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In these times of tight budgets and a lack of funding for capital projects, fire departments have had to become innovative in obtaining apparatus to provide fire protection to the areas that they service. The apparatus that we will take a close look at this month is the fire department tanker. Also known as a tender, mobile water supply unit or other term, these are the pieces of apparatus used to truck water to the scenes of fires in areas not protected by public or private water systems.
In an effort to provide fire protection with limited funds, many fire departments have purchased used tankers. These tankers had been used to haul milk, gasoline, fuel oil or some other liquid commodity. While in theory it would appear to be a viable solution to a basic problem, there are pitfalls associated with retrofitting used tankers for fire department use.
Photo by Michael Wilbur
A former commercial tanker retrofitted for use as a fire department tanker. Emergency vehicle operators must know what makes these vehicles different from tankers that are manufactured for the fire service.
We will compare a fire apparatus built to haul water and a milk tanker. A milk tanker has no baffles. If you have a tandem-axle or tri-axle tanker truck, it may be capable of holding 4,000 or 5,000 gallons of liquid all in just one compartment. There are two reasons why milk tankers are not baffled: first, baffles would make the milk tanks impossible to clean, creating a bacteria and health hazard. If the tanks were baffled, after about an hour of churning and bouncing on the road, the milk could turn into cream or butter. The first fire apparatus tanker that I was associated with had a broken weld in the tank. We removed the tank cover for repairs and found that the tank was baffled every square foot; it was truly impressive and vastly different from most commercial tankers.
What does this mean to the emergency vehicle operator? Water weighs 8.34 pounds per gallon and milk weighs 8.6 pounds per gallon, so there is not much of a weight differential. This means that the milk tanker will be able to safely handle the weight of the water.
There are, however, other questions you must ask about the used milk tanker that the fire department just bought. In what condition are the brakes, springs, tires and steering components? Who is going to drive the apparatus? How will it ride, steer and handle when the tank is full? When it's empty? When the tankers are half full? Remember, the milk tanker has no baffles.
I had the opportunity to run a water supply class with a 3,500-gallon milk tanker retrofitted for fire department use. The apparatus operator drove with a full tank to the dump site. He then began to empty the truck's tank into a portable tank. The operator had emptied about 3,300 gallons of water into the portable tank when the next tanker arrived. The milk tanker was sent to be refilled. I watched the milk tanker operator pull off to the side of the road immediately after he left the dump site. Thinking that the operator had a problem, I went to his aid. I saw that he had opened the dump valve and was emptying the remaining water in his tank onto the ground. I asked the operator why he was doing this. He informed me that the milk tanker had to be completely full or completely empty, that there was no in between. Why, I asked? He replied he could not keep the vehicle on the road if it had water sloshing around in the tank. He said, "In fact, we have had three tankers in our county like this one, that have flipped over in the recent past."
Used petroleum tankers are also purchased by fire departments to haul water. These present some of the same problems and also some very different problems when hauling water. There is a great weight differential between water and petroleum products. We have already stated that water weighs 8.34 pounds per gallon. Diesel fuel weighs 6.951 pounds per gallon, kerosene weighs 6.732 pounds per gallon and gasoline with the wintertime MTB additive weighs 6.041 pounds per gallon.