Fire Rescue Magazine
The Vacuum Tanker: Command Leadership
The Vacuum Tanker
As I have pointed out in previous columns, water-on-wheels (WOW) operations can be very labor-intensive. Anyone who must haul their firefighting water supply to fires knows how critical time and manpower are to these operations. This column is in response to readers who have sent in questions about the use of vacuum tankers in WOW operations.
A number of years ago, I met Larry Reber, owner of Firovac Power Systems and then assistant fire chief of the Apple Creek (Ohio) Volunteer Fire Department, at a trade show where he was exhibiting a Firovac vacuum tanker. I, like many others, was quite impressed with the operation of the vacuum tanker. But I also realized that because it didn't look or operate like a conventional tanker, its acceptance by the fire service would be slow.
Since 1985, Larry and the people at Firovac have improved the design and operation of vacuum tankers. They are now built in a variety of configurations, all NFPA 1901-compliant. Firovac holds numerous patents and pioneered the design of the vacuum tanker specifically for the fire service.
Several years ago, I had the opportunity to witness an ISO evaluation of a WOW operation in Wayne County, Ohio, where Firovac is located; 19 fire departments in the county operate vacuum tankers. The evaluation resulted in a greatly improved ISO rating.
Rural firefighters are familiar with conventional tank vehicles equipped with rectangular or elliptical atmospheric tanks. Conventional tanks generally rely partially or entirely on gravity to offload and require a pressure source for filling. These are called atmospheric tanks because they are not designed to be pressurized above atmospheric pressure or operated under a vacuum.
The first and most obvious difference of the vacuum tank: It's cylindrical with rounded ends, much like a liquefied petroleum (LP) tank. This is because the vacuum tank, like the LP tank, is a pressure vessel, designed to withstand both internal pressure and vacuum. Unlike the conventional tank that's equipped with open atmospheric vents, the vacuum tank is sealed, unless the tank vent is opened.
The second major difference: The Firovac tanker has a PTO-driven pressure-vacuum air pump (Figure 2), which is controlled from inside the cab, has a capacity close to 400 cfm and can pressurize the tank to 5 psi. By reversing the pump's airflow, it becomes a vacuum pump, much like the priming pump used on a fire apparatus pump. The difference is that the vacuum pump has the capability of 125 fire pump primers.
The Firovac tank is designed to offload and fill using 6" tank connections located on each side and the rear. The 6" connections are equipped with male camlock fittings and valves controlled from inside the cab.
The most significant advantage of the vacuum tank vehicle over the conventional tank vehicle: The vacuum tank vehicle can fill itself from a static water source with no need for a fill engine and crew. The standard Firovac tanker carries four 12' lengths of camlock-coupled 6" suction hose. Filling it is a simple, five-step process: 1) connect the strainer to the length of suction hose needed; 2) connect the suction to a tank connection; 3) drop the strainer into the water; 4) open the valve in the tank connection; and 5) engage the pressure-vacuum pump in the vacuum mode. When manpower is short, one person can complete all of these tasks.
Because of the brute power of the pressure-vacuum pump when it's operating in the vacuum mode, the vacuum tanker can fill at well over 1,000 gpm, depending on the lift and length of suction hose used. The amount of vacuum produced also allows the tanker to lift water farther vertically than pumpers and horizontally where long suction hose lays are required (Figure 5).
The Finley Point/Yellow Bay Experience
In the fall of 2004, I conducted a WOW operation in Polson, Mont. During that session, Chief Chris Ricciardi of the Finley Point/Yellow Bay Volunteer Fire Department said that when ISO had recently evaluated the department, they were told by the ISO representative that a vacuum tanker in place of a conventional tanker would result in a better ISO rating. This was because there would be no need to assign an engine and a four-person crew to a dedicated tanker fill site because the vacuum tanker could fill itself. This, in turn, would reduce the overall requirements for personnel. ISO pointed out another benefit: Because the vacuum tank is sealed, no water can be lost en route to a fire. Therefore, ISO uses 100 percent of a vacuum tank's capacity in its tanker delivery rate calculations, rather than the 90 percent allotted to traditional tankers.
Based on these recommendations and our discussions during the class, the department purchased its first Firovac vacuum tanker with a Fire Act grant. This tanker and its filling benefits are shown in Figures 6a and 6b.
More to Follow
As you can see, although vacuum tankers look and act differently than conventional tankers, they get the job done with fewer people and less work. Now that I've covered the basic operation of vacuum tankers, we'll explore in more detail their performance and designs in next month's column.
'Til then, stay safe.
Larry Davis is a full member of the Society of Fire Protection Engineers, a certified Fire-Protection Specialist and a certified Fire-Service Instructor II, with more than 30 years of experience as a fire-service instructor. He is vice president of GBW Associates, LLC, and the chairman of the Rural Firefighting Institute. Davis has conducted more than 400 Rural Firefighting Tactics and Rural Water Supply Operations seminars throughout the United States and Canada. In addition, he has written numerous fire service texts, including “Rural Firefighting Operations,” books I, II and III. Most recently, Davis co-wrote the “Rural Firefighting Handbook” and “Foam Fighting Operations,” book I with Dominic Colletti.