Improvements in Control Systems for Fire Pumps, Class A Foam Systems, and CAFS

Neal E. Brooks

“In the beginning” could refer to a biblical verse or a handful of new fire recruits gathered around an older, experienced firefighter explaining the virtues of “now vs. then.” And, so is the story about the evolution of control systems in the fire service and how it has affected both apparatus builders and end users. I recently visited a small volunteer fire department in rural Seneca, Illinois, and viewed its fully restored 1911 Waterous hand-drawn pumper.

It was the first new fire truck the village of 1,000 purchased, and it arrived via box car on the railroad. I marveled at the simplicity of design but also questioned the quality of gasoline available at the time or how many fingers, wrists, or arms were broken starting the motor with the infamous Model-T-type crank start. There were exposed gears in the pump assembly and rudimentary operating gauges that gave the operator only better than a guess for what the pump pressure was. If the fire stream hit the target, then it must be the correct pressure, right? Yes, the good old days.

Well, to paraphrase my mother, who was raised during the depression, “The good old days are now!” So it is within the rank and file of the modern day fire service and those fire apparatus builders that strive year after year to make operating what has become a complex piece of machinery safer and simpler. Merely three decades ago, a phenomenon known as the Internet was just getting started. Who would have guessed how it would affect the global community or those in their own fire service? The information network, in my humble opinion, affected many changes in our own private fire society in a shorter timeframe than what may have transpired in the good old days. Manufacturers and end users were now able to compile useful information to make the dangerous job of firefighting increasingly more controllable from a safety standpoint. The improvements in training methods, personal protective equipment, thermal imaging, and tools of the trade have evolved into a continuum of progress toward the goal of being safer and smarter. Apparatus manufacturers were quickly on board to take full advantage of this newfound computer age to develop safer, smarter fire apparatus.

Not lost in that desire to improve fireground safety was the fact that the manufacturing industry had to do its part to improve product reliability and safety. National Fire Protection Association (NFPA) 1911, Standard for the Inspection, Maintenance, Testing, and Retirement of In-Service Automotive Fire Apparatus, and NFPA 1901, Standard for Automotive Fire Apparatus, probably bear the brunt of that platform and road map for developing, maintaining, and designing safer fire apparatus. One thing, for sure, is that apparatus operations today are light years ahead of where they were just 10 to 15 years ago. There may be a few of us left who can remember fire trucks with standard transmissions. We arrived on scene, shifted the PTO into gear (many times outside the cab of the truck), placed the transmission shift rod into pump gear, and “locked” it in with the pin or hook that caught the latch on the shift rod. This sounds pretty safe if it is what you had back in the 1950s and 1960s-and decidedly so, because, for many, that was the only option.

The Modern Evolution

With the advent of higher horsepower engines, stronger automatic transmissions, and increasing demand from end users for “bigger pumps” came what I deem the modern evolution of fire apparatus. Manufacturers had the capability to meet all of those demands, but where did safety play into the mix? I can recall far too many stories of apparatus “launching” from their blocks while in pump gear and other tragic fire apparatus accidents. Looking forward, the apparatus industry investigated methods to isolate fire pump control at the pump panel while at the same time disabling the fire apparatus’s ability to operate or be controlled by the accelerator in the cab. This was a monumental improvement, but many new recruits in the fire service consider this a given. However, there still remains a thread of confusion or misinformation about system operation and methods of achieving safe operating parameters.

A good case in point is the governor system that operates the pump rpm and function at the pump panel. Again, there are some “old timers” who did and still believe the vernier governor (the black knob with the red “emergency shutdown” button in the middle) on the pump panel was manually controlling the accelerator pedal in the cab, when in reality it was controlling engine rpm electronically. Once the electronics on fire apparatus improved and computers started monitoring engine function, we entered the “future” of firefighting and apparatus construction. Wonderful things such as electronic pressure governors evolved.


As the larger fire apparatus chassis manufacturers began emulating the auto industry with powertrain control modules (PCMs) and engine control modules (ECMs), it was not long before they developed methods to further harness and enhance those control methods. One of the most recent and advanced methods of enhanced control is multiplexing. It was not without its challenges. Manufacturers found that systems that may have worked in other vehicles did not have the same long-term reliability in fire trucks that encounter severe service demands and constantly wet environments. As waterproof nodes, higher quality components, smaller footprint requirements, and expanded data-sharing capabilities became available, multiplexing overcame the resistance of many mechanics and now, for many, it is the preferred mode of operation.

Multiplexing has allowed apparatus builders to factor in safety redundancy and increased operational reliability into key apparatus components, including pump operations and pumping adjuncts such as Class A foam pumps and compressed air foam system (CAFS) components. With rapid advancement and popularity of Class A foam delivery systems and CAFS, the apparatus industry was presented with additional operational challenges. In the “good old days,” controls for Class A foam injection rates were done manually, as was the injection for the air-driven side of a CAFS unit. Today there are modern and more accurate electronic foam delivery direct-injection systems as well as electronically controlled valves for proper and safe introduction of air into a CAFS handline. Multiplexing has vastly improved safety and delivery system reliability in pump operation, Class A foam injection delivery, and balancing pressure systems in water pumps with CAFS air compressors. The term “interlock” is used in the industry to designate some of the safety redundancy issues overcome by the ability to control communication between these complex electronically controlled components in nanoseconds.

Here are some common system concerns and protection parameters:

  • Prevent accidental shifting of pump into road gear during fireground pumping operations.
  • Prevent damage to the pump with notification systems that indicate overheating and automatic shutdown within the pump or components relying on the pump for cooling.
  • Prevent dangerous pressure spikes with modern adjuncts such as the pressure governor system while pumping in pressure mode. It can react within seconds to changes in pressure sensed on the intake and discharge side of pump operations.
  • Low-foam-tank warning in advance of losing foam concentrate levels while operating on the fireground with Class A foam or CAFS discharge. With CAFS, the system may safely and systematically shut the compressor down when foam concentrate loss occurs to prevent slug flow.
  • Prevent dangerous “overrevving” of the engine and pump in the event of water loss or cavitation.
  • Seamless balancing of pump pressure and compressor output pressure when pumping in a CAFS mode.

In reality, CAFS and Class A foam operations have become increasingly easier to operate and manage on the fireground because of these and many other design improvements. Why is this important? Because the demand for CAFS is increasing, and that, my friends, is a topic for another discussion in this forum.

The Fire Apparatus Manufacturers’ Association (FAMA) is committed to the manufacture and sale of safe, efficient emergency response vehicles and equipment. FAMA urges fire departments to evaluate the full range of safety features offered by its member companies.

NEAL E. BROOKS is the national sales manager of the Apparatus Division for W.S. Darley. Brooks is a 27-year veteran of the fire and EMS services, with 13 years as a chief officer. He is a guest instructor and course designer for TEEX for advanced municipal fire operations and structural firefighting with Class A foam and CAFS.

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