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September 2009
SPECIAL REPORT

Food On The Move

Heated transport carts and mobile hot holding cabinets help you deliver hot product from your kitchen to almost anywhere.

Don't forget to check out our Hot Mobile Cabinet Gallery.

By Mike Sherer

At some point, almost every foodservice operation needs to move prepared food from point A, usually the kitchen, to point B, which could be anywhere. A restaurant opens a party or banquet room and needs to prepare food in advance so the kitchen doesn't fall behind serving its regular customers. A hotel hosts an elaborate evening reception for a corporate meeting out by the pool. A B&I operator starts catering the off-site company picnic. A small chain adds enough stores to warrant a central commissary and wants to deliver products like sauces fresh to stores every day...you get the picture.

Getting food from one place to another is relatively easy. The two most important caveats to moving prepared food are maintaining food quality and safety—and thus making sure food is delivered hot and fresh. Fortunately, today's wide array of heated transport carts and mobile hot holding cabinets do both. Many are energy efficient, and since hot holding cabinets are an Energy Star category, their energy and lifecycle costs are easier to compare.

Improvements in design, construction and technology have allowed manufacturers to expand their range of models from simple to sophisticated. You now can get mobile hot boxes designed for many different types of food as well as almost any type of application. One manufacturer alone, for example, makes more than 150 models and sizes. In other words, no matter what you need it for, you'll find some hot wheels to suit you.

How Do You Define Hot And Mobile?
The sheer number of models available means you should carefully consider your needs. Depending on your application, just any box may not do. And wheels may make a box mobile, but don't necessarily make it suited to all types of transport. An easy way to think of units in broad terms is to lump them into three categories—mobile hot holding cabinets, heated transport carts and banquet carts. What's the difference? Glad you asked.

The broadest category, mobile hot holding cabinets, encompasses an array of what you might consider traditional hot boxes on wheels. Typically tall on a fairly small footprint, they're designed to take up minimum space in the kitchen or on a transport truck. They hold stacked hotel or sheet pans of food at serving temperature, at around 150°F to 165°F. A majority of the models available are on wheels to make it easy for employees to load food from ovens or other cooking equipment.

These holding cabinets are available in full- or half-sizes with a range of options such as Dutch, pass-through or glass doors; humidity control; tow bars; digital controls and more.

Though robust enough to withstand getting pushed around the kitchen or down a hallway, these units typically are not designed to take the abuse of over-the-road transport to off-site locations. For that you need a sturdier breed of hot box typically called a heated transport cart. Built with heavy-duty frames, bumpers and casters, transport carts are designed to survive an errant fall off a loading dock, a mishap that would take out less durable equipment.

Banquet carts come in two basic styles, one for covered plated food, the other designed to hold bulk food. They typically have a more horizontal profile than mobile hot holding cabinets, and, though large, roll easily in hotel service hallways and elevators. Their larger footprint, though, means fewer will fit on a truck for remote feeding, but tow bar options make it easy to move them around a resort property. Standard sizes hold 120, 150 or 180 plated meals to handle high-volume banquet feeding in hotel ballrooms.

(Note: In this story we're not covering hot boxes that transport trays for healthcare. That's a category we'll cover in a future article.)

Well Turned Out
You may find that the hot holding cabinet you purchase to hold excess product for a Friday night rush also works just fine for moving food to a banquet room or somewhere else onsite. If you need something really durable, it pays to look at construction details.

Materials. Mobile hot boxes typically are made of either aluminum or stainless, though there are also very durable molded polyethylene models on the market, too. Polyethylene tends to be the most ding-resistant and weatherproof, and often is an economical alternative depending on your application. Aluminum boxes also tend to be an economical choice, but may not withstand heavy use or abuse.

Stainless, the most expensive material of the three, tends to be the most durable. Remember that the lower the gauge, the thicker and more heavy-duty the steel. Lighter-duty boxes designed primarily for the kitchen often are built with 22-gauge stainless exteriors and 24-gauge interiors. Heavy-duty transport carts typically are constructed of heavier 18- to 20-gauge stainless.

Frames are key to structural integrity. Molded polyethylene boxes don't have or need frames. Even so, they're strong and relatively lightweight. Both aluminum and stainless cabinets are typically constructed with steel frames, either angle-iron or tubular. Here again, heavier gauge steel often indicates a tough box that can stand up to more abuse. You'll find most manufacturers use 18-gauge steel for frames, but at least one builds frames with 12-gauge.

Manufacturers use a couple of different techniques to reinforce frames. Several models are designed with a cross-brace in the back wall. Others use tubular steel on each side of the doorframe and weld it to the base of the unit. An advantage is that door hardware—hinges and latches—can be fastened directly to the frame reinforcement instead of just the skin of the box itself. Some say a disadvantage is that tubular steel takes up space, leaving less in the double-wall construction for insulation.

Another design bends the top and side metal sheets inward to form a seam that's welded together. The seams, like a three-sided square, act like a frame, giving the cabinet greater rigidity.

Take hinges and latches into account if you expect your carts to get banged around on the loading dock or in a truck. Common edge-mounted hinges may be fine for light use; look for flush mounted pin hinges that won't get whacked out of alignment or damaged in transport. Really heavy-duty hinges may have reinforcement plates to which they may be welded or bolted, not just screwed in, to attach them securely.

Look for flush-mounted, not edge-mounted latches, too, for heavy-duty transport applications. Latches may be mechanical or magnetic. Either can pop open in transport, so be sure you add an optional transport latch that twists or swings over the door if you plan on moving your carts around a lot. Many of these catches are designed for use with a padlock, too, giving you added security.

To get a grip on hot holding cabinets and transports carts, manufacturers either add handles or offer recessed finger grips. Handles tend to give employees more control, but like hinges and latches can get banged up since they protrude. A good rule of thumb is to consider recessed grips if you spec cabinets without bumpers, and consider handles as long as they don't protrude outside the bumpers. Handles should be securely bolted or welded on, and it's a good idea to spec back-up reinforcement plates for heavy-duty use.

There are several ways equipment makers add bumpers to cabinets. Some operators don't order them, even on transport carts, because they expand a cart's or cabinet's footprint so fewer fit on a truck. But in most cases bumpers are a good idea.

Heavy-duty cabinets and transport carts generally are manufactured with the bumper as an integral extension of the base (a larger base, in other words), or bolt a free-floating wrap-around bumper to the base. The latter tends to absorb impacts better.

Others simply screw or bolt bumper channels to the base or the lower edge of the cabinet. These designs, while sometimes less expensive, don't absorb impacts as well, and potentially expose the entire cabinet to damage, but may be fine for light-duty use.

And polyethylene units don't add bumpers but incorporate them into the overall construction for durable impact resistance.

The Heat's On
You've got lots of options when it comes to heating cabinets and transport carts. Depending on make and model, you'll find heating elements located at the top of the cabinet, bottom of the cabinet, or in one case, in the walls.

Since heat rises, cabinets and carts with elements located on the bottom let physics take over. Nothing else is required. If something goes wrong, however, they can be hard to get to and service. Some are designed in pull-out drawers; others lift out of a cut-out in the base. Since they're on the bottom they're potentially more prone to damage from impacts and spills.

When heating elements are on top, they're out of the way, and in some cases can be lifted off so employees can hose out the interior of the cabinet or service the heating unit. But cabinets with top-mounted heat require fans to distribute the heat more evenly, meaning one more component that may need service in the future.

Models with heating elements sandwiched in the walls provide gentle, wrap-around radiant heat, so no blower is needed, but may also pose potentially more expensive service problems.

Heating elements typically range in power from 600W to 1000W for half-size units and 1500W to 2000W for full-size cabinets. Those with fans for convection heat may have one or two fans. Typically, units with more power and air circulation provide faster warm-up and recovery time. That could be important if employees will be opening and closing the door frequently. But it also may cost you more in energy; be sure to check how efficient a unit is before you buy.

Convected units also distribute heat differently, which may affect how evenly your food stays warm, depending on what type of products you transport. Some models blow air up the sides of the cabinet in one direction to produce a counterclockwise swirl of warm air inside. Another maker directs air up both the sides and rear of the cabinet for more airflow. Still others blow air up the back through a series of louvers that direct it across each layer of product from back to front. Advocates say this method heats more evenly, but some say it doesn't hold heat in the cabinet as well if you open the door a lot. Compare recovery times to see which might be best for you.

You also have to decide whether you need dry heat or some moisture. Many models now offer humidity control to varying degrees. The least sophisticated, and least expensive, is a simple adjustable vent that you can open to let steam and moisture escape, or keep closed to retain moisture. A step up from that is a passive system that lets you put a pan of water, usually about a gallon's worth, in the cabinet.

Active humidity systems, though, have a separate water tank and heater to add moisture to the cabinet. Some let you adjust relative humidity by manually setting the holding temperature of the cabinet and the temperature of the water heater. Others use sensors to automatically adjust the moisture level in the cabinet.

It may not make sense to use a passive system for transport—all that water sloshing around—though you can add water to the pan once the food reaches its destination. But cabinets with active systems are better suited for travel if you need high levels of moisture.

Power And Control
Maintaining all that heat while the box is in transport requires good insulation. If you're only moving food a five-minute walk from the kitchen, you won't need a fully insulated box, (though you may want the energy savings that better-insulated unit provide). Most double-walled heated carts use fiberglass insulation. More is better, so typical units feature from 1" to 2" in side and back walls, and perhaps a little less on top or bottom.

Some aluminum and stainless cabinets and carts often maintain food temps for only half an hour or so when unplugged. To extend the time cabinets hold food at proper temps, one manufacturer has added a special base plate to some models that retains heat, extending holding times when the unit's unplugged to as long as two hours.

Polyethylene carts use foamed-in-place polyurethane insulation and generally provide the best heat retention in cold weather. They also maintain food temperatures for up to four hours.

Once food has been transported to its destination, heated carts can be plugged into continue holding food at proper temps. Specifying the right power and cord set is important. Most cabinets operate on standard 120V electric service so you can plug them into a typical household outlet. Most are designed to operate between 10 and 15 amps, so you're safe plugging in to most 15- or 20-amp circuits.

Cords are another detail you'll want to pay attention to. Six-foot cords are typical. But depending on where controls are located, cords may be situated at the top of the box or the bottom. If you intend to plug units into overhead utility service, make sure the cords are either top mounted, or long enough. If you're plugging into standard wall service, look for bottom-mounted cords, or, again, longer cords.

If you don't have access to electric service at all where food is being served, some transport carts are designed with special compartments to accommodate canned fuel. Polyethylene carts, because of their holding time, are another good alternative.

Controls may be top mounted, bottom mounted or in some cases, mounted in a false wall on the side of the unit. Top-mounted controls are more ergonomic and less prone to damage from spills and impacts (especially if the unit has a kick latch for the door). Cabinets with bottom-mounted heating elements often have controls there, too, saving manufacturing costs in wiring top-mounted controls to bottom-mounted heaters. Pick the combination that makes most sense for employees in light of your application.

Transport carts typically have little more in the way of controls than a thermometer and an on-off switch. Hot holding cabinets, particularly if they have active humidity control, may have more sophisticated digital controls. Again, your application will dictate which you choose.

Nicely Appointed
You also have a lot of choices when it comes to slide racks. Most are removable to facilitate cleaning the interior of the box. But depending on the maker you'll have a choice of fixed or adjustable racks, universal or channel slides, and angle or wire construction of either stainless or aluminum.

Universal slides and adjustable racks offer you the most flexibility, but if you know what type and size pans you intend to use, you may decide on fixed channel slide racks.

Some manufacturers offer wire pan slides and say they're less likely to get bent out of alignment. Not all equipment makers offer a choice, so make sure the model you choose has the type of pan slides that best fit your operation.

Casters are important, too. Any smaller than 5" aren't really designed for transport, and the type you choose depends on the surfaces and distances you intend to transport carts over. Hard rubber casters, for example, are commonly used on carts designed to stay in the kitchen. Polyurethane casters are the best all-around casters, particularly on carpeted surfaces. Semi-pneumatic casters provide a more cushioned ride over hard surfaces, yet are still suitable for carpets. They require more force to roll than polyurethane. Best for outdoor use over hard surfaces (service drives) or uneven terrain are fully pneumatic tire casters with tread.

Mobile carts typically have two swivel casters and two rigid casters. Swivel casters usually also have locking brakes. Makers of heavier duty transport carts bolt and/or weld casters to the base of the unit, often with a reinforcement plate for added strength.

Some models have offset casters to make them easier to roll over transoms and into elevators.

Most manufacturers have special standard features and an array of options we don't have space to go into here. It pays to spend some time looking at what's available to make sure you get the right hot wheels for the products you want to transport in your particular application.

Checklist For Choosing
With so many options available in hot mobile cabinets, heated transport carts and banquet carts, your best approach is to figure exactly what you need before you go shopping.

Footprint. Make sure carts or cabinets will fit through doorways, on elevators, around corners in hallways, in available storage areas and on transport vehicles.

Construction. Look for a cart built tough enough for your application. Frames, bases, latches, hinges, handles, bumpers, slide racks and casters are all important details. Check holding times when not powered up to see if units are well insulated for your needs.

Design. Decide whether you'll transport plated meals, bulk food or both.

Heating system. You'll want dry heat for items like fried chicken and moist heat for veggies and other items. One model may be able to handle both, or not. Do you want convection heat? A removable heating unit? Look at the pros and cons of each system.

Electric service. Where will carts end up? If there isn't electric service, do you want to use canned fuel?

Ergonomics. Do you want controls on top or bottom? Are employees strong enough to move large carts or would you be better off with half-size cabinets?

Efficiency. Look for Energy Star models, but compare energy costs to help you decide which will best suit your operation.

Don't forget to check out our Hot Mobile Cabinet Gallery.

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