By Bill Adams
Parts 2 and 3 illustrated how several volunteer and career departments operated midi-pumpers for decades with varying levels of success. That provided the Raisin Squad ammunition to bloviate on the topic over morning coffee. Bloviate means to talk pompously and long-windedly about stuff we’re not necessarily well-versed in. Old-timers excel in that. A couple former apparatus dealers and retired white hairs from the apparatus industry voiced their opinions via email. We try to keep tabs on the fire truck world and remain relevant. Consolidated observations follow. Names are withheld to protect the innocent – and the guilty.
Cantankerous Wisdom: The Midi-Pumper | Part 1
Cantankerous Wisdom: The Midi-Pumper | Part 2
Cantankerous Wisdom: The Midi-Pumper | Part 3
Function
Most agreed midi-pumpers can be a valuable asset when used as part of a two-piece engine company. The majority said they can’t replace full-sized pumpers and gave substantiating reasons. Leaving emergency medical services (EMS) out of the equation, they said when used for fire suppression, midi-pumpers are only capable of an initial attack. It’s doubtful they can be self-sufficient. There’re too many variables including limited operational capabilities and scenarios such as a car fire turning into 15 gallons of burning gasoline in a crowded parking lot; a grass fire extending into a barn; and an automatic alarm that’s a working basement fire. A midi-pumper’s size and configuration may not be conducive to sustaining extended operations by itself.
Staffing
Most raisins concur two firefighters are insufficient to staff suppression apparatus. Often, two people may be inadequate to provide primary EMS prior to a transport vehicle arriving. Hence, midis should be equipped with crew cabs, albeit many do not.
Cab size may be irrelevant when a full-size pumper always responds with the midi. Regardless if staffing is career or volunteer, it may not be prudent to send all available firefighters on a midi when additional resources may be delayed or cannot be staffed.
Perception
The National Fire Protection Association’s NFPA 1901 Standard for Automotive Fire Apparatus recognizes Pumper Fire Apparatus and Initial Attack Fire Apparatus. It does not recognize midi-pumpers, mini-pumpers or attacks. Call them what you want. They are undefinable generic terms that are often marketed successfully.
Many believe midi-pumpers (and some mini-pumpers) are smaller, quicker, and more agile than full-size pumpers. That’s not necessarily true. There are no rules specifying their physical size or capabilities. Eager for a sale, some vendors might not be 100% forthcoming with facts and figures. They should. Purchasing committees working with a preferred vendor may not demand facts. They should too. Trust but always verify – preferably in writing. Don’t let vendor preference obscure facts.
Reality
Most full-size custom pumpers today have 1,500-gpm pumps, 750 or 1,000-gallon booster tanks; seating for six; 1,200 to 1,500-foot large diameter hose (LDH) capacity, multiple preconnects, and a large complement of tools and ancillary equipment. Gross vehicle weight ratings (GVWRs) range from around 40,000-lbs to over 50,000-lbs.
When replacing a full-size pumper with one physically smaller with possibly a 30% less GVWR, something has to be reduced or deleted. Is it water, supply hose, preconnects, firefighters, tools, ancillary equipment? What happens if a midi is not the first to arrive on scene? Does it muck up the works if carrying half as much supply hose or tank water? Those are hard questions that should be addressed before purchasing.
Park a midi-pumper next to your full-size pumper and start transferring equipment. Do you sell all the stuff that doesn’t fit? One geezer said a midi-pumper should be built around specific equipment and capabilities. Another said most people just load them up until they’re full. Then they run it hoping everything works.
One former industry white hair asked if a midi-pumper will be used for an initial attack – exactly what is going to be attacked? And how long do you expect a midi-pumper to maintain the attack until reinforcements arrive? Those questions drew some blank stares. Raisins are easily confused. Purchasing committees shouldn’t be.
Dimensions and Weights
Newton’s third law of motion says for every action, there is an equal and opposite reaction. It’s applicable in the fire truck world. The following figures are not reflective of any particular manufacturer. A medium duty two-door commercial chassis in the 35,000-lb GVWR or less range can have a front-axle to back-of-the-cab measurement around 65-inches. If a four-door commercial cab is chosen, that measurement – and the wheelbase – can be increased by 48-inches. Ask vendors what adding four feet does to the turning radius.
Seldom an issue with midi-pumpers, weight is a significant concern with mini-pumpers. The hypothesis is the same. A common mini-pumper chassis GVWR of around 19,500-lbs should not be exceeded when in-service with all its equipment, water and all of its personnel.
Often mischaracterized as the curb weight of a commercial chassis is how much it weighs when delivered to an apparatus manufacturer to build the body. The common two-door mini-pumper chassis weighs around 7,000-lbs leaving 12,500-lbs available to fabricate and equip the rig – with an allowance for the crew. According to one chassis manufacturer’s body builder book, a four-door mini-pumper chassis adds about 1,000-lbs to the curb weight thereby reducing what the fire department can carry. A thousand pounds can equate to about 100 gallons of water or perhaps eight lengths of 5-inch LDH supply hose.
Weight calculations are not as simple as inferred. It is a complex theorem where wheelbase, tires, perhaps tire inflation pressures, recommended front-to-rear weight ratios and physical equipment locations are integral parts. OEMs use computer programs to calculate weights. Reducing the seating capacity by one firefighter is a 250-lb savings equal to perhaps 30 gallons of water which, if properly applied, can turn into over 50,000 gallons of steam. Should a purchasing committee know all this stuff? No. But the vendor should and the information passed along.
Custom Versus Commercial
Manufacturers seldom propose a custom chassis for a midi-pumper. Those that manufacture their own custom cab and chassis ought to. It’s an option worth considering. Just because a custom chassis is chosen, purchasers don’t have to specify the largest motor in the western hemisphere and every bell and whistle available. Entry level custom chassis are available. So is common sense.
One department that ran a four-door commercial 4×4 midi-pumper (photo 1 is at the top of the page) for 15 plus years replaced it with a “short” custom pumper (photo 2, above). The custom features a 164-inch wheelbase compared to around 200-inch plus wheelbases for many four-door commercial rigs. The custom has a 1,500-gpm pump, 500-gallon tank, 27-foot 6-inch overall length, front suction, booster reel, dual crosslays, two 2½-inch discharges and four 3-inch discharges – one adapted for 5-inch LDH and two for rear preconnects. It carries 1,000-feet of 5-inch LDH and seating for five. Four are SCBA seats. Customs might offer more capabilities than commercials in a more compact package.
Points to Ponder
The squad made several comments worth considering. Remember most of these raisins rode the back step years ago and only ride their recliners these days.
*Don’t get in a funk over compartmentation. Make sure there’s enough water and hose; then accept what room is left for compartments.
*A volunteer station that didn’t have enough drivers for its full-size pumpers because they were intimidated by their size. They purchased a midi-pumper as first out – knowing full-size pumpers from multiple close-by stations will be dispatched on all assignments. It works for them.
*Don’t get an extended front bumper if the wall-to-wall turning radius is a concern.
*Trying to make the rig a combination midi-pumper, grass fire truck, EMS response rig and mini-rescue with HRT tools isn’t going to work. There isn’t enough room.
*If you want a Wildland Urban Interface (WUI) apparatus, first define what a WUI rig is. What are you trying to accomplish?
*If vendors propose making after-market modifications to chassis components to increase its GVWR, document in writing who’s going to do the work; who certifies it; and who warranties it.
*If you’re planning on taking a midi off-road, remember how much it weighs.
*Why buy four-wheel drive if you’re not going to use it as a brush truck? Ask vendors how much four-wheel drive costs and if it adds weight to the rig.
*Some midi-pumpers appear top heavy so specify the manufacturer does physical tilt-table testing in lieu of a computer analysis to determine stability especially if going off-road.
*Establish realistic fireground expectations and running order before designing your rig.
*Evaluate staffing availability including a limited number of on-duty career people. Consider the unpredictable response of volunteers and call-back personnel and their time to staff additional in-house resources. Don’t forget the travel times for mutual-aid and automatic mutual assistance.
*Today’s chassis components coupled with advanced extinguishing agents, lightweight materials, and advanced designs can enhance the operational capabilities of these smaller apparatus. Remember water and people put out fires. If there’s not enough of either, it might not happen quickly and efficiently. Good luck.
