Reducing Pump Space For All-Purpose Apparatus

What does the future hold for the pumping system on your next apparatus?

Many of the same trends and issues that drive the rest of the world affect the fire service and what it buys for its apparatus. These include budget, staffing, environmental considerations, demographic shifts, and changing regulations. It does not look like these issues will change during the next couple of years.

The current budget crunch has caused fire departments to adjust their buying habits. Fewer apparatus are being purchased, and when a purchase is made, fewer big-ticket options are being added.

The limited budgets at many paid and some volunteer suburban departments have caused a reduction in staffing or at least the potential of reduced staffing and possibly fewer stations. This reality has accelerated the popularity of two basic styles of apparatus—the all-purpose, do-everything rescue pumpers and quints.

These types of apparatus maximize the crew’s ability to handle almost any call, including trash fires, grass fires, auto fires, and structural initial attack, as well as relay, supply, aerial tower feed, and master stream applications. This commonly requires a 1,500- to 2,000-gpm pump. Given the current need to reduce the space the pumping system uses— thereby leaving more space for compartments without making the apparatus larger—specifying this size pump poses a challenge.

At the same time, there is a need to provide a high performance level throughout the lifetime of the apparatus. Pumping system reliability also impacts maintenance costs, which are also being squeezed by budgetary constraints.

Actual performance depends on the capability of the hydrant system, deliverable power to the pump, intake hose setup and discharge hose arrangement, along with the pump manifolding design and internal hydraulic design.

Not all pumps are created equal. It is possible to have a 1,500-gpm pump that provides only the 1,500 rated gpm or one that can deliver 2,000 gpm. Depending on the limits of the pump drive, the limited performance of the 1,500-only rated pump may be the perfect selection.

For example, a consistently high hydrant flow and pressure combined with a pump drive system capable of delivering flow over 1,000 feet continuously (including the chassis, engine, transmission, PTO if any, drive shafts, and pump gear box) allows a 1,500-gpm pump supplied by a 60-psi hydrant to deliver 2,000 gpm at 200 psi to feed a large ladder tower. A drive system designed for this job is essential if you require this type of performance.

Since a 1,500-gpm pump with the right drive system will provide 2,000 gpm, the next step is to hide the pump to maximize compartment space—a task that is easier to complete than most buyers think. The pump itself can be under the cab, built into the front bumper, between the chassis frame at the rear, as a rear-mounted pump, or as a configuration built into the middle of the body.

What really consumes space are all the inlets and discharges along with their controls and instrumentation. When designing a pump module, we typically run out of space for the discharges, not the pump. Electric valves will help because they can be located and controlled from anywhere on the apparatus. They are common today, but they do cost more.

If you want to save money on the apparatus purchase, lower maintenance costs, and simplify things for the pump operator, don’t buy any intakes or discharges that you do not really need. They only add to the price, take up space, and increase maintenance costs.

The answer is going to come from a careful analysis of the specific fire calls, lines being deployed, and appliances being fed. Each discharge line should be designed to perform the specific job at hand.

Once the total discharge system is understood, it’s time to look at the water supply options. Design to maximize the available water supply. The goal at this point is to minimize the space required to do the firefighting jobs, provide access for servicing and repairs, and keep the cost within the correct range.

One way to do this is to use some of the National Fire Protection Association (NFPA) 1901 apparatus standard’s required 21⁄2-inch discharges as rear panel preconnects, one of which is a one-man monitor. These 350- to 500-gpm monitors allow a single firefighter to deploy a lot of fire knockdown power.

Other 21⁄2-inch outlets—no matter where on the apparatus—can also be counted toward NFPA 1901 requirements, even if they are preconnected or have an adapter or gated wye attached for use with larger or smaller hose when the apparatus is in service.

Since many departments do not use the pump system on every run, another option is roll-up doors over the pump operator’s panel. They shorten apparatus cleanup after a run because the pump panel is not splattered with mud or ice, snow, and salt.

In rural America, the staffing issues also exist, but often what has become limited is water supply support activities. Being capable of deploying both a pumper and a tanker may be an issue with the quantity and speed of response of tankers capable of mutual aid possibly being limited.

The answer for many rural departments is an 1,800- to 3,000-gallon pumper-tanker. These are simple apparatus, with about four lower side compartments, hose bins, a 750-gpm or 1,000-gpm rated pump, preconnects, and basic equipment. Most of these apparatus use the transmission PTO to drive the pump, and the pump is often mounted under the chassis frame with the control panel mounted low on the driver’s side.

Pumper-tankers, due to their simplicity and attractive price, also satisfy another big issue in rural America. They cost less money than just a few years ago. They are easy to use and focused on the immediate job at hand—fighting a fire with limited staffing where water is not readily available. In most states, these apparatus are classified as a pumper and qualify under ISO Class 8.

Another shift that is becoming a problem for the fire service is the metro/suburban expansion into what was once rural wildlands. This, by itself, is an extra challenge to many departments, but to make it even worse, scientists who study weather patterns believe we will see more and bigger wildland fires. To the fire service, this means more interface firefighting, whether you’re a paid or volunteer department, suburban, metro, or rural.

Interface firefighting has driven another hot selling apparatus style—a combination apparatus, which is part pumper, part wildland apparatus, part all-purpose water supply, auto accident, and access pumper in deep snow conditions. Most of these apparatus are built on an International or Freightliner 4x4 chassis with a four-door cab. The pump can be midship-mounted or rear-mounted and is usually rated at 1,000 to 1,500 gpm. A Class A foam system with pump-and-roll capabilities and a bumper turret are all common in this class of apparatus. This apparatus is all about maximum utility with a limited crew.

Let’s look at pump-and-roll capabilities. The NFPA requires 100 psi at 80 gpm at 2 mph for pump-and-roll operations. But, the reality is that driveability during pump-and-roll operations is also very important. It should not take heavy two-foot driving to achieve pump and roll, where every time the engine throttle is backed off the pump the pressure drops so low the fire flow falls off.

For pump-and-roll operation at an acceptable level, the pump and PTO should be geared so the output is about 100 gpm at 100 psi at about 720 engine rpm, which is just off idle.

There are three practical ways to achieve this kind of pump-and-roll performance: a small PTO-driven pump geared correctly; a separate engine-driven pump (commonly a fixed mounted diesel portable fire pump); and a multi-stage PTO-driven pump.

The secrets to making the two PTO drive applications work correctly and not require lots of maintenance are to have sufficient engine power at 700 rpm to operate the pump and move the vehicle on a grade and to have a PTO that has a rating to match the duty cycle. Additionally, the chassis overall first gear reduction must be sufficient to allow the vehicle to operate smoothly and continuously at 2 mph with minimal usage of the chassis brakes.

What doesn’t work is a single-stage PTO pump rated for high gpm on a typical 4x2 chassis. You can get “pump and move,” which is 100 psi at 7 mph, but when you let off the throttle, the pump pressure drops to almost nothing.

Not that long ago many fire departments in Oklahoma, Kansas, Texas, Arkansas, and other states depended on a tank and portable pump to create an ISO Class 9 apparatus, thereby allowing communities to qualify for homeowners’ insurance.

Things are changing; the ISO is moving to up the minimum performance from the current 50 gpm at 150 psi from draft to 250 gpm—a full NFPA 1901-rated pump system. This is going to push these apparatus from 18-hp engine-driven pumps to 50- to 60-hp engine-driven pumps, which are several hundred pounds heavier, are considerably bigger, and cost a lot more.

A 250-gpm PTO pump could be a good option, but on our favorite 4x4 Ford F-550 chassis the PTO is not usable. This makes the apparatus bigger and more costly.

What all this means for pumping systems in the immediate future follows:

  • Small portable pump usage will decrease on ISO Class 9 rural apparatus while small 250-gpm PTO pumps and 50- to 60-hp diesel pump engine packages will become more popular.
  • Pump-and-roll pump setups will continue to be popular along with bumper turrets.
  • Demand for pump packages that save compartment space or shorten the apparatus wheelbase will grow.
  • Currently the 1,500-gpm pump rating is still the most popular rating, which will continue.
  • Tankers (tenders) with pumper capability, commonly using a 750-gpm or 1,000-gpm pump, will continue to satisfy.
  • The battle between midship pump mounting and rear pump mounting will continue. Currently midship is the leader by a large margin, and rear mounts are about where they have been for 10 years.
  • Cost-effective features that maximize firefighter performance or reduce maintenance, such as Class A foam systems, personal monitors, roll-up doors over pump control panels, anode systems, and thermo relief systems, will be purchased.

Gary Handwerk is the engineering manager for Hale Products. He has been involved with the fire service industry for more than 38 years. He has been a member of the NFPA Fire Apparatus Standards Committee for more than 18 years.

 

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