Foam Fire Suppression Systems

Where foam is required

Foam systems are considered wherever liquid fires that cannot be extinguished with water or where water extinguishment is dangerous exist:

• Fuel tank farm and in-tank protection. Different application methods are used in fixed-roof, floating-roof, and internal floating-roof tanks.
• Loading and unloading islands, tanker platforms. Areas where spilled fuel can pool and ignite rapidly.
• Aircraft hangar and helicopter landing pad. In hangars, volume-filling with high-expansion foam is generally preferred, while on landing pads, monitor and nozzle application is preferred.
• Solvent, paint, and chemical storage. For polar solvents, alcohol-resistant concentrate is mandatory.
• Transformer and turbine areas. Foam-water spray combination in oil fire.
• Waste and recycling facilities. Foam with wetting capability in cases where water does not penetrate deep pile fires.
• Overflow pools and fuel separators. Coverage of pool surface to prevent fire spread.

Concentrate selection: the first and most critical decision

The most expensive mistake we have seen in the field is a facility with alcohol-containing fuel yet designed with standard AFFF system. The system is complete on paper, but in a real fire the foam blanket collapses within minutes.

Transition to fluorine-free foam

Restrictions on foam concentrates containing fluorinated compounds are progressively expanding in international regulations. This creates two separate questions for operators: which concentrate to select in newly installed systems and how to convert existing systems.

It must be understood from the outset that conversion is not merely changing the liquid in the tank. Fluorine-free concentrates have different flow and foaming behavior; pipeline and tank flushing, re-verification of mixing ratio, and in some cases nozzle or generator replacement are required. The conversion decision cannot be made without reviewing the facility's fuel inventory and the approval scope of the existing system.

Expansion ratio: how much the foam inflates

In high-expansion foam system, the air supplied by the foam generator is important: generators supplied with external air do not carry smoke produced by the fire into the foam and produce more stable filling.

Mixing (proportioning) methods

The correct ratio mixing of foam concentrate with water determines the actual performance of the system. Common methods:

• Bladder tank. Pressurized water compresses the flexible bladder inside the tank, pushing the concentrate to the line. Requires no electricity or moving parts; the most common solution for fixed systems.
• Line proportioner. Simple and economical; high pressure loss, provides correct ratio only in a narrow flow range.
• Pump injection. A separate concentrate pump is used; maintains ratio over a wide flow range, requires electricity and control.
• Balanced pressure system. Concentrate and water pressure are equalized by a diaphragm valve; preferred in large multi-zone facilities.

Whichever method is selected, the mixing ratio must be verified by measurement during commissioning. The field-measured value obtained by conductivity or refractive index measurement is valid, not the catalog value. An unmeasured ratio is the most frequently overlooked deficiency in systems.

Application methods

• Foam sprinkler / foam-water spray. Application to the entire area via fixed pipe network; generally with a deluge valve.
• Monitor (top). Remote-controlled high-flow application; tank areas and loading islands.
• Top-of-tank application. Foam chamber or in-tank injection; selected according to tank type.
• High-expansion volume filling. Filling the volume to a certain height with generators.
• Foam fire cart and portable equipment. Solution complementary to fixed system for personnel intervention.

Three numbers in design

1. Application flow rate. The amount of foam solution applied per minute per unit area of surface to be protected; determined according to fuel type and application method.
2. Application duration. The period during which the system must operate continuously. In tank fires, this period is significantly longer than in area protection applications.
3. Concentrate stock. Found by flow × duration × mixing ratio; a re-intervention margin is added. In a facility where stock calculation has not been done, the system operates, but the concentrate runs out before the fire is extinguished.

What should really be measured in maintenance

• Concentrate sample analysis. Concentrate settles, degrades, and is affected by freeze-thaw cycles over time. Taking samples at regular intervals and sending them to laboratory analysis is the only method that shows the true condition of the system.
• Mixing ratio verification. Ratio is measured in the solution taken from the test connection.
• Bladder tank inspection. Tank pressure, discharge valve and bladder integrity; corrosion and sediment inspection.
• Deluge valve and line test. Opening the valve, cleaning the line, and confirming nozzles are not clogged.
• Concentrate expiry date and stock level. Resupply period after discharge must be defined in the facility's operation plan.

We conduct periodic maintenance of foam systems foam suppression maintenance within the scope of. For brand-independent technical specification example foam extinguishing specification page; for introductory explanation of the subject, see foam systems article .

Project and product

For foam concentrates, bladder tanks, proportioners, monitors and foam cart equipment foam extinguishing product group you can review, for concentrate selection, flow and stock calculation for your facility contact usA zone monitoring module connects an entire conventional detector line to the addressable loop. Critical areas are renewed with addressable devices while secondary zones continue to operate with their existing wiring. This provides significant cost advantage in capacity upgrade and renovation projects.