It is difficult for me, being from the old school (44 years in the fire service), to call an apparatus that transports water from a source to the fire scene a "tender." I still want to call them "tankers." But whichever term you wish to use, this vehicle is one of the most important units in your fire station, especially when your protection zone has an area not serviced with a static (river or lake) or pressurized municipal water supply.

My mentor in the fire service, the late Larry Seebruck of the Port Edwards (Wis.) Fire Department, many times told me, "When the wheels of a tanker are not turning, the vehicle is not earning its keep." What Larry meant was that the longer it takes to fill a tank with water, or the longer it takes to empty a tank of water, the slower this vehicle is in delivering the much needed commodity to assist in the extinguishment of the fire. Horsepower can only do so much to effectively reduce the time it takes to get from point A to point B. We can reduce the time for the turnaround of a water tender by using efficient methods and equipment to fill the tank and then empty it into a portable tank or reservoir.

Through the years we have seen the adaptation of a number of vehicles in the business world to serve a fire department as a tender/tanker. These adaptations include fuel trucks, milk trucks, concrete trucks and military vehicles — even cattle water tanks slid into the back of a truck. These vehicles worked, but whether they truly worked safely and efficiently is the question.

Truck manufacturers since have developed vehicles that are more powerful and stronger-built to take the load being carried, and easier to shift. The NFPA got involved with a set of guidelines that specifically addressed tankers/tenders. And the ISO began to recognize the importance of tankers/tenders and their ability to significantly affect firefighting in rural areas.

Standard contradictions

The NFPA states that as long as the gross-axle-weight rating is not exceeded, the load can be placed on the truck. This is contrary to many states and the National Highway Traffic Safety Administration standards, which advocate that no more than 20,000 pounds should be carried on the front axle, no more than 19,000 pounds on a single rear axle and no more than 34,000 pounds on a tandem rear axle configuration.

However, there are many options available from truck manufacturers that allow for heaver GAWR, thus allowing for heavier gross-vehicle-weight ratings. The reason for these heavier GAWR axles is to accommodate a heavy load when the vehicle is in a turning mode and the driver has lifted the non-driving lift axle to accommodate the load — pusher (in front of the drive axles) and/or tag (in back of the drive axles). For an axle to be designated with a GAWR, several components must meet minimum requirements, including:

• Frame members
• Suspension springs
• Brake components (including linings and shoe platforms)
• Wheels (and all related components)
• Tires
• Steering components (e.g., tie rods, steering gears)

There is a major safety problem in that the fire apparatus manufacturers will build vehicles that put 31,000 pounds on a single rear axle. The concern is that each tire's footprint for an 18,000-pound GAWR rear axle is the same as for a 31,000-pound GAWR axle. Consequently, the heavier-loaded axle will not have the same stopping performance as the lighter-loaded axle. Most state departments of transportation require that a vehicle in a private or commercial application having more than 19,000 pounds on the rear axle must be supported with a tandem rear axle configuration, not a single axle.

The overall size of the vehicle — its height along with its in-motion weight, i.e., momentum — will determine how difficult it will be for the vehicle to stop in an emergency. Every year we read reports of tankers/tenders that have rolled over because the driver was unable to maintain control while negotiating a curve. These large vehicles will have a very high center of gravity to get an acceptable weight distribution to each axle, front and rear.

With most rural, volunteer and/or paid-on-call fire departments, the drivers/operators normally will not drive a tanker/tender often enough — nor any of the other vehicles in the fleet — to be familiar with every driving characteristic vehicle has. In addition, drivers are subjected to an intensified state of driving, with sirens, flashing emergency lights, radio communications, and the commands of the officer of the vehicle. Most of us are accustomed to driving our cars and maybe a pickup truck. Now, in the heat of the emergency, we expect the fire apparatus to behave and react like our personal vehicles.

There is no way a 50,000-pound vehicle can react the same as a car weighing 3,000 to 5,000 pounds. I have witnessed fire departments that have specified and built tenders with a 20,000-GAWR front axle and a 54,000-pound rear axle. That's not necessarily a bad thing. But now this department and the manufacturer of the tender body decided to put 4,000 gallons of water on this chassis. How did they expect this vehicle to be safe on the road? If this vehicle was owned by a milk hauler or other liquid hauler, they would be required to install additional axles to stabilize the load.

Chassis choices

There are many other factors to consider when purchasing the chassis that will transport water from a source to a fire scene. Starting at the front of the truck we need an engine. In today's world we only can buy diesel-power engines. In making this purchasing decision, departments should consider not only the horsepower but, more importantly, the torque that will be created by moving the load from a standstill, or by maintaining speed as the vehicle negotiates up an incline.

Next in line is the transmission. Fewer departments are purchasing manual-transmission trucks today than in the past. In today's world, where none of our young people are being trained to drive manual transmissions in drivers' education classes, why would a fire department want to take on the burden of educating these individuals? More important is the fact that automatic and auto-shift transmissions allow the driver to concentrate on driving on the road, that is, defensively.

Today, we can chose from the traditional automatic transmission built by Allison or an auto-shift transmission from either Fuller or Eaton that use a clutch-like, electronically controlled shifting mechanism. The advantage to the auto-shift transmission is that more horsepower is delivered to the wheels than its automatic counterpart, though Allison provides a torque-multiplying converter that provides power to the wheels constantly, and with less gears to shift.

Driveline U-joints and the rear-axle configurations are the final components to consider when specifying the chassis. Be sure to specify brakes that are easily serviced in your area. Posit-traction ("Detroit Lockers"), all-wheel axle, rear-drive axle, power-divider options, two-speed differentials, and traction-control brakes all are options to consider. Power dividers allow the operator to use both rear axles in a tandem-drive configuration to move the vehicle. This application, however, should be used only when the vehicle is in mud, sand or snow; it is not designed to be used on dry pavement or when making turns.

The posit-traction feature is very popular in the Snow Belt for single-axle trucks. The driver needs to be aware that both wheels always are turning, thus helping in snow. Also, making a 90° turn while applying engine power very easily can cause an axle shaft to snap on the inside of the curve, because it is making the same number of revolutions per minute as the outside wheel is making. Traction control uses the anti-brake system to apply braking power to that wheel which is spinning; thus, power can be shifted to the other wheel to pull away from a slippery condition.

Some departments have considered purchasing a chassis with an air-ride suspension system. In most cases, the sales engineer for the truck dealership will talk the department out of this option. Such a system gives a comfortable ride and is able to support many heavy loads. But it gets the air needed to inflate its air bags from the air-brake compressor. Air systems on trucks have been known to develop leaks and not maintain the air supply needed to support the load while parked in the station. The truck will need to stay in the station waiting for the air-supply system to fill the reserve air tanks and the air springs. In addition, slow reaction of air-spring systems to shifting loads can create a dangerous situation. Constant-rate leaf springs, or a similar system, for tandem axles should be considered when specifying the vehicle. Stability in all driving environments is tantamount for the safety of the vehicle and its crew.

Whether ordering a new chassis or purchasing a used one, be sure to work with a reputable truck dealer and an apparatus manufacturer to assure that your department purchases a chassis that will provide a safe vehicle.

Body functions

Now we will look at the business end of the apparatus — the tank and body. I once heard it said, "A tanker is a tanker and pumper is a pumper. When we try to combine these operations we create monsters." Many departments have attempted to accomplish too many functions — a water hauler, an equipment hauler, a firefighting foam transporter, and a pumper — within a single apparatus. The result is a huge truck that is dangerous to drive and is not efficiently fulfilling every task it was equipped to do.

When an apparatus has a large-volume pump, three dump valves and 2,000 gallons of water, what is this truck supposed to be? If the department is looking for a vehicle that can haul a significant amount of water to make an effective "blitz" attack with no supporting tenders, it is good to go. However, can that vehicle safely deploy numerous hose lines in a short period of time? Can person who is 5 feet 8 inches tall easily remove a hose line or a ladder? The answer is, probably not.

Through the years debate has been waged over single-wall ("wet side") tankers versus double-wall tankers (an outside, cosmetic steel panel conceals the water tank). I have seen many tenders that "sweat" on muggy days, regardless of whether they are of single-wall or a double-wall construction. Double-wall construction will cause the tank height to be higher than with a single-wall construction, which limits the amount of water that can be carried on the apparatus due to the additional weight.

The next argument concerns rectangular- versus elliptical-shaped tanks. A rectangular tank will provide a lower profile and thus a lower center of gravity, which allows for safer negotiations of curves and corners. NFPA has addressed the use of baffles within the tank to disallow significant movement of water — be sure your manufacturer follows these guidelines. Note that there may be a slight difference in dump time for an elliptical tank compared with a low-profile steel tank, because the elliptical height of the tank will cause a higher head pressure that forces the water out faster.

Dump valves are the next option to consider. Several types are available: rear, on the sides at the rear, on the sides at the front, round and square. Square valves, which are full-flow compared with those where the valve plate slides back into tank, are better.

Recently at a "Water on Wheels" seminar conducted with Roy Hoffman, vice chairman of the Rural Firefighting Institute, we tested some of these dump valves and used weight scales and stop watches to examine several myths.

We noted that a 10-inch square valve has 100 square inches of open area, whereas a 10-inch-diameter round valve has 78.5 inches of open area (less the butterfly plate). The 10-inch square valve delivered more water. There is a notable difference when a 10-inch-square dump valve hinges the sealing plate either up or down into the sump. This configuration allows for water to flow unrestricted. Sumps are areas cut 3 inches to 4 inches lower than the tank floor. This allows more of the water to exit the tank quicker. It should be noted that some tenders use a T configuration for dump valves to the rear and to the sides. When we compared this configuration with boxes cut into the side of the body for dump valves, there was no noticeable difference other than a higher center of gravity.

Front-corner side dumps and rear-corner side dumps are features to consider. The advantage to the front dump is you can nose the truck along the side of a portable tank, possibly behind another tender, allowing two tenders to dump simultaneously. Two disadvantages are: a firefighter has to be located between the portable tank and the apparatus body; and the box cut into the tank wall removes 90 gallons of water. The advantage to rear-corner side dumps is that they allow for the controls to be located at the rear of vehicle.

Air-operated valves are another option to consider. They allow the controller of the dump valve to be in a safe position and allow the switches to be placed in the cab, which lets the driver control the dump valves during a minimum-staff call.

Perhaps the most significant feature to have on a tanker is a lift system. The vehicle we observed that had such a system reduced the dump time by 40% using the air-operated lift system versus when the water was flat dumped. This system is available using hydraulic rams or air bags (as used in air-ride systems).

Filling inlets have been another great discussion point. During the seminar we compared a 25-foot-long hose filling through a single 5-inch inlet with two 25-foot-long hoses filling through two 2H-inch-diameter inlets. The engine was a 1,500-gpm, midship pump operating at 1,600 rpm. There was no real significance in filling times, but some safety concerns were noticed. The 5-inch hose is more difficult to move and it took as many people — two — to move, connect and disconnect the 5-inch as it did the two 2H-inch lines.

Another factor that affects the time needed to dump and fill the tank is the venting that lets air in or out of the tank. The vent placed at the top of the tank should be at least the same size as the dump valve. The opening between the baffle compartments needs to be sufficient to allow water to flow in efficiently. Verify with your builder that your tank with a 10-inch-square dump valve will be able to achieve a minimum 900-gpm fill and flow rate.

In conclusion, consider safety when purchasing your next tender/tanker. Is the vehicle going to be easy to drive for the most senior member to the youngest member of your department? Can you fill the tank safely and effectively? Will the configuration of the tank/body allow for appropriate weight distribution and a 15% safety factor for each axle? Will your driver/operator be able to stop safely, in any conditions? Will the truck handle safely around curves and corners?

Finally, be sure to require the apparatus manufacturer to demonstrate the dumping time — and the actual empty and full weights — to ensure you are getting every gallon you asked for.

Ronald Naab is a 44-year member of the Allenton Volunteer Fire Department, north of Milwaukee. As second assistant chief for 14 years, he was involved with the purchase of equipment and the maintenance of the eight vehicles in the department. For 16 years Naab worked with fire departments in Wisconsin and the Upper Peninsula of Michigan with engineering, design and sales of fire apparatus while representing Monroe Truck Equipment. There he was involved with the development of the lift system for tankers. Naab is an instructor member of the Rural Firefighting Institute, president of the Badger Firemen's Association and a 30-year member of the Wisconsin Society of Fire Service Instructors.

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