Foam Equipment & Systems Sugar Land Fire Department Driver/Operator-Pumper Academy Spring 2003

Know… –Foam Concentrate –Foam proportioner –Foam solution –Foam –Foam expansion

Storing Foam –Pails –Barrels –Apparatus Tanks

Class A Foam

–Application rates—same as the minimum critical flow rate for water –Application of foam types Wet foam: areas requiring maximum penetration foam Dry foam: vertical surfaces Medium foam: areas requiring a balance of penetration and clinging ability

Class B Foam –Used for fires involving flammable and combustible liquids –Proportioning Mixed from 1%-6% Follow the manufacturer’s instructions –Factors that affect degree of expansion Type of foam concentrate used Accurate proportioning of the foam concentrate in the solution Quality of the foam concentrate Method of aspiration

Class B Foam –Foam expansion types/ratios Low expansion: 20 parts finished foam for every part of foam solution Medium expansion: 20:1 through 200:1 High expansion: 200:1 through 2000:1 –Application rates Type of foam concentrate used Whether or not the fuel is on fire Type of fuel involved Whether the fuel is spilled or in a tank

Regular protein foam –Derived from naturally occurring sources of protein such as hoof, horn, or feather meal –Rarely used in the fire service today Fluoroprotein foam –Combination protein based and synthetic based foam –Very high degree of heat resistance and water retention

Film forming fluoroprotein foam (FFFP) –Based on fluoroprotein foam technology with aqueous film forming foam Aqueous film forming foam (AFFF) –Completely synthetic –Consists of fluorochemical and hydrocarbon surfactants combined with high boiling point solvents and water.

3 by 6—3% on hydrocarbon fuels and 6% on polar solvent fuels 3 by 3—3% on hydrocarbon and 3% on polar solvent fuels 1 by 3—1% on hydrocarbon and 3% on polar solvent fuels

Low-Energy Foam –Pressure of the water stream flowing through an orifice creates a venturi action that inducts (drafts) foam concentrate into the water stream. –Pressurized proportioning devices inject foam concentrate into the water stream at a desired ratio and at a higher pressure than that of the water.

In-Line Foam Eductors –Use the Venturi Principle to draft foam concentrate into the water stream –Both nozzle and eductor must have the same rating in gpm –Six rules: The eductor must control the flow through the system Pressure at the outlet of the eductor must not exceed 65 to 70 percent of the eductor inlet pressure Foam solution concentrate is only correct at the rated inlet pressure, usually 150 to 200 psi Eductors must be properly maintained and flushed after each use Metering valves must be set to match the foam concentrate percentage and the burning fuel.

Foam Nozzle Eductors Operate on the same principle as the in-line eductor Are built into the nozzle rather than the hoseline

Self-Educting Master Stream Foam Nozzles –Used where flows in excess of 350 gpm are required –Use a “rich”, overproportioned solution that is diluted at the nozzle deflector plates –Are available with flow capabilities up to 14,000 gpm –May use a jet ratio controller

Variable-flow Variable-rate Injection Systems –Operate off power supplied by the apparatus electrical system –Control foam concentrate injection by monitoring water flow and controlling the speed of a positive displacement foam concentrate pump, thus injecting concentrate at the desired ratio. –Can be used with all Class A foam concentrates and many Class B concentrates

Variable Flow/Rate & Direct Injection Systems –Advantages: Possess the ability to proportion at any flow rate or pressure within the design limits of the system Automatically adjust to changes in water flow when nozzles are either opened or closed May position nozzles either above or below the pump without affecting the foam proportioning May be used with high-energy foam systems

Variable Flow/Rate & Direct Injection Systems –Disadvantage: Foam injection point must be within the piping before any manifolds or distribution to multiply fire pump discharge

Variable Flow, Demand-Type, Balanced Pressure Proportioners The foam concentrate flow and pressure match system demand There is no re-circulation back to the foam concentrate tank. Water and/or foam solution can be discharged simultaneously from any combination of outlets up to rated capacity.

High Energy Foam System –(CAFS) Compressed Air Foam Systems –Introduction of compressed air into the foam solution prior to discharge into the hoseline

Advantages/Disadvantages –Advantages: The reach of the fire stream is considerably longer than streams from low-energy systems A CAFS produces uniformly sized, small air bubbles that are very durable. CAFS-produced foam adheres to the fuel surface and resists heat longer than low-energy foam Hoselines containing high-energy foam solution are lighter than hoselines containing low-energy foam solution or plain water. A CAFS provides a safer fire suppression action that allows effective attack on the fire from a greater distance. Most systems also designed to flow plain water.

Advantages/Disadvantages –Disadvantages: A CAFS adds expense to a vehicle and adds to the maintenance functions that must be performed on the vehicle Hose reaction can be erratic with a CAFS if foam solution is not supplied to the hoseline in sufficient quantities The compressed air accentuates the hose reaction in the event the hose ruptures. Additional training is required for personnel who are expected to make a fire attack using a CAFS or who will operate CAFS equipment