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FT 33FIRE FIXED INSTALLATION SYSTEM

FOAM

OBJECTIVE

1. To explain the function, operation and maintenance of Foam Installation fire fixedinstallation system.

REFERENCE

2. Manual of Fireman ship Book 9.

CONTENTS

3. Introduction. Besides water, foam is also used a media for fire extinguishing

systems. Foam systems are found in various manufacturing and industrial areas or aircrafthangars, primary properties in which there are flammable liquid fire hazards. His expansionfoams systems may be installed in buildings with Class fire Hazards.

4. These notes deals with the equipment and fittings installed for fire protection usingfoam low and high expansion types.

5. Foam Installations:

a. Pump-Operated Mechanical Foam Type. These types consider of:

(1) Water supply line from pumps through an inductor.(2) Distribution piping system to foam generator.(3) Liquid foam tank.

6. Operation. Water control valve is opened and water flows into the foam tank. Wateralso flows through the inductor and by venture effect created the inductor draws the resultantmixture of foam area, where foam is immediately formed.

7. Self-Contained Pressure Type. This system is designed to protected limited

interior hazard such as dip tanks or hazard inside structures used in industries. Theresystems are normally automatically activated.

8. This type consists of:a. Water storage tank with cylinder of CO2 to expel the water through an

inductor.

b. Distribution piping system to foam generators.

c. A liquid foam tank.

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9. Operation. When CO2 is released from the cylinder, it expels the water from thestorage tank through the inductor. The induct draws the concentrate into the water stream.The foam solution it them delivered to generators through a piping system.

10. Pre-Mixed Type. This consists of:

a. A cylindrical storage tank, designed for maximum working pressure of 10bars. This tank is filled with foam concentrate and water.

b. A CO2 gas cylinder with is used to expel the foam solution. The cylinder has

a disc-closure valve and a lever operated piercing head.

Mechanical Foam Installation Pump Operated Type

Mechanical Foam Installation: Self-contained Pressure Type

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11. Operation. To activate the system, the CO2 cylinder valve is pierced and CO2 isreleased into the storage tank. The solution is formed up the siphon tube and piped to thegenerator.

12. Special Discharge Arrangements. To protect both exterior situations severalarrangements of piping and nozzle are also employed. The nozzle producing foamdischarge is similar to the water sprinklers accept nozzle are usually of a larger size andhave corresponding larger flow rates. Sixteen gallons per minute per sq. ft. is recommended.

At least one over head is required to protect 100 sq. ft. of area. The figure below shows apiping and nozzle arrangements for a truck loading rack.

13. Monitor Site. Most fixed monitors are normally activates operated. When choosinglocations for fixed monitors, be sure provide protection for operating personnel and ensureaccessibility of the monitor at the time of a fire.

14. High Expansion Foam System. High expansion foam was first introduced in 1960

and is widely used industrially. It is mean to generate large quantities of foam to flood aroom or a localized area.

15. Basic System. Most system have 3 essential components:

a. The detection or actuating system.b. The generators.c. The piping arrangements for water and foam.

16. Detection System. The detection system is the same as covered in Automatic FireDetection devices.

17. Generators. The generators may be electrically or hydraulically powered or even aninternal combustion engine. New types non-available for local application utilities compressair or nitrogen from a cylinder. A typical foam generator is in the figure below:

A Pre-Mixed Foam Installation

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Foam Generator of Spot Type Local Application System

18. The foam generator is connected to water and foam concentrates solution line andbe located over the hazards. Generators are usually mounted in the roof or ceiling, allowingthe hi-expansion foam to discharge down over the fire area. They may be mounted inexterior walls so that air intake can come from outside to avoid any contamination.

19. Piping. Piping system is arranged to supply generator with water and foam

concentrate. Other piping system may include air lines or high pressure water linesdepending on the power supply used. There is no requirement for piping for expanded foamto the fire hazard.

20. High expansion foam system is installed primarily for protection of class A and Binterior hazards. E.g. large warehouse, storage and assembly.

21. The following considerations are of importance:

a. Foam generator must be mounted high and located when there is a largesource of uncontaminated air.

b. Hi-expansion foam is not compatible with dry chemical powders especiallypotassium bicarbonate: and protein foam.

c. When applying the system, it is important to close an opening at the lowerlevels so that the maximum advantage used. There should be openings situatedhigh up so that there is a free-flow of air. IN the activation of this system, there maybe a need of automatic venting system, enclosing of fire doors or ventilation ducts.

d. The need for personnel evacuation alarm is also considered.

22. Rate of Production. The rate of production is not measure by the production rate ofthe generator. It is the rate in which a room can be filled is the criteria. For example theNavy requires an expansion ratio of 600: 1 and f ill at the rate of ft. per min, for systems usedon ships. The target height is aimed at 1.1 times over the height of the hazard in any caseno less than 2 ft.

23. Operation. The operation of the system is similar to all automatic system. In thiscase the source of the media is different i.e. the generator. Most generators use the ventureproportioned to inject foam concentrate into the water solution line. The foam is produced by

agitating the solution or by passing air trough a net or grill which is saturated with solution.