By Chris Mc Loone
If you are on the East Coast, you know them as tankers. If you're on the West Coast, you know them as tenders.
And, if you're in the fire service, you know them as being the smallest percentage of fire apparatus out on the road with the highest chance of getting killed if you are involved in an accident with one.
Additionally, tankers/tenders have not been immune to the current trend of building apparatus that can perform more than one function. Multipurpose designs have also impacted the tanker/tender market where today we have pumper-tankers and tanker-pumpers. The combination apparatus are sometimes longer, carry more equipment, and can carry more personnel than their two-door, straight water hauler brethren. What is common among whatever type of tanker/tender your department might own is that it will carry at least 1,000 gallons of water. According to National Fire Protection Association (NFPA) 1901, Standard for Automotive Fire Apparatus (2009 ed.), "The mobile water supply apparatus shall be equipped with a water tank(s) that meets the requirements of Chapter 18 and that has a minimum certified capacity (combined, if applicable) of 1,000 gallons (4,000 L)." Although the minimum tank capacity is 1,000 gallons, departments often have larger tanks, and it is the amount of water carried that is a major difference in how a tanker/tender operates vs. a custom pumper.
As with many things, awareness is key. Fire apparatus today is extremely easy to drive. Gone are the days of double clutching and stalling if you don't find the next gear in time. The pool of drivers is far wider and deeper than ever before. But, drivers and operators must be aware of how different a tanker/tender is and why to operate it safely.
Water Weight and Motion
The main difference between a custom pumper and a tanker/tender is the amount of water it carries. Some tanker/tenders are straight water haulers with small pumps on them, while others are designed more as first-out pieces, carrying enough equipment to function as Class A pumpers. Regardless of the type, the handling of a vehicle carrying 1,000 gallons of water or more is going to be different than a truck carrying a 750-gallon water tank. Water in motion directly impacts how the vehicle handles.
One gallon of water weighs slightly more than eight pounds. So, tankers/tenders compliant with NFPA 1901 will carry approximately 8,340 pounds of water. With that much extra water weight-weight that is in motion-operating the apparatus is impacted. "It doesn't matter if you're in a commercial two-door with 3,000 gallons of water or a big four-door custom eight-person cab with 2,500 gallons of water," says Mike Wilbur, president, Emergency Vehicle Response. "The laws of physics dictate that if you don't drive them conservatively at a slower speed and pay attention, you will flip them over. The laws of physics are very unforgiving."
Firefighter Jim Moore, Miami-Dade (FL) Fire Rescue Department, agrees and says the difference between operating a tanker/tender and a custom pumper is the dynamic load of the water itself. "It's a high center of gravity, and when you brake and turn, the longer you are braking and turning, the more apt the vehicle is to roll over and react in a way you're not expecting," he says. "The tanks are baffled. But as you are turning, such as on a full 360-degree cloverleaf, enough water will go through the baffles and climb up the side of the tank that you will have to reduce your speed."
An important point regarding water in motion is driving a tanker/tender when it is half full-a practice that is not recommended. "You see the most drastic change in characteristics while driving if [the tank] is half full," says Moore, "because there is space for the water to disperse to one side and give you a severe load change,