By Bill Adams
In lieu of full-bodied pumps, apparatus manufacturers (OEMs) are using more end-suction pumps mounted in the traditional midship position.
One reason is the popularity of what I call the alphabet trucks-multifunctional apparatus with monikers such as PUC, eMAX, PRV, MVP, IPS, and PRO. That has started a trend to maximize storage space on most pump-equipped apparatus by shortening the length, size, and location of traditional pump houses. Numerous articles published about pump configurations, capacities, and subsequent benefits rarely mentioned what actually can happen behind the pump panel when end-suction pumps are midship mounted. Anything lost? Anything gained? What about performance?
|1 This full-bodied Qmax pump is NFPA-compliant to 2,250 gpm. Its spec sheet says it has 19 flanged discharge ports as well as eight standard and seven optional suction inlets. Use caution when specifying fire pumps-many are rated at 2,000 gpm or greater and are downrated to a customer-specified gallonage, such as 1,500 gpm. Others may only flow 1,500 gpm. Remember, NFPA ratings are from draft. (Photo courtesy of Hale Products.)|
I asked a cross section of industry principals about the advantages, disadvantages, and ramifications of using midship-mounted end-suction pumps. Their comments are revealing. Some, cautionary in nature, reflect what could be hidden behind the pump panel. Purchasers should be aware.
Responding were Gary Handwerk, president of US Fire Pump; Greg Geske, director, North American sales at Waterous; Jeff Van Meter, pump and module product manager for Hale; Jason Darley, North American accounts manager for W.S. Darley; Wyatt Compton, fleet sales application engineer at Spartan Motors; Jason Witmier, who was product manager at KME at press time; Dave Reichman, national sales manager for Rosenbauer; Joe Messmer, owner of Summit Fire Apparatus; Jim Kirvida, owner of CustomFIRE; and Tom Shand, senior partner at Emergency Vehicle Response.
Pedestal pump is a generic and misleading term I use for an end-suction pump, also called a volute pump. Apparatus and pump manufacturers (OEMs) have their own definitions. Handwerk says, “End-suction describes any single-stage (single-suction impeller) unmanifolded midship, rear, or front-mounted pump no matter which drive is integrated with the pump end or its flow rating. Pedestal refers to a single-stage, end-suction pump, which has no integrated gear box. The very few of these used domestically are mostly in rear-mounts.”
Kirvida states, “A pedestal pump, in my world, is one without a pump transmission and can be an end-suction or a full-body pump. It can be a simple end-suction volute body without suction or discharge manifolds or a full-body with integral discharge and suction passages. Pedestal pumps are typically not used in a midship location but instead as rear-mounts. In layman’s terms, the volute is the cavity in which the impeller spins. In the case of two impellers, there are two volutes, one for each impeller.”
|2 A full-bodied Waterous pump for midship mounting being uncrated at CustomFIRE’s factory. (Photo courtesy of CustomFIRE.)|
This article is based on specifying a National Fire Protection Association (NFPA)-compliant, midship-mounted, split-shaft-driven, single-stage 1,500-gallon-per-minute (gpm) pump. I consider a full-bodied pump as one with suction and discharge manifolds supplied by the pump manufacturer as an integral unit (photos 1, 2, and 3). End-suction pumps are usually supplied to apparatus OEMs without manifolds (photos 4, 5, and 6). Full-bodied single-stage pumps have a double-suction impeller, meaning water enters from both sides (aka the “eyes”). Water only enters the one eye of an end-suction pump’s impeller.
Vendors claim end-suction pumps weigh less, take up less space, and are less expensive than full-bodied pumps. They are 100 percent correct-when the pumps are shipped in a crate from point A to point B. There are other consequences not always proffered by vendors nor considered by purchasers. They should be.
|3 A full-bodied Waterous pump for midship mounting being uncrated at CustomFIRE’s factory. (Photo courtesy of CustomFIRE.)|
Pump performance is rated two ways. The NFPA 1901, Standard for Automotive Fire Apparatus, rating is third-party-certified under prescribed conditions from draft (so are annual pump tests). The other is in the eyes of the beholder. Except for annual pump tests, some departments do not draft; they never have and never will. Those that don’t are more concerned with pass-through performance. If I tie into a good plug, how much water can I get out of this pump? That’s difficult to measure and harder to compare.
How can a vendor recommend a pump to a prospective purchaser unless the vendor knows the purchaser’s priority-pass-through performance or an NFPA rating? Some pumps can “just meet their NFPA rating” from draft while flowing much more in pass-through scenarios.
|4 A Darley PSM series end-suction pump sans any optional discharge headers and suction adapters. (Photo courtesy of W.S. Darley.)|
Besides to save space and weight, why would pump OEMs recommend using an end-suction pump in the midship position?
Van Meter: “A volute-style (end-suction) pump offers flexibility for the apparatus OEM to design manifolding to go around obstacles or offer a unique design to its customer base. A fully manifolded midship pump is set up to maximize the internal plumbing of the pump, reducing pressure loss and maximizing flows. But at the same time, this design can overdefine where discharges need to be placed (photo 1). This flexibility can also introduce restrictions impacting the pressure drop to each individual discharge if care is not taken in the design of the plumbing.”
Handwerk: “The big advantage of an end-suction unmanifolded pump is mounting and configuration flexibility to make the truck look like you want it to. Some fire truck builders are not good at making suction manifolds. More piping, fittings, and turns eat pump performance. A cast manifold can also be poorly designed and restrictive.”
Darley: “End-suction pumps, in many cases, provide the same ratings that the department may have enjoyed with a full-bodied pump in the past. It may be more compact and allow the apparatus OEM more flexibility in the plumbing and, in most cases, is as much as one half the weight of a full-bodied traditional midship pump. The weight and space savings provided allow for many benefits to the end user.”
Geske: “The end-suction pump is cheaper than a full-bodied dual-eyed impeller pump. If installed correctly, the end-suction pump with removable components on the intake side requires less time to replace a seal. It has one seal while the dual-eyed impeller pump has two. OEMs can also design intake and discharge plumbing to fit their own pump house designs.”
|5 A Waterous end-suction pump being uncrated at the CustomFIRE factory. Visible are the grooved inlet and flanged discharge. Any pump manufacturer’s reputation can be unfairly jeopardized by an apparatus builder’s subpar piping and manifolding design and installation. (Photos 5 and 6 courtesy of CustomFIRE.)|
Why do some “alphabet” truck builders provide end-suction pumps while some offer full-bodied pumps?
Geske: “It would be my guess, as I do not have knowledge from the OEMs [as to] why. The full-bodied pumps have some advantages over the end-suction pump. They will draft at higher altitudes as they have two eyes on the impeller as opposed to one. They will also flow more at draft than an end-suction pump rated at the same rating, again because of the two eyes. End-suction pumps will cavitate at a lower flow than the full-bodied pump. This tends to make the end-suction pump a noisier pump. We also see more recirculation cavitation in end-suction pumps than we do in full-bodied pumps.”
Darley: “This really comes down to what the OEM is trying to provide to the customer from a rating and functionality standpoint. Some of the ‘alphabet trucks,’ as you call them, are rated at 1,500 gpm, which many of the most common pedestal or end-suction pumps are rated at. The offerings also have a lot to do with the manufacturing and design requirements of the vehicle series the OEM is providing to the market. These trucks are defined products that have plumbing offerings for the majority of the discharges that a customer would request and, between the pump manufacturer and the OEM, are predefined and ready to select from an engineering standpoint.”
|6 A Waterous end-suction pump being uncrated at the CustomFIRE factory. Visible are the grooved inlet and flanged discharge. Any pump manufacturer’s reputation can be unfairly jeopardized by an apparatus builder’s subpar piping and manifolding design and installation. (Photos 5 and 6 courtesy of CustomFIRE.)|
Is there an advantage in providing an end-suction pump in a prefabricated pump module?
Van Meter: “Hale’s module design for volute-style pumps mimics the design of fully manifolded midship pumps. So unless you look on the inside of the module, you would not know what pump was used (photo 7). The main benefit of this design would be weight savings.”
Shand: “I have not seen a pedestal pump in a prebuilt module. The most often used example would be in a midship (aerial) tower where space precludes the use of a full-body pump. Here, most all are rated for 2,000 gpm and use electric valves exclusively with the exception of a left side panel 2½-inch auxiliary suction (photo 8).
Darley: “Absolutely. Most all pumps Darley manufactures, including pumps with compressed-air foam systems (CAFS) and high-pressure booster pump offerings, are available in our modules.”
Geske: “The main reason an end-suction pump would be ordered by one of our customers in a Waterous module would be price. This configuration places valves where the engineering department wants to place them and makes access and repairs difficult at best.”
|7 A very narrow and busy but well laid out pump panel with all electric discharge and inlet controllers including the tank-to-pump and tank-fill valves. The rig also has an onboard foam system and an end-suction pump hidden somewhere behind the panel. The valves, being electrically operated, can be located anyplace. (Photo courtesy of KME.)|
Besides saving space and weight, why would apparatus OEMs recommend using an end-suction pump in the midship position?
Compton: “A pedestal pump allows for some standardization. All single end-suction pumps in the 1,250- to 1,500-gpm range have a six-inch ‘ram’s-horn’ intake (photo 9) or a six-inch grooved connection (photo 10) that allows all of the intake pipe, intake valves, steamer ends, etc. to be common. They all routinely have some version of a five-inch inch flanged discharge (photo 5). The advantage to the manufacturer is consistency and volume of components to keep costs down, and a side benefit is usually because the manufacturing is consistent, it’s of a higher quality. For service, common parts will mean faster turnaround should a repair be needed. Also keep in mind that this isn’t limited to just a split-shaft configuration. Pump manufacturers have power takeoff (PTO) gear boxes to allow for the same consistency.”
Witmier: “Cost savings is another reason, although people definitely misinterpret the cost savings. People tend to look at the cost of a pedestal pump vs. a full cast pump and say, ‘Look, I saved x number of dollars.’ What they miss is the fact that someone still has to build discharge and intake manifolds for that pedestal pump. KME does see some cost savings on the pedestal configuration, mostly because you can build exactly what you need vs. a full cast pump, which might have more than you need built into it (photo 1). The biggest advantage, however, continues to be space.”
Shand: “During prebid plant visits, several manufacturers have stated the pedestal-style fire pump offers cost savings in addition to the perceived weight and space savings. While this may be true in some circumstances, the use of pedestal pumps also may require the use of electric valves (photo 7) for specific discharge locations that can incrementally increase the initial vehicle cost and may, over the lifetime of the unit, increase repair and maintenance costs.”
Reichman: “In some cases, offering a pedestal pump can benefit a customer with a tight budget. We see in many cases that it’s about providing customization for our customers. Rosenbauer has the ability to fine tune the placement of the plumbing to optimize the pump panel. Also, with PTO-driven pedestal pumps, we can offer pump-and-roll capabilities for those customers requiring a multipurpose apparatus.”
Messmer: “I would recommend the pedestal pump for cost and efficiency. Another consideration is weight. You can reduce weight by several hundred pounds. The other factor is the ability to plumb the pump in about any configuration to fit your needs.”
Kirvida: “The only two reasons that I can think of are less initial cost than a full-body pump and slightly more compact (but only in the over-the-frame manifolding).”
Kirvida advocates pointing out the advantages of both full-bodied and end-suction pumps at the same time. He elaborates, “I would explain the merits of a full-body pump, such as integral discharge and suction passages designed, machined, assembled, and pressure- and performance-tested by the pump manufacturer-not by the body builder. The horizontally ‘split’ pump body casting allows for removal of the impeller assembly (shaft, bearings, impeller, wear rings, and seal assemblies) intact, without disturbing any of the suction or discharge valves and piping.”
He adds, “Two-stage centrifugal pumps received a bad rap because of historically troublesome transfer valves. Prior to the introduction of the nonsticking ball-type transfer valve, pump manufacturers migrated to and the fire service accepted single-stage pumps with a resulting loss of improved pump performance (gpm at rpm) during flows of up to half the pump’s rated capacity plus higher operating pressures than are available with an end-suction single-stage pump. They also have an integral tank-to-pump suction port with built-in unrestricted flow check valve and available rear suction port(s), again designed and manufactured by the pump OEM.
“Conversely, I submit an end-suction volute pump is slightly (ranging from $3,000 to $4,000) less expensive, plus, with certain plumbing configurations, may take up less space, possibly allowing for shorter vehicle wheelbase. However, when considering the cost of body-builder-manufactured suction and discharge manifolds, the total cost savings could drop to only $1,000 to $2,000.”
|8 A behind-the-panel view of a crowded pump house with an OEM-fabricated side steamer connection to a ram’s horn-style suction connection on an end-suction pump. (Photo courtesy of Emergency Vehicle Response.)|
Why do some “alphabet” truck builders provide end-suction pumps and some offer full-bodied pumps?
Messmer: “Versatility with stainless plumbing is unbelievable. If you want all the discharges on one side of the rig and all the inlets on the other, you can easily do that with a pedestal but not with a full cast iron pump.”
Kirvida: “Some apparatus manufactures are limited by their body and water tank designs and thus are forced to locate the fire pump in cramped areas as opposed to compromising the apparatus body to accommodate an over-the-frame-rails full-bodied pump.”
Witmier: “KME’s PRO pumper is optimal with a pedestal-style pump, allowing us to fit the pump into the exact position we want and to customize things around the pump like water tanks, ladder storage, etc. This provides a smaller pump house and a nontraditional square box for the pump house, which allows us to build storage around it.”
Compton: “Spartan’s Legend series of apparatus has a pedestal pump as a standard offering. Our ‘alphabet’ truck is designed around a nonbrand-specific pedestal pump design. Not being brand-specific has benefited us because as some of the plumbing designs have evolved, some of that experience has spread out to better methods and components in our more traditional apparatus.”
|9 Another PSM series end-suction pump with an optional “T” style suction header and a full discharge manifold. Purchasers should realize every elbow, twist, and bend in suction piping affects pump efficiency at draft. (Photo courtesy of W.S. Darley.)|
Suction and Discharge Manifolds
As mentioned, end-suction pumps are usually delivered without discharge and suction manifolds. Apparatus OEMs either manufacture them in-house or outsource them. Most pump manufacturers offer various suction manifolding pieces as optional accessories, and some provide discharge manifolding as an option (photo 9). Even when manifolds are outsourced, the final design and fabrication of all piping is done in-house. Some OEMs design manifolds and piping installations on a computer with designated piping design software. Some don’t. Therein could lay potential problems-especially when drafting is a priority. Purchasers should be made aware of them.
If an OEM has a poor plumbing configuration or installation, can that negate the effectiveness of an end-suction pump?
Messmer: “Yes-it’s all about the plumbing. If not accomplished at building stainless manifolds, you will fail with pump performance.”
Darley: “I don’t really see this as a major concern for the end users. OEMs are all familiar with the plumbing requirements, and if they ever have any questions on a pump that may be new to them, Darley has an excellent team of experienced engineers who can provide them with plumbing and installation guidance.”
Kirvida: “Absolutely-end-suction pump manufacturers can be subjected to unfair criticism at no fault of their own. Some stainless suction and discharge manifolds are fabricated by the body builders, some of which may lack the qualified people or advanced technology to design, engineer, and fabricate complex manifolding. If manifolds are not computer-designed, there is no guarantee one can be replicated for a replacement or a future purchase-even from the same builder. Regardless of an individual’s workmanship and work ethics, handmade records and a plumber’s memory do not guarantee identical performance test results for subsequent units. A fire department can purchase identical pumpers with the same model end-suction pump from three different body builders off the same specification and have three levels of performance because each builder has its own manifolding and piping designs. A body builder needs to be qualified to design and fabricate manifolds and identically replicate them in the future.”
Seldom do purchasers prescribe expected levels of quality, design and workmanship in their piping and manifold specifications. They should.
|10 A Waterous CXSC20 end-suction pump with an optional bolt-on suction header to accommodate a steamer connection on each side plus a tank-to-pump connection. The inlet connections feature grooved ends, and the discharge terminates with a flange. (Photo courtesy of Waterous.)|
If a firefighter walked into your booth at a trade show and said, “I want to buy a basic single-stage 1,500-gpm pumper. What kind of pump should I get?” what would you tell him?
Van Meter: “Hale’s best solution for a 1,500-gpm pumper is the Qmax or, if space is a premium, the Qmax-XS. Hale has designed the internal passageways of the Qmax family to provide the most efficient path for the water. The internal manifold is designed in such a manner that the water leaves the pump at the closest point of distribution with little pressure loss. The Qmax and Qmax-XS pumps are essentially 2,250-gpm pumps that are rated at 1,500 gpm. The additional available flow can be used when more flow is needed on the fireground, and the large amounts of reserve power left in the pump can help the pump make pump rating from year to year without needing pump rebuilds to replace worn clearance rings.”
Geske: “I would educate them on the advantages and disadvantages of both an end-suction and a dual-eyed impeller pump and let them make the decision. Other things might affect their decision like how much they draft or at what altitude they are located. It might be my personal way of sales, but I prefer to educate the end users and have them choose instead of me telling them which one.”
He adds, “The most commonly purchased Waterous end-suction pump for a 1,500-gpm rating is the CXSC20C-1500 as compared to the most commonly purchased duel-eyed impeller pump, which is the CSUC20C-1500.”
Darley: “In the majority of cases, the Darley PS Series-whether PTO-driven (PSP) or split shaft (PSM)-would be recommended. The PS series will save the customer in both weight and space as compared to other products on the market and will provide a much higher reserve capacity in terms of flow. It will also do this with less horsepower and torque requirements from the engine because of design efficiencies of the Darley product. The PS series will flow, on average, around 1,900 gpm at 150 pounds per square inch on a max flow test and can be as compact as 19 × 18 × 24 inches and 345 pounds in a PSP 1500 two-gear, offering a lot of design flexibility in mounting with Darley’s modular product design. The PS Series allows space and weight savings to be applied to other equipment necessities on today’s multipurpose apparatus while not giving up the firepower required.”
|11 An end-suction pump with an optional ram’s horn-style suction header that has just been mounted on a chassis. (Photo courtesy of KME.)|
Words of Wisdom
Best efficiency point (BEP) is a term occasionally heard in the industry. I doubt it’s a selling feature fire departments should be concerned with. Supposedly, it’s the point where an efficient amount of engine horsepower has a pump running at its optimum. Paraphrasing Handwerk, the BEP is a point the pump designer selects and, by design, tries to create. The engineer/designer maps out the efficiency of the pump to match the application and pump drive. The better the job done, the better the pump. It is all about impeller and volute design.
My take on it: If the BEP is based on a pump flowing 1,500 gpm and less than 200 gpm is flowing 95 percent of the time the fire department engages the pump, then the BEP is a moot point. BEP may be more relevant in industrial/commercial scenarios where a stationary pump may be running full tilt 24/7.
Asked if you can get the same performance from an end-suction and a full-bodied pump both rated for 1,500 gpm, Messmer says, “Only at draft like an Underwriter’s test is when you can accurately compare a pedestal and a full-bodied pump’s performance. When supplied by a pressurized source, either style pump will basically deliver whatever you put into it.” He adds, “There is nothing wrong with a full-bodied cast iron pump. In a lot of cases, they are the best for an application. But, the end-suction type with stainless plumbing has some distinctive advantages.”
Compton says, “Maximum flow from a pedestal pump, assuming this is split-shaft and not limited by a PTO and rated in the 1,250- to 1,500-gpm range, can typically be at least 250 gpm over its rating from draft. From a good water source, you’re only limited by the discharge plumbing size and could easily work 500 gpm over a pump rating.”
|12 Six-inch main suction manifolds with NST/NH ends built to OEM specifications. Ken Van Ryzin, of Stainless Piping Specialists (SPS), says SPS is the leading manufacturer of custom-built prefabricated plumbing manifolds for the fire service/apparatus industry. (Photo courtesy of Stainless Steel Piping Specialists.)|
An end-suction pump’s impeller eye looks along (parallel to) the chassis frame rails. A ram’s horn fitting (photo 9) or a similar looking fabricated manifold (photos 10 and 13) is used to position a suction inlet toward the rig’s sides. Suction manifolds can be purchased from the pump OEM or another outside vendor or fabricated in-house by the apparatus OEM. One pump manufacturer’s printed literature says such a device on one of its pumps requires the use of both sides of the ram’s horn when drafting to achieve its NFPA 1901-compliant performance. Purchasers might want to ask potential vendors if that’s the case before writing technical purchasing specifications. Don’t spec a 1,500-gpm pump and inadvertently reduce its expected performance from draft with inadequate piping-and poor specifications.
Darley states, “There are a lot of benefits provided with an end-suction pump. Frankly, the difference to the end user between the two may be moot, as the pumps will provide the same performance at the end of the nozzle. What the users may not realize is that by selecting an end-suction pump, in many cases, they are gaining a significant weight and spatial savings, allowing them to add more of what everyone is always looking for in their design-more water- and equipment-carrying capabilities, as the pumps save on both space and the impact on gross vehicle weight rating.”
Kirvida recommends TIG welding in lieu of MIG welding on stainless steel manifolds. He notes that the warranty on some outsourced manifolds may be for product only and not for removal and reinstallation, which could be a very labor-intensive and costly lesson-for someone. He says that regardless of their complexity, CustomFIRE designs and fabricates all its stainless steel manifolds in-house.
As I understand it, TIG welding is an arc welding process using a tungsten electrode to produce the weld. Also called gas tungsten arc welding, it is supposedly the superior method to weld stainless steel including thin wall (Schedule 10) stainless piping. MIG welding is when an electric arc between a consumable wire electrode and the metal causes the metal to melt and join. It is commonly used on aluminum. I take no sides. Prior to writing “technical” purchasing specifications, I encourage purchasing committees to make inquiries of manufacturers or people more learned than I.
|13 Not all end-suction pumps are limited to 1,500 gpm. This US Fire Pump end-suction High Velocity Pump is NFPA-compliant for 6,250 gpm. It includes a 12-inch flanged suction inlet with an impeller eye exceeding 10 inches in diameter. Depending on the desired rating, an eight- or 10-inch-diameter discharge is provided. From pressurized water systems, US Fire pump says it will flow in excess of 10,000 gpm. (Photo courtesy of US Fire Pump.)|
End-Suction Pump History
The 1992 acquisition of Godiva by Hale resulted in bringing U.S.-based Barton/American Godiva pump products into the Hale product offering. Handwerk, who was chief engineer at American pump, says, “The big craze in the end-suction pump market started in the 1980s. The concept gave truck builders and fire departments the flexibility to build a different type of truck. Hide the pump, add compartments, make the truck more compact, or add space in the cab. Builders who took advantage of this concept in the 1980s and 1990s included Saulsbury, Young, Alexis, LTI, E-ONE, LDI, and Gator.”
He finished with a word of caution: “Today, all the alphabet trucks are the latest versions of that concept. But in many of these designs, you give up some pump performance to gain space.”
BILL ADAMS is a member of the Fire Apparatus & Emergency Equipment editorial advisory board, a former fire apparatus salesman, and a past chief of the East Rochester (NY) Fire Department. He has 50 years of experience in the volunteer fire service.