FOAM SYSTEMS

Types of Foam

1. Chemical Foam

When two or more chemicals are added the foam generates due to chemical reaction. The most common ingredients used for chemical foam are sodium bicarbonate and aluminium sulphate with stabilizer. The chemical foam is generally used in Fire extinguishers.
2. Mechanical Foam

It is produced by mechanically mixing a gas or air to a solution of foam compound (concentrate) in water. Various types of foam concentrates are used for generating foam, depending on the requirement & suitability. Each concentrate has its own advantage and limitations.
3. Low Expansion Foam

For combating large hydrocarbon fires particularly in a contained area like storage tank, foam has proved useful for its inherent blanketing ability, best resistance and security against burn-back. Aqueous Film Forming Foam (AFFF) compound is technically superior and compatible with other fire fighting agents.

Efficient and effective foam delivery system is a vital tool for its usefulness in controlling the fire.

The process of adding or injecting the foam to water is called proportioning. The mixture of water & foam compound (foam solution) is then mixed with air in a foam maker for onward transmission to burning surface.

Conveying Systems

The system consists of an adequate water supply, supply of foam concentrate, suitable proportioning equipment, a proper piping system, foam makers and discharge devices designed to adequately distribute the foam over the hazard.

Conventional systems are of the open outlet type in which foam discharges from all outlets at the same time, covering the entire hazard within the confines of the system. There are three types of systems :


i) Fixed
ii) Semi Fixed
iii) Mobile

4. Fixed Foam System

Fixed foam conveying system comprises of fixed piping for water supply at adequate pressure, foam concentrate tank, inductor, suitable proportioning equipment for drawing foam concentrate and making foam solution, fixed piping system for onward conveying to foam makers for making foam, vapour seal box and foam pourer, suitable detection system may be provided to activate the foam system.
5. Semi Fixed Foam System

Semi fixed foam system gets supply of foam solution through the mobile foam tender. A fixed piping system connected to foam makers cum vapour seal box in case of cone roof tanks and foam maker and foam pourers in the case of floating tanks conveys foam to the surface of tank.
6. Mobile Foam System

Mobile system includes foam producing unit mounted on wheels which may be self propelled or towed by a vehicle. These units supply foam through monitors/foam towers to the burning surface.

However, certain other foam systems as follow are also available :

1. Sub Surface Foam Injection :

This is a system for protection of fixed roof storage tanks. This comprises of high back pressure foam generator and connected through product lines or separate lines near the bottom of the tank.
2. Under the Seal Foam Application :

This is a system for floating roof tank where the foam travels through a flexible pipe inside the tank up to the center of the tank roof and exits at the seal rim of the floating roof precisely where the fire is located thus rapidly flooding the seal rim area and quickly extinguishing the fire.
3. Automatic Actuated Foam Flooding System :

In this system all the components and ingredients including premix solution are contained within the system. Such systems usually have a premix solution supply tank pressurized by air or inert gas. The automatic sensing of fire releases this pressure and places the system into operation.
4. Floating Roof Tank Protection

For floating roof tank, foam shall be poured at the foam dam to blanket the roof seal. Features of foam system for floating roof tank protection shall be as follows :
System be designed to create foam blanket on the burning surface in a reasonably short period.
Foam shall be applied to the burning hazard continuously at a rate high enough to overcome the destructive effects of radiant heat.
Foam makers / foam pourers shall be located not more than 24 mtrs. apart on the shell perimeter based on 600 mm foam dam height.
A minimum of two pourers shall be provided.

5. Fixed Roof Tank Protection

Foam conveying system shall have same features as of floating roof tank excepting that a vapour seal chamber is required before the foam discharge outlet.

Features of the foam system for fixed roof protection shall be as follows :

The vapour seal chamber shall be provided with an effective and durable seal, fragile under low pressure, to prevent entrance of vapour into the foam conveying piping system. Where two or more pourers are required this shall be equally spaced at the periphery of the tank & each discharge outlet shall be sized to deliver foam at approximately the same rate. Tank should be provided with foam discharge outlets / pourers depending upon the dia. of the tank.

6. Floating cum Fixed Roof Tank Protection

Protection facilities shall be provided as required for fixed roof tank.

Protection for Dyke Area/Spill Fire

Portable monitors/foam hose streams shall be considered for fighting fires in dyke area and spills.

Water for Foam Making

Water quantity required for making foam solution depends upon the type for foam used. Protein foams is normal use have a 3% to 6% proportioning ratio. However, foam supplier data shall be used for determining water quantity required.

Foam System Components

Projects & Credentials

• Consultancy
• Maintenance
• Project Job
• Supply