By Alan M. Petrillo

Fire departments tend to be traditional in many ways yet often take time to embrace new technologies.

But when it comes to sirens-audible warning devices for fire apparatus-a mix of old and new technology can be found on many fire vehicles. It's not unusual, for instance, to see a new first-due pumper outfitted with both electromechanical and electronic siren systems.

Electromechanical Sirens

Vic Hilbert, owner of Eagle Sirens Inc., makes traditional electromechanical sirens that he says use a forward projection of sound instead of a wall of noise. "We focused the sound from our sirens to send it forward," Hilbert says, "and also off on a 55-degree angle to each side to get great penetration at intersections. A lot of other sirens put up that wall of sound, which puts the noise out front but also has a backwash that penetrates backward into the cab of the fire truck."

Eagle Sirens Inc. makes the Screaming Eagle electromechanical siren, shown here pedestal-mounted on an extended bumper. The siren also can be flange-mounted and nested in a hidden mount. (Photo courtesy of Eagle Sirens Inc.)

Hilbert's company makes the Screaming Eagle siren in one model available in three mountings: a pedestal mount (for apparatus with extended bumpers), a flange mount, and a hidden mount where the siren is nested behind a vehicle's bumper.

Hilbert points out that Eagle Sirens uses a pure silicone formula for all of the noncontact sealed bearings in its sirens. "The silicone makes the siren run much quieter and longer, and it has an anti-vibration effect," he says.

Kevin O'Connell, owner of B&M Siren Manufacturing Co., says B&M has five models of electromechanical sirens in its line: two direct-driven Super Chief versions and three Siro-Drift models. O'Connell maintains that electromechanical sirens move traffic better than electronic sirens. The electromechanical signal sent by a siren depends on the number of ports it has and how fast the air is moving through the ports, he notes. "The faster you run the siren, the more it sounds like you're stepping on a cat's tail," he says.

O'Connell says a siren's spinning rotor is very similar to that of a centrifugal pump. It draws air in at the front of the siren; compresses it slightly; and, as the air escapes out of the ports, the siren pops with sound.

One of the advantages of a mechanical siren over an electronic one, he points out, is that the mechanical siren emits a lower-frequency signal, which travels much farther. "The lower the frequency, the farther the sound travels, which is why air raid sirens operate at a low frequency," he says. "There's no beating a mechanical siren for attracting attention down the road," O'Connell says.

Code 3 has developed the Banshee, an electronic device that can be attached to any siren in the industry to produce attention- getting low-frequency tones among its 25 tone combinations. (Photo courtesy of Code 3.)

Timberwolf Siren Technology also builds an electromechanical siren-the Timberwolf 45, which develops a 123-decibel sound level from a 12-volt, 28-amp power source. The Timberwolf 45 uses an angle-designed rotor that the company says won't lose acoustic energy because the sound is d

By Christian P. Koop

Cooling system maintenance for emergency response vehicles (ERVs), in my book, has become more important than ever.

It seems to me that it often takes a back seat to other major areas such as lubrication, air filtration, and oil filtration in the overall preventive maintenance scheme. However, it is an area where failure can lead to considerable downtime and can be extremely costly to repair. I am sure most in this business will agree that this makes it even more important to ensure the cooling system is properly inspected and maintained. Additionally, the coolant itself has become more important than ever in providing the necessary protection for the highly sophisticated modern engines in use today. This article will cover a brief history, basic required cooling system maintenance and some characteristics of the diesel engine cooling system, and tips on coolant chemistry and how to ensure it is protecting the cooling system adequately.

Using a test strip is simple and quickly reveals glycol percentage, pH, and additive concentrations. Be sure to follow instructions printed on the bottle. (Photos by author.)

Cooling System History

In the early days of internal combustion liquid-cooled engines in the automotive and emerging heavy-duty truck industry, people experimented with different ingredients to keep the cooling system from boiling over in the summer and freezing in the winter. Many will be surprised to know that people added ingredients such as sugar, honey, and molasses to the water in the cooling system for this purpose. This was prior to 1927, when Prestone came out with its all-season antifreeze and coolant, which was formulated with ethylene glycol. Ethylene glycol is actually a weakly toxic, odorless, colorless, sweet, viscous fluid that, when mixed with water, will effectively lower water's freeze point and increase the boiling point. Prestone's all-in-one summer coolant and winter antifreeze, when mixed with the correct proportion of water, offered year-round protection. It did not need to be changed every season, making it a better choice over the ethyl-alcohol-based coolants available at the time. This was also around the introduction of the pressurized radiator cap. Prior to this, ethyl-alcohol-based coolant would slowly evaporate out of the nonpressurized systems that were the norm. This new antifreeze and coolant contained corrosion inhibitors and water pump seal lubricants.

Pressurizing the system greatly increased the boiling point of the fluid when combined with a 50:50 ratio of water to coolant. To this day, it still remains a basic guideline and an important factor. For example, a 15-pound radiator cap will provide freeze protection down to -34°F and will increase the boiling point up to +265°F. Greater concentrations of coolant to water give more protection in both directions. However, once you go beyond a 70:30 ratio of coolant to water you can actually start raising the engine's temperature because water transfers heat better than pure coolant can. On the back of every coolant container is a chart that provides the recommended ratios of coolant to water and the freeze and boil overprotection it can provide based on the radiator pressure cap rating.

Today's engines generate more heat than ever before, making it even more important to stay on top of the cooling system especially because there is no shutdown protection in fire apparatus if the engine overheats. If there is an overheat condition, the only thing allowed is a gradual derating

By Alan M. Petrillo

Pumpers, rescues, and aerials are the workhorses of a fire department's apparatus fleet and often spend considerable time idling at a scene yet not flowing water, raising a ladder, or using rescue tools.

Main engine idling is proving costly to fire departments, eating up pricey diesel fuel, putting additional particles into the diesel particulate filter (DPF) and generating engine wear and tear that requires more frequent maintenance.

Auxiliary power units (APUs) are designed to stand in for the main chassis engine when it is not needed, allowing the APU to provide power for warning and other lighting and electrical needs as well as heating and cooling of the apparatus cab. Despite these realities, manufacturers report that APU integration into fire department fleets has been a slow process.

KME installed APUs on each of the 20 pumpers it built for the United States Air Force. The units, located in the pumpers' dunnage areas, use 10-kW Westerbek generators. (Photo courtesy of KME.)

Growth, but Slow

Joel Konecky, regional sales director for Smeal Fire Apparatus, says that sales of APUs continue to grow, particularly in the southeastern United States and in Canada. "We've made some changes to our SG-09 units operationally," Konecky points out. Smeal offers two models of its APU-a parallel system that has completely independent chassis heating, ventilation and air conditioning (HVAC) and SG-09 HVAC systems-and an integrated system where the chassis evaporator, fan, and air conditioning controls are used with the air conditioning compressor of the SG-09.

"Charlotte (NC) Fire Department has been using our parallel system SG-09 and reports good experience with it, especially in fuel savings and reduction of maintenance frequency," Konecky says. He adds that Smeal is considering upsizing the SG-09 system to work with larger generators and that the company continues to improve the product for climates with weather extremes. "It's especially a concern in the Midwest and other areas where they have very cold temperatures," he notes.

Konecky maintains that Smeal's APU is the most sophisticated system on the market and the easiest to use because of the unit's electronics. "It's a part of the vehicle that an operator doesn't have to think about or do anything about," he says. Because the SG-09 will automatically shut down the chassis engine after a preset amount of idling time, Konecky says "there is no operator intervention to turn the system on."

The control panel displays made for the KME APUs on the Air Force pumpers are located inside the cab (shown here) and on the pump panel. (Photo courtesy of KME.)

Battery Innovations

Rosenbauer's vice president of sales Scott Oyen says that Rosenbauer offers its Green Star idle reduction technology as a dual system where the vehicle's systems can be run either off the diesel-driven APU or through Smart Batteries-lithium-ion or lithium-polymer batteries separate from the chassis battery. Depending on what emergency lighting and electronics systems are to be used, the vehicle can run those systems off of two to six batteries, O

By James Chinni, Marius Magdun, and Marissa Cotten

Saving the lives of others can be a very dangerous business, especially for firefighters whose job it is to protect our communities.

In 2012, 81 firefighters died while on duty-18, or one fifth, died while responding to or returning from the scene.1 To address and reduce deaths in vehicular accidents, many fire chiefs across the nation stress the importance of buckling up. However, many take their firefighters' safety a step further by specifying supplemental restraint systems (air bags) on their apparatus.

History of Air Bags in Passenger Vehicles

The first commercial air bag systems were offered on some GM cars in the early and mid 1970s. These systems were much larger, heavier, and slower than today's air bag systems. They were strictly a supplement to seat belts and were marketed by GM as the Air Cushion Restraint System.

In the late 1980s and early 1990s, frontal air bags were reintroduced and federally legislated in passenger vehicles as supplemental restraint systems (SRS). Mercedes-Benz and Chrysler were among the first manufacturers to introduce a driver-side, steering-wheel air bag as standard equipment. Within a few years, driver- and passenger-side frontal air bags were standard in most vehicles sold in North America and Europe. By the mid 1990s, side-impact air bags started showing up, either integrated in a door panel or within the side bolster of the front seats. The 1995 Volvo 850 was the first vehicle to offer side air bags. The pyrotechnic air bag inflator was mechanically triggered by intrusion of the front door into a pyrotechnic primer charge. Today, all air bag systems are monitored and triggered by electronic sensors. It was the same company, Volvo, that introduced the first rollover air bag in 2003.

Rollover Air Bags

Although most people are familiar with air bags in their personal vehicles, their application in fire apparatus is specially designed for the unique seating environment, duty cycles, and crash characteristics of their installation. Air bags in fire apparatus originated with the discovery that rollover crashes accounted for roughly five percent of all heavy truck crashes, but were the cause of more than 60 percent of fatalities and 45 percent of incapacitating injuries to heavy truck occupants involved in a crash.2 To improve the outcome for firefighters and truck drivers in crashes, the industry researched rollovers to develop effective countermeasures. The first step in addressing this issue was to understand what happened to people inside a vehicle cabin during a rollover. That need drove the construction of a one-of-a-kind 90-degree dynamic rollover impact machine.

Engineers discovered that rollovers in heavy trucks are dramatically different than those in a passenger car or SUV. The air bag systems needed to protect the occupants would have to be different as well. After years of extensive testing and validation, including the rollover test of an entire vehicle, the first roll-protection-equipped fire apparatus was introduced in the spring of 2003. About the same time, Volvo introduced the XC90 SUV with roll stability control (RSC). The RSC contained an algorithm that deployed rollover curtain air bags and was touted as the first of its kind in the world. Today all makes of custom fire apparatus offer roll-protection systems as an option to better protect firefighters in a rollover. In addition to fire trucks, rollover air bags can also be found on commercial trucks and ambulances.

Rollover System

The brain of the system in a fire apparatus is a roll sensor that is mounted centrally within the cab. As soon as the driver turns the vehicle ignition on, the sensor goes through a self-diagnosis that typically lasts five to 10 seconds, then begins to sample vehicle status and conditions every 12 milliseconds, or about