In today's economy, many departments are postponing new apparatus purchases and keeping existing apparatus in service. A large number of these apparatus were built without foam capability. However, many of them may be candidates for foam or CAFS retrofits. There are two main reasons for a fire department to retrofit with compressed-air foam systems. The first is that the department wants to upgrade and take advantage of the benefits of the technology. The second is that the department may have purchased a new apparatus with CAFS and wants to bring the rest of its fleet up to the same capability. This helps to standardize operations throughout the department.

When a department wants to upgrade an apparatus to CAFS, certain criteria need to be examined to determine whether the vehicle is a viable retrofit candidate. These include the condition of the apparatus, the expected remaining service life, the apparatus power train, existing discharges, and existing foam systems.

The apparatus to be upgraded should be well-maintained and in good mechanical condition. A poorly maintained rig will require more time and will be more costly to retrofit due to additional work that may have to be performed. The apparatus also should have a significant service life before replacement is necessary, in order to make the investment in CAFS a viable option. To determine whether upgrading the technology would be cost-effective, divide the cost of the retrofit by the number of years that the apparatus will remain in service. A truck with only a 3- to 5-year life expectancy may not be a good candidate for a retrofit, while a truck with 10 to 12 years left would be.

Compressed-air foam systems are available in various configurations. The differences are the size of the system and how the compressor is powered. Compressor size ranges from ?60 cfm to 200 cfm. Configurations include auxiliary engine-powered slide-in and cross-mount systems, auxiliary-powered compressors, and power take-off (PTO) systems.

The method by which the air compressor will be powered must be determined. This first requires looking at the apparatus power train. An available PTO port is a good choice for powering the compressor. If there is an open PTO port with room to run a driveshaft and to mount the compressor, the system can be run directly off the PTO system. If no PTO port is available, the compressor may have to be driven by an auxiliary engine. This option, while providing a method to do the retrofit, does require more space for the engine along with additional weight, cost, and maintenance requirements. It also may require the fire department to be willing to sacrifice some space in the dunnage area, or set aside a compartment to house the compressor and drive engine.

Once the apparatus has been determined to be a candidate for a CAFS retrofit, the next mission is to choose the appropriate system configuration.

Wildland apparatus typically will flow smaller hose lines and volumes of foam, so a smaller system would be appropriate. Typical compressor size would be 60 cfm to 120 cfm. Such apparatus often are required to pump and roll. While pump and roll is possible with a PTO-driven compressor, the compressor speed is tied directly to road speed. This may limit the effective range for pump-and-roll operations. A better choice may be an auxiliary-powered system that is completely independent and can be operated effectively at any speed. Many wildland rigs have skid-type pump units. When upgrading these apparatus to CAFS, it is much easier and more cost-effective to simply replace a water-only skid with a new CAFS skid, as opposed to trying to add CAFS to the existing unit.

Structure engines will require higher flows, so the compressor and proportioner must be sized appropriately. Typical compressor sizes would range from 80 cfm to 200 cfm. The size needed will be determined by the number and size of discharges that the department desires to be CAFS-capable. PTO systems are good choice for this application as they are versatile and cost-effective. They also work well, as this type of application does not typically require pump and roll.

Discharge Decisions

When planning the retrofit, consideration must be given to which of the discharges will be CAFS-capable. Flexibility in this decision will help keep the installation cost reasonable. The possibilities may be driven by existing plumbing. Each CAFS discharge will need to be plumbed to the foam manifold, so some discharges will be easier — and therefore cheaper — to plumb than others. By choosing the proper discharges, it may be possible to have more CAFS-capable lines for close to the same cost.

Consideration should be given to whether the apparatus has an existing foam-proportioning system. If no system is currently on the apparatus, the price of adding the proportioner must be figured into the retrofit. If a foam system is installed, it must be examined to determine whether it is usable for a CAFS application. The unit must be an automatic proportioning system, meaning that it automatically adjusts to changes in water pressure and flow while maintaining the correct foam-solution percentage. The most common proportioner for CAFS is an electronic direct-injection system.

Retrofits are done by numerous fire apparatus dealers and service centers. Some original equipment manufacturers also can handle retrofits. A well-equipped fire department shop with experienced technicians may be able to handle the job as well. Be prepared to have the apparatus out of service for a period of time. The length of time will be determined in large measure by the complexity of the retrofit. The cost of the retrofit will vary with the existing configuration of the apparatus, the complexity of the system, how the compressor is powered, and the existence of an appropriate proportioner. The amount of labor required also will be a significant factor. The shop doing the retrofit will need to thoroughly examine the apparatus to determine an accurate cost estimate.

Diligent homework done by both the fire department and the retrofit installer prior to the project is critical. Installing a retrofit CAFS will require some compromises and realistic expectations by the fire department. Research and planning will help ensure a cost-effective installation that will operate correctly.

Do not forget the all-important CAFS training component. Make certain that the price of the retrofit includes instruction by an experienced, qualified CAFS instructor at your facility. Proper operational instruction is critical to effectively implementing the use of CAFS in your fire department.

To illustrate the feasibility of such retrofits, a class for emergency vehicle technicians will retrofit a CAFS on a pumper during the 2011 International Class A Foam and CAFS Academy. The installation will take place over three days, during which time the technicians will learn the proper method to install the system. Other students in the Academy's basic foam, foam and live-fire tactics, and chief/administrative classes also will be able to observe the project's progress. More information on the academy, which will be held in Glendale, Ariz., from Feb 3-5 can be found at http://elkhartbrass.com/thecafsacademy

Keith Klassen has nearly 35 years of experience in the fire service, both as a volunteer and as a career firefighter. He is currently a captain for Summit Fire Department in Flagstaff, Ariz. Klassen also is the CAFS instruction program manager for Waterous Co.

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