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| Darley’s flagship LDM midship-mounted pump has a double suction design that allows for highly efficient operation in a compact package. |
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| Install seat belt monitoring devices, such as this one made by Akron Brass, on all your trucks. Similar systems are made by Class 1 and Fire Research. |
Pumps on motorized fire trucks have been around since September, 1913 almost as long as the automobile, and it didn’t take engineers long to determine that midship was the seemingly-optimum pump location—the favored location to this day.
But what has changed in the United States, according to pump makers and apparatus manufacturers, is a shift from two-stage to single-stage pumps. One of the main reasons for this shift is the declining need for higher pressures, industry experts say. This demand for higher pressures is waning due to the advent of larger diameter, 1.75-inch hand lines.
The physical size of pumps has been shrinking, so apparatus can be used more in multi-purpose roles where compartment space is needed for specialized gear. But the widespread switch from gasoline powered trucks of all types to the diesel engine was the real impetus for single stage pump development. Diesels provided the torque and horsepower to provide high pressures with the single stage pump.
Three companies—Waterous, Hale Products and W.S. Darley—are the prime apparatus pump manufacturers.
Waterous in South Saint Paul, Minn., has been in business since 1886, first making complete fire trucks and then concentrating only on pumps beginning in 1929. Today, the most popular single-stage midship pump is the company’s CS line, which is available in pumping capacities ranging from 750- to 2,250-gpm.
“Many of the departments choose a single-stage pump for their equipment,” said Mark Severin, the company’s communications and marketing manager. “At one time our most popular pump was a two-stage pump, but that has changed in the last 10 to 15 years.”
A single-stage pump has one large impeller and housing, while a two-stage pump has two impellers and a transfer valve—one allows water to pass through both impellers simultaneously while the other allows water to pass from one impeller to the other. Transfer valves are either mechanically operated or hydraulically operated, and settings are switched only at a low pressure to avoid over-pressurizing a hose line and possible injury.
Waterous makes two-stage pumps in its CM series that range from 550- to 2,250-gpm. Severin said bigger city departments use the company’s two-stage CM-series pumps because of the high-rise buildings.
“I think the change [to single stage pumps] is due to the ease of use,” he said. “With a single stage you don’t have to worry about the transfer valve.”
Gary Handwerk, global pump product manager for Hale Products in Ocala, Fla., believes that only a small percentage of two-stage pumps are sold today industry-wide.
“The 1970s was a decade of change where we saw the diesel engine and automatic transmission come into pumpers, which led to a shift from two-stage to single-stage pumps,” Handwerk said.
In addition, he added, “The hose shift to inch-and-three-quarter attack hose and four- or five-inch [large diameter supply hose] means you don’t use high pressures anymore, unless you’re feeding skyscrapers and flows are low enough so you have enough horsepower left.”
High Volume, High Pressure
Handwerk agreed with Severin about the transfer valve aversion. Many departments, he said, “don’t want the maintenance associated with transfer valves in two-stage pumps and don’t want to have to teach engineers to use a transfer valve.”
Hale’s best-selling pump is the Qmax single-stage midship split drive line manifolded pump, available in up to 2,250-gpm. Hale’s next most-requested pump is the Qflo, a high-flow midship pump that’s available in up to 1,250-gpm. Hale also makes the Qtwo two-stage pump that can exceed 2,000-gpm.
Paul Darley, president of W. S. Darley & Co. in Itasca, Ill., said his company makes “compact, highly efficient pumps in applications for the fire service and industry where high volume and high pressure are needed.”
The company manufacturers single-stage through six-stage centrifugal pumps. While most U.S. pump purchases are single stage, he said, “a lot of the world buys two- and three-stage pumps.”
“The old mentality of surround-and-drown in the United States has changed in the last 15 years with the advent of Class A foam and compressed air foam,” he said. In addition, he said, “the background of large, single-stage pumps is that there are much bigger spaces here in this country, where the rest of the world has tighter streets, which requires a more compact, two-stage pump.”
Darley said he’s seen a paradigm shift in the last five years toward a Power Take OffPTO pump. “We spend a lot of time looking at trends and seeing where the market is going,” he said, “and we see a trend toward multipurpose vehicles.”
PTO-Driven Pumps
First there were pumpers, he said, then pumper-rescues and now rescue-pumpers. “Today the pump is engaged roughly five percent of the time the truck rolls out of the station,” he said. “It used to be 50 percent.”
With structure fires decreasing, he said the role of first responders has changed drastically, he added.
“Most of the time is spent on rescue calls, EMS, car fires and hazardous materials,” Darleyhe said. “You no longer can have a pump panel on a truck take up 60 inches behind the cab because it doesn’t allow enough space for the department to carry all the hazardous materials equipment, rescue tools and the gear they need to respond to other calls. But you still need big pumping capability in the event of a fire., Thiswhich lends itself to PTO-driven pumps for high volume in a smaller package.”
Darley said his company is known for very compact pumps that fulfill space-saving needs. “They’re modular in design,” he said, “so you can mix pumps and transmissions instead of being locked into full-cast manifolds.”
W.S. Darley makes fire service pumps from 10- to 2,500-gpm and larger pumps for industrial and other applications.
“Our PTO pump is mounted midship, but instead of being driven by the truck drive line, it’s driven by a separate shaft and PTO,” Darley said. “We do all our own manifolding, which gives us a compact pump panel and saves space in a lot of ways. And pumping with a PTO is safer because you’re pumping in neutral instead of drive.”
Two years ago, Pierce Manufacturing of Appleton, Wisc., introduced a new pump and body configuration called the Pierce Ultimate Configuration (PUC). It uses a 1,500-gpm, single-stage midship pump that fits underneath the cab’s back seat over the transmission. The Pierce-designed pump—built by W.S. Darley—runs by a rear-engine PTO, which Pierce calls REPTO, and is available in both side control and top-mount configurations.
PUC Advantages
“It provides a lot of advantages where we’ve eliminated the large pump house,” said Mike Moore, Pierce’s director of strategic business development. “That means a shortened wheelbase, an increase in compartments, the attack hose cross lays are down lower so they’re easier to reach, and the water tank’s stretched out longer and the hose bed is lowered so it’s easier to reload hoseach.”
Pierce’s REPTO is a set of gears between the transmission and engine that drives the pump. “Engine manufacturers have built it onto the back of their engines,” Moore said. “The gears are live all the time and turn when the engine is turning. This allows us to do pump and roll with this pump, which is used in wildland fire and airport applications.”
Changing Needs
In addition, he said, the design allows both forward and reverse pumping. With the PUC, Moore said Pierce simply improved existing technology.
“When you look at pumps, midship fire pumps are centrifugal pump technology that’s been around since the late 1800s,” he said. “What we changed is how the pump is integrated into the fire apparatus. With fire departments doing so much more than just fire calls with their trucks, we wanted to provide a vehicle that can meet those changing needs.”
The PUC design has another important advantage, he said. “With a tilt cab vehicle,” he said, “you’ll have full access to service on that pump, which shortens downservice time.”
Pierce also builds other pumpers using Waterous, Hale and Darley-manufactured pumps.
Arnold Heller, director of sales and marketing for Seagrave Fire Apparatus in Clintonville, Wisc., said his firm builds approximately 180 trucks with pumps each year.
“W. S. Darley makes the Triton pump for us in 750- to 1,750-gpm configurations,” he said, “and we install approximately 35 a year. We also sell Waterous and Hale pumps.”
Most Seagrave apparatus have 1,500-gpm single-stage pumps, Heller pointed out.
“Almost all our product mix is custom-based with larger engines,” he said. “The average fire department seems to home in on the 1,500-gpm single-stage pumps, although some have requirements for 1,750- and 2,000-gpm.”
Heller said his company has frequent discussions with firefighters about their needs and desires, often producing surprises.
“We always think trucks will get smaller based on our discussions with fire department people who come for a visit or an inspection of our plant and its engineering capabilities,” he noted. “We ask them what they see for the future, and we think they’ll go for smaller, more specialized units, but they actually go for the larger, custom trucks.”
Claude Wait, Seagrave’s engineering manager for pumps and plumbing, pointed out that change comes slowly to most fire departments.
Plumbing Affected
“A lot of customers are trying to hold onto their current practices in how they fight fires,” Wait said. “They don’t want to change; they want to use the trucks as they are and want to keep new trucks as close to the existing trucks as possible.”
However, change will be unavoidable with next year’s looming emissions standards. “The federal [Environmental Protection Agency] 2010 rule to reduce diesel emissions means repackaging of the exhaust system,” Heller said. “That will impact the plumbing real estate on the trucks because that plumbing is predominantly in the exhaust area.”
The repackaging, he said, may take up extra space, especially on the right side of the apparatus, and may entail lengthening the package that houses the midship pump.
“We might have to make space available to keep the exhaust cool,” he notedsaid. “With a diesel particulate filter and urea injection in series, it could elongate the unit by 40 inches, which would elongate the wheelbase the same distance.”
Repackaging Pumps
If that happens, Heller said it might cause departments to relocate the pumps on the apparatus or repackage them differently.
Scott Oyen, vice president of sales for Rosenbauer in Lyons, S.D., said they purchase pumps from their sister company in Austria, but they also install Darley, Hale and Waterous pumps in their apparatus.
The Rosenbauer pump is a normal pressure and simultaneous high-pressure discharge pump (NP/HP). “The difference between the NP/HP and other high pressure pumps,” Oyen said, “is that ours are all on a common shaft.”
The Rosenbauer-built pumps run from 500- to 1,250-gpm. “We’re seeing quite a bit of gain for this pump in urban interface departments,” Oyen noted, “especially in wildland-fire applications.”
He said the pumps can be either midship or rear mounted, and most are PTO driven. He believes PTO pumps are becoming fashionable again.
“They’re a little less expensive and with the way that cities are being built into rural areas, the PTO pumps allow pump and roll,” he said. “We sell a lot of these pumps out west, but they’re also gaining quite a bit of ground in the Carolinas and on the East Coast.”
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