Compressed air foam systems (CAFS) have made their way into an increasing number of fire apparatus and the use has grown exponentially. This can be attributed to a combination of factors such as an increased acceptance of this technology, more frequent exposure to the available systems, faster knock down, and the benefit of substantial suppression power when water resources are limited. As with many technologies that have found their place on fire department vehicles; the reliability and creditability of such equipment is only guaranteed by routine exercise, inspection, maintenance, and deficiency reporting to the maintenance department or service center.
Exercise and routine use are the best safeguards against sticking components or failure to perform at an emergency scene. Every system will have a factory predetermined schedule of visual and operational inspection that can easily be incorporated into daily, weekly, or monthly checks already in place. Most inspections add minimal time to routine checks and combat the most costly of failures; for example, lack of lubrication and contamination. The majority of CAFS daily inspections may simply include verifying proper compressor and/or hydraulic oil tank levels. In addition, some manufacturers require the compressor to be operated for a certain period of time once activated to reduce condensation in the oil. It is important to note required time a system must sit after operation before checking the oil level; if specified, some systems need additional time to sit before this reading will be accurate. Do refer to the service manual to avoid potential injury when checking or adding fluids and avoid overfilling. Excessive moisture has the ability to drastically reduce the lifespan of the compressor, fittings, valves, and piping by increasing wear and corrosion. Materials from these degraded components may dislodge and become caught in instruments or valves rendering them inoperable. In house pump classes can greatly benefit by having three samples of hydraulic fluid in sealed glass containers; the first with new fluid, second with dirty fluid, and the third having fluid contaminated with water. Props will allow the operator a chance to view the differences in fluid characteristics which may again be recognized and identified as potential component failure on future inspections.
Maintenance manuals will provide the recommended procedures and service intervals for the system installed on a particular vehicle; it is very beneficial to include these manuals with apparatus when dropped off for service and repair. The information contained in the factory documents are necessary to ensure any warranty guidelines are met and to aid in diagnosis by the mechanic if required. Departments without internal maintenance programs should verify with their repair center that the CAFS equipment is serviced with the vehicle’s routine maintenance. Coordinating annual CAFS maintenance in conjunction with the annual pump test can potentially decrease maintenance costs by reducing the chance of redundancy in pump performance testing should repairs be deemed necessary.
Before use of the system, it is important to understand CAFS full capabilities and limitations. It would be advisable to incorporate re-familiarization with the system on an annual basis and even more often if utilized infrequently. Some CAFS complaints and perceived performance issues can be corrected through more frequent hands on exposure to the components. Many times performance problems can be difficult to reproduce in the shop; detailed documentation of an issue is extremely helpful to the mechanic provided the account is objective. Information such as foam tank level, pump pressures, air pressures, what lines were flowing, type of nozzle, foam percentage desired, expectations, observed quality, and more are needed to form a reasonable suspicion as to the component at fault. Incomplete documentation can result in the inability to identify or repair a problem and may require extensive testing to reproduce the complaint. At the fire scene there are many things to think about other than the future write up; however, when it is possible to gather this information it provides a better chance of correcting issues.
Various levels in an organization play a role in the ability of compressed air foam systems to perform as designed. A comprehensive maintenance program including exercise, service, and reporting at the appropriate level will ultimately ensure it continues to deliver as the agency anticipated and at a reasonable cost.
By: Justin Claibourn
Washington Fire Mechanics