Waste & Recycling Fire Suppression →
Underground Mining and BEV
Battery-electric mining equipment introduces lithium-ion battery risks into confined underground environments where access, ventilation and water availability may be constrained.
Explore Underground Mining BEV Fire Protection →
Data Centres
Lithium-ion UPS systems and other battery installations introduce fire risks into facilities where continuity, electrical infrastructure and protection from excessive water application are important considerations.
Explore Data Centre Fire Protection →
Wind Energy
Wind turbines combine electrical ignition sources, combustible materials, difficult access and limited water availability at height.
Fixed CAFS can provide an engineered suppression option for appropriate wind-energy applications.
Explore Wind Turbine Fire Protection →
Testing and Technical Evidence
RML AU's approach is based on evidence before claims.
RML AU/EZCAFS testing has examined CAFS performance across relevant fire scenarios and applications, including lithium-ion battery fires and other defined test configurations.
Technical assessment should consider the actual test conditions rather than relying on headline extinguishment or water-reduction figures alone.
Depending on the test, relevant information can include:
fuel or battery chemistry;
battery capacity and state of charge;
fire initiation method;
pre-burn period;
CAFS configuration;
water and foam flow;
application rate;
application duration;
temperature response;
flame-control time;
total water consumption;
propagation observations; and
post-suppression monitoring.
RML AU can provide relevant technical information and available test documentation to support project-specific engineering assessment.
An Engineered Approach to CAFS
There is no single CAFS configuration suitable for every fire hazard.
The suppression strategy should be selected around the risk.
RML AU's approach is:
Understand the hazard
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Identify the required detection and intervention strategy
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Select the appropriate CAFS configuration
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Control flaming combustion
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Remove heat and provide sustained cooling
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Limit escalation or propagation where applicable
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Optimise firefighting-water demand
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Consider runoff and environmental management
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Support the design with testing and technical evidence
Frequently Asked Questions
What does CAFS stand for?
CAFS stands for Compressed Air Foam System.
It combines water, foam concentrate and compressed air within the system to produce finished compressed air foam for firefighting applications.
Is CAFS the same as conventional foam?
No.
Both use water and foam concentrate, but a CAFS system mechanically introduces compressed air into the foam solution within the system before discharge.
This provides greater control over the characteristics of the finished foam.
Does CAFS use water?
Yes.
Water remains a fundamental component of CAFS and provides important cooling and heat absorption.
CAFS is designed to use that water efficiently rather than eliminate it.
Does CAFS stop thermal runaway?
CAFS should not be assumed to prevent an initiating lithium-ion cell from entering thermal runaway.
For lithium-ion applications, the objective is rapid fire control, heat removal and sustained cooling, reducing thermal energy transfer to neighbouring cells and helping limit propagation.
Does CAFS use less water?
RML AU/EZCAFS testing has demonstrated reductions of approximately 75–85% under defined test configurations compared with the conventional water application used as the test benchmark.
Actual project requirements depend on the hazard, fire scenario and system design.
Is RML AU CAFS suitable for every fire?
No single suppression technology should be assumed to be appropriate for every hazard.
RML AU assesses the application, fire risk, fuel, system configuration and engineering objectives before recommending a CAFS solution.
Can CAFS be used around electrical equipment?
CAFS can be engineered for appropriate electrical applications subject to the system configuration, required electrical clearances, applicable testing, risk assessment and project-specific engineering requirements.
RML AU can provide relevant technical information regarding available electrical testing.
Discuss Your CAFS Application
RML AU works with asset owners, engineers, fire-safety professionals, developers and emergency-response stakeholders to assess CAFS applications for high-risk fire protection.
Whether the challenge involves BESS, lithium-ion batteries, electrical infrastructure, EVs, mining, recycling or other industrial fire risks, the objective remains the same:
Understand the risk. Control the fire. Remove heat. Use water efficiently. Support the solution with evidence.
Talk to RML AU about your fire protection requirements.