2012年7月21日 星期六

Ice Makers and Dispensers


All food service operations need ice, and the simplest way to meet that need is to have an icemaking machine that freezes, "harvests," and stores ice automatically. There are large, standalone machines that produce up to 3000 pounds of ice per day; medium-size, undercounter models that make up to 200 pounds per day; or small, countertop ice makers that deliver as little as 1 pound of ice per hour. You will sometimes see ice makers referred to as ice cubers. Before you buy an ice machine, you should not just determine how much ice you'll need, but where you will need it. If there are several sites for ice consumption-garde manger area, bar, wait stations-you might be better off with several smaller machines in various locations instead of everyone hauling ice from a single, large unit.

We'll talk in a moment about how to determine your ice needs. Ice-making machines are refrigeration units. The ice is made when a pump circulates water from a tank. The water runs trough tubing to a freezing assembly, which freezes it into a single sheet. The frozen sheet is then cruhed or forced through a screen to produce ice cubes. Different types of screens produce different sizes and shapes of cubes. After the ice is crushed or cubed, it is automatically dumped into a storage bin. When the bin fills to capacity, a sensor inside the machine shuts it down until there is room to make and store more ice. Because most of the ice maker's parts come into direct contact with water, it is important that components be made of rustproof materials.

Ice maker capacity is determined by how many pounds of ice the unit can produce in a 24-hour period. However, any machine's output (and the quality of the ice itself) will be affected by several factors: Incoming water temperature. The ideal is 50 degrees Fahrenheit; warmer water makes the machine work harder. Room temperature. The ideal is about 70 degrees Fahrenheit. If installed in an environment that has an ambient temperature of 80 degrees Fahrenheit or higher, consider getting a unit with a water-cooled condenser to compensate for hot, humid, or grease-laden air. Incoming water pressure. The minimum water pressure should be 20 pounds per square inch (psi); recommended pressure is between 45 and 55 psi.

Anything higher than 80 psi will cause malfunctions. Water quality. Hard water will cause the machine to work more slowly and almost always necessitates some kind of pretreatment before the water enters the machine. The fewer minerals and chemicals in the water, the more quickly and harder it will freeze, and the more slowly it will melt. Filtration is almost always a good idea. Read manufacturers' output claims carefully and you'll find they are often based on ideal conditions: incoming water temperature of 50 degrees Fahrenheit and ambient air temperature of 70 degrees Fahrenheit. Generally, a 10-degree increase in air temperature means daily ice output decreases by 10 percent.

Also examine the water and energy usage figures provided by the manufacturer. You'll note that there is a wide range: from 15 to 27 gallons of water to produce 100 pounds of ice, using from 5 to 10 kilowatts of electricity. An additional source to check is the Air Conditioning and Refrigeration Institute (ARI), the national trade association that represents about 90 percent of manufacturers. Ironically, ARI data rates ice machine production capacities using more realistic conditions than the manufacturers' sales literature-with incoming water temperature at 70 degrees Fahrenheit and ambient air at 90 degrees Fahrenheit. ARI also rates machines by how many kilowatthours and how much water they need to produce 100 pounds of ice. The group's "CoolNet" Web site can be found at http://www.ari.org.

No matter where the ice maker is located, it needs a source of cold water and drainage. Particularly critical is a one-inch air gap between the ice maker's drain line and the nearest floor drain. This is a necessary precaution to prevent a backflow of soiled water into the ice bin. Wherever you install the ice maker, proper plumbing will be mandated by your local health department. A recessed floor beneath the unit is also recommended. Along with nearby drainage, this ensures that spilled ice does not melt on the floor and cause accidents. One smart option is to install an inlet chiller along with your ice machine. About the size of a household fire extinguisher, it collects the water that would normally be discharged from the ice maker into the drain. Instead, the water recirculates first through a series of copper coils in a chamber that contains fresh water on its way into the ice maker.

The cold outgoing water chills the coils, which chill the fresh incoming water and allow it to freeze more quickly for faster ice production. The inlet chiller, which has no moving parts and uses no electricity, can save up to 30 percent on the electricity used to run the ice maker and boost its capacity by 50 percent. There is also a need for air circulation around the unit. An ice maker gives off warm air, like any refrigerator, and should be placed at least 4 inches from the wall to allow for ventilation. Those are just a few of the factors to consider in your "life cycle" calculation. Others are listed in the next "Foodservice Equipment" box.

Just as there are different machine capacities, there are also various sizes of storage bins. Most operators choose a combination ice maker and storage bin; by adding an extra 20 percent to the total capacity of each, you'll (theoretically) never run out. Ergonomics experts add that bins with a depth of more than 16 or 18 inches are hard to reach for employees that must scoop from the bottom. Look for storage compartments with volume sensors, so production cuts off automatically when the bin is full. When ice tumbles out every time you open the bin, you're just wasting it.

A final important consideration is the length of time it takes the machine to complete one ice-making cycle. Under normal conditions, the whole freezing-harvesting-ejection period should take no longer than 15 to 20 minutes for the finished cubes to hit the storage bin. Now that we've discussed the machine itself, what kinds of ice do you want it to make? There are many different cubed-ice options. Large cubes (full cubes) melt more slowly, so they're good for banquet situations where glasses must be set out early. They may be awkward in some glasses and may give the appearance of a less-than-full drink.

Smaller, half cubes stock better into most glasses and are preferred in bar settings. Even smaller cubelets are suggested for soft drinks, because they fill the glass or cup so well (and therefore make your soft drink supply go further). Nugget ice is flaked ice that has been compacted into high-density, random-size chunks that melt slowly and are easier on blender blades than cubed ice. Nugget ice is a good choice for soft drinks and smoothies. Round shapes fit a glass better at its edges. Rectangular cubes stack better than round ones, leaving fewer voids in the glass. Your clientele, your glassware, and your type of service will determine the right shape for you.




Franco Zinzi has been involved with online marketing for nearly 3 years and likes to write on various subjects. Come visit his latest website which discusses of restaurant fridges and refrigerator supplies for the owner of his own business.





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