By Jonathan M. Hinson

Firefighting foam has been around for many years, from the powder foam to protein foam to the synthetic foam in use today.

Originally designed to extinguish simple hydrocarbon-based fuel fires, today’s foams can be used on Class A fires; alcohol-based fuel fires; and, of course, hydrocarbon fuel fires. Technology has advanced to make foam operations more effective, simplistic, and cost-effective. Flammable and combustible liquids are everywhere and being transported through all modes of transportation. Hopefully, all fire departments have enough foam resources readily available to effect a rescue from a flammable liquid incident. Some communities may have a higher risk or threat, so more foam resources are needed. Whether a department has an eductor and three buckets of foam or thousands of gallons of foam with master stream devices, there are still some basic principles and tips that can apply to both situations to facilitate a successful foam operation.

Foam Percentages

Whether using onboard foam systems or portable foam eductors, the proper percentage of foam must be educted into the water stream to combat the problem at hand. The proper percentage depends on the fuel burning and, most importantly, the manufacturer’s recommendations. Class B foam is used at one, three, or six percent, describing the percentage of foam concentrate in the foam solution. The manufacturer through testing has determined at what percentage foam should be used. If the foam is alcohol-resistive, then the recommendations will also cover what percentage is appropriate for both hydrocarbon-based fires and polar solvents.

These recommendations are generally clearly stated in big numbers on the foam’s storage container. Using a percentage less than the recommendation will make the operation ineffective; increasing the percentage can make operations more effective with quicker extinguishment. However, when using a higher percentage, foam system operators must understand that they will use double if not triple the amount of concentrate required, potentially depleting the concentrate supply prematurely.

1 Photos by author.

Class A foams are generally used at 0.1 to 1.0 percent, once again depending on the manufacturer’s recommendations. In most cases, the lower percentages are used for fire attack and extinguishment while the higher end of the range can be used for exposure protection. Using higher than recommended percentages of Class A foam generally does not result in more effective operations like seen with Class B foams.

Use onboard foam systems and eductors to properly mix foam concentrate and water to make foam solution. You must perform this process flawlessly to have a successful foam operation. However, the foam concentrate must be made into finished foam through proper application to have a completely successful foam operation. The foam must be applied continuously and without failures. Proper application is critical with Class B foams, as they make a film or membrane to properly extinguish. Class A is a direct application just like water, so no film or membrane is produced.

Foam Application

The ensuing discussion about foam application applies to Class B foams. In basic training, firefighters are taught to apply foam with three different methods: roll on, bank on, and rain down. Nozzle operators must ensure that the stream is not plunged into the product, causing the foam to be pushed under the product and thus less effec

By Jonathan M. Hinson

Firefighting foam has been around for many years, from the powder foam to protein foam to the synthetic foam in use today.

Originally designed to extinguish simple hydrocarbon-based fuel fires, today’s foams can be used on Class A fires; alcohol-based fuel fires; and, of course, hydrocarbon fuel fires. Technology has advanced to make foam operations more effective, simplistic, and cost-effective. Flammable and combustible liquids are everywhere and being transported through all modes of transportation. Hopefully, all fire departments have enough foam resources readily available to effect a rescue from a flammable liquid incident. Some communities may have a higher risk or threat, so more foam resources are needed. Whether a department has an eductor and three buckets of foam or thousands of gallons of foam with master stream devices, there are still some basic principles and tips that can apply to both situations to facilitate a successful foam operation.

Foam Percentages

Whether using onboard foam systems or portable foam eductors, the proper percentage of foam must be educted into the water stream to combat the problem at hand. The proper percentage depends on the fuel burning and, most importantly, the manufacturer’s recommendations. Class B foam is used at one, three, or six percent, describing the percentage of foam concentrate in the foam solution. The manufacturer through testing has determined at what percentage foam should be used. If the foam is alcohol-resistive, then the recommendations will also cover what percentage is appropriate for both hydrocarbon-based fires and polar solvents.

These recommendations are generally clearly stated in big numbers on the foam’s storage container. Using a percentage less than the recommendation will make the operation ineffective; increasing the percentage can make operations more effective with quicker extinguishment. However, when using a higher percentage, foam system operators must understand that they will use double if not triple the amount of concentrate required, potentially depleting the concentrate supply prematurely.

1 Photos by author.

Class A foams are generally used at 0.1 to 1.0 percent, once again depending on the manufacturer’s recommendations. In most cases, the lower percentages are used for fire attack and extinguishment while the higher end of the range can be used for exposure protection. Using higher than recommended percentages of Class A foam generally does not result in more effective operations like seen with Class B foams.

Use onboard foam systems and eductors to properly mix foam concentrate and water to make foam solution. You must perform this process flawlessly to have a successful foam operation. However, the foam concentrate must be made into finished foam through proper application to have a completely successful foam operation. The foam must be applied continuously and without failures. Proper application is critical with Class B foams, as they make a film or membrane to properly extinguish. Class A is a direct application just like water, so no film or membrane is produced.

Foam Application

The ensuing discussion about foam application applies to Class B foams. In basic training, firefighters are taught to apply foam with three different methods: roll on, bank on, and rain down. Nozzle operators must ensure that the stream is not plunged into the product, causing the foam to be pushed under the product and thus less effec

Christian P. Koop

One of the worst situations an emergency response vehicle (ERV) driver/operator can find himself in, when called on to respond to an emergency, is when an engine won’t start because the batteries are low or dead.

Pushing the starter button and hearing the tell-tale click-click-click sound of a starter solenoid that won’t engage because the batteries are low is never a good thing! This should not happen with ERVs, but it does and more often than you would think. For ERVs to be reliable, the charging system - alternators, batteries, and onboard shoreline charger - must be system-matched. Think about it as the trinity, a phrase coined to express how important it is to understand how these three critical components need to be properly matched so they can operate as a complete and balanced system in a cohesive manner.

This is something that should be accomplished when ERVs are being manufactured; however, there are many rigs that leave the factory with alternators, batteries, and shoreline chargers that don’t make for a happy marriage and are destined to be unreliable until a solution is found. Some of these units could be the result of poorly written technical specifications while others could be from wiring that is the wrong gauge or from a poorly designed charging system circuit that has built-in high-resistance connections that create excessive voltage drops. Many reading this can probably relate to and think about rigs that have had problems in this critical area. This article will delve into the basic types and operation of alternators, batteries, and vehicle-mounted shoreline chargers to help explain the importance of how these components must be matched to become a balanced system where the components can support each other.

Alternators

Alternators are the main power source of the electrical system when a rig’s engine is running. Not only do they keep the batteries charged when the rig is not connected to shore power, they also provide the current to keep the electrical accessories operating properly when the engine is running. To do this, alternators must be sized properly to produce enough current or amperage to maintain all the connected loads used during an emergency. I refer to this as the total connected load, and it will vary from rig to rig depending on the specified 12-VDC electrical accessories. When ERVs are specified, a load analysis must be done based on the electrical accessories that will be used to determine what size alternator is needed. Although switching from incandescent lighting to LED lighting has reduced the lighting load considerably, more and more 12-volt accessories are being added. This, in turn, requires higher-amperage alternators to keep up with power demands. If memory serves me, I believe 500-amp alternators are now available. Back when I started working on apparatus, the biggest alternators in use were between 100 and 160 amps. Matching the size of the alternator to the loads that will be imposed on it is critical for proper accessory operation and longer alternator and battery life. Think trinity.

Keep in mind that although alternators do keep batteries charged, they are not battery chargers. They were never designed to charge dead batteries, and when you have six very low or dead batteries in a pack and jump start before recharging, you can overheat the alternator and shorten its useful life. In a nutshell, alternators generate alternating current (AC) when magnetism produced by a rotating direct current (DC) field coil is induced into a stationary stator and rectified to D

Christian P. Koop

One of the worst situations an emergency response vehicle (ERV) driver/operator can find himself in, when called on to respond to an emergency, is when an engine won’t start because the batteries are low or dead.

Pushing the starter button and hearing the tell-tale click-click-click sound of a starter solenoid that won’t engage because the batteries are low is never a good thing! This should not happen with ERVs, but it does and more often than you would think. For ERVs to be reliable, the charging system - alternators, batteries, and onboard shoreline charger - must be system-matched. Think about it as the trinity, a phrase coined to express how important it is to understand how these three critical components need to be properly matched so they can operate as a complete and balanced system in a cohesive manner.

This is something that should be accomplished when ERVs are being manufactured; however, there are many rigs that leave the factory with alternators, batteries, and shoreline chargers that don’t make for a happy marriage and are destined to be unreliable until a solution is found. Some of these units could be the result of poorly written technical specifications while others could be from wiring that is the wrong gauge or from a poorly designed charging system circuit that has built-in high-resistance connections that create excessive voltage drops. Many reading this can probably relate to and think about rigs that have had problems in this critical area. This article will delve into the basic types and operation of alternators, batteries, and vehicle-mounted shoreline chargers to help explain the importance of how these components must be matched to become a balanced system where the components can support each other.

Alternators

Alternators are the main power source of the electrical system when a rig’s engine is running. Not only do they keep the batteries charged when the rig is not connected to shore power, they also provide the current to keep the electrical accessories operating properly when the engine is running. To do this, alternators must be sized properly to produce enough current or amperage to maintain all the connected loads used during an emergency. I refer to this as the total connected load, and it will vary from rig to rig depending on the specified 12-VDC electrical accessories. When ERVs are specified, a load analysis must be done based on the electrical accessories that will be used to determine what size alternator is needed. Although switching from incandescent lighting to LED lighting has reduced the lighting load considerably, more and more 12-volt accessories are being added. This, in turn, requires higher-amperage alternators to keep up with power demands. If memory serves me, I believe 500-amp alternators are now available. Back when I started working on apparatus, the biggest alternators in use were between 100 and 160 amps. Matching the size of the alternator to the loads that will be imposed on it is critical for proper accessory operation and longer alternator and battery life. Think trinity.

Keep in mind that although alternators do keep batteries charged, they are not battery chargers. They were never designed to charge dead batteries, and when you have six very low or dead batteries in a pack and jump start before recharging, you can overheat the alternator and shorten its useful life. In a nutshell, alternators generate alternating current (AC) when magnetism produced by a rotating direct current (DC) field coil is induced into a stationary stator and rectified to D

Christian P. Koop

One of the worst situations an emergency response vehicle (ERV) driver/operator can find himself in, when called on to respond to an emergency, is when an engine won’t start because the batteries are low or dead.

Pushing the starter button and hearing the tell-tale click-click-click sound of a starter solenoid that won’t engage because the batteries are low is never a good thing! This should not happen with ERVs, but it does and more often than you would think. For ERVs to be reliable, the charging system - alternators, batteries, and onboard shoreline charger - must be system-matched. Think about it as the trinity, a phrase coined to express how important it is to understand how these three critical components need to be properly matched so they can operate as a complete and balanced system in a cohesive manner.

This is something that should be accomplished when ERVs are being manufactured; however, there are many rigs that leave the factory with alternators, batteries, and shoreline chargers that don’t make for a happy marriage and are destined to be unreliable until a solution is found. Some of these units could be the result of poorly written technical specifications while others could be from wiring that is the wrong gauge or from a poorly designed charging system circuit that has built-in high-resistance connections that create excessive voltage drops. Many reading this can probably relate to and think about rigs that have had problems in this critical area. This article will delve into the basic types and operation of alternators, batteries, and vehicle-mounted shoreline chargers to help explain the importance of how these components must be matched to become a balanced system where the components can support each other.

Alternators

Alternators are the main power source of the electrical system when a rig’s engine is running. Not only do they keep the batteries charged when the rig is not connected to shore power, they also provide the current to keep the electrical accessories operating properly when the engine is running. To do this, alternators must be sized properly to produce enough current or amperage to maintain all the connected loads used during an emergency. I refer to this as the total connected load, and it will vary from rig to rig depending on the specified 12-VDC electrical accessories. When ERVs are specified, a load analysis must be done based on the electrical accessories that will be used to determine what size alternator is needed. Although switching from incandescent lighting to LED lighting has reduced the lighting load considerably, more and more 12-volt accessories are being added. This, in turn, requires higher-amperage alternators to keep up with power demands. If memory serves me, I believe 500-amp alternators are now available. Back when I started working on apparatus, the biggest alternators in use were between 100 and 160 amps. Matching the size of the alternator to the loads that will be imposed on it is critical for proper accessory operation and longer alternator and battery life. Think trinity.

Keep in mind that although alternators do keep batteries charged, they are not battery chargers. They were never designed to charge dead batteries, and when you have six very low or dead batteries in a pack and jump start before recharging, you can overheat the alternator and shorten its useful life. In a nutshell, alternators generate alternating current (AC) when magnetism produced by a rotating direct current (DC) field coil is induced into a stationary stator and rectified to D