Apparatus Fire Pumps: More GPM Are Not Always Better

 The Waterous Endurance CSUS20 pump offers fire departments functionality, light weight, and compact design in a single-stage midship pump design. (Photo courtesy of Waterous.)
The Waterous Endurance CSUS20 pump offers fire departments functionality, light weight, and compact design in a single-stage midship pump design. (Photo courtesy of Waterous.)
W.S. Darley & Co. makes a fire pump, available in 1,000- to 1,500-gpm versions, used exclusively by Pierce Manufacturing in its Pierce Ultimate Configuration (PUC) vehicles. (Photo courtesy of W.S. Darley & Co.)
W.S. Darley & Co. makes a fire pump, available in 1,000- to 1,500-gpm versions, used exclusively by Pierce Manufacturing in its Pierce Ultimate Configuration (PUC) vehicles. (Photo courtesy of W.S. Darley & Co.)
 W.S. Darley’s PSP pump is a compact PTO-driven pump that means less weight and space are used on the fire vehicle, while allowing for flows over 1,500 gpm and offering pump-and-roll capability. (Photo courtesy of W.S. Darley & Co.)
W.S. Darley’s PSP pump is a compact PTO-driven pump that means less weight and space are used on the fire vehicle, while allowing for flows over 1,500 gpm and offering pump-and-roll capability. (Photo courtesy of W.S. Darley & Co.)

In terms of fire pumps on apparatus, the question is often asked, “Are bigger pumps necessarily better?” The answer depends on a number of factors, including how the apparatus will be used, the types of fires it will be called on to fight, and the size of the chassis on which the pump will be mounted.

Current Trends

Paul Darley, president and CEO of W.S. Darley & Co., says that a look at the most recent Fire Apparatus Manufacturers’ Association (FAMA) statistics shows that the vast majority of the pumps sold for fire apparatus are 1,250- and 1,500-gpm single-stage pumps.

Even with fire departments asking manufacturers to cram more equipment onto larger vehicles, Darley says “the market for 1,750-gpm and larger pumps has not grown substantially in the last five years or so.”

Mike Sterbentz, Waterous OEM sales manager for North America, agrees. “The majority of pumps being sold for municipal applications are in the 1,250- and 1,500-gpm size,” Sterbentz says. “The trend I see with a lot of departments, especially with the state of the economy and limited budgets, is that some are going in the opposite direction, not bigger.”

Calling the 1,250- to 1,500-gpm fire pumps as the “settling point for municipal apparatus,” Sterbentz points out that some departments are moving toward PTO-driven pumps instead of fully manifolded midship pumps.

“A PTO can drive either an end-suction or midship pump, and we’re seeing bigger and higher torque PTOs being developed,” he notes. “We’ve seen applications where you can drive 1,500 gpm off of a PTO pump.”

Jon Moore, national sales manager for Hale Products Inc., says while pump buying is regional, Hale’s QMAX large-body single-stage pumps in the 1,250- to 1,500-gpm models are the number one sellers in his company by three to one over all the other pumps that Hale sells.

“That pump can be configured to accommodate a lot of different conditions, from 1,000 to 2,250 gpm, depending on what the fire department wants and how much horsepower it puts in the apparatus,” Moore points out. “When we look at Class A pumpers, especially in the Northeast, that number [of QMAX sales] goes to eight to one.”

In the West, Moore observes, Hale has sold a lot of 500-gpm pumps, as well as two-stage 750-gpm models. “For instance, in the city of San Diego’s municipal area, they use our large QMAX for high-rise and other structure fires, but once they get out of the city and into the wildlands and urban interface areas, the pumps get smaller so they’re not using as much water,” Moore says. “However, they might add a second or third stage to the pump to fight wildland fires with higher pressure.”

In Los Angeles County, Moore says the fire department “is using the 1,500-gpm QMAX with a jockey pump to get high pressure at low flow. The AP50 PTO pump boosts the pressure to over 300 psi with a lower gpm to conserve on water use.”

Pumps Aid in Apparatus Design

Moore notes that apparatus manufacturers are looking at different methods to make apparatus pumps more effective.

“With Pierce Manufacturing and its Pierce Ultimate Configuration (PUC) pump, W.S. Darley made the pump to Pierce’s specifications, tucking the pump up under the cab and down low to pick up compartment space,” Moore says. “Usually a 1,250-gpm pump in there gets the job done, but if you need to draft water, you’d want a larger-bodied pump in the apparatus to get the lift you want.”

Moore says that Ferarra Fire Apparatus “is taking a large-bodied pump and turning the gearbox to face forward to fit the larger pump. That’s their MVP pumper, which has a shorter wheelbase than the Pierce PUC.”

And, although proper packaging can allow a manufacturer to get a bigger pump into the same apparatus real estate, Moore observes, “at the end of the day, the large-body pump is still king. Fire departments want the big water that a large-body pump gives in the 1,250- to 1,500-gpm range.”

Darley believes the biggest trend taking place in fire pumps is a movement away from large and bulky full cast midship pumps that take up to 50 to 70 inches of space behind an apparatus cab to customized nonmanifolded pumps with customized suction and discharge manifolds.

“Those customized manifolds allow the manufacturer to make a vehicle that meets the needs of the fire department on a shorter wheelbase, with easier-to-reach speedlays and crosslays and with pump-and-roll capability,” Darley says. “A lot of those pumps are PTO-driven, but they can be split-shaft pumps as well.”

Larger pumps also bring potential problems with them, Darley points out. “Each pump has a best efficiency point (BEP),” he says. “In general, larger pumps have a higher BEP than smaller pumps, but most single-stage pumps can operate down to 50 percent of the BEP without any problems.”

However, Darley continues, “The disadvantage to a larger pump is when it operates at lower flow rates, it will operate below its BEP, and over time that can damage the pump. The problem is compounded when a fire department uses a $400,000 pumper as a hose tester, dead heading the pump with no water flowing and bringing up the rpm. It heats up the pump quickly, and problems can develop.”

Smaller Vehicles Mean Smaller Pumps

Peter Darley, W.S. Darley’s COO, says that, in talking with fire chiefs at FAMA meetings, his company has heard that many chiefs are leaning toward purchasing smaller attack vehicles. “They’re saying that such vehicles cost less to purchase and to operate,” he notes, “and they have smaller pumps on them.”

Sterbentz agrees there is some movement toward smaller vehicles. “We’ve seen a lot of interest in the Ford F-550 chassis by fire departments,” he says, “and we think it’s directly related to the cost of the chassis, which has enough horsepower to drive a 1,250-gpm pump. However, we’ve heard talk in the industry that under-hood engine issues may limit that diesel chassis to a 1,000-gpm pump.”

And, although Sterbentz says several manufacturers have been successful in building pumpers on the Ford F-550 chassis, he observes, “Their use is still limited. I don’t see them as first-out pumper replacements any time soon.”

To minimize the space used in pump compartments, Sterbentz says Waterous has developed outside-the-frame-rail pump applications driven off of PTOs in 500-, 750-, 1,000-, and 1,250-gpm models.

“Going outside the frame rail allows the water tank to be moved forward because the pump and plumbing have been moved into the front driver’s side compartment,” Sterbentz notes. “When you minimize the pump compartment, you can have a smaller chassis or the same size chassis and expand compartment space, allow a larger size water tank, and lower hosebed heights. A lot of different apparatus features benefit from moving and shrinking the pump compartment.”

Waterous also builds pump modules for outside-the-frame-rail pumps. “We can supply the pump, the pump and its plumbing, or a full module with everything on it, like controls and gauges,” Sterbentz notes.

Greater Horsepower

Sterbentz says that the biggest change in fire apparatus over the years has been in horsepower ratings. “Back in 1995, we were seeing chassis with 300- and 330-hp engines,” he says. “Today, many chassis are using well over 400-hp engines. A lot of that has to do with when the Allison 3000 EVS transmission had its rating increased, making 400- and 425-hp engines a lot more popular.”

And yet, Sterbentz says Waterous still isn’t seeing big pumps with those higher-horsepower chassis. “Just because they have 500-hp on the chassis doesn’t mean they’re putting a 1,750- or 2,000-gpm pump on it,” he says. “We’ve found that while the trend in engine horsepower has come up, the trend in pump size has remained stable.”

ALAN M. PETRILLO is a Tucson, Arizona-based freelance writer and is a member of the Fire Apparatus & Emergency Equipment editorial advisory board. He served 22 years with the Verdoy (NY) Fire Department, including in the position of chief.

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