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Cast iron has been the traditional material for fire truck water pumps for decades. “There was a real apprehension to using composites in pumps, especially in firefighting,” says Kyle Chandler, president of (KASE, Coatesville, Pa., U.S.). Today, though, companies are starting to become more receptive to the idea of composites in these applications, he says, as the cost of metal castings rises and also — most vitally — to combat the persistent problem of corrosion.

Firefighting units in municipalities have access to potable water, but industrial or military firefighting units often need to work with brackish water or even saltwater, Chandler says, which leads to corrosion and frequent repair or replacement of metal pump components.

KASE Pumping Systems offers a longer-life and lower-maintenance alternative, including a lifetime warranty on saltwater-based corrosion for its composite pumps and fluid handling equipment. Compared to other corrosion-resistant options like stainless steel, nickel or bronze, composites can also be much more cost-competitive, with shorter lead times.

Manufacturing CFRP pumps: Beginnings and current operations

Chandler founded KASE in 2019 after more than a decade of experience in materials research and industrial firefighting systems manufacturing. He and his team manufactured their first composite pump about 10 years ago — and since then, have continued to advance this technology to increasingly higher-performance, lightweight designs.

Ten years ago, at his previous company, Chandler was primarily working on submersible pumps. These are a type of centrifugal pump that uses the energy from rotating impellers to transfer fluid. Designs and specifics vary, but at a high level these pumps consist of an exterior, spiral-shaped volute casing surrounding the pump’s impeller, which is powered by a motor. The impeller draws water in through the suction bell opening, and expels it out through a discharge diffuser. The design of the volute, suction bell, impeller and motor/bearing system play a large part in determining the volume and pressure (called “head”) capabilities of the overall pump.

On a fire truck, pumps are often mounted to the truck directly through a split-drive gearbox and are connected via hose to a fire hydrant or suction line into a nearby water source such as a pond. The fire truck’s engine rotates the impeller to pull the water from the hydrant or suction line through the firefighter’s hose. In instances where a hydrant isn’t available and the closest available water source is too far away for drafting (siphoning water from a surface), or for situations like flood mitigation, a type of pump called a floating submersible pump may be employed. These are floated via a top-mounted pontoon onto a water source like a pond, river or the ocean, with the main pump body submerged into the water source. The system is powered through a hydraulic fluid umbilical connected to a power unit on shore operated by the fire crew.

“We were approached by a fire chief who needed to be able to deploy a submersible pump from a ladder truck. The challenge was that the ladder had a weight limit so that the pump could only weigh about 300 pounds, but they still needed the pump to be able to push over 4,000 gallons of water per minute. Unfortunately, the closest available pump with that level of performance weighed about 450 pounds,” Chandler says.

He and his team began to test and experiment with designs using lightweight materials, and in this case were ultimately able to develop a fiberglass composite pump that met both the fire chief’s performance and weight requirements. “That was our first composite part, and it was pretty rough,” Chandler admits. Over the next 4 years, the team continued to develop and optimize the design, eventually switching to carbon fiber composites to save even more weight. “It all started from a customer asking me to make a pump lighter,” he says.

As he continued to work on composite pump designs, Chandler started his own company, first from his home garage, with the construction of a small composites lab complete with an autoclave, oven and machine shop. “This is still where I do research and test some of the things I’m thinking about developing,” he says.

Since 2020, KASE’s operations have been co-located at a steel fabrication plant, and the team has grown to 15 employees. This location is only temporary, however — KASE is currently constructing a dedicated 50,000-square-foot manufacturing site nearby, with plans to expand the team to up to 50.

Today, KASE Pumping Systems manufactures several families of pump types, as well as related products like fluid couplings. “We focus on industrial applications with CFRP [carbon fiber-reinforced polymer] well over 1 inch in thickness,” Chandler says. All of the company’s parts are made from carbon fiber composites, sometimes integrating Kevlar, glass fiber or other reinforcement depending on the application. For example, a wastewater pump that needs to be able to withstand impact from rocks might integrate Dyneema or Innegra fiber.

Chandler explains that a thermoset resin is used — one that doesn’t produce a large amount of volatile organic compounds (VOCs) and has high impact resistance because submersible pumps are most likely to be dropped. The resin can be modified “to act like a snap-cure system, with cycle times down to 5 minutes, if we play with the formulation and temperature,” he notes. “But, our system doesn’t ever go into thermal runaway.”

The process technology had to be optimized over time for the resin system used — it isn’t compatible with all typical coatings and release agents, Chandler notes. All pumps are made in a closed molding process like high-pressure compression molding (HPCM) or resin transfer molding (RTM). Parts are molded to near-net shape, but are machined to final dimensions as needed to meet a tight tolerance to mate to another part of the truck. In the company’s current facility, KASE’s production capacity is limited by two compact autoclaves, but the new site will feature additional larger autoclaves to enable production of larger- and higher-volume part production.

“There was a lot we had to figure out, and it took us a few years to get where we are now,” Chandler says. “We’re also continuously improving our processing.”

CFRP pump design: Reliability, circularity, complexity

Over time, KASE has been able to develop pumps with increasing design complexity, growing alongside the company’s expertise in composite materials and processing. Along the way, there have been a number of design challenges that KASE has had to solve.

Reliability. For example, firefighting equipment is intended for use in unpredictable emergency situations, so durability is vital. KASE designs its parts for a 20-plus-year service life. “This is difficult, especially in pumps, because the operation can be a little rough,” he says. Submersible pumps in particular, designed for portability and deployed by hand, are at high risk for damage in the field — they can be dropped, accidentally draw in rocks or other debris, or be deployed in too shallow a body of water, which will cause cavitation.

“If for some reason our pump gets damaged, it will keep working. You would still need to get it replaced, but it won’t immediately crack and fracture like a metal part would. It gets beat up but it doesn’t blow apart. This is a game-changer in this industry,” he says.

He adds, “There are only so many things you can design for, but the most common and pressing issue is corrosion, so we at least can account for that and solve that issue. We get asked how long the pumps will last in saltwater, and we tell them ‘The composites will outlast you.’”

Circularity. Composites are built to last a long time, but for when they do reach the end of their service life, KASE is working with carbon fiber recyclers on an end-of-life solution for its pumps. “We want, first of all, to provide products that last a long time, that don’t corrode or deteriorate. But if a customer does want to replace the pump or it becomes obsolete, then we don’t want them to dump it into a landfill, because the carbon fiber still has so much value. So, we’re creating a path for it to go to carbon fiber recycling facilities, and then we’ll buy recycled chopped fibers back for our compression molded parts.”

Complexity. Over years of iteration, KASE has developed and optimized its proprietary closed molding process in order to manufacture increasingly complex parts, including hollow parts and those with blind cavities — holes that do not go all the way through the part.

An example of a blind cavity part, Chandler explains, is a closed impeller, which has interior curved vane geometry that is difficult for CNC machines to reach. “It’s technically challenging to mold hollow and blind cavity parts in one piece,” he says.

Designing a 6,500-gpm CFRP fire truck pump

One of KASE’s most ambitious pump designs to date is in production this year after about 3 years of development work with fire apparatus manufacturer Rosenbauer America (Lyons, S.D., U.S.), a division of Rosenbauer International (Leonding, Austria).

The pump, a National Fire Protection Association (NFPA) rated fire pump called the RFP6, is said to hold the world’s highest fire truck NFPA flow capacity rating of 6,500 gallons per minute (gpm). For context, Chandler explains that typical fire trucks are rated from below 1,500 gpm (for small municipal fire trucks) to up to 2,500 gpm (for more standard-sized municipal trucks) to up to 3,500 gpm (for standard industrial trucks). “This 6,500 gpm rating is a very niche industrial rating, typically used for petroleum, oil and gas [POG] facilities,” he says.

Rosenbauer manufactures several of its own standard pump designs up to 3,500 gpm, and partners with other U.S. pump manufacturers for custom builds. In the case of what would become the RFP6 pump, the customer required the pump to meet a 5,500 NFPA rating — a challenge that led Rosenbauer to seek other industry options. KASE told them that they could make a pump to the original 5,500 gpm, but that it would be, like all of their pumps, made from CFRP — a material that Rosenbauer hadn’t previously used for its pumps.

The company and its customer considered, and then accepted KASE’s proposal. The fact that Rosenbauer and its customer were receptive to the idea of a composite pump at all was a win, Chandler explains, noting, “the fire truck industry is very conservative.”

Why did they decide to accept the switch to CFRP? “The light weight is a selling point too attractive to pass over. The fire industry is recognizing that the whole pump, manifold and gear assembly can weigh in excess of 2,000 pounds depending on the design layout, and with CFRP we can take that weight and drop up to 70% of it,” Chandler says.

There were several challenges inherent in the design: KASE needed to develop an optimal volute and impeller geometry that met the gpm and head requirements of the pump specification. It also had to operate within the appropriate power band of the fire truck engine and transmission and use a bearing assembly that could handle those axial and radial loads.

“You have to design things differently when you’re switching from metal to composites, and then there’s a whole new set of challenges when trying to design something that can move that much water. It took some time to make all the adjustments needed,” Chandler says.

Design and validation: Prototyping and iteration

Based on the requirements given by Rosenbauer, KASE’s engineering team began by developing preliminary CAD models of the pump’s internal geometry, and then ran many computational fluid dynamics (CFD) simulations to narrow down the performance output. This was followed by finite element analysis (FEA) of the pump body to ensure structural integrity.

Next, a full-sized physical model was built for early testing, and the numbers then imported back into the CFD software to validate and improve the design. KASE runs extensive CFD analyses on all pump models, Chandler explains. “The fluid design for this type of pump is driven by velocity. Using CFD can get you within 3-5% of your target. For one pump, we’ll probably do 100-plus CFD analyses just to get a model where we can build a prototype for testing. And we get a lot of data from the field that we then feed back into that modeling.”

He continues, “After we get the performance pretty close to what we want, we’ll build a small-scale unit and perform actual running tests. For the hydrostatic testing, the loading we use is usually two to four times greater than the actual operating realm of the pump. Eventually, we’ll do mechanical tests on a full-size product.”

Unfortunately, the initial CFRP prototype was only able to deliver 4,800 gpm in full-scale testing. So the team went back to the drawing board. “We got it right in terms of structure, but the flow for the fluid performance wasn’t quite right. That’s probably the biggest difficulty, getting the right vane geometry in place, which requires a lot of fluid dynamics analysis,” Chandler says. “We also had to expand our analysis to include the fire truck water manifold system, something we did not manufacture.”

One of the biggest challenges in developing a part with multiple iterations like the RFP6, Chandler notes, is the investment required for each mold. In this instance, the casing mold alone is 4 feet wide — representing a large tooling investment for this type of part.

With the substantial and continuous support of Rosenbauer America and its engineering and manufacturing staff, especially its chief engineer, Chris Kleinhuizen, the second iteration managed 5,750 gpm, exceeding the initial requirement. “But we kept working to optimize the impeller design, and eventually achieved 6,500 gpm while still being ultra-compact and very lightweight,” Chandler says — less than 200 pounds total, and only 58 pounds for the casing, which is the largest single component. He notes that a typical pump assembly would weigh from 600-1,200 pounds.  

Manufacture and assembly: Casing, suction bell, impeller, motor plate

The RFP6 pump, which measures roughly 2 × 2 × 2.5 feet, comprises four primary composite parts connected to the motor system: the casing/volute, suction bell, impeller and motor plate.

Suction bell. The suction bell is manufactured using a combination of a mechanically compressed dry chopped carbon fiber preform with HP-RTM to produce a high fiber ratio composite structure. After molding, final machining is completed on all mating surfaces.

Impeller. For this part, the 18-inch-diameter impeller is designed to run up to 2,200 rpm to achieve the high volume and head performance goals. The impeller comprises seven curved vanes encircling a stainless steel spline shaft adapter that will mount to the metallic pump shaft.

Chandler notes that for fire engine pumps, a wide performance curve and optimal draft (ability to draw water up from a surface below the pump eye) are critical. “That’s why in this case we have this unique vane entry angle that was designed to reduce net positive suction head required [NPSHr],” a parameter that determines a pump’s tendency to cavitate and collapse fluid caused by a drop in localized pressure at the eye of the impeller, which can cause damage to the pump. “Essentially, this geometry allows it to pull up more water a lot easier.”

For the RFP6 impeller, chopped recycled carbon fiber (rCF) and a thermoset resin are molded via RTM. The ability to mold these impellers is something KASE is particularly proud of. “Some companies make large composite blocks and then machine the impellers, but that is expensive and creates a lot of waste. That’s why we’ve worked on methods to mold this type of blind cavity system. There’s also very little material waste. That took a lot of time to figure out, how to do this kind of blind cavity system,” Chandler says.

In this system, the impeller vanes are between 3/8 to 7/16 inch thick. “You could go a bit thinner, especially if you use a woven material, but in this case we wanted a little more reinforcement as a cushion to prevent failure for any reason,” Chandler says.

Volute/casing. The largest component of the assembly, this tank-like part that receives discharge from the impeller is also one of the most complex. The RFP6 is a double-volute pump, meaning that it features an exterior case as well as a spiraling internal channel through which water flows at high pressure (and which is completely inaccessible for CNC machining).

The pump casing is molded via RTM, requiring careful layering of an outer aesthetic woven veil material, an inner heavy-duty carbon fiber structural layer, and remaining open spaces filled with chopped carbon fiber. “It can be quite thick in places — up to 8 inches — does not have a uniform cross-section, incorporates interior channels and uses a significant amount of composite material,” Chandler says.

Motor plate. This is the 4-inch-thick plate at the back of the pump that provides the mounting configuration for the bearing housing and holds all of the components together. “It does a lot of work in the whole pump system,” Chandler says. It is also made from chopped rCF in an RTM process.

To create the final assembly, the pieces are bolted together using integrated threaded steel inserts that penetrate deep into the pump casing “and provide a very simple and durable alternative to molded or machined inserts. It has to withstand installation and removal of bolts over and over,” Chandler says. These are mechanically locked and bonded in place and “hold up extremely well with a really substantial pull-out strength.”

After extensive field testing, the RFP6 launched this year on Rosenbauer’s new industrial pumper system, designed for either high-volume water or a mix of water and firefighting foam solution (see video below). The industrial pumper is used for quick reaction fire protection in petroleum, oil and gas facilities as well as other heavy infrastructure installations.

Growth plans and new industrial applications

Beyond continued manufacture of this pump, KASE has big plans for its future, including moving into its new facility. In the next 3-5 years, Chandler predicts that, thanks to continued adoption of composites for anti-corrosion benefits, KASE will become one of the largest-volume fire truck pump manufacturers.

The company is also continuing to innovate its fire truck pump designs, including work on a high-pressure 300 psi aerial fire truck pump and a standardized, broad-usage municipal pump offering 2,000-3,000 gpm.

Ultimately, though, the company doesn’t plan to stop at fire truck pumps. “The energy market is much larger, and there’s a real opportunity for composites because they more frequently work with corrosive materials like brine,” Chandler says.

On the process side, once in its new site the company plans to work toward automating some of its operations within the next few years. “This will make it easier for our staff, and really enable us to start scaling up both in production and size,” he says.

The new building will also feature an education center. The company already works frequently with a nearby STEM-focused high school, and aims to continue allowing students hands-on experience to learn about engineering and composite fabrication.

Chandler reflects, “Our biggest success is being able to introduce a new material technology like composites into a very well-developed industrial market. Our products have proven they are durable and high-performing, and are in service all over the world with a variety of customers in firefighting, energy and flood mitigation. From a garage to now building a new 50,000-square-foot dedicated facility for composites — I think this is a big achievement.”