Types: Commercial warewashers can be differentiated based on size, what they are intended to wash and sanitization method.

With regard to size, smaller models require ware to be loaded into a rack. Smaller models encompass single-rack undercounter machines, single- and dual-rack lifting door-type machines connected to dish tables as well as rack conveyor models, which also attach to dish tables. Flight-type rackless conveyors are suitable for higher capacity applications and eliminate the need to load ware into a dish rack.

Continuous pot and pan washing systems are three-bay sinks with a wash pump in the tank that agitates the wash water. These units have various wash flow designs.

Looking at ware type, most machines are designed primarily as dishwashers. Dedicated glasswashers use a longer wash cycle and lower water pressure to avoid damaging more fragile ware and often incorporate special systems to reduce visible spotting on glasses, such as reverse osmosis. Dedicated pot-and-pan washers and tray washers use higher water pressure and longer wash cycles to improve soil removal performance for baked-on soiling.

Capacities: Warewasher capacities are distinguished by the number of dishes or racks that can be washed per hour. Most glasswashers can wash 1,000 to 2,000 glasses per hour. Single-rack undercounter and door-type dishwashers are best for small operations, as they handle between 21 and 60 racks per hour, while faster or dual-rack door-type machines are best suited for small- to medium-sized operations with capacities of 60 to 100 racks per hour. Rack conveyor and circular conveyor machines clean between 100 and 300 racks an hour in medium- and high-volume kitchens, and come in a variety of tank configurations. Flight-type or rackless conveyor units, geared for high-volume applications, can wash more than 21,000 dishes per hour at belt speeds approaching 14 feet per minute. Pot, pan and utensil washing machines can have a 6- to 60-pan capacity.

Energy Source(s): Dishwashers are one of the biggest energy users in the kitchen. The majority of warewashing machines operate on electric power levels ranging from 115 volts for smaller machines to 208 or 460 volts for larger units. Some warewashers offer the option of either electric, steam or gas water-heating systems.

Standard Features: While most warewashing machines are constructed of stainless steel and almost all feature common utility connections, door safety switches, idle pump shut-offs, tank heaters and low-water tank heat protection, almost all other features vary greatly.

New Features/Technology/Options: Most recent dishwasher innovations are associated with reduction of rinse water and energy consumption.

Purchasing Guidelines: Since different wares have different washing requirements, operators must determine what they intend to wash in order to specify the correct unit. They also should take into account the warewasher's design. This will help determine if racks or tables are appropriate.

With continuous pot and pan washing systems, operators need to consider how many pots, pans and sheet pans need to be washed in a specific time frame and the size of the wash tank.

Maintenance Requirements: To maintain the performance of a warewashing machine, most manufacturers suggest using commercial-grade detergents and that water temperature and pressure do not exceed specifications. It is recommended that dish machines be cleaned after every shift, since flushing out the water removes accumulated soil from the machine (which in turn improves washing performance and reduces detergent usage), as well as preserves the longevity, sanitation and cleanliness of the machine.

Food Safety Essentials: Warewashing machines eliminate any contamination of cooking, eating and drinking utensils by effectively sanitizing wares at high temperatures. Many local codes require warewashers' water temperatures reach a minimum of between 160 and 180 degrees F.

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