Overview
Foam baldder tank is a storage vessel that holds firefighting foam concentrate, which is later mixed with water and air to generate firefighting foam. Foam is essential in controlling and extinguishing fires involving flammable liquids (Class B fires) because it forms a stable blanket that cools the fire and suppresses vapors.
Working Principle of a Foam Tank
- Storage of Foam Concentrate
The tank stores foam concentrate (such as AFFF, AR-AFFF, or protein-based foam).
Tanks can be atmospheric (vented, non-pressurized) or bladder type (pressurized).
- Foam Proportioning
When a fire occurs, water from a fire pump is directed through a foam proportioning system (e.g., foam inductor, foam bladder tank system, or foam pump).
The system automatically mixes the foam concentrate with water at a set ratio (commonly 1%, 3%, or 6%).
- Foam Solution Delivery
The water-foam mixture (foam solution) travels through piping to discharge devices like foam chambers, monitors, nozzles, or sprinklers.
- Foam Generation
At the discharge point, air is introduced into the foam solution to create an expanded foam blanket.
The foam spreads across the fuel surface, cutting off oxygen and suppressing flammable vapors, while also providing a cooling effect.
Types of Foam Tanks
Atmospheric Foam Tank
Non-pressurized, vented to atmosphere.
Foam concentrate is drawn by a foam pump or proportioner.
Commonly used in large fixed systems like storage tank protection.
Bladder Foam Tank
Pressurized tank containing a bladder (rubber bag) filled with foam concentrate.
Fire water pressure squeezes the bladder, pushing foam concentrate into the proportioner.
Simple, reliable, and doesn't require an external foam pump.
Pressure-Type Foam Tank (Balanced Pressure System)
Uses a foam pump and balance valve to ensure accurate proportioning.
Suitable for systems with varying flow rates and large-scale industrial hazards.
Key Functions of a Foam Tank
Storage of foam concentrate in a ready-to-use condition.
Proportioning foam concentrate into the water supply at precise ratios.
Continuous supply of foam solution during firefighting operations.
Integration with other fire protection systems (deluge valves, monitors, sprinklers).
Applications
Petroleum refineries and chemical plants.
Fuel storage tanks (floating or fixed roof).
Aircraft hangars.
Marine and offshore platforms.
Warehouses storing flammable liquids.