What is Foam Fire Suppression System? How it’s Work? »

What will You learn after Completion of this Blog?

How to Choose Deluge Foam Valves?
Understanding the Mechanical Operation of Deluge Foam Systems
Understanding the Electrical Operation of Deluge Foam Systems
How to Perform Foam Tank Sizing?
Understanding the Different Types of Foam Used
Understanding Fire Fighting Foam Terminology, Types, and Concentration

Introduction to Foam & Fuels

General Components

Hydrocarbons

Products of Crude Oil Float On Water.

—- Gasoline
—- Diesel
—- Heptane
—- Kerosene

Polar Solvent

Products of Distillation Mix With Water.
– Ketones
– Ethanol
– Alcohols
–MTBE – Gasoline additive (Methyl-tert-butyl ether)

How Foam System Work?

Removes heat at a faster rate than it is released
Separates the fuel from the oxidizing agent
Dilutes the vapor-phase concentration of the fuel and/or oxidizing agent below that necessary for combustion

Foam Quality

History of Foam

Protein & Fluoroprotein, (for hydrocarbons), 1940’s

AFFF (for hydrocarbons fuels), 1960’s

AR-AFFF (multi-purpose), 1970’s

High Expansion (total flooding capability)

Class A (wetting agents), 1980’s

Protein / Fluoroprotein Foam (For hydrocarbons, 1940’s)

Synthetic Foam

Synthetic foams are based on synthetic surfactants. Synthetic foams provide better flow and faster knockdown of flames.
Aqueous film forming foams (AFFF) are water-based and frequently contain hydrocarbon-based surfactant such as sodium alkyl sulfate, and fluorosurfactant — such as fluorotelomers, perfluorooctanoic acid (PFOA), or perfluorooctanesulfonic acid (PFOS). They have the ability to spread over the surface of hydrocarbon-based
liquids.
Alcohol-resistant aqueous film-forming foams (AR-AFFF) are foams resistant to the action of alcohols, able to form a protective film when they are present.

AFFF-Aqueous Film Forming Foam Low or Medium Expansion (for hydrocarbon fuels, 1960’s)

Does not require aspiration, unlike Proteins
Cannot be used on polar solvents (i.e., alcohols, acetone, methanol)
Available in 1%, 3% or 6% Storage temperature 35OF to 120OF
freeze-protected available to -20 F
20 to 25 years Shelf-life

AR-AFFF Foams Alcohol Resistant-Aqueous Film Forming Foam: Low or Medium Expansion for polar solvent fuels, 1970’s

Multi-purpose foams created for both Polar-solvents (alcohols) & Hydrocarbons (fossil fuels).
available in 3% or 6%
does not require aspiration
storage temperature 35OF to 120OF (optional freeze-protected available to -0O)
20 to 25 year Shelf-life

High Expansion Foam

Detergent based foam effective on hydrocarbons only
works by Cooling, Smothering, Penetrating and Insulating
can be used for Local and Total Flooding applications 35OF to 120OF storage temperature range
20 year Shelf-life

Foam Expansion Categories

Low Expansion Foam Ratio: 8:1
Medium Expansion Foam Ratio: 100:1
High Expansion Foam Ratio: 500:1
Compressed Air Foam Ratio: 10:1

Expansion ratio is the comparison between the final foam volume to the original foam solution before air is added to the solution.

What is Foam System?

An automatic or manually actuated fixed pipe system connected to a foam solution supply and equipped with foam discharge nozzles designed to provide a specific foam discharge and distribution over the protected surfaces or area to be protected.

Objective :
Extinguishment of fire, Cooling, Control of burning, Exposure protection, and Prevention of fire

Types Of Foam System:

There are three types of foam systems
i. Fixed Foam System
ii. Semi-Fixed Foam System
iii. Mobile Foam System

Fixed Foam System:

Fixed foam conveying system comprises of fixed piping for water supply at adequate pressure, foam concentrate tank, eductor, 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.

Semi fixed foam System:
Semifixed foam system gets supply of foam solution through mobile 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 roof tanks conveys foam to the surface of tank.

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

HOW PROPORTIONING EQUIPMENT WORKS?

Fire breaks out in the rack storage area of a flammable liquid storage warehouse.
Rising heat ruptures the heat sensing device in the sprinkler heads, starting the flow of water.
Flowing water through the alarm check valve opens the hydraulic foam concentrate valve to the foam proportioner, if required.
Foam concentrate flows from the bladder tank into the proportioner where it is mixed with the flowing
water at the designed foam solution percentage. Foam is generated as the foam solution discharges through the sprinkler heads onto the fire.